[00/60] xen: add core scheduling support
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Message ID 20190528103313.1343-1-jgross@suse.com
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  • xen: add core scheduling support
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Jürgen Groß May 28, 2019, 10:32 a.m. UTC
Add support for core- and socket-scheduling in the Xen hypervisor.

Via boot parameter sched-gran=core (or sched-gran=socket)
it is possible to change the scheduling granularity from cpu (the
default) to either whole cores or even sockets.

All logical cpus (threads) of the core or socket are always scheduled
together. This means that on a core always vcpus of the same domain
will be active, and those vcpus will always be scheduled at the same
time.

This is achieved by switching the scheduler to no longer see vcpus as
the primary object to schedule, but "schedule units". Each schedule
unit consists of as many vcpus as each core has threads on the current
system. The vcpu->unit relation is fixed.

I have done some very basic performance testing: on a 4 cpu system
(2 cores with 2 threads each) I did a "make -j 4" for building the Xen
hypervisor. With This test has been run on dom0, once with no other
guest active and once with another guest with 4 vcpus running the same
test. The results are (always elapsed time, system time, user time):

sched-gran=cpu,    no other guest: 116.10 177.65 207.84
sched-gran=core,   no other guest: 114.04 175.47 207.45
sched-gran=cpu,    other guest:    202.30 334.21 384.63
sched-gran=core,   other guest:    207.24 293.04 371.37

The performance tests have been performed with credit2, the other
schedulers are tested only briefly to be able to create a domain in a
cpupool.

Cpupools have been moderately tested (cpu add/remove, create, destroy,
move domain).

Cpu on-/offlining has been moderately tested, too.

The complete patch series is available under:

  git://github.com/jgross1/xen/ sched-v1

Changes in V1:
- cpupools are working now
- cpu on-/offlining working now
- all schedulers working now
- renamed "items" to "units"
- introduction of "idle scheduler"
- several new patches (see individual patches, mostly splits of
  former patches or cpupool and cpu on-/offlining support)
- all review comments addressed
- some minor changes (see individual patches)

Changes in RFC V2:
- ARM is building now
- HVM domains are working now
- idling will always be done with idle_vcpu active
- other small changes see individual patches

Juergen Gross (60):
  xen/sched: only allow schedulers with all mandatory functions
    available
  xen/sched: add inline wrappers for calling per-scheduler functions
  xen/sched: let sched_switch_sched() return new lock address
  xen/sched: use new sched_unit instead of vcpu in scheduler interfaces
  xen/sched: alloc struct sched_unit for each vcpu
  xen/sched: move per-vcpu scheduler private data pointer to sched_unit
  xen/sched: build a linked list of struct sched_unit
  xen/sched: introduce struct sched_resource
  xen/sched: let pick_cpu return a scheduler resource
  xen/sched: switch schedule_data.curr to point at sched_unit
  xen/sched: move per cpu scheduler private data into struct
    sched_resource
  xen/sched: switch vcpu_schedule_lock to unit_schedule_lock
  xen/sched: move some per-vcpu items to struct sched_unit
  xen/sched: add scheduler helpers hiding vcpu
  xen/sched: add domain pointer to struct sched_unit
  xen/sched: add id to struct sched_unit
  xen/sched: rename scheduler related perf counters
  xen/sched: switch struct task_slice from vcpu to sched_unit
  xen/sched: add is_running indicator to struct sched_unit
  xen/sched: make null scheduler vcpu agnostic.
  xen/sched: make rt scheduler vcpu agnostic.
  xen/sched: make credit scheduler vcpu agnostic.
  xen/sched: make credit2 scheduler vcpu agnostic.
  xen/sched: make arinc653 scheduler vcpu agnostic.
  xen: add sched_unit_pause_nosync() and sched_unit_unpause()
  xen: let vcpu_create() select processor
  xen/sched: use sched_resource cpu instead smp_processor_id in
    schedulers
  xen/sched: switch schedule() from vcpus to sched_units
  xen/sched: switch sched_move_irqs() to take sched_unit as parameter
  xen: switch from for_each_vcpu() to for_each_sched_unit()
  xen/sched: add runstate counters to struct sched_unit
  xen/sched: rework and rename vcpu_force_reschedule()
  xen/sched: Change vcpu_migrate_*() to operate on schedule unit
  xen/sched: move struct task_slice into struct sched_unit
  xen/sched: add code to sync scheduling of all vcpus of a sched unit
  xen/sched: introduce unit_runnable_state()
  xen/sched: add support for multiple vcpus per sched unit where missing
  x86: make loading of GDT at context switch more modular
  x86: optimize loading of GDT at context switch
  xen/sched: modify cpupool_domain_cpumask() to be an unit mask
  xen/sched: support allocating multiple vcpus into one sched unit
  xen/sched: add a scheduler_percpu_init() function
  xen/sched: add a percpu resource index
  xen/sched: add fall back to idle vcpu when scheduling unit
  xen/sched: make vcpu_wake() and vcpu_sleep() core scheduling aware
  xen/sched: carve out freeing sched_unit memory into dedicated function
  xen/sched: move per-cpu variable scheduler to struct sched_resource
  xen/sched: move per-cpu variable cpupool to struct sched_resource
  xen/sched: reject switching smt on/off with core scheduling active
  xen/sched: prepare per-cpupool scheduling granularity
  xen/sched: use one schedule lock for all free cpus
  xen/sched: populate cpupool0 only after all cpus are up
  xen/sched: remove cpu from pool0 before removing it
  xen/sched: add minimalistic idle scheduler for free cpus
  xen/sched: split schedule_cpu_switch()
  xen/sched: protect scheduling resource via rcu
  xen/sched: support multiple cpus per scheduling resource
  xen/sched: support differing granularity in schedule_cpu_[add/rm]()
  xen/sched: support core scheduling for moving cpus to/from cpupools
  xen/sched: add scheduling granularity enum

 xen/arch/arm/domain.c             |    2 +-
 xen/arch/arm/domain_build.c       |   13 +-
 xen/arch/x86/acpi/cpu_idle.c      |    1 -
 xen/arch/x86/cpu/common.c         |    3 +
 xen/arch/x86/cpu/mcheck/mce.c     |    1 -
 xen/arch/x86/cpu/mcheck/mctelem.c |    1 -
 xen/arch/x86/dom0_build.c         |   10 +-
 xen/arch/x86/domain.c             |   93 +-
 xen/arch/x86/hvm/dom0_build.c     |    9 +-
 xen/arch/x86/pv/dom0_build.c      |   10 +-
 xen/arch/x86/pv/emul-priv-op.c    |    1 +
 xen/arch/x86/pv/shim.c            |    4 +-
 xen/arch/x86/pv/traps.c           |    5 +-
 xen/arch/x86/setup.c              |    1 -
 xen/arch/x86/smpboot.c            |    1 -
 xen/arch/x86/sysctl.c             |    3 +-
 xen/arch/x86/traps.c              |    9 +-
 xen/common/cpupool.c              |  326 ++++---
 xen/common/domain.c               |   34 +-
 xen/common/domctl.c               |   23 +-
 xen/common/keyhandler.c           |    4 +-
 xen/common/sched_arinc653.c       |  270 +++---
 xen/common/sched_credit.c         |  783 ++++++++-------
 xen/common/sched_credit2.c        | 1134 +++++++++++-----------
 xen/common/sched_null.c           |  443 +++++----
 xen/common/sched_rt.c             |  555 +++++------
 xen/common/schedule.c             | 1923 +++++++++++++++++++++++++++++--------
 xen/common/softirq.c              |    6 +-
 xen/common/wait.c                 |    4 +-
 xen/include/asm-arm/current.h     |    1 +
 xen/include/asm-x86/cpuidle.h     |   11 -
 xen/include/asm-x86/current.h     |    7 +-
 xen/include/asm-x86/desc.h        |    1 +
 xen/include/asm-x86/dom0_build.h  |    3 +-
 xen/include/asm-x86/smp.h         |    3 +
 xen/include/xen/domain.h          |    3 +-
 xen/include/xen/perfc_defn.h      |   32 +-
 xen/include/xen/sched-if.h        |  444 +++++++--
 xen/include/xen/sched.h           |   99 +-
 xen/include/xen/softirq.h         |    1 +
 40 files changed, 3905 insertions(+), 2372 deletions(-)

Comments

Sergey Dyasli July 5, 2019, 1:17 p.m. UTC | #1
Hi Juergen,

I did some testing of this series (with sched-gran=core) and posting a couple of
crash backtraces here for your information.

Additionally, resuming a Debian 7 guest after suspend is broken.

I will be able to provide any additional information only after XenSummit :)

1) This crash is quite likely to happen:

[2019-07-04 18:22:46 UTC] (XEN) [ 3425.220660] Watchdog timer detects that CPU2 is stuck!
[2019-07-04 18:22:46 UTC] (XEN) [ 3425.226293] ----[ Xen-4.13.0-8.0.6-d  x86_64  debug=y   Not tainted ]----
[2019-07-04 18:22:46 UTC] (XEN) [ 3425.233576] CPU:    2
[2019-07-04 18:22:46 UTC] (XEN) [ 3425.236348] RIP:    e008:[<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
[2019-07-04 18:22:46 UTC] (XEN) [ 3425.243458] RFLAGS: 0000000000000202   CONTEXT: hypervisor (d34v0)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.250129] rax: 0000000000000001   rbx: ffff8305f29e6000   rcx: ffff8305f29e6128
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.258101] rdx: 0000000000000000   rsi: 0000000000000296   rdi: ffff8308066f9128
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.266076] rbp: ffff8308066f7cb8   rsp: ffff8308066f7ca8   r8:  00000000deadf00d
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.274052] r9:  00000000deadf00d   r10: 0000000000000000   r11: 0000000000000000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.282026] r12: 0000000000000000   r13: ffff8305f29e6000   r14: 0000000000000000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.289994] r15: 0000000000000003   cr0: 000000008005003b   cr4: 00000000001526e0
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.297970] cr3: 00000005f2de3000   cr2: 00000000c012ae78
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.303864] fsb: 0000000004724000   gsb: 00000000c52c4a20   gss: 0000000000000000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.311836] ds: 007b   es: 007b   fs: 00d8   gs: 00e0   ss: 0000   cs: e008
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.319290] Xen code around <ffff82d08023d578> (vcpu_sleep_sync+0x50/0x71):
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.326744]  ec 01 00 00 09 d0 48 98 <48> 0b 83 20 01 00 00 74 09 80 bb 07 01 00 00 00
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.335152] Xen stack trace from rsp=ffff8308066f7ca8:
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.340783]    ffff82d0802aede4 ffff8305f29e6000 ffff8308066f7cc8 ffff82d080208370
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.348844]    ffff8308066f7ce8 ffff82d08023e25d 0000000000000001 ffff8305f33f0000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.356904]    ffff8308066f7d58 ffff82d080209682 0000031c63c966ad 00000000ed601000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.364963]    0000000092920063 0000000000000009 ffff8305f33f0000 0000000000000001
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.373024]    0000000000000292 ffff82d080242ee2 0000000000000001 ffff8305f29e6000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.381084]    0000000000000000 ffff8305f33f0000 ffff8308066f7e28 ffff82d08024f970
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.389144]    ffff8305f33f00d4 000000000000000c ffff8305f33f0000 00000000deadf00d
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.397207]    ffff8308066f7da8 ffff82d0802b3754 ffff82d080209d46 ffff82d08020b6e7
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.405262]    ffff8308066f7e28 ffff82d08020c658 00000002ec86be74 0000000000000002
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.413325]    ffff8305c33d8300 ffff8305f33f00d4 aaaaaaaaaaaaaaaa 0000000c00000008
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.421383]    0000000000000009 ffff83081cca1000 ffff82d08038835a ffff8308066f7ef8
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.429445]    ffff8306a2b11000 00000000deadf00d 0000000000000180 0000000000000003
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.437503]    ffff8308066f7ec8 ffff82d080383964 ffff82d08038835a ffff82d000000007
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.445565]    ffff82d000000001 ffff82d000000000 ffff82d0deadf00d ffff82d0deadf00d
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.453624]    ffff82d08038835a ffff82d08038834e ffff82d08038835a ffff82d08038834e
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.461683]    ffff82d08038835a ffff82d08038834e ffff82d08038835a ffff8308066f7ef8
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.469744]    0000000000000000 0000000000000000 0000000000000000 0000000000000000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.477803]    ffff8308066f7ee8 ffff82d080385644 ffff82d08038835a ffff8306a2b11000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.485865]    00007cf7f99080e7 ffff82d08038839b 0000000000000000 0000000000000000
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.493923]    0000000000000000 0000000000000000 0000000000000001 0000000000000007
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.501989] Xen call trace:
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.505278]    [<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.511518]    [<ffff82d080208370>] vcpu_pause+0x21/0x23
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.517326]    [<ffff82d08023e25d>] vcpu_set_periodic_timer+0x27/0x73
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.524258]    [<ffff82d080209682>] do_vcpu_op+0x2c9/0x668
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.530238]    [<ffff82d08024f970>] compat_vcpu_op+0x250/0x390
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.536566]    [<ffff82d080383964>] pv_hypercall+0x364/0x564
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.542719]    [<ffff82d080385644>] do_entry_int82+0x26/0x2d
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.548876]    [<ffff82d08038839b>] entry_int82+0xbb/0xc0
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.554764]
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.556760] CPU1 @ beef:fffff88000a5f495 (0000000000000000)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.562825] CPU0 @ e008:ffff82d080253c51 (ns16550.c#ns16550_interrupt+0/0x79)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.570452] CPU7 @ e033:ffffffff810fb49b (0000000000000000)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.576518] CPU6 @ e008:ffff82d080279bc1 (domain.c#default_idle+0xc3/0xda)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.583887] CPU3 @ 0061:c04b668a (0000000000000000)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.589259] CPU4 @ 0061:c053468e (0000000000000000)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.594636] CPU5 @ e008:ffff82d080279bc1 (domain.c#default_idle+0xc3/0xda)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.602537]
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.604532] ****************************************
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.609991] Panic on CPU 2:
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.613283] FATAL TRAP: vector = 2 (nmi)
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.617706] [error_code=0000]
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.621257] ****************************************
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.626715]
[2019-07-04 18:22:47 UTC] (XEN) [ 3425.628711] Reboot in five seconds...

2) This one has been seen only once so far:

[2019-07-05 00:37:16 UTC] (XEN) [24907.482686] Watchdog timer detects that CPU30 is stuck!
[2019-07-05 00:37:16 UTC] (XEN) [24907.514180] ----[ Xen-4.13.0-8.0.6-d  x86_64  debug=y   Not tainted ]----
[2019-07-05 00:37:16 UTC] (XEN) [24907.552070] CPU:    30
[2019-07-05 00:37:16 UTC] (XEN) [24907.565281] RIP:    e008:[<ffff82d0802406fc>] sched_context_switched+0xaf/0x101
[2019-07-05 00:37:16 UTC] (XEN) [24907.601232] RFLAGS: 0000000000000202   CONTEXT: hypervisor
[2019-07-05 00:37:16 UTC] (XEN) [24907.629998] rax: 0000000000000002   rbx: ffff83202782e880   rcx: 000000000000001e
[2019-07-05 00:37:16 UTC] (XEN) [24907.669651] rdx: ffff83202782e904   rsi: ffff832027823000   rdi: ffff832027823000
[2019-07-05 00:37:16 UTC] (XEN) [24907.706560] rbp: ffff83403cab7d20   rsp: ffff83403cab7d00   r8:  0000000000000000
[2019-07-05 00:37:16 UTC] (XEN) [24907.743258] r9:  0000000000000000   r10: 0200200200200200   r11: 0100100100100100
[2019-07-05 00:37:16 UTC] (XEN) [24907.779940] r12: ffff832027823000   r13: ffff832027823000   r14: ffff83202782e7b0
[2019-07-05 00:37:16 UTC] (XEN) [24907.816849] r15: ffff83202782e880   cr0: 000000008005003b   cr4: 00000000000426e0
[2019-07-05 00:37:16 UTC] (XEN) [24907.854125] cr3: 00000000bd8a1000   cr2: 000000001851b798
[2019-07-05 00:37:16 UTC] (XEN) [24907.881483] fsb: 0000000000000000   gsb: 0000000000000000   gss: 0000000000000000
[2019-07-05 00:37:16 UTC] (XEN) [24907.918309] ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: 0000   cs: e008
[2019-07-05 00:37:16 UTC] (XEN) [24907.952619] Xen code around <ffff82d0802406fc> (sched_context_switched+0xaf/0x101):
[2019-07-05 00:37:16 UTC] (XEN) [24907.990277]  00 00 eb 18 f3 90 8b 02 <85> c0 75 f8 eb 0e 49 8b 7e 30 48 85 ff 74 05 e8
[2019-07-05 00:37:16 UTC] (XEN) [24908.032393] Xen stack trace from rsp=ffff83403cab7d00:
[2019-07-05 00:37:16 UTC] (XEN) [24908.061298]    ffff832027823000 ffff832027823000 0000000000000000 ffff83202782e880
[2019-07-05 00:37:16 UTC] (XEN) [24908.098529]    ffff83403cab7d60 ffff82d0802407c0 0000000000000082 ffff83202782e7c8
[2019-07-05 00:37:16 UTC] (XEN) [24908.135622]    000000000000001e ffff83202782e7c8 000000000000001e ffff82d080602628
[2019-07-05 00:37:16 UTC] (XEN) [24908.172671]    ffff83403cab7dc0 ffff82d080240d83 000000000000df99 000000000000001e
[2019-07-05 00:37:16 UTC] (XEN) [24908.210212]    ffff832027823000 000016a62dc8c6bc 000000fc00000000 000000000000001e
[2019-07-05 00:37:16 UTC] (XEN) [24908.247181]    ffff83202782e7c8 ffff82d080602628 ffff82d0805da460 000000000000001e
[2019-07-05 00:37:16 UTC] (XEN) [24908.284279]    ffff83403cab7e60 ffff82d080240ea4 00000002802aecc5 ffff832027823000
[2019-07-05 00:37:16 UTC] (XEN) [24908.321128]    ffff83202782e7b0 ffff83202782e880 ffff83403cab7e10 ffff82d080273b4e
[2019-07-05 00:37:16 UTC] (XEN) [24908.358308]    ffff83403cab7e10 ffff82d080242f7f ffff83403cab7e60 ffff82d08024663a
[2019-07-05 00:37:17 UTC] (XEN) [24908.395662]    ffff83403cab7ea0 ffff82d0802ec32a ffff8340000000ff ffff82d0805bc880
[2019-07-05 00:37:17 UTC] (XEN) [24908.432376]    ffff82d0805bb980 ffffffffffffffff ffff83403cab7fff 000000000000001e
[2019-07-05 00:37:17 UTC] (XEN) [24908.469812]    ffff83403cab7e90 ffff82d080242575 0000000000000f00 ffff82d0805bb980
[2019-07-05 00:37:17 UTC] (XEN) [24908.508373]    000000000000001e ffff82d0806026f0 ffff83403cab7ea0 ffff82d0802425ca
[2019-07-05 00:37:17 UTC] (XEN) [24908.549856]    ffff83403cab7ef0 ffff82d08027a601 ffff82d080242575 0000001e7ffde000
[2019-07-05 00:37:17 UTC] (XEN) [24908.588022]    ffff832027823000 ffff832027823000 ffff83127ffde000 ffff83203ffe5000
[2019-07-05 00:37:17 UTC] (XEN) [24908.625217]    000000000000001e ffff831204092000 ffff83403cab7d78 00000000ffffffed
[2019-07-05 00:37:17 UTC] (XEN) [24908.662932]    ffffffff81800000 0000000000000000 ffffffff81800000 0000000000000000
[2019-07-05 00:37:17 UTC] (XEN) [24908.703246]    ffffffff818f4580 ffff880039118848 00000e6a3c4b2698 00000000148900db
[2019-07-05 00:37:17 UTC] (XEN) [24908.743671]    0000000000000000 ffffffff8101e650 ffffffff8185c3e0 0000000000000000
[2019-07-05 00:37:17 UTC] (XEN) [24908.781927]    0000000000000000 0000000000000000 0000beef0000beef ffffffff81054eb2
[2019-07-05 00:37:17 UTC] (XEN) [24908.820986] Xen call trace:
[2019-07-05 00:37:17 UTC] (XEN) [24908.836789]    [<ffff82d0802406fc>] sched_context_switched+0xaf/0x101
[2019-07-05 00:37:17 UTC] (XEN) [24908.869916]    [<ffff82d0802407c0>] schedule.c#sched_context_switch+0x72/0x151
[2019-07-05 00:37:17 UTC] (XEN) [24908.907384]    [<ffff82d080240d83>] schedule.c#sched_slave+0x2a3/0x2b2
[2019-07-05 00:37:17 UTC] (XEN) [24908.941241]    [<ffff82d080240ea4>] schedule.c#schedule+0x112/0x2a1
[2019-07-05 00:37:17 UTC] (XEN) [24908.973939]    [<ffff82d080242575>] softirq.c#__do_softirq+0x85/0x90
[2019-07-05 00:37:17 UTC] (XEN) [24909.007101]    [<ffff82d0802425ca>] do_softirq+0x13/0x15
[2019-07-05 00:37:17 UTC] (XEN) [24909.035971]    [<ffff82d08027a601>] domain.c#idle_loop+0xad/0xc0
[2019-07-05 00:37:17 UTC] (XEN) [24909.070546]
[2019-07-05 00:37:17 UTC] (XEN) [24909.080286] CPU0 @ e008:ffff82d0802431ba (stop_machine.c#stopmachine_wait_state+0x1a/0x24)
[2019-07-05 00:37:17 UTC] (XEN) [24909.122896] CPU1 @ e008:ffff82d0802406f8 (sched_context_switched+0xab/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.159518] CPU3 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.199607] CPU2 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.235773] CPU5 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.276039] CPU4 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.312371] CPU7 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.352930] CPU6 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.388928] CPU8 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.424664] CPU9 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.465376] CPU10 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.507449] CPU11 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.544703] CPU13 @ e008:ffff82d0802431f2 (stop_machine.c#stopmachine_action+0x2e/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.588884] CPU12 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.625781] CPU15 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.666649] CPU14 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.703396] CPU17 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.744089] CPU16 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.781117] CPU23 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.821692] CPU22 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:18 UTC] (XEN) [24909.858139] CPU27 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
[2019-07-05 00:37:18 UTC] (XEN) [24909.898704] CPU26 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:19 UTC] (XEN) [24909.936069] CPU19 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:19 UTC] (XEN) [24909.977291] CPU18 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:19 UTC] (XEN) [24910.014078] CPU31 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:19 UTC] (XEN) [24910.055692] CPU21 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:19 UTC] (XEN) [24910.100486] CPU24 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
[2019-07-05 00:37:19 UTC] (XEN) [24910.136824] CPU25 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
[2019-07-05 00:37:19 UTC] (XEN) [24910.177529] CPU29 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
[2019-07-05 00:37:19 UTC] (XEN) [24910.218420] CPU28 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
[2019-07-05 00:37:19 UTC] (XEN) [24910.255219] CPU20 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
[2019-07-05 00:37:19 UTC] (XEN) [24910.292152]
[2019-07-05 00:37:19 UTC] (XEN) [24910.301667] ****************************************
[2019-07-05 00:37:19 UTC] (XEN) [24910.327892] Panic on CPU 30:
[2019-07-05 00:37:19 UTC] (XEN) [24910.344165] FATAL TRAP: vector = 2 (nmi)
[2019-07-05 00:37:19 UTC] (XEN) [24910.365476] [error_code=0000]
[2019-07-05 00:37:19 UTC] (XEN) [24910.382509] ****************************************
[2019-07-05 00:37:19 UTC] (XEN) [24910.408547]
[2019-07-05 00:37:19 UTC] (XEN) [24910.418129] Reboot in five seconds...

Thanks,
Sergey
Jürgen Groß July 5, 2019, 1:22 p.m. UTC | #2
On 05.07.19 15:17, Sergey Dyasli wrote:
> Hi Juergen,
> 
> I did some testing of this series (with sched-gran=core) and posting a couple of
> crash backtraces here for your information.
> 
> Additionally, resuming a Debian 7 guest after suspend is broken.
> 
> I will be able to provide any additional information only after XenSummit :)

Thanks for the reports!

I will look at this after XenSummit. :-)


Juergen
Dario Faggioli July 5, 2019, 1:56 p.m. UTC | #3
On Fri, 2019-07-05 at 14:17 +0100, Sergey Dyasli wrote:
> 1) This crash is quite likely to happen:
> 
> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.220660] Watchdog timer detects
> that CPU2 is stuck!
> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.226293] ----[ Xen-4.13.0-
> 8.0.6-d  x86_64  debug=y   Not tainted ]----
> [...]
> [2019-07-04 18:22:47 UTC] (XEN) [ 3425.501989] Xen call trace:
> [2019-07-04 18:22:47 UTC] (XEN) [
> 3425.505278]    [<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
> [2019-07-04 18:22:47 UTC] (XEN) [
> 3425.511518]    [<ffff82d080208370>] vcpu_pause+0x21/0x23
> [2019-07-04 18:22:47 UTC] (XEN) [
> 3425.517326]    [<ffff82d08023e25d>]
> vcpu_set_periodic_timer+0x27/0x73
> [2019-07-04 18:22:47 UTC] (XEN) [
> 3425.524258]    [<ffff82d080209682>] do_vcpu_op+0x2c9/0x668
> [2019-07-04 18:22:47 UTC] (XEN) [
> 3425.530238]    [<ffff82d08024f970>] compat_vcpu_op+0x250/0x390
> [2019-07-04 18:22:47 UTC] (XEN) [
> 3425.536566]    [<ffff82d080383964>] pv_hypercall+0x364/0x564
> [2019-07-04 18:22:47 UTC] (XEN) [
> 3425.542719]    [<ffff82d080385644>] do_entry_int82+0x26/0x2d
> [2019-07-04 18:22:47 UTC] (XEN) [
> 3425.548876]    [<ffff82d08038839b>] entry_int82+0xbb/0xc0
>
Mmm... vcpu_set_periodic_timer?

What kernel is this and when does this crash happen?

Thanks and Regards
Dario Faggioli July 11, 2019, 1:40 p.m. UTC | #4
On Tue, 2019-05-28 at 12:32 +0200, Juergen Gross wrote:
> Add support for core- and socket-scheduling in the Xen hypervisor.
> 
> [...]
>
> I have done some very basic performance testing: on a 4 cpu system
> (2 cores with 2 threads each) I did a "make -j 4" for building the
> Xen
> hypervisor. With This test has been run on dom0, once with no other
> guest active and once with another guest with 4 vcpus running the
> same
> test. The results are (always elapsed time, system time, user time):
> 
> sched-gran=cpu,    no other guest: 116.10 177.65 207.84
> sched-gran=core,   no other guest: 114.04 175.47 207.45
> sched-gran=cpu,    other guest:    202.30 334.21 384.63
> sched-gran=core,   other guest:    207.24 293.04 371.37
> 
> The performance tests have been performed with credit2, the other
> schedulers are tested only briefly to be able to create a domain in a
> cpupool.
> 
I have done some more, and I'd like to report the results here.

For those that are attending the Xen-Project Dev Summit, and has seen
Juergen's talk about core-scheduling, these are the numbers he had in
his slides.

They're quite a few number, and there are multiple way to show them.

We arranged them in two different ways, and I'm showing both. Since
it's quite likely that the result will be poor in mail clients, here
they are the links to view in browser or download text files:

http://xenbits.xen.org/people/dariof/benchmarks/results/2019/07-July/xen/core-sched/mmtests/boxes/wayrath/summary.txt

http://xenbits.xen.org/people/dariof/benchmarks/results/2019/07-July/xen/core-sched/mmtests/boxes/wayrath/summary-5columns.txt

They're the same numbers, in the two files, but in
'summary-5columns.txt' has them arranged in tables that show, for each
combination of benchmark and configuration, the differences between the
various options (i.e., no core-scheduling, core-scheduling not used,
core-scheduling in use, etc).

The 'summary.txt' file, contains some more data (such as the results of
runs done on baremetal), arranged in different tables. It also contains
some of my thoughts and analysis about what the numbers tells us.

It's quite hard to come up with a concise summary, as results vary a
lot on a case by case basis, and there are a few things that needs
being investigated mode.

I'll try anyway, but please, if you are interested in the subject, do
have a look at the numbers themselves, even if there's a lot of them:

- Overhead: the cost of having this patch series applied, and not 
  using core-scheduling, seems acceptable to me. In most cases, the 
  overhead is within the noise margin of the measurements. There are a 
  couple of benchmarks where this is not the case. But that means we 
  can go trying figuring out why this happens only there, and, 
  potentially, optimize and tune.

- PV vs. HVM: there seem to be some differences, in some of the 
  results, for different type of guest (well, for PV I used dom0). In 
  general, HVM seems to behave a little worse, i.e., suffers from more 
  overhead and perf degradation, but this is not the case for all 
  benchmarks, so it's hard to tell whether it's something specific or 
  an actual trend.
  I don't have the numbers for proper PV guests and for PVH. I expect 
  the former to be close to dom0 numbers and the latter to HVM 
  numbers, but I'll try to do those runs as well (as soon as the 
  testbox is free again).

- HT vs. noHT: even before considering core-scheduling at all, the 
  debate is still open about whether or not Hyperthreading help in the 
  first place. These numbers shows that this very much depend on the 
  workload and on the load, which is no big surprise.
  It is quite a solid trend, however, than when load is high (look, 
  for instance, at runs that saturate the CPU, or at oversubscribed 
  runs), Hyperthreading let us achieve better results.

- Regressions versus no core-scheduling: this happens, as it could 
  have been expected. It does not happen 100% of the times, and 
  mileage may vary, but in most benchmarks and in most configurations, 
  we do regress.

- Core-scheduling vs. no-Hyperthreading: this is again a mixed bag. 
  There are cases where things are faster in one setup, and cases 
  where it is the other one that wins. Especially in the non 
  overloaded case.

- Core-scheduling and overloading: when more vCPUs than pCPUs are used 
  (and there is actual overload, i.e., the vCPUs actually generate 
  more load than there are pCPUs to satisfy), core-scheduling shows 
  pretty decent performance. This is easy to see, comparing core-
  scheduling with no-Hyperthreading, in the overloaded cases. In most 
  benchmark, both the configuration perform worse than default, but 
  core-scheduling regresses a lot less than no-Hyperthreading. And 
  this, I think, is quite important!

- Core-scheduling and HT-aware scheduling: currently, the scheduler 
  tend to spread vCPUs among cores. That is, if we have 2 vCPUs and 2 
  cores with two threads each, the vCPUs run faster if we put each one 
  on a core, because each one of them has the full core resources 
  available. With core-scheduling implemented this way, this happens a 
  lot less. Actually, most of the times work is run on siblings, 
  leaving full cores entirely idle. This is what hurts pretty much the 
  results of  the runs done inside an HVM guest with 4 vCPUs. It must  
  be said, however:
  * that this also means performance are more consistent, and 
    independent on the actual CPU load. So, if you have a VM and share 
    an host with other VMs, performance of your workload depend less   
    on whether the others are running or idle;
  * I expect this issue to be addressed, at least partially, by 
    exposing a topology to the guest that takes into account that, 
    thanks to core-scheduling, some vCPUs are actually SMT-siblings.  
    In fact, at that point, it will be the guest's scheduler job to 
    decide whether to consolidate or spread the work. And if it 
    decides to spread it, that means tasks will run on vCPUs that are 
    not virtual SMT-siblings, and hence run on different cores (if \
    they are available) at the host level.

Anyway, I've written way too much. Have a look at the results, and feel
free to share what you think about them.

Regards,
Dario
---
XEN CORE-SCHEDULING BENCHMARK
=============================

Code: 
 - Juergen's v1 patches, rebased
   git: https://github.com/jgross1/xen/tree/sched-v1-rebase

Host:
 - CPU: 1 socket, 4 cores, 2 threads
 - RAM: 32 GB
 - distro: opneSUSE Tumbleweed
 - Kernel: 5.1.7
 - HW Bugs Mitigations: fully disabled (both in Xen and dom0)
 - Filesys: XFS

VMs:
 - vCPUs: either 8 or 4
 - distro: opneSUSE Tumbleweed
 - Kernel: 5.1.7
 - HW Bugs Mitigations: fully disabled
 - Filesys: XFS

Configurations:
 - BM-HT: baremetal, HyperThreading enabled (8 CPUs)
 - BM-noHT: baremetal, Hyperthreading disabled (4 CPUs)
 - v-XEN-HT: Xen staging (no coresched patches applied), Xen dom0, 8 vCPUs, Hyperthreading enabled (8 CPUs)
 - v-XEN-noHT: Xen staging (no coresched patches applied), Xen dom0, 4 vCPUs, Hyperthreading disabled (4 CPUs)
 - XEN-HT: Xen with coresched patches applied, Xen dom0, 8 vCPUs, Hyperthreading enabled (8 CPUs), sched-gran=cpu (default)
 - XEN-noHT: Xen with coresched patches applied, Xen dom0, 4 vCPUs, Hyperthreading disabled (4 CPUs), sched-gran=cpu (default)
 - XEN-csc: Xen with coresched patches applied, Xen dom0, 8 vCPUs, Hyperthreading enabled (8 CPUs), sched-gran=core
 - v-HVM-v8-HT: Xen staging (no coresched patches applied), HVM guest, 8 vCPUs, Hyperthreading enabled (8 CPUs)
 - v-HVM-v8-noHT: Xen staging (no coresched patches applied), HVM guest, 8 vCPUs, Hyperthreading enabled (4 CPUs)
 - HVM-v8-HT: Xen with coresched patches applied, HVM guest, 8 vCPUs, Hyperthreading enabled (8 CPUs), sched-gran=cpu (default)
 - HVM-v8-noHT: Xen with coresched patches applied, HVM guest, 8 vCPUs, Hyperthreading enabled (4 CPUs), sched-gran=cpu (default)
 - HVM-v8-csc: Xen with coresched patches applied, HVM guest, 8 vCPUs, Hyperthreading enabled (8 CPUs), sched-gran=core
 - v-HVM-v4-HT: Xen staging (no coresched patches applied), HVM guest, 4 vCPUs, Hyperthreading enabled (8 CPUs)
 - v-HVM-v4-noHT: Xen staging (no coresched patches applied), HVM guest, 4 vCPUs, Hyperthreading enabled (4 CPUs)
 - HVM-v4-HT: Xen with coresched patches applied, HVM guest, 4 vCPUs, Hyperthreading enabled (8 CPUs), sched-gran=cpu (default)
 - HVM-v4-noHT: Xen with coresched patches applied, HVM guest, 4 vCPUs, Hyperthreading enabled (4 CPUs), sched-gran=cpu (default)
 - HVM-v4-csc: Xen with coresched patches applied, HVM guest, 4 vCPUs, Hyperthreading enabled (8 CPUs), sched-gran=core
 - v-HVMx2-v8-HT: Xen staging (no coresched patches applied), 2x HVM guest, 8 vCPUs, Hyperthreading enabled (8 CPUs)
 - v-HVMx2-v8-noHT: Xen staging (no coresched patches applied), 2x HVM guest, 8 vCPUs, Hyperthreading enabled (4 CPUs)
 - HVMx2-v8-HT: Xen with coresched patches applied, 2x HVM guest, 8 vCPUs, Hyperthreading enabled (8 CPUs), sched-gran=cpu (default)
 - HVMx2-v8-noHT: Xen with coresched patches applied, 2x HVM guest, 8 vCPUs, Hyperthreading enabled (4 CPUs), sched-gran=cpu (default)
 - HVMx2-v8-csc: Xen with coresched patches applied, 2x HVM guest, 8 vCPUs, Hyperthreading enabled (8 CPUs), sched-gran=core

Benchmarks:
 - Suite: MMTests, https://github.com/gormanm/mmtests (e.g., see: https://lkml.org/lkml/2019/4/25/588)
   * Stream: pure memory benchmark (various kind of mem-ops done in parallel). Parallelism is NR_CPUS/2 tasks (i.e, . Ideally, we wouldn't see any difference between HT, noHT and csc;
   * Kernbench: builds a kernel, with varying number of compile jobs. HT is, in general, known to help, at least a little, as it let us do more parallel builds;
   * Hackbench: communication (via pipes, in this case) between group of processes. As we deal with _groups_ of tasks, we're already in saturation with 1 group, hence we expect noHT to suffer;
   * mutilate: load generator for memcached, with high request rate;
   * netperf-{udp,tcp,unix}: two communicating tasks. Without any pinning (either at hypervisor and dom0/guest level), we expect HT to play a role, as depending on where the two task are scheduler (i.e., whether on two core of the same thread, or not) performance may vary;
  * pgioperfbench: Postgres microbenchmark (I wanted to use pgbench, but had issues);
  * iozone: I have the number, but they're not shown here (needs time for looking at them and properly present them).

Raw results:
 - On my test box. I'll put them somewhere soon... :-)

Result comparisons:
 1) BM-HT vs. BM-noHT: check whether, on baremetal, for the given benchmark, HT has a positive or negative impact on performance
 2) v-XEN-HT vs. XEN-HT: check the overhead introduced by having the coresched patches applied, but not in use, in case HT is enabled. This tells us how expensive it is to have these patches in, for someone that does not need or want to use them, and keeps HT enabled;
 3) v-XEN-noHT vs. XEN-noHT: check the overhead introduced by having the coresched patches applied, but not in use, in case HT is disabled. This tells us how expensive it is to have these patches in, for someone that does not need or want them, and keeps HT disabled;
 4) XEN-HT vs. XEN-noHT vs. XEN-csc: with coresched patches applied, compare sched-gran=cpu and HT enabled (current default), with turning HT off and with sched-gran=core (and HT enabled, of course). This tells us how much perf we lose (or gain!) when using core-scheduling, as compared to both default and disabling hyperthreading disabled. Ideally, we'd end up a bit slower than default, but not as slow(er) as with HT disabled.
 5) HVM-v8-HT vs. HVM-v8-noHT vs. HVM-v8-csc: same as above, but benchmarks are running in an HVM guest with 8 vCPUs.
 6) HVM-v4-HT vs. HVM-v4-noHT vs. HVM-v4-csc: same as 5), but the HVM VM has now only 4 vCPUs.
 7) HVMx2-v8-HT vs.  HVMx2-v8-noHT vs. HVMx2-v8-csc: now there are 2 HVM guests, both with 8 vCPUs. One runs synthetic workloads (CPU and memory) producing ~600% CPU load. The other runs our benchmarks. So, the host is in overload by 2x factor, in terms of number of vCPUs vs. number of pCPUs (not counting dom0!). In terms of CPU load, it's almost the same, but harder to tell exactly, as the synthetic load is ~600% (and not 800%) and the various benchmarks have variable CPU load.

STREAM
======
1)                            BM-HT                BM-noHT
MB/sec copy     32623.20 (   0.00%)    33906.18 (   3.93%)
MB/sec scale    22056.18 (   0.00%)    23005.44 (   4.30%)
MB/sec add      25827.70 (   0.00%)    26707.06 (   3.40%)
MB/sec triad    25771.70 (   0.00%)    26705.98 (   3.63%)

I was expecting nearly identical performance between 'HT' and 'noHT'. For sure, I wasn't expecting 'noHT' to regress. It's actually going a little faster, which does indeed makes sense (as we don't use any task pinning).

2)                         v-XEN-HT                 XEN-HT
MB/sec copy     33076.00 (   0.00%)    33112.76 (   0.11%)
MB/sec scale    24170.98 (   0.00%)    24225.04 (   0.22%)
MB/sec add      27060.58 (   0.00%)    27195.52 (   0.50%)
MB/sec triad    27172.34 (   0.00%)    27296.42 (   0.46%)

3)                       v-XEN-noHT               XEN-noHT
MB/sec copy     33054.78 (   0.00%)    33070.62 (   0.05%)
MB/sec scale    24198.12 (   0.00%)    24335.76 (   0.57%)
MB/sec add      27084.58 (   0.00%)    27360.86 (   1.02%)
MB/sec triad    27199.12 (   0.00%)    27468.54 (   0.99%)

4)                           XEN-HT               XEN-noHT                XEN-csc
MB/sec copy     33112.76 (   0.00%)    33070.62 (  -0.13%)    31811.06 (  -3.93%)
MB/sec scale    24225.04 (   0.00%)    24335.76 (   0.46%)    22745.18 (  -6.11%)
MB/sec add      27195.52 (   0.00%)    27360.86 (   0.61%)    25088.74 (  -7.75%)
MB/sec triad    27296.42 (   0.00%)    27468.54 (   0.63%)    25170.02 (  -7.79%)

I wasn't expecting a degradation for 'csc' (as, in fact, we don't see any in 'noHT'). Perhaps, re-run the 'csc' case with 2 threads, and see if it makes any difference.

5)                        HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
MB/sec copy     33338.56 (   0.00%)    34168.32 (   2.49%)    29568.34 ( -11.31%)
MB/sec scale    22001.94 (   0.00%)    23023.06 (   4.64%)    18635.30 ( -15.30%)
MB/sec add      25442.48 (   0.00%)    26676.96 (   4.85%)    21632.14 ( -14.98%)
MB/sec triad    26376.48 (   0.00%)    26542.96 (   0.63%)    21751.54 ( -17.53%)

(Unexpected) Impact is way more than just "noticeable". Furthermore, 'HT' and 'noHT' results are only a little worse than the PV (well, dom0) case, while 'csc' is much worse. I suspect this may be caused by the benchmark's tasks running on siblings, even if there are fully idle cores, but this needs more investigation.

6)                        HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
MB/sec copy     31917.34 (   0.00%)    33820.44 (   5.96%)    31186.82 (  -2.29%)
MB/sec scale    20741.28 (   0.00%)    22320.82 (   7.62%)    19471.54 (  -6.12%)
MB/sec add      25120.08 (   0.00%)    26553.58 (   5.71%)    22348.62 ( -11.03%)
MB/sec triad    24979.40 (   0.00%)    26075.40 (   4.39%)    21988.46 ( -11.97%)

Not as bad as the 8 vCPU case, but still not great.

7)                      HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
MB/sec copy     28821.94 (   0.00%)    22508.84 ( -21.90%)    27223.16 (  -5.55%)
MB/sec scale    20544.64 (   0.00%)    15269.06 ( -25.68%)    17813.02 ( -13.30%)
MB/sec add      22774.16 (   0.00%)    16733.48 ( -26.52%)    19659.98 ( -13.67%)
MB/sec triad    22163.52 (   0.00%)    16508.20 ( -25.52%)    19722.54 ( -11.01%)

Under load, core-scheduling does better than 'noHT'. Good! :-D


KERNBENCH
=========
Done runs with 2, 4,8 or 16 threads. So, with HT on, we saturate at 8 threads, with HT off, at 4.
------------------------------------------------------------
1)                                 BM-HT                BM-noHT
Amean     elsp-2       199.46 (   0.00%)      196.25 *   1.61%*
Amean     elsp-4       114.96 (   0.00%)      108.73 *   5.42%*
Amean     elsp-8        83.65 (   0.00%)      109.77 * -31.22%*
Amean     elsp-16       84.46 (   0.00%)      112.61 * -33.33%*
Stddev    elsp-2         0.09 (   0.00%)        0.05 (  46.12%)
Stddev    elsp-4         0.08 (   0.00%)        0.19 (-126.04%)
Stddev    elsp-8         0.15 (   0.00%)        0.15 (  -2.80%)
Stddev    elsp-16        0.03 (   0.00%)        0.50 (-1328.97%)

Things are (slightly) better, on 'noHT', before saturation, but get substantially worse after that point.

2)                              v-XEN-HT                 XEN-HT
Amean     elsp-2       234.13 (   0.00%)      233.63 (   0.21%)
Amean     elsp-4       139.89 (   0.00%)      140.21 *  -0.23%*
Amean     elsp-8        98.15 (   0.00%)       98.22 (  -0.08%)
Amean     elsp-16       99.05 (   0.00%)       99.65 *  -0.61%*
Stddev    elsp-2         0.40 (   0.00%)        0.14 (  64.63%)
Stddev    elsp-4         0.11 (   0.00%)        0.14 ( -33.77%)
Stddev    elsp-8         0.23 (   0.00%)        0.40 ( -68.71%)
Stddev    elsp-16        0.05 (   0.00%)        0.47 (-855.23%)

3)                            v-XEN-noHT               XEN-noHT
Amean     elsp-2       233.23 (   0.00%)      233.16 (   0.03%)
Amean     elsp-4       130.00 (   0.00%)      130.43 (  -0.33%)
Amean     elsp-8       132.86 (   0.00%)      132.34 *   0.39%*
Amean     elsp-16      135.61 (   0.00%)      135.51 (   0.07%)
Stddev    elsp-2         0.10 (   0.00%)        0.06 (  39.87%)
Stddev    elsp-4         0.04 (   0.00%)        0.67 (-1795.94%)
Stddev    elsp-8         0.37 (   0.00%)        0.04 (  89.24%)
Stddev    elsp-16        0.20 (   0.00%)        0.34 ( -69.82%)

4)                                XEN-HT               XEN-noHT                XEN-csc
Amean     elsp-2       233.63 (   0.00%)      233.16 *   0.20%*      248.12 *  -6.20%*
Amean     elsp-4       140.21 (   0.00%)      130.43 *   6.98%*      145.65 *  -3.88%*
Amean     elsp-8        98.22 (   0.00%)      132.34 * -34.73%*       98.15 (   0.07%)
Amean     elsp-16       99.65 (   0.00%)      135.51 * -35.98%*       99.58 (   0.07%)
Stddev    elsp-2         0.14 (   0.00%)        0.06 (  56.88%)        0.19 ( -36.79%)
Stddev    elsp-4         0.14 (   0.00%)        0.67 (-369.64%)        0.57 (-305.25%)
Stddev    elsp-8         0.40 (   0.00%)        0.04 (  89.89%)        0.03 (  91.88%)
Stddev    elsp-16        0.47 (   0.00%)        0.34 (  27.80%)        0.47 (   0.53%)

'csc' proves to be quite effective for this workload. It does cause some small regressions at low job count, but it lets us get back all the perf we lost when disabling Hyperthreading.

5)                             HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Amean     elsp-2       202.45 (   0.00%)      205.87 *  -1.69%*      218.87 *  -8.11%*
Amean     elsp-4       121.90 (   0.00%)      115.41 *   5.32%*      128.78 *  -5.64%*
Amean     elsp-8        85.94 (   0.00%)      125.71 * -46.28%*       87.26 *  -1.54%*
Amean     elsp-16       87.37 (   0.00%)      128.52 * -47.09%*       88.03 *  -0.76%*
Stddev    elsp-2         0.09 (   0.00%)        0.34 (-299.25%)        1.30 (-1433.24%)
Stddev    elsp-4         0.44 (   0.00%)        0.27 (  38.66%)        0.60 ( -36.58%)
Stddev    elsp-8         0.14 (   0.00%)        0.22 ( -63.81%)        0.35 (-153.50%)
Stddev    elsp-16        0.02 (   0.00%)        0.40 (-1627.17%)        0.32 (-1300.67%)

Trend is pretty much the same than in the dom0 case.

6)                             HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Amean     elsp-2       206.05 (   0.00%)      208.49 *  -1.18%*      237.58 * -15.30%*
Amean     elsp-4       114.53 (   0.00%)      115.46 *  -0.82%*      162.61 * -41.98%*
Amean     elsp-8       127.22 (   0.00%)      117.63 *   7.54%*      166.22 * -30.66%*
Amean     elsp-16      133.70 (   0.00%)      120.53 *   9.85%*      170.05 * -27.19%*
Stddev    elsp-2         0.26 (   0.00%)        0.24 (   7.38%)        0.34 ( -30.97%)
Stddev    elsp-4         0.29 (   0.00%)        0.23 (  20.88%)        0.24 (  17.16%)
Stddev    elsp-8         2.21 (   0.00%)        0.12 (  94.48%)        0.24 (  89.01%)
Stddev    elsp-16        2.00 (   0.00%)        0.57 (  71.34%)        0.34 (  82.87%)

Quite bad, this time. Basically, with only 4 vCPUs in the VM, we never saturate the machine, even in the 'noHT' case. In fact, 'noHT' goes similarly than 'HT' (even a little better, actually), as it could have been expected. OTOH, 'csc' regresses badly.

I did some more investigation, and found out that, with core-scheduling, we no longer spread the work among cores. E.g., with 4 cores and 4 busy vCPUs, in the 'HT' case, we run (most of the time) one vCPU on each core. In the 'csc' case, they often on 2 cores and leaves 2 cores idle. This means lower, but also more deterministic, performance. Whether or not is something we like, needs to be discussed.

7)                           HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Amean     elsp-2       288.82 (   0.00%)      437.79 * -51.58%*      339.86 * -17.67%*
Amean     elsp-4       196.18 (   0.00%)      294.95 * -50.35%*      242.91 * -23.82%*
Amean     elsp-8       153.27 (   0.00%)      229.25 * -49.57%*      182.50 * -19.07%*
Amean     elsp-16      156.59 (   0.00%)      235.63 * -50.48%*      185.82 * -18.67%*
Stddev    elsp-2         0.20 (   0.00%)        0.34 ( -67.23%)        2.56 (-1175.73%)
Stddev    elsp-4         0.48 (   0.00%)        0.07 (  86.25%)        0.41 (  15.93%)
Stddev    elsp-8         0.39 (   0.00%)        0.81 (-109.26%)        1.30 (-235.77%)
Stddev    elsp-16        0.88 (   0.00%)        0.87 (   1.97%)        1.75 ( -98.28%)

In overload, 'csc' regresses noticeably, as compared to 'HT'. But improves things a lot, as compared to 'noHT'.


HACKBENCH-PROCESS-PIPE
======================
1)                            BM-HT                BM-noHT
Amean     1       0.3838 (   0.00%)      0.6752 * -75.92%*
Amean     3       1.1718 (   0.00%)      1.9740 * -68.46%*
Amean     5       1.9334 (   0.00%)      2.5968 * -34.31%*
Amean     7       2.6592 (   0.00%)      2.6656 (  -0.24%)
Amean     12      3.0228 (   0.00%)      3.2494 (  -7.50%)
Amean     18      3.4848 (   0.00%)      3.7932 *  -8.85%*
Amean     24      4.1308 (   0.00%)      5.2044 * -25.99%*
Amean     30      4.7290 (   0.00%)      5.8558 * -23.83%*
Amean     32      4.9450 (   0.00%)      6.2686 * -26.77%*
Stddev    1       0.0391 (   0.00%)      0.0308 (  21.27%)
Stddev    3       0.0349 (   0.00%)      0.1551 (-344.67%)
Stddev    5       0.1620 (   0.00%)      0.1590 (   1.90%)
Stddev    7       0.1166 (   0.00%)      0.3178 (-172.48%)
Stddev    12      0.3413 (   0.00%)      0.4880 ( -43.00%)
Stddev    18      0.2202 (   0.00%)      0.0784 (  64.40%)
Stddev    24      0.4053 (   0.00%)      0.3042 (  24.95%)
Stddev    30      0.1251 (   0.00%)      0.1655 ( -32.33%)
Stddev    32      0.0344 (   0.00%)      0.2019 (-486.80%)

'noHT' hurts (as could have been anticipated), even quite significantly in some cases (actually, I'm not sure why 7, 12 and 18 groups went so much better than others...)

2)                         v-XEN-HT                 XEN-HT
Amean     1       0.7356 (   0.00%)      0.7470 (  -1.55%)
Amean     3       2.3506 (   0.00%)      2.4632 (  -4.79%)
Amean     5       4.1084 (   0.00%)      4.0418 (   1.62%)
Amean     7       5.8314 (   0.00%)      5.9784 (  -2.52%)
Amean     12      9.9694 (   0.00%)     10.4374 *  -4.69%*
Amean     18     14.2844 (   0.00%)     14.1366 (   1.03%)
Amean     24     19.0304 (   0.00%)     17.6314 (   7.35%)
Amean     30     21.8334 (   0.00%)     21.9030 (  -0.32%)
Amean     32     22.8946 (   0.00%)     22.0216 *   3.81%*
Stddev    1       0.0213 (   0.00%)      0.0327 ( -53.61%)
Stddev    3       0.1634 (   0.00%)      0.0952 (  41.73%)
Stddev    5       0.3934 (   0.00%)      0.1954 (  50.33%)
Stddev    7       0.1796 (   0.00%)      0.2809 ( -56.40%)
Stddev    12      0.1695 (   0.00%)      0.3725 (-119.74%)
Stddev    18      0.1392 (   0.00%)      0.4003 (-187.67%)
Stddev    24      1.5323 (   0.00%)      0.7330 (  52.16%)
Stddev    30      0.4214 (   0.00%)      1.0668 (-153.14%)
Stddev    32      0.8221 (   0.00%)      0.3849 (  53.18%)

With the core-scheduling patches applied, even if 'csc' is not used, there were runs where the overhead is noticeable (but also other runs where patched Xen was faster, so...)

3)                       v-XEN-noHT               XEN-noHT
Amean     1       1.2154 (   0.00%)      1.2200 (  -0.38%)
Amean     3       3.9274 (   0.00%)      3.9302 (  -0.07%)
Amean     5       6.6430 (   0.00%)      6.6584 (  -0.23%)
Amean     7       9.2772 (   0.00%)      9.8144 (  -5.79%)
Amean     12     14.8220 (   0.00%)     14.4464 (   2.53%)
Amean     18     21.6266 (   0.00%)     20.2166 *   6.52%*
Amean     24     27.2974 (   0.00%)     26.1082 *   4.36%*
Amean     30     32.2406 (   0.00%)     31.1702 *   3.32%*
Amean     32     34.8984 (   0.00%)     33.8204 *   3.09%*
Stddev    1       0.0727 (   0.00%)      0.0560 (  22.95%)
Stddev    3       0.2564 (   0.00%)      0.1332 (  48.04%)
Stddev    5       0.6043 (   0.00%)      0.5454 (   9.75%)
Stddev    7       0.6785 (   0.00%)      0.4508 (  33.56%)
Stddev    12      0.5074 (   0.00%)      0.8115 ( -59.92%)
Stddev    18      0.9622 (   0.00%)      0.8868 (   7.84%)
Stddev    24      0.4904 (   0.00%)      0.8453 ( -72.38%)
Stddev    30      0.5542 (   0.00%)      0.6499 ( -17.27%)
Stddev    32      0.4986 (   0.00%)      0.7965 ( -59.77%)

4)                           XEN-HT               XEN-noHT                XEN-csc
Amean     1       0.7470 (   0.00%)      1.2200 * -63.32%*      0.7160 *   4.15%*
Amean     3       2.4632 (   0.00%)      3.9302 * -59.56%*      2.2284 *   9.53%*
Amean     5       4.0418 (   0.00%)      6.6584 * -64.74%*      4.0492 (  -0.18%)
Amean     7       5.9784 (   0.00%)      9.8144 * -64.16%*      5.8718 (   1.78%)
Amean     12     10.4374 (   0.00%)     14.4464 * -38.41%*     10.1488 (   2.77%)
Amean     18     14.1366 (   0.00%)     20.2166 * -43.01%*     14.7450 *  -4.30%*
Amean     24     17.6314 (   0.00%)     26.1082 * -48.08%*     18.0072 (  -2.13%)
Amean     30     21.9030 (   0.00%)     31.1702 * -42.31%*     21.1058 (   3.64%)
Amean     32     22.0216 (   0.00%)     33.8204 * -53.58%*     22.7300 (  -3.22%)
Stddev    1       0.0327 (   0.00%)      0.0560 ( -71.05%)      0.0168 (  48.71%)
Stddev    3       0.0952 (   0.00%)      0.1332 ( -39.92%)      0.0944 (   0.88%)
Stddev    5       0.1954 (   0.00%)      0.5454 (-179.08%)      0.3064 ( -56.79%)
Stddev    7       0.2809 (   0.00%)      0.4508 ( -60.47%)      0.5762 (-105.11%)
Stddev    12      0.3725 (   0.00%)      0.8115 (-117.83%)      0.3594 (   3.53%)
Stddev    18      0.4003 (   0.00%)      0.8868 (-121.54%)      0.2580 (  35.56%)
Stddev    24      0.7330 (   0.00%)      0.8453 ( -15.32%)      0.8976 ( -22.45%)
Stddev    30      1.0668 (   0.00%)      0.6499 (  39.08%)      0.8666 (  18.76%)
Stddev    32      0.3849 (   0.00%)      0.7965 (-106.96%)      1.4428 (-274.86%)

This looks similar to 'kernbench'. 'noHT' hurts the workload badly, but 'csc' seems to come quite a bit to the rescue!

5)                        HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Amean     1       0.8992 (   0.00%)      1.1826 * -31.52%*      0.9462 *  -5.23%*
Amean     3       2.4524 (   0.00%)      2.4990 (  -1.90%)      2.5514 *  -4.04%*
Amean     5       3.6710 (   0.00%)      3.5258 (   3.96%)      3.9270 *  -6.97%*
Amean     7       4.6588 (   0.00%)      4.6430 (   0.34%)      5.0420 (  -8.23%)
Amean     12      7.7872 (   0.00%)      7.6310 (   2.01%)      7.6498 (   1.76%)
Amean     18     10.9800 (   0.00%)     12.2772 ( -11.81%)     11.1940 (  -1.95%)
Amean     24     16.5552 (   0.00%)     18.1368 (  -9.55%)     15.1922 (   8.23%)
Amean     30     17.1778 (   0.00%)     24.0352 * -39.92%*     17.7776 (  -3.49%)
Amean     32     19.1966 (   0.00%)     25.3104 * -31.85%*     19.8716 (  -3.52%)
Stddev    1       0.0306 (   0.00%)      0.0440 ( -44.08%)      0.0419 ( -36.94%)
Stddev    3       0.0681 (   0.00%)      0.1289 ( -89.35%)      0.0975 ( -43.30%)
Stddev    5       0.1214 (   0.00%)      0.2722 (-124.14%)      0.2080 ( -71.33%)
Stddev    7       0.5810 (   0.00%)      0.2687 (  53.75%)      0.3038 (  47.71%)
Stddev    12      1.4867 (   0.00%)      1.3196 (  11.24%)      1.5775 (  -6.11%)
Stddev    18      1.9110 (   0.00%)      1.8377 (   3.83%)      1.3230 (  30.77%)
Stddev    24      1.4038 (   0.00%)      1.2938 (   7.84%)      1.2301 (  12.37%)
Stddev    30      2.0035 (   0.00%)      1.3529 (  32.47%)      2.4480 ( -22.19%)
Stddev    32      1.8277 (   0.00%)      1.1786 (  35.52%)      2.4069 ( -31.69%)

Similar to the dom0 case, but it's rather weird how the 'noHT' case is, in some cases, quite good. Even better than 'HT'. :-O

6)                        HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Amean     1       1.4962 (   0.00%)      1.4424 (   3.60%)      1.6824 * -12.44%*
Amean     3       2.5826 (   0.00%)      2.9692 ( -14.97%)      2.9984 ( -16.10%)
Amean     5       3.4330 (   0.00%)      3.5064 (  -2.14%)      4.7144 * -37.33%*
Amean     7       5.3896 (   0.00%)      4.5122 (  16.28%)      5.7828 (  -7.30%)
Amean     12      7.6862 (   0.00%)      8.1164 (  -5.60%)     10.3868 * -35.14%*
Amean     18     10.8628 (   0.00%)     10.8600 (   0.03%)     14.5226 * -33.69%*
Amean     24     16.1058 (   0.00%)     13.9238 (  13.55%)     17.3746 (  -7.88%)
Amean     30     17.9462 (   0.00%)     20.1588 ( -12.33%)     22.2760 * -24.13%*
Amean     32     20.8922 (   0.00%)     15.2004 *  27.24%*     22.5168 (  -7.78%)
Stddev    1       0.0353 (   0.00%)      0.0996 (-181.94%)      0.0573 ( -62.13%)
Stddev    3       0.4556 (   0.00%)      0.6097 ( -33.81%)      0.4727 (  -3.73%)
Stddev    5       0.7936 (   0.00%)      0.6409 (  19.25%)      1.0294 ( -29.71%)
Stddev    7       1.3387 (   0.00%)      0.9335 (  30.27%)      1.5652 ( -16.92%)
Stddev    12      1.1304 (   0.00%)      1.8932 ( -67.48%)      1.6302 ( -44.21%)
Stddev    18      2.6187 (   0.00%)      2.2309 (  14.81%)      0.9304 (  64.47%)
Stddev    24      2.2138 (   0.00%)      1.6892 (  23.70%)      1.4706 (  33.57%)
Stddev    30      1.6264 (   0.00%)      2.1632 ( -33.01%)      1.6574 (  -1.91%)
Stddev    32      3.5272 (   0.00%)      2.5166 (  28.65%)      2.0956 (  40.59%)

7)                      HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Amean     1       1.4736 (   0.00%)      1.2224 *  17.05%*      1.6544 * -12.27%*
Amean     3       3.1764 (   0.00%)      2.4984 *  21.34%*      2.9720 *   6.43%*
Amean     5       4.7694 (   0.00%)      3.4870 *  26.89%*      4.4406 *   6.89%*
Amean     7       6.3958 (   0.00%)      4.6320 *  27.58%*      5.9150 *   7.52%*
Amean     12     11.0484 (   0.00%)      7.6534 *  30.73%*      9.7064 (  12.15%)
Amean     18     16.8658 (   0.00%)     12.8028 *  24.09%*     17.0654 (  -1.18%)
Amean     24     23.6798 (   0.00%)     18.8692 *  20.32%*     24.1742 (  -2.09%)
Amean     30     29.6202 (   0.00%)     25.4126 *  14.21%*     30.5034 (  -2.98%)
Amean     32     31.7582 (   0.00%)     28.5946 *   9.96%*     33.0222 *  -3.98%*
Stddev    1       0.0309 (   0.00%)      0.0294 (   5.09%)      0.0526 ( -69.92%)
Stddev    3       0.1102 (   0.00%)      0.0670 (  39.25%)      0.0956 (  13.30%)
Stddev    5       0.2023 (   0.00%)      0.1089 (  46.16%)      0.0694 (  65.68%)
Stddev    7       0.3783 (   0.00%)      0.1408 (  62.79%)      0.2421 (  36.01%)
Stddev    12      1.5160 (   0.00%)      0.3483 (  77.02%)      1.3210 (  12.87%)
Stddev    18      1.3000 (   0.00%)      1.2858 (   1.09%)      0.8736 (  32.80%)
Stddev    24      0.8749 (   0.00%)      0.8663 (   0.98%)      0.8197 (   6.31%)
Stddev    30      1.3074 (   0.00%)      1.4297 (  -9.36%)      1.2882 (   1.46%)
Stddev    32      1.2521 (   0.00%)      1.0791 (  13.81%)      0.7319 (  41.54%)

'noHT' becomes _super_fast_ (as compared to 'HT') when the system is overloaded. And that is (continues to be) quite weird. About 'csc', it's not too bad, as it performs in line with 'HT'.


MUTILATE
========
1)                           BM-HT                BM-noHT
Hmean     1    60932.67 (   0.00%)    60817.19 (  -0.19%)
Hmean     3   150762.70 (   0.00%)   123570.43 * -18.04%*
Hmean     5   197564.84 (   0.00%)   176716.37 * -10.55%*
Hmean     7   178089.27 (   0.00%)   170859.21 *  -4.06%*
Hmean     8   151372.16 (   0.00%)   160742.09 *   6.19%*
Stddev    1      591.29 (   0.00%)      513.06 (  13.23%)
Stddev    3     1358.38 (   0.00%)     1783.77 ( -31.32%)
Stddev    5     3477.60 (   0.00%)     5380.83 ( -54.73%)
Stddev    7     2676.96 (   0.00%)     5119.18 ( -91.23%)
Stddev    8      696.32 (   0.00%)     2888.47 (-314.82%)

It's less of a clear cut whether or not HT helps or not...

2)                        v-XEN-HT                 XEN-HT
Hmean     1    31121.40 (   0.00%)    31063.01 (  -0.19%)
Hmean     3    75847.21 (   0.00%)    75373.02 (  -0.63%)
Hmean     5   113823.13 (   0.00%)   113127.84 (  -0.61%)
Hmean     7   112553.93 (   0.00%)   112467.16 (  -0.08%)
Hmean     8   103472.02 (   0.00%)   103246.75 (  -0.22%)
Stddev    1      147.14 (   0.00%)      175.64 ( -19.37%)
Stddev    3      920.80 (   0.00%)     1017.40 ( -10.49%)
Stddev    5      339.23 (   0.00%)      781.99 (-130.52%)
Stddev    7      248.83 (   0.00%)      404.74 ( -62.66%)
Stddev    8      132.22 (   0.00%)      274.16 (-107.35%)

3)                      v-XEN-noHT               XEN-noHT
Hmean     1    31182.90 (   0.00%)    31107.06 (  -0.24%)
Hmean     3    83473.18 (   0.00%)    84387.92 *   1.10%*
Hmean     5    90322.68 (   0.00%)    91396.40 (   1.19%)
Hmean     7    91082.97 (   0.00%)    91296.28 (   0.23%)
Hmean     8    89529.42 (   0.00%)    89442.61 (  -0.10%)
Stddev    1      369.37 (   0.00%)      336.37 (   8.93%)
Stddev    3      300.44 (   0.00%)      333.46 ( -10.99%)
Stddev    5      842.22 (   0.00%)      816.23 (   3.08%)
Stddev    7      907.80 (   0.00%)     1084.18 ( -19.43%)
Stddev    8      362.90 (   0.00%)      890.80 (-145.47%)

4)                          XEN-HT               XEN-noHT                XEN-csc
Hmean     1    31063.01 (   0.00%)    31107.06 (   0.14%)    29609.98 *  -4.68%*
Hmean     3    75373.02 (   0.00%)    84387.92 *  11.96%*    73419.60 *  -2.59%*
Hmean     5   113127.84 (   0.00%)    91396.40 * -19.21%*   100843.37 * -10.86%*
Hmean     7   112467.16 (   0.00%)    91296.28 * -18.82%*   108439.16 *  -3.58%*
Hmean     8   103246.75 (   0.00%)    89442.61 * -13.37%*   101164.18 *  -2.02%*
Stddev    1      175.64 (   0.00%)      336.37 ( -91.51%)      271.28 ( -54.46%)
Stddev    3     1017.40 (   0.00%)      333.46 (  67.22%)      367.95 (  63.83%)
Stddev    5      781.99 (   0.00%)      816.23 (  -4.38%)      549.77 (  29.70%)
Stddev    7      404.74 (   0.00%)     1084.18 (-167.87%)      376.92 (   6.87%)
Stddev    8      274.16 (   0.00%)      890.80 (-224.93%)      987.59 (-260.23%)

And it's a mixed bag even here, but it clearly looks like 'csc' helps (i.e., let us achieve better perf than 'noHT' when in and above saturation).

5)                       HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Hmean     1    39583.53 (   0.00%)    38828.65 *  -1.91%*    35103.76 * -11.32%*
Hmean     3    87210.00 (   0.00%)    57874.31 * -33.64%*    47160.22 * -45.92%*
Hmean     5   130676.61 (   0.00%)    42883.21 * -67.18%*    85504.60 * -34.57%*
Hmean     7   157586.93 (   0.00%)    59146.02 * -62.47%*   136717.21 * -13.24%*
Hmean     8   174113.49 (   0.00%)    75503.09 * -56.64%*   159666.07 *  -8.30%*
Stddev    1      160.68 (   0.00%)      232.01 ( -44.39%)      547.91 (-240.99%)
Stddev    3     1158.62 (   0.00%)      654.05 (  43.55%)    18841.25 (-1526.19%)
Stddev    5      298.35 (   0.00%)      542.51 ( -81.84%)     1274.93 (-327.32%)
Stddev    7     2569.12 (   0.00%)     1034.22 (  59.74%)     4163.80 ( -62.07%)
Stddev    8      982.48 (   0.00%)      692.10 (  29.56%)     1324.30 ( -34.79%)

'csc' helps, and it let us achieve better performance than 'noHT', overall. Absolute performance looks worse than in dom0, but the 'noHT' case seems to be affected even more.

6)                       HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Hmean     1    37156.88 (   0.00%)    36938.92 (  -0.59%)    34869.19 *  -6.16%*
Hmean     3    91170.71 (   0.00%)    91469.09 (   0.33%)    76214.51 * -16.40%*
Hmean     5   119020.55 (   0.00%)   126949.11 *   6.66%*   109062.82 *  -8.37%*
Hmean     7   119924.66 (   0.00%)   133372.57 *  11.21%*   110466.18 *  -7.89%*
Hmean     8   121329.34 (   0.00%)   136100.78 (  12.17%)   114071.36 *  -5.98%*
Stddev    1      214.02 (   0.00%)      362.58 ( -69.42%)      516.53 (-141.35%)
Stddev    3     2554.47 (   0.00%)     1549.81 (  39.33%)      748.72 (  70.69%)
Stddev    5     1061.32 (   0.00%)     2250.11 (-112.01%)     2377.12 (-123.98%)
Stddev    7     5486.68 (   0.00%)     3214.60 (  41.41%)     4147.45 (  24.41%)
Stddev    8     1857.60 (   0.00%)    12837.92 (-591.10%)     3400.78 ( -83.07%)

7)                     HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Hmean     1    30194.08 (   0.00%)     2457.66 * -91.86%*     4940.93 * -83.64%*
Hmean     3    33860.02 (   0.00%)    11209.64 * -66.89%*    23274.26 * -31.26%*
Hmean     5    45606.53 (   0.00%)    15984.89 * -64.95%*    38599.75 ( -15.36%)
Hmean     7    70754.93 (   0.00%)    23045.58 * -67.43%*    55799.74 * -21.14%*
Hmean     8    88529.15 (   0.00%)    36532.64 * -58.73%*    70367.33 * -20.52%*
Stddev    1      214.55 (   0.00%)        2.87 (  98.66%)    13159.62 (-6033.62%)
Stddev    3      440.61 (   0.00%)      179.15 (  59.34%)     4463.14 (-912.95%)
Stddev    5      900.27 (   0.00%)      161.20 (  82.09%)     6286.95 (-598.34%)
Stddev    7      706.22 (   0.00%)      708.81 (  -0.37%)     3845.49 (-444.52%)
Stddev    8     3197.46 (   0.00%)      818.97 (  74.39%)     4477.51 ( -40.03%)

Similar to kernbench: 'csc' a lot better than 'noHT' in overload.


PGIOPERFBENCH
=============
1)                                BM-HT                BM-noHT
Amean     commit        7.72 (   0.00%)        9.73 * -26.14%*
Amean     read          6.99 (   0.00%)        8.15 * -16.66%*
Amean     wal           0.02 (   0.00%)        0.02 (   3.63%)
Stddev    commit        1.35 (   0.00%)        5.48 (-304.84%)
Stddev    read          0.61 (   0.00%)        3.82 (-521.73%)
Stddev    wal           0.04 (   0.00%)        0.04 (   1.36%)

Commit and read runs are suffering withough HT.

2)                             v-XEN-HT                 XEN-HT
Amean     commit        7.88 (   0.00%)        8.78 * -11.43%*
Amean     read          6.85 (   0.00%)        7.71 * -12.54%*
Amean     wal           0.07 (   0.00%)        0.07 (   1.15%)
Stddev    commit        1.86 (   0.00%)        3.59 ( -92.56%)
Stddev    read          0.53 (   0.00%)        2.89 (-450.88%)
Stddev    wal           0.05 (   0.00%)        0.05 (  -0.86%)

Significant overhead introduced by core scheduler patches, with sched-gran=cpu and HT enabled.

3)                           v-XEN-noHT               XEN-noHT
Amean     commit        8.53 (   0.00%)        7.64 *  10.47%*
Amean     read          7.30 (   0.00%)        6.86 *   6.02%*
Amean     wal           0.08 (   0.00%)        0.08 (   2.61%)
Stddev    commit        4.27 (   0.00%)        1.35 (  68.46%)
Stddev    read          3.12 (   0.00%)        0.39 (  87.45%)
Stddev    wal           0.04 (   0.00%)        0.04 (   6.28%)

While not so much (actually, things are faster) with sched-gran=cpu and HT disabled.

4)                               XEN-HT               XEN-noHT                XEN-csc
Amean     commit        8.78 (   0.00%)        7.64 *  13.03%*        8.20 (   6.63%)
Amean     read          7.71 (   0.00%)        6.86 *  10.95%*        7.21 *   6.43%*
Amean     wal           0.07 (   0.00%)        0.08 * -12.33%*        0.08 (  -7.96%)
Stddev    commit        3.59 (   0.00%)        1.35 (  62.41%)        3.50 (   2.37%)
Stddev    read          2.89 (   0.00%)        0.39 (  86.46%)        2.50 (  13.52%)
Stddev    wal           0.05 (   0.00%)        0.04 (  11.34%)        0.04 (   6.71%)

Interestingly, when running under Xen and without HT, 'commit' and 'read' runs are not suffering any longer (they're actually faster!). 'wal' is. With core scheduling, WAL still slows down, but a little bit less, and commit and read are still fine (although they speed-up less).

5)                            HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Amean     commit        7.83 (   0.00%)        7.74 (   1.16%)        7.68 (   1.87%)
Amean     read          6.97 (   0.00%)        6.97 (  -0.03%)        6.92 *   0.62%*
Amean     wal           0.04 (   0.00%)        0.01 *  79.85%*        0.07 * -84.69%*
Stddev    commit        1.60 (   0.00%)        1.54 (   3.79%)        1.59 (   0.35%)
Stddev    read          0.53 (   0.00%)        0.55 (  -3.61%)        0.68 ( -27.35%)
Stddev    wal           0.05 (   0.00%)        0.03 (  45.88%)        0.05 (   2.11%)

'commit' and 'read' looks similar to the dom0 case. 'wal' is weird, as it went very very good in the 'noHT' case... I'm not sure how significant this benchmark is, to be honest.

6)                            HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Stddev    commit        1.62 (   0.00%)        1.51 (   7.24%)        1.65 (  -1.80%)
Stddev    read          0.55 (   0.00%)        0.66 ( -19.98%)        0.57 (  -2.02%)
Stddev    wal           0.05 (   0.00%)        0.05 (  -6.25%)        0.05 (  -5.64%)

7)                          HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Amean     commit        7.94 (   0.00%)        8.31 *  -4.57%*       10.28 * -29.45%*
Amean     read          6.98 (   0.00%)        7.91 * -13.20%*        9.47 * -35.58%*
Amean     wal           0.01 (   0.00%)        0.07 *-415.01%*        0.24 *-1752.46%*
Stddev    commit        1.75 (   0.00%)        1.30 (  26.10%)        2.17 ( -23.63%)
Stddev    read          0.67 (   0.00%)        0.79 ( -17.48%)        2.21 (-228.37%)
Stddev    wal           0.03 (   0.00%)        0.09 (-157.29%)        0.39 (-1057.77%)

Here, on the other hand, 'csc' regresses against 'noHT'. We've seen 'wal' fluctuating a bit. But in this case, even if we'd ignore it, we see that also 'commit' and 'read' slow down significantly.


NETPERF-UDP
===========
1)                                   BM-HT                BM-noHT
Hmean     send-64        395.57 (   0.00%)      402.32 *   1.70%*
Hmean     send-256      1474.96 (   0.00%)     1515.87 *   2.77%*
Hmean     send-2048    10592.86 (   0.00%)    11137.39 *   5.14%*
Hmean     send-8192    27861.86 (   0.00%)    29965.72 *   7.55%*
Hmean     recv-64        395.51 (   0.00%)      402.30 *   1.72%*
Hmean     recv-256      1474.96 (   0.00%)     1515.61 *   2.76%*
Hmean     recv-2048    10591.01 (   0.00%)    11135.47 *   5.14%*
Hmean     recv-8192    27858.04 (   0.00%)    29956.95 *   7.53%*
Stddev    send-64          4.61 (   0.00%)        3.01 (  34.70%)
Stddev    send-256        28.10 (   0.00%)       11.44 (  59.29%)
Stddev    send-2048      164.91 (   0.00%)      112.24 (  31.94%)
Stddev    send-8192      930.19 (   0.00%)      416.78 (  55.19%)
Stddev    recv-64          4.73 (   0.00%)        3.00 (  36.49%)
Stddev    recv-256        28.10 (   0.00%)       11.86 (  57.79%)
Stddev    recv-2048      163.52 (   0.00%)      111.83 (  31.61%)
Stddev    recv-8192      930.48 (   0.00%)      415.22 (  55.38%)

'noHT' being consistently --although marginally, in most cases-- better seems to reveal non-ideality in how SMT is handled in the Linux scheduler.

2)                                v-XEN-HT                 XEN-HT
Hmean     send-64        223.35 (   0.00%)      220.23 *  -1.39%*
Hmean     send-256       876.26 (   0.00%)      863.81 *  -1.42%*
Hmean     send-2048     6575.95 (   0.00%)     6542.13 (  -0.51%)
Hmean     send-8192    20882.75 (   0.00%)    20999.88 (   0.56%)
Hmean     recv-64        223.35 (   0.00%)      220.23 *  -1.39%*
Hmean     recv-256       876.22 (   0.00%)      863.81 *  -1.42%*
Hmean     recv-2048     6575.00 (   0.00%)     6541.22 (  -0.51%)
Hmean     recv-8192    20881.63 (   0.00%)    20996.13 (   0.55%)
Stddev    send-64          1.16 (   0.00%)        0.94 (  19.15%)
Stddev    send-256         7.50 (   0.00%)        7.71 (  -2.79%)
Stddev    send-2048       29.58 (   0.00%)       57.84 ( -95.56%)
Stddev    send-8192      106.01 (   0.00%)      172.69 ( -62.90%)
Stddev    recv-64          1.16 (   0.00%)        0.94 (  19.15%)
Stddev    recv-256         7.50 (   0.00%)        7.70 (  -2.70%)
Stddev    recv-2048       28.84 (   0.00%)       56.58 ( -96.20%)
Stddev    recv-8192      105.96 (   0.00%)      167.07 ( -57.68%)

3)                              v-XEN-noHT               XEN-noHT
Hmean     send-64        222.53 (   0.00%)      220.12 *  -1.08%*
Hmean     send-256       874.65 (   0.00%)      866.59 (  -0.92%)
Hmean     send-2048     6595.97 (   0.00%)     6568.38 (  -0.42%)
Hmean     send-8192    21537.45 (   0.00%)    21163.69 *  -1.74%*
Hmean     recv-64        222.52 (   0.00%)      220.08 *  -1.10%*
Hmean     recv-256       874.55 (   0.00%)      866.47 (  -0.92%)
Hmean     recv-2048     6595.64 (   0.00%)     6566.75 (  -0.44%)
Hmean     recv-8192    21534.73 (   0.00%)    21157.86 *  -1.75%*
Stddev    send-64          1.45 (   0.00%)        1.64 ( -13.12%)
Stddev    send-256         4.96 (   0.00%)        8.92 ( -79.63%)
Stddev    send-2048       35.06 (   0.00%)       64.88 ( -85.05%)
Stddev    send-8192      199.63 (   0.00%)      161.66 (  19.02%)
Stddev    recv-64          1.44 (   0.00%)        1.62 ( -12.50%)
Stddev    recv-256         4.94 (   0.00%)        9.03 ( -82.65%)
Stddev    recv-2048       34.99 (   0.00%)       65.80 ( -88.02%)
Stddev    recv-8192      201.10 (   0.00%)      162.03 (  19.43%)

4)                                  XEN-HT               XEN-noHT                XEN-csc
Hmean     send-64        220.23 (   0.00%)      220.12 (  -0.05%)      199.70 *  -9.32%*
Hmean     send-256       863.81 (   0.00%)      866.59 (   0.32%)      791.34 *  -8.39%*
Hmean     send-2048     6542.13 (   0.00%)     6568.38 (   0.40%)     5758.09 * -11.98%*
Hmean     send-8192    20999.88 (   0.00%)    21163.69 (   0.78%)    19706.48 *  -6.16%*
Hmean     recv-64        220.23 (   0.00%)      220.08 (  -0.07%)      199.70 *  -9.32%*
Hmean     recv-256       863.81 (   0.00%)      866.47 (   0.31%)      791.09 *  -8.42%*
Hmean     recv-2048     6541.22 (   0.00%)     6566.75 (   0.39%)     5757.50 * -11.98%*
Hmean     recv-8192    20996.13 (   0.00%)    21157.86 (   0.77%)    19703.65 *  -6.16%*
Stddev    send-64          0.94 (   0.00%)        1.64 ( -74.89%)       21.30 (-2173.95%)
Stddev    send-256         7.71 (   0.00%)        8.92 ( -15.74%)       63.89 (-729.17%)
Stddev    send-2048       57.84 (   0.00%)       64.88 ( -12.18%)      112.05 ( -93.72%)
Stddev    send-8192      172.69 (   0.00%)      161.66 (   6.39%)      276.33 ( -60.02%)
Stddev    recv-64          0.94 (   0.00%)        1.62 ( -72.94%)       21.30 (-2173.74%)
Stddev    recv-256         7.70 (   0.00%)        9.03 ( -17.23%)       64.08 (-732.24%)
Stddev    recv-2048       56.58 (   0.00%)       65.80 ( -16.28%)      112.00 ( -97.94%)
Stddev    recv-8192      167.07 (   0.00%)      162.03 (   3.01%)      276.84 ( -65.70%)

In this case, 'csc' is performing worse than 'noHT', pretty consistently. This again may be due to sub-optimal placement of the vCPUs, with core-scheduling enabled.

5)                               HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Hmean     send-64        518.85 (   0.00%)      487.85 *  -5.97%*      505.10 (  -2.65%)
Hmean     send-256      1955.77 (   0.00%)     1784.00 *  -8.78%*     1931.18 (  -1.26%)
Hmean     send-2048    12849.78 (   0.00%)    13027.81 (   1.39%)    13485.59 (   4.95%)
Hmean     send-8192    37659.20 (   0.00%)    35773.79 *  -5.01%*    35040.88 *  -6.95%*
Hmean     recv-64        518.32 (   0.00%)      487.76 *  -5.89%*      504.86 (  -2.60%)
Hmean     recv-256      1954.42 (   0.00%)     1782.90 *  -8.78%*     1930.33 (  -1.23%)
Hmean     recv-2048    12830.91 (   0.00%)    13018.47 (   1.46%)    13475.39 (   5.02%)
Hmean     recv-8192    37619.84 (   0.00%)    35768.42 *  -4.92%*    35035.40 *  -6.87%*
Stddev    send-64         29.69 (   0.00%)        6.43 (  78.34%)       17.36 (  41.53%)
Stddev    send-256        64.17 (   0.00%)       26.82 (  58.21%)       33.37 (  47.99%)
Stddev    send-2048     1342.98 (   0.00%)      246.21 (  81.67%)      353.97 (  73.64%)
Stddev    send-8192      224.20 (   0.00%)      467.40 (-108.48%)      928.70 (-314.24%)
Stddev    recv-64         29.96 (   0.00%)        6.54 (  78.16%)       17.64 (  41.11%)
Stddev    recv-256        64.29 (   0.00%)       27.28 (  57.56%)       34.17 (  46.85%)
Stddev    recv-2048     1353.73 (   0.00%)      251.38 (  81.43%)      368.14 (  72.81%)
Stddev    recv-8192      206.98 (   0.00%)      467.59 (-125.91%)      928.73 (-348.71%)

This looks different than the dom0 case. Basically, here, 'noHT' and 'csc' look on par (maybe 'csc' is even a little bit better). Another difference is that 'noHT' slows down more, as compared to 'HT'.

6)                               HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Hmean     send-64        513.95 (   0.00%)      511.96 (  -0.39%)      458.46 * -10.80%*
Hmean     send-256      1928.30 (   0.00%)     1930.57 (   0.12%)     1831.70 *  -5.01%*
Hmean     send-2048    13509.70 (   0.00%)    13802.90 *   2.17%*    12739.81 *  -5.70%*
Hmean     send-8192    35966.73 (   0.00%)    36086.45 (   0.33%)    35293.89 (  -1.87%)
Hmean     recv-64        513.90 (   0.00%)      511.91 (  -0.39%)      458.34 * -10.81%*
Hmean     recv-256      1927.94 (   0.00%)     1930.48 (   0.13%)     1831.50 *  -5.00%*
Hmean     recv-2048    13506.19 (   0.00%)    13799.61 *   2.17%*    12734.53 *  -5.71%*
Hmean     recv-8192    35936.42 (   0.00%)    36069.50 (   0.37%)    35266.17 (  -1.87%)
Stddev    send-64         12.88 (   0.00%)        3.89 (  69.78%)       16.11 ( -25.10%)
Stddev    send-256        37.13 (   0.00%)       19.62 (  47.16%)       30.54 (  17.75%)
Stddev    send-2048       86.00 (   0.00%)      100.64 ( -17.03%)      311.99 (-262.80%)
Stddev    send-8192      926.89 (   0.00%)     1088.50 ( -17.44%)     2801.65 (-202.26%)
Stddev    recv-64         12.93 (   0.00%)        3.96 (  69.36%)       16.15 ( -24.90%)
Stddev    recv-256        37.76 (   0.00%)       19.75 (  47.68%)       30.68 (  18.73%)
Stddev    recv-2048       88.84 (   0.00%)      100.51 ( -13.13%)      313.79 (-253.20%)

7)                             HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Hmean     send-64        359.65 (   0.00%)      251.84 * -29.98%*      348.95 (  -2.97%)
Hmean     send-256      1376.16 (   0.00%)      969.58 * -29.54%*     1293.19 *  -6.03%*
Hmean     send-2048    10212.34 (   0.00%)     6893.41 * -32.50%*     8933.39 * -12.52%*
Hmean     send-8192    30442.79 (   0.00%)    18372.42 * -39.65%*    25486.82 * -16.28%*
Hmean     recv-64        359.01 (   0.00%)      240.67 * -32.96%*      319.95 * -10.88%*
Hmean     recv-256      1372.71 (   0.00%)      923.23 * -32.74%*     1206.20 * -12.13%*
Hmean     recv-2048    10185.94 (   0.00%)     6258.59 * -38.56%*     8371.03 * -17.82%*
Hmean     recv-8192    30272.47 (   0.00%)    16888.08 * -44.21%*    22719.70 * -24.95%*
Stddev    send-64          6.49 (   0.00%)        7.35 ( -13.35%)       18.06 (-178.42%)
Stddev    send-256        29.41 (   0.00%)       15.84 (  46.15%)       25.77 (  12.38%)
Stddev    send-2048       97.12 (   0.00%)      238.24 (-145.32%)      276.14 (-184.34%)
Stddev    send-8192      680.48 (   0.00%)      336.65 (  50.53%)      482.57 (  29.08%)
Stddev    recv-64          6.80 (   0.00%)        3.56 (  47.64%)        6.62 (   2.60%)
Stddev    recv-256        31.00 (   0.00%)       10.11 (  67.39%)       14.94 (  51.80%)
Stddev    recv-2048       99.42 (   0.00%)       96.49 (   2.94%)       42.24 (  57.51%)
Stddev    recv-8192      759.75 (   0.00%)      108.46 (  85.72%)      745.22 (   1.91%)

And even for this benchmark, for which 'csc' does not perform very well in general, under load, it does good vs. 'noHT'.


NETPERF-TCP
===========
1)                              BM-HT                BM-noHT
Hmean     64       2495.25 (   0.00%)     2509.94 *   0.59%*
Hmean     256      7331.05 (   0.00%)     7350.96 (   0.27%)
Hmean     2048    32003.90 (   0.00%)    31975.79 (  -0.09%)
Hmean     8192    50482.11 (   0.00%)    51254.29 (   1.53%)
Stddev    64         12.54 (   0.00%)        9.28 (  26.01%)
Stddev    256        20.90 (   0.00%)       35.47 ( -69.76%)
Stddev    2048      160.50 (   0.00%)      186.36 ( -16.12%)
Stddev    8192      944.33 (   0.00%)      365.62 (  61.28%)

Basically on par.

2)                           v-XEN-HT                 XEN-HT
Hmean     64        674.18 (   0.00%)      677.61 (   0.51%)
Hmean     256      2424.16 (   0.00%)     2448.40 *   1.00%*
Hmean     2048    15114.37 (   0.00%)    15160.59 (   0.31%)
Hmean     8192    32626.11 (   0.00%)    32056.40 (  -1.75%)
Stddev    64          5.99 (   0.00%)        5.93 (   0.98%)
Stddev    256        12.07 (   0.00%)       15.11 ( -25.17%)
Stddev    2048      106.56 (   0.00%)      180.05 ( -68.97%)
Stddev    8192      649.77 (   0.00%)      329.45 (  49.30%)

3)                         v-XEN-noHT               XEN-noHT
Hmean     64        674.89 (   0.00%)      679.64 (   0.70%)
Hmean     256      2426.14 (   0.00%)     2443.24 *   0.70%*
Hmean     2048    15273.97 (   0.00%)    15372.31 *   0.64%*
Hmean     8192    32895.01 (   0.00%)    32473.01 *  -1.28%*
Stddev    64          3.90 (   0.00%)        6.01 ( -54.19%)
Stddev    256         8.14 (   0.00%)       18.76 (-130.35%)
Stddev    2048       35.02 (   0.00%)       86.00 (-145.62%)
Stddev    8192      123.38 (   0.00%)      448.67 (-263.64%)

4)                             XEN-HT               XEN-noHT                XEN-csc
Hmean     64        677.61 (   0.00%)      679.64 (   0.30%)      660.08 (  -2.59%)
Hmean     256      2448.40 (   0.00%)     2443.24 (  -0.21%)     2402.64 *  -1.87%*
Hmean     2048    15160.59 (   0.00%)    15372.31 *   1.40%*    14591.20 *  -3.76%*
Hmean     8192    32056.40 (   0.00%)    32473.01 (   1.30%)    32024.74 (  -0.10%)
Stddev    64          5.93 (   0.00%)        6.01 (  -1.39%)       31.04 (-423.45%)
Stddev    256        15.11 (   0.00%)       18.76 ( -24.13%)       46.90 (-210.39%)
Stddev    2048      180.05 (   0.00%)       86.00 (  52.23%)      339.19 ( -88.39%)
Stddev    8192      329.45 (   0.00%)      448.67 ( -36.18%)     1120.36 (-240.07%)

Also basically on par. Well, 'csc' is a little worse, but not as much as the UDP case was. This suggests looking at differences in ways in which, from a scheduling point of view, the two protocols are handled, could help understand what is
happening.

5)                          HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Hmean     64       1756.72 (   0.00%)     1687.44 *  -3.94%*     1644.27 *  -6.40%*
Hmean     256      6335.31 (   0.00%)     6142.90 *  -3.04%*     5850.62 *  -7.65%*
Hmean     2048    29738.54 (   0.00%)    28871.57 *  -2.92%*    27437.72 *  -7.74%*
Hmean     8192    46926.01 (   0.00%)    46011.63 *  -1.95%*    42627.47 *  -9.16%*
Stddev    64         35.93 (   0.00%)       13.81 (  61.56%)       14.56 (  59.48%)
Stddev    256       110.09 (   0.00%)       53.63 (  51.28%)      142.11 ( -29.08%)
Stddev    2048      172.37 (   0.00%)      189.21 (  -9.77%)     1004.81 (-482.94%)
Stddev    8192      453.49 (   0.00%)      239.72 (  47.14%)     1262.32 (-178.36%)

'csc' not vastly, but consistently worse than 'noHT'.

6)                          HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Stddev    64         20.10 (   0.00%)       10.70 (  46.75%)       45.83 (-128.07%)
Stddev    256        47.00 (   0.00%)       32.37 (  31.14%)       45.15 (   3.95%)
Stddev    2048      205.29 (   0.00%)      148.42 (  27.70%)     1950.42 (-850.08%)
Stddev    8192      515.92 (   0.00%)       62.10 (  87.96%)    11909.19 (-2208.33%)
CoeffVar  64          1.19 (   0.00%)        0.64 (  46.37%)        2.79 (-135.02%)
CoeffVar  256         0.77 (   0.00%)        0.53 (  31.25%)        0.76 (   1.48%)
CoeffVar  2048        0.71 (   0.00%)        0.51 (  27.61%)        7.00 (-887.77%)
CoeffVar  8192        1.13 (   0.00%)        0.13 (  88.04%)       24.76 (-2096.20%)

7)                        HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Hmean     64       1272.66 (   0.00%)      996.12 * -21.73%*      968.44 * -23.90%*
Hmean     256      4376.58 (   0.00%)     3565.25 * -18.54%*     4088.77 *  -6.58%*
Hmean     2048    24077.77 (   0.00%)    17496.21 * -27.33%*    21709.20 *  -9.84%*
Hmean     8192    43332.46 (   0.00%)    32506.09 * -24.98%*    36700.18 * -15.31%*
Stddev    64         13.14 (   0.00%)        3.25 (  75.23%)      221.08 (-1582.74%)
Stddev    256        38.64 (   0.00%)       43.54 ( -12.66%)      316.66 (-719.41%)
Stddev    2048      202.53 (   0.00%)      117.33 (  42.07%)      208.33 (  -2.86%)
Stddev    8192      274.71 (   0.00%)      299.39 (  -8.98%)      412.99 ( -50.33%)

Mixed. Some transfer size are better with 'csc' than 'noHT', some are worse.


NETPERF-UNIX
============
1)                              BM-HT                BM-noHT
Hmean     64        998.53 (   0.00%)     1000.92 (   0.24%)
Hmean     256      3672.82 (   0.00%)     3822.29 *   4.07%*
Hmean     2048     7951.98 (   0.00%)     7987.46 (   0.45%)
Hmean     8192     8218.97 (   0.00%)     8329.87 (   1.35%)
Stddev    64         38.66 (   0.00%)       15.94 (  58.78%)
Stddev    256        99.05 (   0.00%)       93.25 (   5.86%)
Stddev    2048       87.53 (   0.00%)       40.49 (  53.75%)
Stddev    8192      133.15 (   0.00%)       74.00 (  44.42%)

Substantially on par.

2)                           v-XEN-HT                 XEN-HT
Hmean     64        499.62 (   0.00%)      492.89 (  -1.35%)
Hmean     256      1900.97 (   0.00%)     1852.77 (  -2.54%)
Hmean     2048     2892.22 (   0.00%)     2765.65 *  -4.38%*
Hmean     8192     3105.85 (   0.00%)     2996.64 *  -3.52%*
Stddev    64          4.49 (   0.00%)       10.64 (-137.15%)
Stddev    256        87.54 (   0.00%)       54.63 (  37.59%)
Stddev    2048       35.26 (   0.00%)       18.20 (  48.39%)
Stddev    8192       21.32 (   0.00%)       15.74 (  26.15%)

3)                         v-XEN-noHT               XEN-noHT
Hmean     64        509.03 (   0.00%)      485.34 *  -4.65%*
Hmean     256      1894.53 (   0.00%)     1835.34 *  -3.12%*
Hmean     2048     2906.15 (   0.00%)     2747.32 *  -5.47%*
Hmean     8192     3158.33 (   0.00%)     2968.85 *  -6.00%*
Stddev    64          3.39 (   0.00%)       20.01 (-489.71%)
Stddev    256        51.32 (   0.00%)       15.13 (  70.52%)
Stddev    2048       33.35 (   0.00%)        9.37 (  71.89%)
Stddev    8192       32.53 (   0.00%)       11.30 (  65.26%)

In both 'HT' and 'noHT' cases, overhead of just having the patch applied is not too big, but it's there. It may be worth studying this workload, trying to figure what are the paths that are introducing such overhead (with the goal of optimizing them).

4)                             XEN-HT               XEN-noHT                XEN-csc
Hmean     64        492.89 (   0.00%)      485.34 (  -1.53%)      451.13 *  -8.47%*
Hmean     256      1852.77 (   0.00%)     1835.34 (  -0.94%)     1272.07 * -31.34%*
Hmean     2048     2765.65 (   0.00%)     2747.32 *  -0.66%*     3086.19 (  11.59%)
Hmean     8192     2996.64 (   0.00%)     2968.85 *  -0.93%*     2731.31 *  -8.85%*
Stddev    64         10.64 (   0.00%)       20.01 ( -88.04%)       25.28 (-137.53%)
Stddev    256        54.63 (   0.00%)       15.13 (  72.31%)      393.61 (-620.45%)
Stddev    2048       18.20 (   0.00%)        9.37 (  48.48%)      946.82 (-5103.09%)
Stddev    8192       15.74 (   0.00%)       11.30 (  28.21%)      104.54 (-564.07%)

Mixed-bag, with higher (both positive and negative, mostly negative) peaks.

5)                          HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Hmean     64        275.22 (   0.00%)      288.06 (   4.66%)      277.23 (   0.73%)
Hmean     256       977.34 (   0.00%)      877.63 ( -10.20%)      761.25 * -22.11%*
Hmean     2048     4702.72 (   0.00%)     5819.12 (  23.74%)     5531.96 (  17.63%)
Hmean     8192     5962.89 (   0.00%)     6462.60 (   8.38%)     5387.48 (  -9.65%)
Stddev    64         48.37 (   0.00%)       46.27 (   4.34%)       59.79 ( -23.61%)
Stddev    256       123.98 (   0.00%)       48.93 (  60.54%)      163.00 ( -31.47%)
Stddev    2048     1181.41 (   0.00%)      761.99 (  35.50%)      827.15 (  29.99%)
Stddev    8192     1708.12 (   0.00%)     1247.83 (  26.95%)     1065.82 (  37.60%)

What we see here, is that 'noHT' deviates more from 'HT'. For 3 configurations out of 4, for the better (i.e., 'noHT' is faster than 'HT'). 'csc' is, again, generally worse than 'noHT'.

6)                          HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Hmean     64        225.32 (   0.00%)      239.36 (   6.23%)      203.05 (  -9.88%)
Hmean     256       707.19 (   0.00%)      782.19 (  10.60%)      751.77 (   6.30%)
Hmean     2048     2719.26 (   0.00%)     4156.29 *  52.85%*     3624.27 (  33.28%)
Hmean     8192     4263.18 (   0.00%)     5724.08 *  34.27%*     3579.16 ( -16.04%)
Stddev    64         46.49 (   0.00%)       31.12 (  33.07%)       11.06 (  76.21%)
Stddev    256       119.32 (   0.00%)      130.87 (  -9.67%)       87.78 (  26.44%)
Stddev    2048     1030.34 (   0.00%)      907.53 (  11.92%)     1715.05 ( -66.46%)
Stddev    8192      821.15 (   0.00%)      275.68 (  66.43%)     1131.40 ( -37.78%)

7)                        HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Hmean     64        243.29 (   0.00%)      165.06 * -32.16%*      188.01 * -22.72%*
Hmean     256       711.91 (   0.00%)      472.92 * -33.57%*      504.46 * -29.14%*
Hmean     2048     3163.60 (   0.00%)     1955.93 * -38.17%*     2880.11 (  -8.96%)
Hmean     8192     4277.51 (   0.00%)     2377.98 * -44.41%*     3086.59 * -27.84%*
Stddev    64         21.43 (   0.00%)       19.08 (  10.96%)       29.45 ( -37.42%)
Stddev    256        86.25 (   0.00%)       50.56 (  41.38%)      112.78 ( -30.76%)
Stddev    2048      311.30 (   0.00%)      317.03 (  -1.84%)      610.38 ( -96.07%)
Stddev    8192      208.86 (   0.00%)      314.18 ( -50.42%)      580.38 (-177.88%)
---
STREAM
======
Dom0
----
                           v-XEN-HT             v-XEN-noHT                 XEN-HT                XEN-noHT                 XEN-csc
MB/sec copy     33076.00 (   0.00%)    33054.78 (  -0.06%)    33112.76 (   0.11%)    33070.62       -0.02    31811.06       -3.82
MB/sec scale    24170.98 (   0.00%)    24198.12 (   0.11%)    24225.04 (   0.22%)    24335.76        0.68    22745.18       -5.90
MB/sec add      27060.58 (   0.00%)    27084.58 (   0.09%)    27195.52 (   0.50%)    27360.86        1.11    25088.74       -7.29
MB/sec triad    27172.34 (   0.00%)    27199.12 (   0.10%)    27296.42 (   0.46%)    27468.54        1.09    25170.02       -7.37

HVM-v8
------
                        v-HVM-v8-HT          v-HVM-v8-noHT              HVM-v8-HT             HVM-v8-noHT              HVM-v8-csc
MB/sec copy     32690.84 (   0.00%)    33611.24 (   2.82%)    33338.56 (   1.98%)    34168.32        4.52    29568.34       -9.55
MB/sec scale    21899.94 (   0.00%)    22677.44 (   3.55%)    22001.94 (   0.47%)    23023.06        5.13    18635.30      -14.91
MB/sec add      25256.10 (   0.00%)    26822.30 (   6.20%)    25442.48 (   0.74%)    26676.96        5.63    21632.14      -14.35
MB/sec triad    25104.72 (   0.00%)    26821.96 (   6.84%)    26376.48 (   5.07%)    26542.96        5.73    21751.54      -13.36

HVM-v4
------
                        v-HVM-v4-HT          v-HVM-v4-noHT              HVM-v4-HT             HVM-v4-noHT              HVM-v4-csc
MB/sec copy     34027.40 (   0.00%)    32887.74 (  -3.35%)    31917.34 (  -6.20%)    33820.44       -0.61    31186.82       -8.35
MB/sec scale    22269.94 (   0.00%)    20785.18 (  -6.67%)    20741.28 (  -6.86%)    22320.82        0.23    19471.54      -12.57
MB/sec add      26549.00 (   0.00%)    25561.32 (  -3.72%)    25120.08 (  -5.38%)    26553.58        0.02    22348.62      -15.82
MB/sec triad    26431.74 (   0.00%)    26365.78 (  -0.25%)    24979.40 (  -5.49%)    26075.40       -1.35    21988.46      -16.81

HVMx2
-----
                      v-HVMx2-v8-HT        v-HVMx2-v8-noHT            HVMx2-v8-HT           HVMx2-v8-noHT            HVMx2-v8-csc
MB/sec copy     29073.86 (   0.00%)    22403.74 ( -22.94%)    28821.94 (  -0.87%)    22508.84      -22.58    27223.16       -6.37
MB/sec scale    20555.88 (   0.00%)    15184.40 ( -26.13%)    20544.64 (  -0.05%)    15269.06      -25.72    17813.02      -13.34
MB/sec add      22447.72 (   0.00%)    16661.36 ( -25.78%)    22774.16 (   1.45%)    16733.48      -25.46    19659.98      -12.42
MB/sec triad    22261.18 (   0.00%)    16654.90 ( -25.18%)    22163.52 (  -0.44%)    16508.20      -25.84    19722.54      -11.40


KERNBENCH
=========
Dom0
----
                                v-XEN-HT             v-XEN-noHT                 XEN-HT               XEN-noHT                XEN-csc
Amean     elsp-2       234.13 (   0.00%)      233.23 *   0.38%*      233.63 (   0.21%)      233.16 *   0.42%*      248.12 *  -5.98%*
Amean     elsp-4       139.89 (   0.00%)      130.00 *   7.07%*      140.21 *  -0.23%*      130.43 *   6.77%*      145.65 *  -4.12%*
Amean     elsp-8        98.15 (   0.00%)      132.86 * -35.37%*       98.22 (  -0.08%)      132.34 * -34.84%*       98.15 (  -0.01%)
Amean     elsp-16       99.05 (   0.00%)      135.61 * -36.90%*       99.65 *  -0.61%*      135.51 * -36.81%*       99.58 (  -0.53%)
Stddev    elsp-2         0.40 (   0.00%)        0.10 (  74.63%)        0.14 (  64.63%)        0.06 (  84.75%)        0.19 (  51.61%)
Stddev    elsp-4         0.11 (   0.00%)        0.04 (  66.87%)        0.14 ( -33.77%)        0.67 (-528.22%)        0.57 (-442.09%)
Stddev    elsp-8         0.23 (   0.00%)        0.37 ( -58.43%)        0.40 ( -68.71%)        0.04 (  82.95%)        0.03 (  86.30%)
Stddev    elsp-16        0.05 (   0.00%)        0.20 (-306.12%)        0.47 (-855.23%)        0.34 (-589.65%)        0.47 (-850.20%)

HVM-v8
------
                             v-HVM-v8-HT          v-HVM-v8-noHT              HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Amean     elsp-2       204.73 (   0.00%)      206.77 *  -1.00%*      202.45 *   1.11%*      205.87 *  -0.56%*      218.87 *  -6.91%*
Amean     elsp-4       123.10 (   0.00%)      115.66 *   6.04%*      121.90 *   0.98%*      115.41 *   6.25%*      128.78 *  -4.61%*
Amean     elsp-8        87.42 (   0.00%)      125.83 * -43.94%*       85.94 *   1.70%*      125.71 * -43.79%*       87.26 (   0.19%)
Amean     elsp-16       87.78 (   0.00%)      128.51 * -46.41%*       87.37 (   0.46%)      128.52 * -46.42%*       88.03 (  -0.29%)
Stddev    elsp-2         0.08 (   0.00%)        0.11 ( -32.29%)        0.09 (  -5.22%)        0.34 (-320.09%)        1.30 (-1513.29%)
Stddev    elsp-4         0.41 (   0.00%)        0.07 (  82.57%)        0.44 (  -8.26%)        0.27 (  33.60%)        0.60 ( -47.86%)
Stddev    elsp-8         1.11 (   0.00%)        0.42 (  61.72%)        0.14 (  87.69%)        0.22 (  79.83%)        0.35 (  68.79%)
Stddev    elsp-16        0.45 (   0.00%)        0.41 (   8.89%)        0.02 (  94.90%)        0.40 (  12.00%)        0.32 (  28.63%)

HVM-v4
------
                             v-HVM-v4-HT          v-HVM-v4-noHT              HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Amean     elsp-2       208.43 (   0.00%)      205.99 *   1.17%*      206.05 *   1.14%*      208.49 (  -0.03%)      237.58 * -13.99%*
Amean     elsp-4       116.18 (   0.00%)      113.77 *   2.07%*      114.53 *   1.42%*      115.46 (   0.62%)      162.61 * -39.96%*
Amean     elsp-8       135.79 (   0.00%)      116.07 *  14.52%*      127.22 *   6.31%*      117.63 *  13.37%*      166.22 * -22.41%*
Amean     elsp-16      139.37 (   0.00%)      119.35 *  14.37%*      133.70 *   4.07%*      120.53 *  13.52%*      170.05 * -22.01%*
Stddev    elsp-2         0.12 (   0.00%)        0.08 (  31.03%)        0.26 (-118.28%)        0.24 (-102.17%)        0.34 (-185.87%)
Stddev    elsp-4         0.64 (   0.00%)        0.02 (  96.39%)        0.29 (  54.24%)        0.23 (  63.79%)        0.24 (  62.09%)
Stddev    elsp-8         1.69 (   0.00%)        0.21 (  87.34%)        2.21 ( -31.12%)        0.12 (  92.76%)        0.24 (  85.59%)
Stddev    elsp-16        1.55 (   0.00%)        0.13 (  91.93%)        2.00 ( -28.78%)        0.57 (  63.08%)        0.34 (  77.94%)

HVMx2
-----
                           v-HVMx2-v8-HT        v-HVMx2-v8-noHT            HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Amean     elsp-2       288.41 (   0.00%)      433.37 * -50.26%*      288.82 (  -0.14%)      437.79 * -51.79%*      339.86 * -17.84%*
Amean     elsp-4       195.93 (   0.00%)      292.53 * -49.30%*      196.18 (  -0.13%)      294.95 * -50.54%*      242.91 * -23.98%*
Amean     elsp-8       152.94 (   0.00%)      226.94 * -48.38%*      153.27 (  -0.21%)      229.25 * -49.89%*      182.50 * -19.33%*
Amean     elsp-16      156.21 (   0.00%)      233.02 * -49.17%*      156.59 (  -0.24%)      235.63 * -50.84%*      185.82 * -18.95%*
Stddev    elsp-2         0.52 (   0.00%)        0.36 (  30.55%)        0.20 (  61.63%)        0.34 (  35.83%)        2.56 (-389.55%)
Stddev    elsp-4         0.58 (   0.00%)        0.32 (  44.47%)        0.48 (  16.07%)        0.07 (  88.46%)        0.41 (  29.44%)
Stddev    elsp-8         0.15 (   0.00%)        0.87 (-477.96%)        0.39 (-157.52%)        0.81 (-438.90%)        1.30 (-764.70%)
Stddev    elsp-16        0.71 (   0.00%)        0.16 (  77.40%)        0.88 ( -25.43%)        0.87 ( -22.96%)        1.75 (-148.69%)


HACKBENCH-PROCESS-PIPE
======================
Dom0
----
                           v-XEN-HT             v-XEN-noHT                 XEN-HT               XEN-noHT                XEN-csc
Amean     1       0.7356 (   0.00%)      1.2154 * -65.23%*      0.7470 (  -1.55%)      1.2200 * -65.85%*      0.7160 (   2.66%)
Amean     3       2.3506 (   0.00%)      3.9274 * -67.08%*      2.4632 (  -4.79%)      3.9302 * -67.20%*      2.2284 (   5.20%)
Amean     5       4.1084 (   0.00%)      6.6430 * -61.69%*      4.0418 (   1.62%)      6.6584 * -62.07%*      4.0492 (   1.44%)
Amean     7       5.8314 (   0.00%)      9.2772 * -59.09%*      5.9784 (  -2.52%)      9.8144 * -68.30%*      5.8718 (  -0.69%)
Amean     12      9.9694 (   0.00%)     14.8220 * -48.67%*     10.4374 *  -4.69%*     14.4464 * -44.91%*     10.1488 (  -1.80%)
Amean     18     14.2844 (   0.00%)     21.6266 * -51.40%*     14.1366 (   1.03%)     20.2166 * -41.53%*     14.7450 *  -3.22%*
Amean     24     19.0304 (   0.00%)     27.2974 * -43.44%*     17.6314 (   7.35%)     26.1082 * -37.19%*     18.0072 (   5.38%)
Amean     30     21.8334 (   0.00%)     32.2406 * -47.67%*     21.9030 (  -0.32%)     31.1702 * -42.76%*     21.1058 (   3.33%)
Amean     32     22.8946 (   0.00%)     34.8984 * -52.43%*     22.0216 *   3.81%*     33.8204 * -47.72%*     22.7300 (   0.72%)
Stddev    1       0.0213 (   0.00%)      0.0727 (-241.00%)      0.0327 ( -53.61%)      0.0560 (-162.76%)      0.0168 (  21.21%)
Stddev    3       0.1634 (   0.00%)      0.2564 ( -56.92%)      0.0952 (  41.73%)      0.1332 (  18.47%)      0.0944 (  42.24%)
Stddev    5       0.3934 (   0.00%)      0.6043 ( -53.61%)      0.1954 (  50.33%)      0.5454 ( -38.63%)      0.3064 (  22.12%)
Stddev    7       0.1796 (   0.00%)      0.6785 (-277.74%)      0.2809 ( -56.40%)      0.4508 (-150.96%)      0.5762 (-220.78%)
Stddev    12      0.1695 (   0.00%)      0.5074 (-199.31%)      0.3725 (-119.74%)      0.8115 (-378.66%)      0.3594 (-111.98%)
Stddev    18      0.1392 (   0.00%)      0.9622 (-591.50%)      0.4003 (-187.67%)      0.8868 (-537.31%)      0.2580 ( -85.37%)
Stddev    24      1.5323 (   0.00%)      0.4904 (  68.00%)      0.7330 (  52.16%)      0.8453 (  44.83%)      0.8976 (  41.42%)
Stddev    30      0.4214 (   0.00%)      0.5542 ( -31.51%)      1.0668 (-153.14%)      0.6499 ( -54.22%)      0.8666 (-105.64%)
Stddev    32      0.8221 (   0.00%)      0.4986 (  39.35%)      0.3849 (  53.18%)      0.7965 (   3.11%)      1.4428 ( -75.50%)

HVM-v8
------
                        v-HVM-v8-HT          v-HVM-v8-noHT              HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Amean     1       0.9110 (   0.00%)      1.1916 * -30.80%*      0.8992 (   1.30%)      1.1826 * -29.81%*      0.9462 (  -3.86%)
Amean     3       2.5652 (   0.00%)      2.5224 (   1.67%)      2.4524 *   4.40%*      2.4990 (   2.58%)      2.5514 (   0.54%)
Amean     5       3.7944 (   0.00%)      3.6360 (   4.17%)      3.6710 (   3.25%)      3.5258 (   7.08%)      3.9270 (  -3.49%)
Amean     7       4.9098 (   0.00%)      4.7782 (   2.68%)      4.6588 (   5.11%)      4.6430 (   5.43%)      5.0420 (  -2.69%)
Amean     12      7.7490 (   0.00%)      7.8662 (  -1.51%)      7.7872 (  -0.49%)      7.6310 (   1.52%)      7.6498 (   1.28%)
Amean     18     11.5028 (   0.00%)     13.6472 * -18.64%*     10.9800 (   4.54%)     12.2772 (  -6.73%)     11.1940 (   2.68%)
Amean     24     14.5122 (   0.00%)     18.7738 * -29.37%*     16.5552 * -14.08%*     18.1368 * -24.98%*     15.1922 (  -4.69%)
Amean     30     19.9878 (   0.00%)     23.7490 * -18.82%*     17.1778 *  14.06%*     24.0352 * -20.25%*     17.7776 *  11.06%*
Amean     32     17.0554 (   0.00%)     25.6216 * -50.23%*     19.1966 ( -12.55%)     25.3104 * -48.40%*     19.8716 * -16.51%*
Stddev    1       0.0403 (   0.00%)      0.0441 (  -9.28%)      0.0306 (  24.17%)      0.0440 (  -9.25%)      0.0419 (  -3.84%)
Stddev    3       0.0681 (   0.00%)      0.0243 (  64.28%)      0.0681 (   0.11%)      0.1289 ( -89.14%)      0.0975 ( -43.14%)
Stddev    5       0.2333 (   0.00%)      0.1336 (  42.73%)      0.1214 (  47.96%)      0.2722 ( -16.65%)      0.2080 (  10.83%)
Stddev    7       0.3640 (   0.00%)      0.3416 (   6.16%)      0.5810 ( -59.58%)      0.2687 (  26.18%)      0.3038 (  16.56%)
Stddev    12      1.4176 (   0.00%)      0.7817 (  44.85%)      1.4867 (  -4.88%)      1.3196 (   6.91%)      1.5775 ( -11.28%)
Stddev    18      2.0262 (   0.00%)      1.4042 (  30.70%)      1.9110 (   5.69%)      1.8377 (   9.30%)      1.3230 (  34.71%)
Stddev    24      1.9163 (   0.00%)      1.2319 (  35.71%)      1.4038 (  26.75%)      1.2938 (  32.49%)      1.2301 (  35.81%)
Stddev    30      0.8934 (   0.00%)      0.5216 (  41.62%)      2.0035 (-124.27%)      1.3529 ( -51.44%)      2.4480 (-174.03%)
Stddev    32      1.9707 (   0.00%)      1.1169 (  43.32%)      1.8277 (   7.26%)      1.1786 (  40.20%)      2.4069 ( -22.13%)

HVM-v4
------
                        v-HVM-v4-HT          v-HVM-v4-noHT              HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Amean     1       1.4166 (   0.00%)      1.5276 (  -7.84%)      1.4962 (  -5.62%)      1.4424 (  -1.82%)      1.6824 * -18.76%*
Amean     3       2.8812 (   0.00%)      2.5782 (  10.52%)      2.5826 (  10.36%)      2.9692 (  -3.05%)      2.9984 (  -4.07%)
Amean     5       3.6958 (   0.00%)      2.9828 *  19.29%*      3.4330 (   7.11%)      3.5064 (   5.12%)      4.7144 * -27.56%*
Amean     7       4.0368 (   0.00%)      4.3646 (  -8.12%)      5.3896 ( -33.51%)      4.5122 ( -11.78%)      5.7828 * -43.25%*
Amean     12      8.5918 (   0.00%)      7.5160 (  12.52%)      7.6862 (  10.54%)      8.1164 (   5.53%)     10.3868 * -20.89%*
Amean     18     11.8664 (   0.00%)      9.6676 (  18.53%)     10.8628 (   8.46%)     10.8600 (   8.48%)     14.5226 * -22.38%*
Amean     24     15.1868 (   0.00%)     14.3044 (   5.81%)     16.1058 (  -6.05%)     13.9238 (   8.32%)     17.3746 ( -14.41%)
Amean     30     18.1732 (   0.00%)     13.3870 *  26.34%*     17.9462 (   1.25%)     20.1588 ( -10.93%)     22.2760 * -22.58%*
Amean     32     20.1886 (   0.00%)     18.9476 (   6.15%)     20.8922 (  -3.49%)     15.2004 *  24.71%*     22.5168 ( -11.53%)
Stddev    1       0.1570 (   0.00%)      0.0459 (  70.75%)      0.0353 (  77.49%)      0.0996 (  36.54%)      0.0573 (  63.51%)
Stddev    3       0.2794 (   0.00%)      0.3201 ( -14.55%)      0.4556 ( -63.07%)      0.6097 (-118.20%)      0.4727 ( -69.16%)
Stddev    5       0.5446 (   0.00%)      0.2571 (  52.80%)      0.7936 ( -45.73%)      0.6409 ( -17.68%)      1.0294 ( -89.03%)
Stddev    7       1.0122 (   0.00%)      0.5749 (  43.20%)      1.3387 ( -32.26%)      0.9335 (   7.78%)      1.5652 ( -54.63%)
Stddev    12      1.3820 (   0.00%)      1.3625 (   1.41%)      1.1304 (  18.21%)      1.8932 ( -36.98%)      1.6302 ( -17.96%)
Stddev    18      1.7693 (   0.00%)      2.4127 ( -36.37%)      2.6187 ( -48.01%)      2.2309 ( -26.09%)      0.9304 (  47.41%)
Stddev    24      2.4119 (   0.00%)      3.0559 ( -26.70%)      2.2138 (   8.21%)      1.6892 (  29.96%)      1.4706 (  39.03%)
Stddev    30      1.5649 (   0.00%)      1.5202 (   2.85%)      1.6264 (  -3.93%)      2.1632 ( -38.24%)      1.6574 (  -5.91%)
Stddev    32      1.8988 (   0.00%)      2.5294 ( -33.21%)      3.5272 ( -85.76%)      2.5166 ( -32.54%)      2.0956 ( -10.36%)

HVMx2
-----
                    v-HVMx2-v8-HT        v-HVMx2-v8-noHT            HVMx2-v8-HT           HVMx2-v8-noHT            HVMx2-v8-csc
Amean     1       1.4746 (   0.00%)      1.1486 *  22.11%*      1.4736 (   0.07%)      1.2224 *  17.10%*      1.6544 * -12.19%*
Amean     3       3.2278 (   0.00%)      2.3356 *  27.64%*      3.1764 (   1.59%)      2.4984 *  22.60%*      2.9720 *   7.92%*
Amean     5       4.8324 (   0.00%)      3.4158 *  29.31%*      4.7694 (   1.30%)      3.4870 *  27.84%*      4.4406 *   8.11%*
Amean     7       6.2532 (   0.00%)      4.4590 *  28.69%*      6.3958 (  -2.28%)      4.6320 *  25.93%*      5.9150 (   5.41%)
Amean     12     11.6814 (   0.00%)      7.5236 *  35.59%*     11.0484 (   5.42%)      7.6534 *  34.48%*      9.7064 *  16.91%*
Amean     18     16.7618 (   0.00%)     11.7750 *  29.75%*     16.8658 (  -0.62%)     12.8028 *  23.62%*     17.0654 (  -1.81%)
Amean     24     23.3174 (   0.00%)     17.8512 *  23.44%*     23.6798 (  -1.55%)     18.8692 *  19.08%*     24.1742 (  -3.67%)
Amean     30     29.7604 (   0.00%)     25.2918 *  15.02%*     29.6202 (   0.47%)     25.4126 *  14.61%*     30.5034 (  -2.50%)
Amean     32     31.9166 (   0.00%)     26.6520 *  16.49%*     31.7582 (   0.50%)     28.5946 *  10.41%*     33.0222 *  -3.46%*
Stddev    1       0.0496 (   0.00%)      0.0159 (  67.85%)      0.0309 (  37.60%)      0.0294 (  40.77%)      0.0526 (  -6.03%)
Stddev    3       0.0469 (   0.00%)      0.1044 (-122.37%)      0.1102 (-134.80%)      0.0670 ( -42.65%)      0.0956 (-103.57%)
Stddev    5       0.1882 (   0.00%)      0.1189 (  36.79%)      0.2023 (  -7.51%)      0.1089 (  42.12%)      0.0694 (  63.10%)
Stddev    7       0.3875 (   0.00%)      0.1279 (  66.99%)      0.3783 (   2.36%)      0.1408 (  63.67%)      0.2421 (  37.52%)
Stddev    12      1.1041 (   0.00%)      0.3356 (  69.61%)      1.5160 ( -37.30%)      0.3483 (  68.45%)      1.3210 ( -19.64%)
Stddev    18      1.1648 (   0.00%)      0.9867 (  15.29%)      1.3000 ( -11.61%)      1.2858 ( -10.39%)      0.8736 (  25.00%)
Stddev    24      1.8746 (   0.00%)      1.7346 (   7.47%)      0.8749 (  53.33%)      0.8663 (  53.79%)      0.8197 (  56.27%)
Stddev    30      0.8898 (   0.00%)      0.8720 (   2.01%)      1.3074 ( -46.92%)      1.4297 ( -60.67%)      1.2882 ( -44.77%)
Stddev    32      0.8406 (   0.00%)      0.9333 ( -11.03%)      1.2521 ( -48.95%)      1.0791 ( -28.38%)      0.7319 (  12.93%)


MUTILATE
========
Dom0
----
                          v-XEN-HT             v-XEN-noHT                 XEN-HT               XEN-noHT                XEN-csc
Hmean     1    31121.40 (   0.00%)    31182.90 (   0.20%)    31063.01 (  -0.19%)    31107.06 (  -0.05%)    29609.98 *  -4.86%*
Hmean     3    75847.21 (   0.00%)    83473.18 *  10.05%*    75373.02 (  -0.63%)    84387.92 *  11.26%*    73419.60 *  -3.20%*
Hmean     5   113823.13 (   0.00%)    90322.68 * -20.65%*   113127.84 (  -0.61%)    91396.40 * -19.70%*   100843.37 * -11.40%*
Hmean     7   112553.93 (   0.00%)    91082.97 * -19.08%*   112467.16 (  -0.08%)    91296.28 * -18.89%*   108439.16 *  -3.66%*
Hmean     8   103472.02 (   0.00%)    89529.42 * -13.47%*   103246.75 (  -0.22%)    89442.61 * -13.56%*   101164.18 *  -2.23%*
Stddev    1      147.14 (   0.00%)      369.37 (-151.04%)      175.64 ( -19.37%)      336.37 (-128.61%)      271.28 ( -84.38%)
Stddev    3      920.80 (   0.00%)      300.44 (  67.37%)     1017.40 ( -10.49%)      333.46 (  63.79%)      367.95 (  60.04%)
Stddev    5      339.23 (   0.00%)      842.22 (-148.27%)      781.99 (-130.52%)      816.23 (-140.61%)      549.77 ( -62.06%)
Stddev    7      248.83 (   0.00%)      907.80 (-264.83%)      404.74 ( -62.66%)     1084.18 (-335.72%)      376.92 ( -51.48%)
Stddev    8      132.22 (   0.00%)      362.90 (-174.47%)      274.16 (-107.35%)      890.80 (-573.74%)      987.59 (-646.94%)

HVM-v8
------
                       v-HVM-v8-HT          v-HVM-v8-noHT              HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Hmean     1    40028.72 (   0.00%)    37434.58 *  -6.48%*    39583.53 *  -1.11%*    38828.65 *  -3.00%*    35103.76 * -12.30%*
Hmean     3    86535.13 (   0.00%)    55588.26 * -35.76%*    87210.00 (   0.78%)    57874.31 * -33.12%*    47160.22 * -45.50%*
Hmean     5   129214.62 (   0.00%)    40925.40 * -68.33%*   130676.61 (   1.13%)    42883.21 * -66.81%*    85504.60 * -33.83%*
Hmean     7   156682.49 (   0.00%)    51225.56 * -67.31%*   157586.93 (   0.58%)    59146.02 * -62.25%*   136717.21 * -12.74%*
Hmean     8   170156.78 (   0.00%)    67430.68 * -60.37%*   174113.49 *   2.33%*    75503.09 * -55.63%*   159666.07 *  -6.17%*
Stddev    1      151.77 (   0.00%)      288.75 ( -90.25%)      160.68 (  -5.87%)      232.01 ( -52.87%)      547.91 (-261.01%)
Stddev    3      322.96 (   0.00%)      557.82 ( -72.72%)     1158.62 (-258.75%)      654.05 (-102.51%)    18841.25 (-5733.90%)
Stddev    5     1396.24 (   0.00%)     1741.63 ( -24.74%)      298.35 (  78.63%)      542.51 (  61.14%)     1274.93 (   8.69%)
Stddev    7      808.54 (   0.00%)     2547.30 (-215.05%)     2569.12 (-217.75%)     1034.22 ( -27.91%)     4163.80 (-414.98%)
Stddev    8     2411.73 (   0.00%)     3538.44 ( -46.72%)      982.48 (  59.26%)      692.10 (  71.30%)     1324.30 (  45.09%)

HVM-v4
------
                       v-HVM-v4-HT          v-HVM-v4-noHT              HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Hmean     1    38127.59 (   0.00%)    37939.84 (  -0.49%)    37156.88 *  -2.55%*    36938.92 *  -3.12%*    34869.19 *  -8.55%*
Hmean     3    91447.41 (   0.00%)    91291.57 (  -0.17%)    91170.71 (  -0.30%)    91469.09 (   0.02%)    76214.51 * -16.66%*
Hmean     5   119169.44 (   0.00%)   130797.85 *   9.76%*   119020.55 (  -0.12%)   126949.11 *   6.53%*   109062.82 *  -8.48%*
Hmean     7   122588.88 (   0.00%)   129802.50 (   5.88%)   119924.66 (  -2.17%)   133372.57 *   8.80%*   110466.18 *  -9.89%*
Hmean     8   127027.63 (   0.00%)   137217.76 *   8.02%*   121329.34 (  -4.49%)   136100.78 (   7.14%)   114071.36 * -10.20%*
Stddev    1      100.77 (   0.00%)      271.37 (-169.31%)      214.02 (-112.39%)      362.58 (-259.82%)      516.53 (-412.61%)
Stddev    3      980.00 (   0.00%)     1264.82 ( -29.06%)     2554.47 (-160.66%)     1549.81 ( -58.14%)      748.72 (  23.60%)
Stddev    5      545.35 (   0.00%)     2910.89 (-433.76%)     1061.32 ( -94.61%)     2250.11 (-312.60%)     2377.12 (-335.89%)
Stddev    7     6082.18 (   0.00%)     9179.69 ( -50.93%)     5486.68 (   9.79%)     3214.60 (  47.15%)     4147.45 (  31.81%)
Stddev    8     6445.70 (   0.00%)      433.52 (  93.27%)     1857.60 (  71.18%)    12837.92 ( -99.17%)     3400.78 (  47.24%)

HVMx2
-----
                     v-HVMx2-v8-HT        v-HVMx2-v8-noHT            HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Hmean     1    30318.06 (   0.00%)     1864.40 * -93.85%*    30194.08 (  -0.41%)     2457.66 * -91.89%*     4940.93 * -83.70%*
Hmean     3    34617.67 (   0.00%)     7414.77 * -78.58%*    33860.02 (  -2.19%)    11209.64 * -67.62%*    23274.26 * -32.77%*
Hmean     5    44382.41 (   0.00%)    11534.71 * -74.01%*    45606.53 (   2.76%)    15984.89 * -63.98%*    38599.75 ( -13.03%)
Hmean     7    65170.13 (   0.00%)    23530.68 * -63.89%*    70754.93 *   8.57%*    23045.58 * -64.64%*    55799.74 * -14.38%*
Hmean     8    85619.81 (   0.00%)    36969.39 * -56.82%*    88529.15 (   3.40%)    36532.64 * -57.33%*    70367.33 * -17.81%*
Stddev    1      532.15 (   0.00%)        3.55 (  99.33%)      214.55 (  59.68%)        2.87 (  99.46%)    13159.62 (-2372.92%)
Stddev    3      520.12 (   0.00%)       66.14 (  87.28%)      440.61 (  15.29%)      179.15 (  65.56%)     4463.14 (-758.09%)
Stddev    5      730.81 (   0.00%)       52.70 (  92.79%)      900.27 ( -23.19%)      161.20 (  77.94%)     6286.95 (-760.27%)
Stddev    7     1851.68 (   0.00%)     1217.81 (  34.23%)      706.22 (  61.86%)      708.81 (  61.72%)     3845.49 (-107.68%)
Stddev    8     2002.34 (   0.00%)      868.00 (  56.65%)     3197.46 ( -59.69%)      818.97 (  59.10%)     4477.51 (-123.61%)


PGIOPERFBENCH
=============
Dom0
----
                               v-XEN-HT             v-XEN-noHT                 XEN-HT               XEN-noHT                XEN-csc
Amean     commit        7.88 (   0.00%)        8.53 (  -8.25%)        8.78 * -11.43%*        7.64 (   3.09%)        8.20 (  -4.04%)
Amean     read          6.85 (   0.00%)        7.30 *  -6.63%*        7.71 * -12.54%*        6.86 (  -0.21%)        7.21 *  -5.30%*
Amean     wal           0.07 (   0.00%)        0.08 * -14.01%*        0.07 (   1.15%)        0.08 * -11.04%*        0.08 (  -6.71%)
Stddev    commit        1.86 (   0.00%)        4.27 (-129.47%)        3.59 ( -92.56%)        1.35 (  27.62%)        3.50 ( -88.00%)
Stddev    read          0.53 (   0.00%)        3.12 (-494.65%)        2.89 (-450.88%)        0.39 (  25.38%)        2.50 (-376.42%)
Stddev    wal           0.05 (   0.00%)        0.04 (   4.58%)        0.05 (  -0.86%)        0.04 (  10.58%)        0.04 (   5.91%)

HVM-v8
------
                            v-HVM-v8-HT          v-HVM-v8-noHT              HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Amean     commit        7.71 (   0.00%)        7.64 (   0.79%)        7.83 (  -1.62%)        7.74 (  -0.44%)        7.68 (   0.28%)
Amean     read          6.96 (   0.00%)        6.88 *   1.12%*        6.97 (  -0.12%)        6.97 (  -0.15%)        6.92 *   0.51%*
Amean     wal           0.04 (   0.00%)        0.00 *  94.25%*        0.04 *  19.02%*        0.01 *  83.68%*        0.07 * -49.56%*
Stddev    commit        1.55 (   0.00%)        1.69 (  -8.82%)        1.60 (  -3.09%)        1.54 (   0.81%)        1.59 (  -2.73%)
Stddev    read          0.61 (   0.00%)        0.81 ( -32.60%)        0.53 (  12.82%)        0.55 (   9.68%)        0.68 ( -11.02%)
Stddev    wal           0.05 (   0.00%)        0.02 (  68.16%)        0.05 (   3.33%)        0.03 (  47.69%)        0.05 (   5.37%)

HVM-v4
------
                            v-HVM-v4-HT          v-HVM-v4-noHT              HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Amean     commit        7.85 (   0.00%)        7.57 (   3.57%)        7.71 (   1.77%)        7.67 (   2.33%)        7.82 (   0.38%)
Amean     read          6.92 (   0.00%)        6.83 *   1.26%*        6.90 (   0.23%)        6.90 (   0.28%)        6.91 (   0.10%)
Amean     wal           0.05 (   0.00%)        0.05 (  -1.47%)        0.07 * -29.63%*        0.05 (   5.48%)        0.04 (  13.85%)
Stddev    commit        1.78 (   0.00%)        1.47 (  17.89%)        1.62 (   8.98%)        1.51 (  15.57%)        1.65 (   7.34%)
Stddev    read          0.61 (   0.00%)        0.53 (  13.75%)        0.55 (   9.47%)        0.66 (  -8.62%)        0.57 (   7.64%)
Stddev    wal           0.05 (   0.00%)        0.05 (   0.07%)        0.05 (   5.86%)        0.05 (  -0.02%)        0.05 (   0.56%)

HVMx2
-----
                          v-HVMx2-v8-HT        v-HVMx2-v8-noHT            HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Amean     commit        7.86 (   0.00%)        8.16 *  -3.81%*        7.94 (  -1.01%)        8.31 *  -5.63%*       10.28 * -30.76%*
Amean     read          7.00 (   0.00%)        7.52 *  -7.32%*        6.98 (   0.30%)        7.91 * -12.85%*        9.47 * -35.17%*
Amean     wal           0.00 (   0.00%)        0.00 (  -2.18%)        0.01 *-231.22%*        0.07 *-1605.80%*        0.24 *-6035.64%*
Stddev    commit        1.63 (   0.00%)        1.43 (  11.96%)        1.75 (  -7.70%)        1.30 (  20.41%)        2.17 ( -33.15%)
Stddev    read          0.62 (   0.00%)        0.69 ( -12.39%)        0.67 (  -8.79%)        0.79 ( -27.80%)        2.21 (-257.25%)
Stddev    wal           0.02 (   0.00%)        0.02 ( -16.40%)        0.03 ( -73.40%)        0.09 (-346.15%)        0.39 (-1907.58%)


NETPERF-UDP
===========
Dom0
----
                                  v-XEN-HT             v-XEN-noHT                 XEN-HT               XEN-noHT                XEN-csc
Hmean     send-64        223.35 (   0.00%)      222.53 (  -0.36%)      220.23 *  -1.39%*      220.12 *  -1.44%*      199.70 * -10.59%*
Hmean     send-256       876.26 (   0.00%)      874.65 (  -0.18%)      863.81 *  -1.42%*      866.59 (  -1.10%)      791.34 *  -9.69%*
Hmean     send-2048     6575.95 (   0.00%)     6595.97 (   0.30%)     6542.13 (  -0.51%)     6568.38 (  -0.12%)     5758.09 * -12.44%*
Hmean     send-8192    20882.75 (   0.00%)    21537.45 *   3.14%*    20999.88 (   0.56%)    21163.69 *   1.35%*    19706.48 *  -5.63%*
Hmean     recv-64        223.35 (   0.00%)      222.52 (  -0.37%)      220.23 *  -1.39%*      220.08 *  -1.46%*      199.70 * -10.59%*
Hmean     recv-256       876.22 (   0.00%)      874.55 (  -0.19%)      863.81 *  -1.42%*      866.47 (  -1.11%)      791.09 *  -9.72%*
Hmean     recv-2048     6575.00 (   0.00%)     6595.64 (   0.31%)     6541.22 (  -0.51%)     6566.75 (  -0.13%)     5757.50 * -12.43%*
Hmean     recv-8192    20881.63 (   0.00%)    21534.73 *   3.13%*    20996.13 (   0.55%)    21157.86 *   1.32%*    19703.65 *  -5.64%*
Stddev    send-64          1.16 (   0.00%)        1.45 ( -25.00%)        0.94 (  19.15%)        1.64 ( -41.40%)       21.30 (-1738.47%)
Stddev    send-256         7.50 (   0.00%)        4.96 (  33.77%)        7.71 (  -2.79%)        8.92 ( -18.97%)       63.89 (-752.31%)
Stddev    send-2048       29.58 (   0.00%)       35.06 ( -18.54%)       57.84 ( -95.56%)       64.88 (-119.37%)      112.05 (-278.84%)
Stddev    send-8192      106.01 (   0.00%)      199.63 ( -88.31%)      172.69 ( -62.90%)      161.66 ( -52.49%)      276.33 (-160.67%)
Stddev    recv-64          1.16 (   0.00%)        1.44 ( -24.28%)        0.94 (  19.15%)        1.62 ( -39.82%)       21.30 (-1738.30%)
Stddev    recv-256         7.50 (   0.00%)        4.94 (  34.09%)        7.70 (  -2.70%)        9.03 ( -20.39%)       64.08 (-754.67%)
Stddev    recv-2048       28.84 (   0.00%)       34.99 ( -21.34%)       56.58 ( -96.20%)       65.80 (-128.14%)      112.00 (-288.34%)
Stddev    recv-8192      105.96 (   0.00%)      201.10 ( -89.80%)      167.07 ( -57.68%)      162.03 ( -52.92%)      276.84 (-161.28%)

HVM-v8
------
                               v-HVM-v8-HT          v-HVM-v8-noHT              HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Hmean     send-64        496.94 (   0.00%)      447.92 *  -9.86%*      518.85 (   4.41%)      487.85 (  -1.83%)      505.10 (   1.64%)
Hmean     send-256      1952.73 (   0.00%)     1720.99 * -11.87%*     1955.77 (   0.16%)     1784.00 *  -8.64%*     1931.18 (  -1.10%)
Hmean     send-2048    13443.20 (   0.00%)    12361.56 *  -8.05%*    12849.78 (  -4.41%)    13027.81 (  -3.09%)    13485.59 (   0.32%)
Hmean     send-8192    37350.97 (   0.00%)    34440.52 *  -7.79%*    37659.20 (   0.83%)    35773.79 *  -4.22%*    35040.88 *  -6.18%*
Hmean     recv-64        495.88 (   0.00%)      447.65 *  -9.73%*      518.32 (   4.52%)      487.76 (  -1.64%)      504.86 (   1.81%)
Hmean     recv-256      1951.43 (   0.00%)     1720.97 * -11.81%*     1954.42 (   0.15%)     1782.90 *  -8.64%*     1930.33 (  -1.08%)
Hmean     recv-2048    13418.66 (   0.00%)    12358.40 *  -7.90%*    12830.91 (  -4.38%)    13018.47 (  -2.98%)    13475.39 (   0.42%)
Hmean     recv-8192    37326.31 (   0.00%)    34420.53 *  -7.78%*    37619.84 (   0.79%)    35768.42 *  -4.17%*    35035.40 *  -6.14%*
Stddev    send-64         15.80 (   0.00%)       11.38 (  27.94%)       29.69 ( -87.96%)        6.43 (  59.29%)       17.36 (  -9.89%)
Stddev    send-256        18.04 (   0.00%)       17.00 (   5.75%)       64.17 (-255.76%)       26.82 ( -48.67%)       33.37 ( -85.02%)
Stddev    send-2048      924.84 (   0.00%)       47.89 (  94.82%)     1342.98 ( -45.21%)      246.21 (  73.38%)      353.97 (  61.73%)
Stddev    send-8192      477.71 (   0.00%)      673.42 ( -40.97%)      224.20 (  53.07%)      467.40 (   2.16%)      928.70 ( -94.41%)
Stddev    recv-64         16.27 (   0.00%)       11.73 (  27.93%)       29.96 ( -84.12%)        6.54 (  59.80%)       17.64 (  -8.43%)
Stddev    recv-256        19.80 (   0.00%)       17.02 (  14.06%)       64.29 (-224.73%)       27.28 ( -37.81%)       34.17 ( -72.59%)
Stddev    recv-2048      948.89 (   0.00%)       48.42 (  94.90%)     1353.73 ( -42.66%)      251.38 (  73.51%)      368.14 (  61.20%)
Stddev    recv-8192      500.51 (   0.00%)      685.63 ( -36.99%)      206.98 (  58.65%)      467.59 (   6.58%)      928.73 ( -85.56%)

HVM-v4
------
                               v-HVM-v4-HT          v-HVM-v4-noHT              HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Hmean     send-64        501.41 (   0.00%)      502.90 (   0.30%)      513.95 (   2.50%)      511.96 *   2.11%*      458.46 *  -8.57%*
Hmean     send-256      1881.72 (   0.00%)     1898.71 (   0.90%)     1928.30 (   2.48%)     1930.57 (   2.60%)     1831.70 (  -2.66%)
Hmean     send-2048    13544.27 (   0.00%)    13626.68 (   0.61%)    13509.70 (  -0.26%)    13802.90 (   1.91%)    12739.81 *  -5.94%*
Hmean     send-8192    36486.91 (   0.00%)    36897.96 (   1.13%)    35966.73 (  -1.43%)    36086.45 (  -1.10%)    35293.89 (  -3.27%)
Hmean     recv-64        501.13 (   0.00%)      502.67 (   0.31%)      513.90 (   2.55%)      511.91 *   2.15%*      458.34 *  -8.54%*
Hmean     recv-256      1880.67 (   0.00%)     1897.95 (   0.92%)     1927.94 (   2.51%)     1930.48 (   2.65%)     1831.50 (  -2.61%)
Hmean     recv-2048    13540.53 (   0.00%)    13623.45 (   0.61%)    13506.19 (  -0.25%)    13799.61 (   1.91%)    12734.53 *  -5.95%*
Hmean     recv-8192    36462.71 (   0.00%)    36888.91 (   1.17%)    35936.42 (  -1.44%)    36069.50 (  -1.08%)    35266.17 (  -3.28%)
Stddev    send-64         11.94 (   0.00%)        7.15 (  40.09%)       12.88 (  -7.85%)        3.89 (  67.41%)       16.11 ( -34.93%)
Stddev    send-256        68.31 (   0.00%)       53.85 (  21.17%)       37.13 (  45.65%)       19.62 (  71.28%)       30.54 (  55.30%)
Stddev    send-2048      310.13 (   0.00%)      314.36 (  -1.36%)       86.00 (  72.27%)      100.64 (  67.55%)      311.99 (  -0.60%)
Stddev    send-8192      443.37 (   0.00%)      260.08 (  41.34%)      926.89 (-109.06%)     1088.50 (-145.50%)     2801.65 (-531.89%)
Stddev    recv-64         12.13 (   0.00%)        7.36 (  39.32%)       12.93 (  -6.59%)        3.96 (  67.34%)       16.15 ( -33.13%)
Stddev    recv-256        69.46 (   0.00%)       54.17 (  22.01%)       37.76 (  45.64%)       19.75 (  71.56%)       30.68 (  55.82%)
Stddev    recv-2048      314.18 (   0.00%)      318.63 (  -1.41%)       88.84 (  71.72%)      100.51 (  68.01%)      313.79 (   0.13%)
Stddev    recv-8192      461.94 (   0.00%)      261.06 (  43.49%)      937.92 (-103.04%)     1098.48 (-137.80%)     2822.43 (-511.00%)

HVMx2
-----
                             v-HVMx2-v8-HT        v-HVMx2-v8-noHT            HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Hmean     send-64        334.22 (   0.00%)      238.90 * -28.52%*      359.65 *   7.61%*      251.84 * -24.65%*      348.95 (   4.41%)
Hmean     send-256      1303.20 (   0.00%)      916.12 * -29.70%*     1376.16 *   5.60%*      969.58 * -25.60%*     1293.19 (  -0.77%)
Hmean     send-2048     9759.14 (   0.00%)     6606.50 * -32.30%*    10212.34 *   4.64%*     6893.41 * -29.36%*     8933.39 *  -8.46%*
Hmean     send-8192    29504.19 (   0.00%)    19067.47 * -35.37%*    30442.79 *   3.18%*    18372.42 * -37.73%*    25486.82 * -13.62%*
Hmean     recv-64        333.71 (   0.00%)      217.71 * -34.76%*      359.01 *   7.58%*      240.67 * -27.88%*      319.95 *  -4.13%*
Hmean     recv-256      1300.47 (   0.00%)      804.88 * -38.11%*     1372.71 *   5.55%*      923.23 * -29.01%*     1206.20 *  -7.25%*
Hmean     recv-2048     9740.73 (   0.00%)     5448.32 * -44.07%*    10185.94 *   4.57%*     6258.59 * -35.75%*     8371.03 * -14.06%*
Hmean     recv-8192    29416.78 (   0.00%)    14566.32 * -50.48%*    30272.47 *   2.91%*    16888.08 * -42.59%*    22719.70 * -22.77%*
Stddev    send-64          8.65 (   0.00%)        6.86 (  20.73%)        6.49 (  25.00%)        7.35 (  14.99%)       18.06 (-108.81%)
Stddev    send-256        35.52 (   0.00%)       10.83 (  69.50%)       29.41 (  17.19%)       15.84 (  55.41%)       25.77 (  27.45%)
Stddev    send-2048      167.61 (   0.00%)       42.08 (  74.89%)       97.12 (  42.06%)      238.24 ( -42.14%)      276.14 ( -64.75%)
Stddev    send-8192      291.17 (   0.00%)      305.17 (  -4.81%)      680.48 (-133.70%)      336.65 ( -15.62%)      482.57 ( -65.73%)
Stddev    recv-64          8.88 (   0.00%)        6.20 (  30.19%)        6.80 (  23.42%)        3.56 (  59.90%)        6.62 (  25.41%)
Stddev    recv-256        35.77 (   0.00%)       10.66 (  70.21%)       31.00 (  13.35%)       10.11 (  71.74%)       14.94 (  58.23%)
Stddev    recv-2048      169.57 (   0.00%)       52.21 (  69.21%)       99.42 (  41.37%)       96.49 (  43.10%)       42.24 (  75.09%)
Stddev    recv-8192      308.98 (   0.00%)      156.60 (  49.32%)      759.75 (-145.89%)      108.46 (  64.90%)      745.22 (-141.18%)


NETPERF-TCP
===========
Dom0
----
                             v-XEN-HT             v-XEN-noHT                 XEN-HT               XEN-noHT                XEN-csc
Hmean     64        674.18 (   0.00%)      674.89 (   0.11%)      677.61 (   0.51%)      679.64 (   0.81%)      660.08 (  -2.09%)
Hmean     256      2424.16 (   0.00%)     2426.14 (   0.08%)     2448.40 *   1.00%*     2443.24 *   0.79%*     2402.64 (  -0.89%)
Hmean     2048    15114.37 (   0.00%)    15273.97 *   1.06%*    15160.59 (   0.31%)    15372.31 *   1.71%*    14591.20 *  -3.46%*
Hmean     8192    32626.11 (   0.00%)    32895.01 (   0.82%)    32056.40 (  -1.75%)    32473.01 (  -0.47%)    32024.74 (  -1.84%)
Stddev    64          5.99 (   0.00%)        3.90 (  34.89%)        5.93 (   0.98%)        6.01 (  -0.40%)       31.04 (-418.30%)
Stddev    256        12.07 (   0.00%)        8.14 (  32.55%)       15.11 ( -25.17%)       18.76 ( -55.37%)       46.90 (-288.51%)
Stddev    2048      106.56 (   0.00%)       35.02 (  67.14%)      180.05 ( -68.97%)       86.00 (  19.29%)      339.19 (-218.32%)
Stddev    8192      649.77 (   0.00%)      123.38 (  81.01%)      329.45 (  49.30%)      448.67 (  30.95%)     1120.36 ( -72.42%)

HVM-v8
------
                          v-HVM-v8-HT          v-HVM-v8-noHT              HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Hmean     64       1682.93 (   0.00%)     1685.11 (   0.13%)     1756.72 *   4.38%*     1687.44 (   0.27%)     1644.27 *  -2.30%*
Hmean     256      6203.93 (   0.00%)     6125.84 *  -1.26%*     6335.31 *   2.12%*     6142.90 *  -0.98%*     5850.62 *  -5.69%*
Hmean     2048    29253.76 (   0.00%)    28671.53 *  -1.99%*    29738.54 *   1.66%*    28871.57 *  -1.31%*    27437.72 *  -6.21%*
Hmean     8192    46374.69 (   0.00%)    45277.03 *  -2.37%*    46926.01 *   1.19%*    46011.63 *  -0.78%*    42627.47 *  -8.08%*
Stddev    64         22.20 (   0.00%)       20.70 (   6.78%)       35.93 ( -61.82%)       13.81 (  37.79%)       14.56 (  34.43%)
Stddev    256        21.74 (   0.00%)       72.01 (-231.20%)      110.09 (-406.36%)       53.63 (-146.70%)      142.11 (-553.63%)
Stddev    2048      286.90 (   0.00%)      147.25 (  48.68%)      172.37 (  39.92%)      189.21 (  34.05%)     1004.81 (-250.23%)
Stddev    8192      259.59 (   0.00%)      232.26 (  10.53%)      453.49 ( -74.70%)      239.72 (   7.65%)     1262.32 (-386.28%)

HVM-v4
------
                          v-HVM-v4-HT          v-HVM-v4-noHT              HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Hmean     64       1685.06 (   0.00%)     1699.80 (   0.87%)     1693.76 (   0.52%)     1681.73 (  -0.20%)     1642.82 *  -2.51%*
Hmean     256      6210.06 (   0.00%)     6134.29 *  -1.22%*     6131.33 *  -1.27%*     6141.35 *  -1.11%*     5977.71 *  -3.74%*
Hmean     2048    28890.04 (   0.00%)    28999.17 (   0.38%)    28965.94 (   0.26%)    28931.03 (   0.14%)    27758.99 (  -3.92%)
Hmean     8192    45729.95 (   0.00%)    45801.43 (   0.16%)    45750.33 (   0.04%)    46037.28 *   0.67%*    46301.78 (   1.25%)
Stddev    64         20.94 (   0.00%)       22.24 (  -6.24%)       20.10 (   4.03%)       10.70 (  48.90%)       45.83 (-118.87%)
Stddev    256        26.43 (   0.00%)       51.40 ( -94.47%)       47.00 ( -77.85%)       32.37 ( -22.46%)       45.15 ( -70.82%)
Stddev    2048      169.64 (   0.00%)      149.97 (  11.60%)      205.29 ( -21.01%)      148.42 (  12.51%)     1950.42 (-1049.71%)
Stddev    8192      227.60 (   0.00%)      116.14 (  48.97%)      515.92 (-126.67%)       62.10 (  72.72%)    11909.19 (-5132.40%)
CoeffVar  64          1.24 (   0.00%)        1.31 (  -5.31%)        1.19 (   4.52%)        0.64 (  48.79%)        2.79 (-124.39%)
CoeffVar  256         0.43 (   0.00%)        0.84 ( -96.86%)        0.77 ( -80.12%)        0.53 ( -23.83%)        0.76 ( -77.46%)
CoeffVar  2048        0.59 (   0.00%)        0.52 (  11.93%)        0.71 ( -20.69%)        0.51 (  12.63%)        7.00 (-1092.17%)
CoeffVar  8192        0.50 (   0.00%)        0.25 (  49.05%)        1.13 (-126.56%)        0.13 (  72.90%)       24.76 (-4875.60%)

HVMx2
-----
                        v-HVMx2-v8-HT        v-HVMx2-v8-noHT            HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Hmean     64       1252.34 (   0.00%)     1020.91 * -18.48%*     1272.66 *   1.62%*      996.12 * -20.46%*      968.44 * -22.67%*
Hmean     256      4369.71 (   0.00%)     3680.51 * -15.77%*     4376.58 (   0.16%)     3565.25 * -18.41%*     4088.77 *  -6.43%*
Hmean     2048    23712.23 (   0.00%)    18259.78 * -22.99%*    24077.77 *   1.54%*    17496.21 * -26.21%*    21709.20 *  -8.45%*
Hmean     8192    43290.16 (   0.00%)    35700.62 * -17.53%*    43332.46 (   0.10%)    32506.09 * -24.91%*    36700.18 * -15.22%*
Stddev    64         13.74 (   0.00%)        3.98 (  71.03%)       13.14 (   4.38%)        3.25 (  76.32%)      221.08 (-1509.09%)
Stddev    256        40.68 (   0.00%)        5.67 (  86.06%)       38.64 (   5.01%)       43.54 (  -7.02%)      316.66 (-678.40%)
Stddev    2048      304.70 (   0.00%)       62.11 (  79.62%)      202.53 (  33.53%)      117.33 (  61.49%)      208.33 (  31.63%)
Stddev    8192      659.30 (   0.00%)      116.45 (  82.34%)      274.71 (  58.33%)      299.39 (  54.59%)      412.99 (  37.36%)


NETPERF-UNIX
============
Dom0
----
                             v-XEN-HT             v-XEN-noHT                 XEN-HT               XEN-noHT                XEN-csc
Hmean     64        499.62 (   0.00%)      509.03 *   1.88%*      492.89 (  -1.35%)      485.34 (  -2.86%)      451.13 *  -9.70%*
Hmean     256      1900.97 (   0.00%)     1894.53 (  -0.34%)     1852.77 (  -2.54%)     1835.34 (  -3.45%)     1272.07 * -33.08%*
Hmean     2048     2892.22 (   0.00%)     2906.15 (   0.48%)     2765.65 *  -4.38%*     2747.32 *  -5.01%*     3086.19 (   6.71%)
Hmean     8192     3105.85 (   0.00%)     3158.33 *   1.69%*     2996.64 *  -3.52%*     2968.85 *  -4.41%*     2731.31 * -12.06%*
Stddev    64          4.49 (   0.00%)        3.39 (  24.38%)       10.64 (-137.15%)       20.01 (-345.94%)       25.28 (-463.31%)
Stddev    256        87.54 (   0.00%)       51.32 (  41.37%)       54.63 (  37.59%)       15.13 (  82.72%)      393.61 (-349.64%)
Stddev    2048       35.26 (   0.00%)       33.35 (   5.41%)       18.20 (  48.39%)        9.37 (  73.41%)      946.82 (-2585.23%)
Stddev    8192       21.32 (   0.00%)       32.53 ( -52.60%)       15.74 (  26.15%)       11.30 (  46.98%)      104.54 (-390.43%)

HVM-v8
------
                          v-HVM-v8-HT          v-HVM-v8-noHT              HVM-v8-HT            HVM-v8-noHT             HVM-v8-csc
Hmean     64        312.04 (   0.00%)      291.15 (  -6.69%)      275.22 ( -11.80%)      288.06 (  -7.68%)      277.23 ( -11.15%)
Hmean     256       853.06 (   0.00%)      929.15 (   8.92%)      977.34 (  14.57%)      877.63 (   2.88%)      761.25 ( -10.76%)
Hmean     2048     5564.16 (   0.00%)     5332.08 (  -4.17%)     4702.72 ( -15.48%)     5819.12 (   4.58%)     5531.96 (  -0.58%)
Hmean     8192     6570.41 (   0.00%)     8275.74 *  25.95%*     5962.89 (  -9.25%)     6462.60 (  -1.64%)     5387.48 ( -18.00%)
Stddev    64         35.97 (   0.00%)       34.70 (   3.53%)       48.37 ( -34.46%)       46.27 ( -28.62%)       59.79 ( -66.21%)
Stddev    256       143.59 (   0.00%)       68.75 (  52.12%)      123.98 (  13.65%)       48.93 (  65.92%)      163.00 ( -13.52%)
Stddev    2048     1182.43 (   0.00%)      842.67 (  28.73%)     1181.41 (   0.09%)      761.99 (  35.56%)      827.15 (  30.05%)
Stddev    8192     1331.69 (   0.00%)     1099.39 (  17.44%)     1708.12 ( -28.27%)     1247.83 (   6.30%)     1065.82 (  19.96%)

HVM-v4
------
                          v-HVM-v4-HT          v-HVM-v4-noHT              HVM-v4-HT            HVM-v4-noHT             HVM-v4-csc
Hmean     64        248.93 (   0.00%)      245.55 (  -1.36%)      225.32 (  -9.49%)      239.36 (  -3.84%)      203.05 * -18.43%*
Hmean     256       717.78 (   0.00%)      741.28 (   3.27%)      707.19 (  -1.48%)      782.19 (   8.97%)      751.77 (   4.74%)
Hmean     2048     4658.71 (   0.00%)     5209.89 (  11.83%)     2719.26 * -41.63%*     4156.29 ( -10.78%)     3624.27 ( -22.20%)
Hmean     8192     4874.84 (   0.00%)     4483.10 (  -8.04%)     4263.18 ( -12.55%)     5724.08 *  17.42%*     3579.16 * -26.58%*
Stddev    64         23.09 (   0.00%)       58.27 (-152.37%)       46.49 (-101.39%)       31.12 ( -34.79%)       11.06 (  52.09%)
Stddev    256       104.17 (   0.00%)      133.06 ( -27.73%)      119.32 ( -14.54%)      130.87 ( -25.62%)       87.78 (  15.74%)
Stddev    2048      417.11 (   0.00%)      521.74 ( -25.09%)     1030.34 (-147.02%)      907.53 (-117.58%)     1715.05 (-311.18%)
Stddev    8192      825.38 (   0.00%)     1426.19 ( -72.79%)      821.15 (   0.51%)      275.68 (  66.60%)     1131.40 ( -37.08%)

HVMx2
-----
                        v-HVMx2-v8-HT        v-HVMx2-v8-noHT            HVMx2-v8-HT          HVMx2-v8-noHT           HVMx2-v8-csc
Hmean     64        230.53 (   0.00%)      148.42 * -35.62%*      243.29 (   5.53%)      165.06 * -28.40%*      188.01 * -18.45%*
Hmean     256       790.90 (   0.00%)      482.51 * -38.99%*      711.91 (  -9.99%)      472.92 * -40.21%*      504.46 * -36.22%*
Hmean     2048     3783.93 (   0.00%)     2172.49 * -42.59%*     3163.60 * -16.39%*     1955.93 * -48.31%*     2880.11 * -23.89%*
Hmean     8192     4051.12 (   0.00%)     2764.79 * -31.75%*     4277.51 (   5.59%)     2377.98 * -41.30%*     3086.59 * -23.81%*
Stddev    64         26.71 (   0.00%)       15.99 (  40.13%)       21.43 (  19.76%)       19.08 (  28.56%)       29.45 ( -10.26%)
Stddev    256       112.58 (   0.00%)       24.49 (  78.25%)       86.25 (  23.39%)       50.56 (  55.09%)      112.78 (  -0.18%)
Stddev    2048      535.34 (   0.00%)      395.47 (  26.13%)      311.30 (  41.85%)      317.03 (  40.78%)      610.38 ( -14.02%)
Stddev    8192      490.41 (   0.00%)      835.97 ( -70.46%)      208.86 (  57.41%)      314.18 (  35.94%)      580.38 ( -18.35%)
Sergey Dyasli July 15, 2019, 2:08 p.m. UTC | #5
On 05/07/2019 14:56, Dario Faggioli wrote:
> On Fri, 2019-07-05 at 14:17 +0100, Sergey Dyasli wrote:
>> 1) This crash is quite likely to happen:
>>
>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.220660] Watchdog timer detects
>> that CPU2 is stuck!
>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.226293] ----[ Xen-4.13.0-
>> 8.0.6-d  x86_64  debug=y   Not tainted ]----
>> [...]
>> [2019-07-04 18:22:47 UTC] (XEN) [ 3425.501989] Xen call trace:
>> [2019-07-04 18:22:47 UTC] (XEN) [
>> 3425.505278]    [<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
>> [2019-07-04 18:22:47 UTC] (XEN) [
>> 3425.511518]    [<ffff82d080208370>] vcpu_pause+0x21/0x23
>> [2019-07-04 18:22:47 UTC] (XEN) [
>> 3425.517326]    [<ffff82d08023e25d>]
>> vcpu_set_periodic_timer+0x27/0x73
>> [2019-07-04 18:22:47 UTC] (XEN) [
>> 3425.524258]    [<ffff82d080209682>] do_vcpu_op+0x2c9/0x668
>> [2019-07-04 18:22:47 UTC] (XEN) [
>> 3425.530238]    [<ffff82d08024f970>] compat_vcpu_op+0x250/0x390
>> [2019-07-04 18:22:47 UTC] (XEN) [
>> 3425.536566]    [<ffff82d080383964>] pv_hypercall+0x364/0x564
>> [2019-07-04 18:22:47 UTC] (XEN) [
>> 3425.542719]    [<ffff82d080385644>] do_entry_int82+0x26/0x2d
>> [2019-07-04 18:22:47 UTC] (XEN) [
>> 3425.548876]    [<ffff82d08038839b>] entry_int82+0xbb/0xc0
>>
> Mmm... vcpu_set_periodic_timer?
> 
> What kernel is this and when does this crash happen?

Hi Dario,

I can easily reproduce this crash using a Debian 7 PV VM (2 vCPUs, 2GB RAM)
which has the following kernel:

# uname -a

Linux localhost 3.2.0-4-amd64 #1 SMP Debian 3.2.78-1 x86_64 GNU/Linux

All I need to do is suspend and resume the VM.

Thanks,
Sergey
Sergey Dyasli July 16, 2019, 3:45 p.m. UTC | #6
On 05/07/2019 14:17, Sergey Dyasli wrote:
> [2019-07-05 00:37:16 UTC] (XEN) [24907.482686] Watchdog timer detects that CPU30 is stuck!
> [2019-07-05 00:37:16 UTC] (XEN) [24907.514180] ----[ Xen-4.13.0-8.0.6-d  x86_64  debug=y   Not tainted ]----
> [2019-07-05 00:37:16 UTC] (XEN) [24907.552070] CPU:    30
> [2019-07-05 00:37:16 UTC] (XEN) [24907.565281] RIP:    e008:[<ffff82d0802406fc>] sched_context_switched+0xaf/0x101
> [2019-07-05 00:37:16 UTC] (XEN) [24907.601232] RFLAGS: 0000000000000202   CONTEXT: hypervisor
> [2019-07-05 00:37:16 UTC] (XEN) [24907.629998] rax: 0000000000000002   rbx: ffff83202782e880   rcx: 000000000000001e
> [2019-07-05 00:37:16 UTC] (XEN) [24907.669651] rdx: ffff83202782e904   rsi: ffff832027823000   rdi: ffff832027823000
> [2019-07-05 00:37:16 UTC] (XEN) [24907.706560] rbp: ffff83403cab7d20   rsp: ffff83403cab7d00   r8:  0000000000000000
> [2019-07-05 00:37:16 UTC] (XEN) [24907.743258] r9:  0000000000000000   r10: 0200200200200200   r11: 0100100100100100
> [2019-07-05 00:37:16 UTC] (XEN) [24907.779940] r12: ffff832027823000   r13: ffff832027823000   r14: ffff83202782e7b0
> [2019-07-05 00:37:16 UTC] (XEN) [24907.816849] r15: ffff83202782e880   cr0: 000000008005003b   cr4: 00000000000426e0
> [2019-07-05 00:37:16 UTC] (XEN) [24907.854125] cr3: 00000000bd8a1000   cr2: 000000001851b798
> [2019-07-05 00:37:16 UTC] (XEN) [24907.881483] fsb: 0000000000000000   gsb: 0000000000000000   gss: 0000000000000000
> [2019-07-05 00:37:16 UTC] (XEN) [24907.918309] ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: 0000   cs: e008
> [2019-07-05 00:37:16 UTC] (XEN) [24907.952619] Xen code around <ffff82d0802406fc> (sched_context_switched+0xaf/0x101):
> [2019-07-05 00:37:16 UTC] (XEN) [24907.990277]  00 00 eb 18 f3 90 8b 02 <85> c0 75 f8 eb 0e 49 8b 7e 30 48 85 ff 74 05 e8
> [2019-07-05 00:37:16 UTC] (XEN) [24908.032393] Xen stack trace from rsp=ffff83403cab7d00:
> [2019-07-05 00:37:16 UTC] (XEN) [24908.061298]    ffff832027823000 ffff832027823000 0000000000000000 ffff83202782e880
> [2019-07-05 00:37:16 UTC] (XEN) [24908.098529]    ffff83403cab7d60 ffff82d0802407c0 0000000000000082 ffff83202782e7c8
> [2019-07-05 00:37:16 UTC] (XEN) [24908.135622]    000000000000001e ffff83202782e7c8 000000000000001e ffff82d080602628
> [2019-07-05 00:37:16 UTC] (XEN) [24908.172671]    ffff83403cab7dc0 ffff82d080240d83 000000000000df99 000000000000001e
> [2019-07-05 00:37:16 UTC] (XEN) [24908.210212]    ffff832027823000 000016a62dc8c6bc 000000fc00000000 000000000000001e
> [2019-07-05 00:37:16 UTC] (XEN) [24908.247181]    ffff83202782e7c8 ffff82d080602628 ffff82d0805da460 000000000000001e
> [2019-07-05 00:37:16 UTC] (XEN) [24908.284279]    ffff83403cab7e60 ffff82d080240ea4 00000002802aecc5 ffff832027823000
> [2019-07-05 00:37:16 UTC] (XEN) [24908.321128]    ffff83202782e7b0 ffff83202782e880 ffff83403cab7e10 ffff82d080273b4e
> [2019-07-05 00:37:16 UTC] (XEN) [24908.358308]    ffff83403cab7e10 ffff82d080242f7f ffff83403cab7e60 ffff82d08024663a
> [2019-07-05 00:37:17 UTC] (XEN) [24908.395662]    ffff83403cab7ea0 ffff82d0802ec32a ffff8340000000ff ffff82d0805bc880
> [2019-07-05 00:37:17 UTC] (XEN) [24908.432376]    ffff82d0805bb980 ffffffffffffffff ffff83403cab7fff 000000000000001e
> [2019-07-05 00:37:17 UTC] (XEN) [24908.469812]    ffff83403cab7e90 ffff82d080242575 0000000000000f00 ffff82d0805bb980
> [2019-07-05 00:37:17 UTC] (XEN) [24908.508373]    000000000000001e ffff82d0806026f0 ffff83403cab7ea0 ffff82d0802425ca
> [2019-07-05 00:37:17 UTC] (XEN) [24908.549856]    ffff83403cab7ef0 ffff82d08027a601 ffff82d080242575 0000001e7ffde000
> [2019-07-05 00:37:17 UTC] (XEN) [24908.588022]    ffff832027823000 ffff832027823000 ffff83127ffde000 ffff83203ffe5000
> [2019-07-05 00:37:17 UTC] (XEN) [24908.625217]    000000000000001e ffff831204092000 ffff83403cab7d78 00000000ffffffed
> [2019-07-05 00:37:17 UTC] (XEN) [24908.662932]    ffffffff81800000 0000000000000000 ffffffff81800000 0000000000000000
> [2019-07-05 00:37:17 UTC] (XEN) [24908.703246]    ffffffff818f4580 ffff880039118848 00000e6a3c4b2698 00000000148900db
> [2019-07-05 00:37:17 UTC] (XEN) [24908.743671]    0000000000000000 ffffffff8101e650 ffffffff8185c3e0 0000000000000000
> [2019-07-05 00:37:17 UTC] (XEN) [24908.781927]    0000000000000000 0000000000000000 0000beef0000beef ffffffff81054eb2
> [2019-07-05 00:37:17 UTC] (XEN) [24908.820986] Xen call trace:
> [2019-07-05 00:37:17 UTC] (XEN) [24908.836789]    [<ffff82d0802406fc>] sched_context_switched+0xaf/0x101
> [2019-07-05 00:37:17 UTC] (XEN) [24908.869916]    [<ffff82d0802407c0>] schedule.c#sched_context_switch+0x72/0x151
> [2019-07-05 00:37:17 UTC] (XEN) [24908.907384]    [<ffff82d080240d83>] schedule.c#sched_slave+0x2a3/0x2b2
> [2019-07-05 00:37:17 UTC] (XEN) [24908.941241]    [<ffff82d080240ea4>] schedule.c#schedule+0x112/0x2a1
> [2019-07-05 00:37:17 UTC] (XEN) [24908.973939]    [<ffff82d080242575>] softirq.c#__do_softirq+0x85/0x90
> [2019-07-05 00:37:17 UTC] (XEN) [24909.007101]    [<ffff82d0802425ca>] do_softirq+0x13/0x15
> [2019-07-05 00:37:17 UTC] (XEN) [24909.035971]    [<ffff82d08027a601>] domain.c#idle_loop+0xad/0xc0
> [2019-07-05 00:37:17 UTC] (XEN) [24909.070546]
> [2019-07-05 00:37:17 UTC] (XEN) [24909.080286] CPU0 @ e008:ffff82d0802431ba (stop_machine.c#stopmachine_wait_state+0x1a/0x24)
> [2019-07-05 00:37:17 UTC] (XEN) [24909.122896] CPU1 @ e008:ffff82d0802406f8 (sched_context_switched+0xab/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.159518] CPU3 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.199607] CPU2 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.235773] CPU5 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.276039] CPU4 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.312371] CPU7 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.352930] CPU6 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.388928] CPU8 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.424664] CPU9 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.465376] CPU10 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.507449] CPU11 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.544703] CPU13 @ e008:ffff82d0802431f2 (stop_machine.c#stopmachine_action+0x2e/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.588884] CPU12 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.625781] CPU15 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.666649] CPU14 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.703396] CPU17 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.744089] CPU16 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.781117] CPU23 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.821692] CPU22 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.858139] CPU27 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
> [2019-07-05 00:37:18 UTC] (XEN) [24909.898704] CPU26 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:19 UTC] (XEN) [24909.936069] CPU19 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:19 UTC] (XEN) [24909.977291] CPU18 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.014078] CPU31 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.055692] CPU21 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.100486] CPU24 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.136824] CPU25 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.177529] CPU29 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.218420] CPU28 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.255219] CPU20 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.292152]
> [2019-07-05 00:37:19 UTC] (XEN) [24910.301667] ****************************************
> [2019-07-05 00:37:19 UTC] (XEN) [24910.327892] Panic on CPU 30:
> [2019-07-05 00:37:19 UTC] (XEN) [24910.344165] FATAL TRAP: vector = 2 (nmi)
> [2019-07-05 00:37:19 UTC] (XEN) [24910.365476] [error_code=0000]
> [2019-07-05 00:37:19 UTC] (XEN) [24910.382509] ****************************************
> [2019-07-05 00:37:19 UTC] (XEN) [24910.408547]
> [2019-07-05 00:37:19 UTC] (XEN) [24910.418129] Reboot in five seconds...

On a closer look, the second crash happens when you try to shutdown
the host ("poweroff" in my case).

Thanks,
Sergey
Jürgen Groß July 18, 2019, 2:48 p.m. UTC | #7
On 15.07.19 16:08, Sergey Dyasli wrote:
> On 05/07/2019 14:56, Dario Faggioli wrote:
>> On Fri, 2019-07-05 at 14:17 +0100, Sergey Dyasli wrote:
>>> 1) This crash is quite likely to happen:
>>>
>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.220660] Watchdog timer detects
>>> that CPU2 is stuck!
>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.226293] ----[ Xen-4.13.0-
>>> 8.0.6-d  x86_64  debug=y   Not tainted ]----
>>> [...]
>>> [2019-07-04 18:22:47 UTC] (XEN) [ 3425.501989] Xen call trace:
>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>> 3425.505278]    [<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>> 3425.511518]    [<ffff82d080208370>] vcpu_pause+0x21/0x23
>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>> 3425.517326]    [<ffff82d08023e25d>]
>>> vcpu_set_periodic_timer+0x27/0x73
>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>> 3425.524258]    [<ffff82d080209682>] do_vcpu_op+0x2c9/0x668
>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>> 3425.530238]    [<ffff82d08024f970>] compat_vcpu_op+0x250/0x390
>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>> 3425.536566]    [<ffff82d080383964>] pv_hypercall+0x364/0x564
>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>> 3425.542719]    [<ffff82d080385644>] do_entry_int82+0x26/0x2d
>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>> 3425.548876]    [<ffff82d08038839b>] entry_int82+0xbb/0xc0
>>>
>> Mmm... vcpu_set_periodic_timer?
>>
>> What kernel is this and when does this crash happen?
> 
> Hi Dario,
> 
> I can easily reproduce this crash using a Debian 7 PV VM (2 vCPUs, 2GB RAM)
> which has the following kernel:
> 
> # uname -a
> 
> Linux localhost 3.2.0-4-amd64 #1 SMP Debian 3.2.78-1 x86_64 GNU/Linux
> 
> All I need to do is suspend and resume the VM.

Happens with a more recent kernel, too.

I can easily reproduce the issue with any PV guest with more than 1 vcpu
by doing "xl save" and then "xl restore" again.

With the reproducer being available I'm now diving into the issue...


Juergen
Sergey Dyasli July 18, 2019, 3:14 p.m. UTC | #8
On 18/07/2019 15:48, Juergen Gross wrote:
> On 15.07.19 16:08, Sergey Dyasli wrote:
>> On 05/07/2019 14:56, Dario Faggioli wrote:
>>> On Fri, 2019-07-05 at 14:17 +0100, Sergey Dyasli wrote:
>>>> 1) This crash is quite likely to happen:
>>>>
>>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.220660] Watchdog timer detects
>>>> that CPU2 is stuck!
>>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.226293] ----[ Xen-4.13.0-
>>>> 8.0.6-d  x86_64  debug=y   Not tainted ]----
>>>> [...]
>>>> [2019-07-04 18:22:47 UTC] (XEN) [ 3425.501989] Xen call trace:
>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>> 3425.505278]    [<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>> 3425.511518]    [<ffff82d080208370>] vcpu_pause+0x21/0x23
>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>> 3425.517326]    [<ffff82d08023e25d>]
>>>> vcpu_set_periodic_timer+0x27/0x73
>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>> 3425.524258]    [<ffff82d080209682>] do_vcpu_op+0x2c9/0x668
>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>> 3425.530238]    [<ffff82d08024f970>] compat_vcpu_op+0x250/0x390
>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>> 3425.536566]    [<ffff82d080383964>] pv_hypercall+0x364/0x564
>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>> 3425.542719]    [<ffff82d080385644>] do_entry_int82+0x26/0x2d
>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>> 3425.548876]    [<ffff82d08038839b>] entry_int82+0xbb/0xc0
>>>>
>>> Mmm... vcpu_set_periodic_timer?
>>>
>>> What kernel is this and when does this crash happen?
>>
>> Hi Dario,
>>
>> I can easily reproduce this crash using a Debian 7 PV VM (2 vCPUs, 2GB RAM)
>> which has the following kernel:
>>
>> # uname -a
>>
>> Linux localhost 3.2.0-4-amd64 #1 SMP Debian 3.2.78-1 x86_64 GNU/Linux
>>
>> All I need to do is suspend and resume the VM.
> 
> Happens with a more recent kernel, too.
> 
> I can easily reproduce the issue with any PV guest with more than 1 vcpu
> by doing "xl save" and then "xl restore" again.
> 
> With the reproducer being available I'm now diving into the issue...

One further thing to add is that I was able to avoid the crash by reverting

	xen/sched: rework and rename vcpu_force_reschedule()

which is a part of the series. This made all tests with PV guests pass.

Another question I have is do you have a git branch with core-scheduling
patches rebased on top of current staging available somewhere?

Thanks,
Sergey
Dario Faggioli July 18, 2019, 4:04 p.m. UTC | #9
On Thu, 2019-07-18 at 16:14 +0100, Sergey Dyasli wrote:
> On 18/07/2019 15:48, Juergen Gross wrote:
> > 
> > I can easily reproduce the issue with any PV guest with more than 1
> > vcpu
> > by doing "xl save" and then "xl restore" again.
> > 
> > With the reproducer being available I'm now diving into the
> > issue...
> 
> One further thing to add is that I was able to avoid the crash by
> reverting
> 
> 	xen/sched: rework and rename vcpu_force_reschedule()
> 
Ah, interesting!

> which is a part of the series. This made all tests with PV guests
> pass.
> 
That's good news. :-)

> Another question I have is do you have a git branch with core-
> scheduling
> patches rebased on top of current staging available somewhere?
> 
For my benchmarks, I used this:

https://github.com/jgross1/xen/tree/sched-v1-rebase

I don't know if Juergen has another one which is even more updated.

Regards
Jürgen Groß July 19, 2019, 5:41 a.m. UTC | #10
On 18.07.19 17:14, Sergey Dyasli wrote:
> On 18/07/2019 15:48, Juergen Gross wrote:
>> On 15.07.19 16:08, Sergey Dyasli wrote:
>>> On 05/07/2019 14:56, Dario Faggioli wrote:
>>>> On Fri, 2019-07-05 at 14:17 +0100, Sergey Dyasli wrote:
>>>>> 1) This crash is quite likely to happen:
>>>>>
>>>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.220660] Watchdog timer detects
>>>>> that CPU2 is stuck!
>>>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.226293] ----[ Xen-4.13.0-
>>>>> 8.0.6-d  x86_64  debug=y   Not tainted ]----
>>>>> [...]
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [ 3425.501989] Xen call trace:
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.505278]    [<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.511518]    [<ffff82d080208370>] vcpu_pause+0x21/0x23
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.517326]    [<ffff82d08023e25d>]
>>>>> vcpu_set_periodic_timer+0x27/0x73
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.524258]    [<ffff82d080209682>] do_vcpu_op+0x2c9/0x668
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.530238]    [<ffff82d08024f970>] compat_vcpu_op+0x250/0x390
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.536566]    [<ffff82d080383964>] pv_hypercall+0x364/0x564
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.542719]    [<ffff82d080385644>] do_entry_int82+0x26/0x2d
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.548876]    [<ffff82d08038839b>] entry_int82+0xbb/0xc0
>>>>>
>>>> Mmm... vcpu_set_periodic_timer?
>>>>
>>>> What kernel is this and when does this crash happen?
>>>
>>> Hi Dario,
>>>
>>> I can easily reproduce this crash using a Debian 7 PV VM (2 vCPUs, 2GB RAM)
>>> which has the following kernel:
>>>
>>> # uname -a
>>>
>>> Linux localhost 3.2.0-4-amd64 #1 SMP Debian 3.2.78-1 x86_64 GNU/Linux
>>>
>>> All I need to do is suspend and resume the VM.
>>
>> Happens with a more recent kernel, too.
>>
>> I can easily reproduce the issue with any PV guest with more than 1 vcpu
>> by doing "xl save" and then "xl restore" again.
>>
>> With the reproducer being available I'm now diving into the issue...
> 
> One further thing to add is that I was able to avoid the crash by reverting
> 
> 	xen/sched: rework and rename vcpu_force_reschedule()
> 
> which is a part of the series. This made all tests with PV guests pass.

Yeah, but removing this patch is just papering over a general issue.
The main problem seems to be a vcpu trying to pause another vcpu of the
same sched_unit. I already have an idea what is really happening, I just
need to verify it.

> Another question I have is do you have a git branch with core-scheduling
> patches rebased on top of current staging available somewhere?

Only the one Dario already mentioned.


Juergen
Jürgen Groß July 19, 2019, 11:24 a.m. UTC | #11
On 19.07.19 07:41, Juergen Gross wrote:
> On 18.07.19 17:14, Sergey Dyasli wrote:
>> On 18/07/2019 15:48, Juergen Gross wrote:
>>> On 15.07.19 16:08, Sergey Dyasli wrote:
>>>> On 05/07/2019 14:56, Dario Faggioli wrote:
>>>>> On Fri, 2019-07-05 at 14:17 +0100, Sergey Dyasli wrote:
>>>>>> 1) This crash is quite likely to happen:
>>>>>>
>>>>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.220660] Watchdog timer detects
>>>>>> that CPU2 is stuck!
>>>>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.226293] ----[ Xen-4.13.0-
>>>>>> 8.0.6-d  x86_64  debug=y   Not tainted ]----
>>>>>> [...]
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [ 3425.501989] Xen call trace:
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>>> 3425.505278]    [<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>>> 3425.511518]    [<ffff82d080208370>] vcpu_pause+0x21/0x23
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>>> 3425.517326]    [<ffff82d08023e25d>]
>>>>>> vcpu_set_periodic_timer+0x27/0x73
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>>> 3425.524258]    [<ffff82d080209682>] do_vcpu_op+0x2c9/0x668
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>>> 3425.530238]    [<ffff82d08024f970>] compat_vcpu_op+0x250/0x390
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>>> 3425.536566]    [<ffff82d080383964>] pv_hypercall+0x364/0x564
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>>> 3425.542719]    [<ffff82d080385644>] do_entry_int82+0x26/0x2d
>>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>>> 3425.548876]    [<ffff82d08038839b>] entry_int82+0xbb/0xc0
>>>>>>
>>>>> Mmm... vcpu_set_periodic_timer?
>>>>>
>>>>> What kernel is this and when does this crash happen?
>>>>
>>>> Hi Dario,
>>>>
>>>> I can easily reproduce this crash using a Debian 7 PV VM (2 vCPUs, 
>>>> 2GB RAM)
>>>> which has the following kernel:
>>>>
>>>> # uname -a
>>>>
>>>> Linux localhost 3.2.0-4-amd64 #1 SMP Debian 3.2.78-1 x86_64 GNU/Linux
>>>>
>>>> All I need to do is suspend and resume the VM.
>>>
>>> Happens with a more recent kernel, too.
>>>
>>> I can easily reproduce the issue with any PV guest with more than 1 vcpu
>>> by doing "xl save" and then "xl restore" again.
>>>
>>> With the reproducer being available I'm now diving into the issue...
>>
>> One further thing to add is that I was able to avoid the crash by 
>> reverting
>>
>>     xen/sched: rework and rename vcpu_force_reschedule()
>>
>> which is a part of the series. This made all tests with PV guests pass.
> 
> Yeah, but removing this patch is just papering over a general issue.
> The main problem seems to be a vcpu trying to pause another vcpu of the
> same sched_unit. I already have an idea what is really happening, I just
> need to verify it.

Was another problem as I thought initially, but I've found it.

xl restore is working now. :-)


Juergen
Jürgen Groß July 19, 2019, 1:35 p.m. UTC | #12
On 16.07.19 17:45, Sergey Dyasli wrote:
> On 05/07/2019 14:17, Sergey Dyasli wrote:
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.482686] Watchdog timer detects that CPU30 is stuck!
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.514180] ----[ Xen-4.13.0-8.0.6-d  x86_64  debug=y   Not tainted ]----
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.552070] CPU:    30
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.565281] RIP:    e008:[<ffff82d0802406fc>] sched_context_switched+0xaf/0x101
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.601232] RFLAGS: 0000000000000202   CONTEXT: hypervisor
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.629998] rax: 0000000000000002   rbx: ffff83202782e880   rcx: 000000000000001e
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.669651] rdx: ffff83202782e904   rsi: ffff832027823000   rdi: ffff832027823000
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.706560] rbp: ffff83403cab7d20   rsp: ffff83403cab7d00   r8:  0000000000000000
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.743258] r9:  0000000000000000   r10: 0200200200200200   r11: 0100100100100100
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.779940] r12: ffff832027823000   r13: ffff832027823000   r14: ffff83202782e7b0
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.816849] r15: ffff83202782e880   cr0: 000000008005003b   cr4: 00000000000426e0
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.854125] cr3: 00000000bd8a1000   cr2: 000000001851b798
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.881483] fsb: 0000000000000000   gsb: 0000000000000000   gss: 0000000000000000
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.918309] ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: 0000   cs: e008
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.952619] Xen code around <ffff82d0802406fc> (sched_context_switched+0xaf/0x101):
>> [2019-07-05 00:37:16 UTC] (XEN) [24907.990277]  00 00 eb 18 f3 90 8b 02 <85> c0 75 f8 eb 0e 49 8b 7e 30 48 85 ff 74 05 e8
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.032393] Xen stack trace from rsp=ffff83403cab7d00:
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.061298]    ffff832027823000 ffff832027823000 0000000000000000 ffff83202782e880
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.098529]    ffff83403cab7d60 ffff82d0802407c0 0000000000000082 ffff83202782e7c8
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.135622]    000000000000001e ffff83202782e7c8 000000000000001e ffff82d080602628
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.172671]    ffff83403cab7dc0 ffff82d080240d83 000000000000df99 000000000000001e
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.210212]    ffff832027823000 000016a62dc8c6bc 000000fc00000000 000000000000001e
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.247181]    ffff83202782e7c8 ffff82d080602628 ffff82d0805da460 000000000000001e
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.284279]    ffff83403cab7e60 ffff82d080240ea4 00000002802aecc5 ffff832027823000
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.321128]    ffff83202782e7b0 ffff83202782e880 ffff83403cab7e10 ffff82d080273b4e
>> [2019-07-05 00:37:16 UTC] (XEN) [24908.358308]    ffff83403cab7e10 ffff82d080242f7f ffff83403cab7e60 ffff82d08024663a
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.395662]    ffff83403cab7ea0 ffff82d0802ec32a ffff8340000000ff ffff82d0805bc880
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.432376]    ffff82d0805bb980 ffffffffffffffff ffff83403cab7fff 000000000000001e
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.469812]    ffff83403cab7e90 ffff82d080242575 0000000000000f00 ffff82d0805bb980
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.508373]    000000000000001e ffff82d0806026f0 ffff83403cab7ea0 ffff82d0802425ca
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.549856]    ffff83403cab7ef0 ffff82d08027a601 ffff82d080242575 0000001e7ffde000
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.588022]    ffff832027823000 ffff832027823000 ffff83127ffde000 ffff83203ffe5000
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.625217]    000000000000001e ffff831204092000 ffff83403cab7d78 00000000ffffffed
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.662932]    ffffffff81800000 0000000000000000 ffffffff81800000 0000000000000000
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.703246]    ffffffff818f4580 ffff880039118848 00000e6a3c4b2698 00000000148900db
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.743671]    0000000000000000 ffffffff8101e650 ffffffff8185c3e0 0000000000000000
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.781927]    0000000000000000 0000000000000000 0000beef0000beef ffffffff81054eb2
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.820986] Xen call trace:
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.836789]    [<ffff82d0802406fc>] sched_context_switched+0xaf/0x101
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.869916]    [<ffff82d0802407c0>] schedule.c#sched_context_switch+0x72/0x151
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.907384]    [<ffff82d080240d83>] schedule.c#sched_slave+0x2a3/0x2b2
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.941241]    [<ffff82d080240ea4>] schedule.c#schedule+0x112/0x2a1
>> [2019-07-05 00:37:17 UTC] (XEN) [24908.973939]    [<ffff82d080242575>] softirq.c#__do_softirq+0x85/0x90
>> [2019-07-05 00:37:17 UTC] (XEN) [24909.007101]    [<ffff82d0802425ca>] do_softirq+0x13/0x15
>> [2019-07-05 00:37:17 UTC] (XEN) [24909.035971]    [<ffff82d08027a601>] domain.c#idle_loop+0xad/0xc0
>> [2019-07-05 00:37:17 UTC] (XEN) [24909.070546]
>> [2019-07-05 00:37:17 UTC] (XEN) [24909.080286] CPU0 @ e008:ffff82d0802431ba (stop_machine.c#stopmachine_wait_state+0x1a/0x24)
>> [2019-07-05 00:37:17 UTC] (XEN) [24909.122896] CPU1 @ e008:ffff82d0802406f8 (sched_context_switched+0xab/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.159518] CPU3 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.199607] CPU2 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.235773] CPU5 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.276039] CPU4 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.312371] CPU7 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.352930] CPU6 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.388928] CPU8 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.424664] CPU9 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.465376] CPU10 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.507449] CPU11 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.544703] CPU13 @ e008:ffff82d0802431f2 (stop_machine.c#stopmachine_action+0x2e/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.588884] CPU12 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.625781] CPU15 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.666649] CPU14 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.703396] CPU17 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.744089] CPU16 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.781117] CPU23 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.821692] CPU22 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.858139] CPU27 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
>> [2019-07-05 00:37:18 UTC] (XEN) [24909.898704] CPU26 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:19 UTC] (XEN) [24909.936069] CPU19 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:19 UTC] (XEN) [24909.977291] CPU18 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.014078] CPU31 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.055692] CPU21 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.100486] CPU24 @ e008:ffff82d0802406fa (sched_context_switched+0xad/0x101)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.136824] CPU25 @ e008:ffff82d0802431fa (stop_machine.c#stopmachine_action+0x36/0xa0)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.177529] CPU29 @ e008:ffff82d0802431f4 (stop_machine.c#stopmachine_action+0x30/0xa0)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.218420] CPU28 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.255219] CPU20 @ e008:ffff82d0802406fc (sched_context_switched+0xaf/0x101)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.292152]
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.301667] ****************************************
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.327892] Panic on CPU 30:
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.344165] FATAL TRAP: vector = 2 (nmi)
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.365476] [error_code=0000]
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.382509] ****************************************
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.408547]
>> [2019-07-05 00:37:19 UTC] (XEN) [24910.418129] Reboot in five seconds...
> 
> On a closer look, the second crash happens when you try to shutdown
> the host ("poweroff" in my case).

And that was just another bug: the scheduler is still active when
trying to enter ACPI deep sleep states. As non-boot cpus are being
taken down via tasklets this will result in syncing problems when
one cpu of a sched_resource is down already and the other is waiting
for it to finish scheduling...

Replacing the common scheuling softirq handler with one doing only
tasklet scheduling in that case makes it work again.


Juergen
Jürgen Groß July 19, 2019, 1:57 p.m. UTC | #13
On 18.07.19 17:14, Sergey Dyasli wrote:
> On 18/07/2019 15:48, Juergen Gross wrote:
>> On 15.07.19 16:08, Sergey Dyasli wrote:
>>> On 05/07/2019 14:56, Dario Faggioli wrote:
>>>> On Fri, 2019-07-05 at 14:17 +0100, Sergey Dyasli wrote:
>>>>> 1) This crash is quite likely to happen:
>>>>>
>>>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.220660] Watchdog timer detects
>>>>> that CPU2 is stuck!
>>>>> [2019-07-04 18:22:46 UTC] (XEN) [ 3425.226293] ----[ Xen-4.13.0-
>>>>> 8.0.6-d  x86_64  debug=y   Not tainted ]----
>>>>> [...]
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [ 3425.501989] Xen call trace:
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.505278]    [<ffff82d08023d578>] vcpu_sleep_sync+0x50/0x71
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.511518]    [<ffff82d080208370>] vcpu_pause+0x21/0x23
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.517326]    [<ffff82d08023e25d>]
>>>>> vcpu_set_periodic_timer+0x27/0x73
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.524258]    [<ffff82d080209682>] do_vcpu_op+0x2c9/0x668
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.530238]    [<ffff82d08024f970>] compat_vcpu_op+0x250/0x390
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.536566]    [<ffff82d080383964>] pv_hypercall+0x364/0x564
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.542719]    [<ffff82d080385644>] do_entry_int82+0x26/0x2d
>>>>> [2019-07-04 18:22:47 UTC] (XEN) [
>>>>> 3425.548876]    [<ffff82d08038839b>] entry_int82+0xbb/0xc0
>>>>>
>>>> Mmm... vcpu_set_periodic_timer?
>>>>
>>>> What kernel is this and when does this crash happen?
>>>
>>> Hi Dario,
>>>
>>> I can easily reproduce this crash using a Debian 7 PV VM (2 vCPUs, 2GB RAM)
>>> which has the following kernel:
>>>
>>> # uname -a
>>>
>>> Linux localhost 3.2.0-4-amd64 #1 SMP Debian 3.2.78-1 x86_64 GNU/Linux
>>>
>>> All I need to do is suspend and resume the VM.
>>
>> Happens with a more recent kernel, too.
>>
>> I can easily reproduce the issue with any PV guest with more than 1 vcpu
>> by doing "xl save" and then "xl restore" again.
>>
>> With the reproducer being available I'm now diving into the issue...
> 
> One further thing to add is that I was able to avoid the crash by reverting
> 
> 	xen/sched: rework and rename vcpu_force_reschedule()
> 
> which is a part of the series. This made all tests with PV guests pass.
> 
> Another question I have is do you have a git branch with core-scheduling
> patches rebased on top of current staging available somewhere?

I have now a git branch with the two problems corrected and rebased to
current staging available:

github.com/jgross1/xen.git sched-v1b


Juergen
Sergey Dyasli July 22, 2019, 2:22 p.m. UTC | #14
On 19/07/2019 14:57, Juergen Gross wrote:

> I have now a git branch with the two problems corrected and rebased to
> current staging available:
> 
> github.com/jgross1/xen.git sched-v1b

Many thanks for the branch! As for the crashes, vcpu_sleep_sync() one
seems to be fixed now. But I can still reproduce the shutdown one.
Interestingly, it now happens only if a host has running VMs (which
are automatically powered off via PV tools):

(XEN) [  332.981355] Preparing system for ACPI S5 state.
(XEN) [  332.981419] Disabling non-boot CPUs ...
(XEN) [  337.703896] Watchdog timer detects that CPU1 is stuck!
(XEN) [  337.709532] ----[ Xen-4.13.0-8.0.6-d  x86_64  debug=y   Not tainted ]----
(XEN) [  337.716808] CPU:    1
(XEN) [  337.719582] RIP:    e008:[<ffff82d08024041c>] sched_context_switched+0xaf/0x101
(XEN) [  337.727384] RFLAGS: 0000000000000202   CONTEXT: hypervisor
(XEN) [  337.733364] rax: 0000000000000002   rbx: ffff83081cc615b0   rcx: 0000000000000001
(XEN) [  337.741338] rdx: ffff83081cc61634   rsi: ffff83081cc72000   rdi: ffff83081cc72000
(XEN) [  337.749312] rbp: ffff83081cc8fdc0   rsp: ffff83081cc8fda0   r8:  0000000000000000
(XEN) [  337.757284] r9:  0000000000000000   r10: 0000004d88fc535e   r11: 0000004df8675ce7
(XEN) [  337.765256] r12: ffff83081cc72000   r13: ffff83081cc72000   r14: ffff83081ccb0e80
(XEN) [  337.773232] r15: ffff83081cc615b0   cr0: 000000008005003b   cr4: 00000000001526e0
(XEN) [  337.781206] cr3: 00000000dd2a1000   cr2: ffff88809ed1fb80
(XEN) [  337.787100] fsb: 0000000000000000   gsb: ffff8880a38c0000   gss: 0000000000000000
(XEN) [  337.795072] ds: 002b   es: 002b   fs: 0000   gs: 0000   ss: e010   cs: e008
(XEN) [  337.802525] Xen code around <ffff82d08024041c> (sched_context_switched+0xaf/0x101):
(XEN) [  337.810672]  00 00 eb 18 f3 90 8b 02 <85> c0 75 f8 eb 0e 49 8b 7e 30 48 85 ff 74 05 e8
(XEN) [  337.819080] Xen stack trace from rsp=ffff83081cc8fda0:
(XEN) [  337.824713]    ffff83081cc72000 ffff83081cc72000 0000000000000000 ffff83081cc615b0
(XEN) [  337.832772]    ffff83081cc8fe00 ffff82d0802404e0 0000000000000082 ffff83081ccb0e98
(XEN) [  337.840832]    0000000000000001 ffff83081ccb0e98 0000000000000001 ffff82d080602628
(XEN) [  337.848895]    ffff83081cc8fe60 ffff82d080240aca 0000004d873bd669 0000000000000001
(XEN) [  337.856952]    ffff83081cc72000 0000004d873bdc1c ffff8308000000ff ffff82d0805bba00
(XEN) [  337.865012]    ffff82d0805bb980 ffffffffffffffff ffff83081cc8ffff 0000000000000001
(XEN) [  337.873072]    ffff83081cc8fe90 ffff82d080242315 0000000000000080 ffff82d0805bb980
(XEN) [  337.881132]    0000000000000001 ffff82d0806026f0 ffff83081cc8fea0 ffff82d08024236a
(XEN) [  337.889196]    ffff83081cc8fef0 ffff82d08027a151 ffff82d080242315 000000010665f000
(XEN) [  337.897256]    ffff83081cc72000 ffff83081cc72000 ffff83080665f000 ffff83081cc63000
(XEN) [  337.905313]    0000000000000001 ffff830806684000 ffff83081cc8fd78 ffff88809ee08000
(XEN) [  337.913373]    ffff88809ee08000 0000000000000000 0000000000000000 0000000000000003
(XEN) [  337.921434]    ffff88809ee08000 0000000000000246 aaaaaaaaaaaaaaaa 0000000000000000
(XEN) [  337.929497]    0000000096968abe 0000000000000000 ffffffff810013aa ffffffff8203c190
(XEN) [  337.937554]    deadbeefdeadf00d deadbeefdeadf00d 0000010000000000 ffffffff810013aa
(XEN) [  337.945615]    000000000000e033 0000000000000246 ffffc900400afeb0 000000000000e02b
(XEN) [  337.953674]    000000000000beef 000000000000beef 000000000000beef 000000000000beef
(XEN) [  337.961736]    0000e01000000001 ffff83081cc72000 000000379c66db80 00000000001526e0
(XEN) [  337.969797]    0000000000000000 0000000000000000 0000060000000000 0000000000000000
(XEN) [  337.977856] Xen call trace:
(XEN) [  337.981152]    [<ffff82d08024041c>] sched_context_switched+0xaf/0x101
(XEN) [  337.988083]    [<ffff82d0802404e0>] schedule.c#sched_context_switch+0x72/0x151
(XEN) [  337.995796]    [<ffff82d080240aca>] schedule.c#sched_slave+0x2a3/0x2b2
(XEN) [  338.002817]    [<ffff82d080242315>] softirq.c#__do_softirq+0x85/0x90
(XEN) [  338.009664]    [<ffff82d08024236a>] do_softirq+0x13/0x15
(XEN) [  338.015471]    [<ffff82d08027a151>] domain.c#idle_loop+0xb2/0xc9
(XEN) [  338.021970]
(XEN) [  338.023965] CPU7 @ e008:ffff82d080242f94 (stop_machine.c#stopmachine_action+0x30/0xa0)
(XEN) [  338.032372] CPU5 @ e008:ffff82d080242f94 (stop_machine.c#stopmachine_action+0x30/0xa0)
(XEN) [  338.040776] CPU4 @ e008:ffff82d080242f94 (stop_machine.c#stopmachine_action+0x30/0xa0)
(XEN) [  338.049182] CPU2 @ e008:ffff82d080242f9a (stop_machine.c#stopmachine_action+0x36/0xa0)
(XEN) [  338.057591] CPU6 @ e008:ffff82d080242f9a (stop_machine.c#stopmachine_action+0x36/0xa0)
(XEN) [  338.065999] CPU3 @ e008:ffff82d080242f9a (stop_machine.c#stopmachine_action+0x36/0xa0)
(XEN) [  338.074406] CPU0 @ e008:ffff82d0802532d1 (ns16550.c#ns_read_reg+0x21/0x42)
(XEN) [  338.081773]
(XEN) [  338.083764] ****************************************
(XEN) [  338.089226] Panic on CPU 1:
(XEN) [  338.092521] FATAL TRAP: vector = 2 (nmi)
(XEN) [  338.096940] [error_code=0000]
(XEN) [  338.100491] ****************************************
(XEN) [  338.105951]
(XEN) [  338.107946] Reboot in five seconds...
(XEN) [  338.112105] Executing kexec image on cpu1
(XEN) [  338.117383] Shot down all CPUs

And since Igor managed to fix kdump, I can now post backtraces from
all CPUs as well: https://paste.debian.net/1092609/

Thanks,
Sergey
Jürgen Groß July 24, 2019, 9:13 a.m. UTC | #15
On 22.07.19 16:22, Sergey Dyasli wrote:
> On 19/07/2019 14:57, Juergen Gross wrote:
> 
>> I have now a git branch with the two problems corrected and rebased to
>> current staging available:
>>
>> github.com/jgross1/xen.git sched-v1b
> 
> Many thanks for the branch! As for the crashes, vcpu_sleep_sync() one
> seems to be fixed now. But I can still reproduce the shutdown one.
> Interestingly, it now happens only if a host has running VMs (which
> are automatically powered off via PV tools):
> 
> (XEN) [  332.981355] Preparing system for ACPI S5 state.
> (XEN) [  332.981419] Disabling non-boot CPUs ...
> (XEN) [  337.703896] Watchdog timer detects that CPU1 is stuck!
> (XEN) [  337.709532] ----[ Xen-4.13.0-8.0.6-d  x86_64  debug=y   Not tainted ]----
> (XEN) [  337.716808] CPU:    1
> (XEN) [  337.719582] RIP:    e008:[<ffff82d08024041c>] sched_context_switched+0xaf/0x101
> (XEN) [  337.727384] RFLAGS: 0000000000000202   CONTEXT: hypervisor
> (XEN) [  337.733364] rax: 0000000000000002   rbx: ffff83081cc615b0   rcx: 0000000000000001
> (XEN) [  337.741338] rdx: ffff83081cc61634   rsi: ffff83081cc72000   rdi: ffff83081cc72000
> (XEN) [  337.749312] rbp: ffff83081cc8fdc0   rsp: ffff83081cc8fda0   r8:  0000000000000000
> (XEN) [  337.757284] r9:  0000000000000000   r10: 0000004d88fc535e   r11: 0000004df8675ce7
> (XEN) [  337.765256] r12: ffff83081cc72000   r13: ffff83081cc72000   r14: ffff83081ccb0e80
> (XEN) [  337.773232] r15: ffff83081cc615b0   cr0: 000000008005003b   cr4: 00000000001526e0
> (XEN) [  337.781206] cr3: 00000000dd2a1000   cr2: ffff88809ed1fb80
> (XEN) [  337.787100] fsb: 0000000000000000   gsb: ffff8880a38c0000   gss: 0000000000000000
> (XEN) [  337.795072] ds: 002b   es: 002b   fs: 0000   gs: 0000   ss: e010   cs: e008
> (XEN) [  337.802525] Xen code around <ffff82d08024041c> (sched_context_switched+0xaf/0x101):
> (XEN) [  337.810672]  00 00 eb 18 f3 90 8b 02 <85> c0 75 f8 eb 0e 49 8b 7e 30 48 85 ff 74 05 e8
> (XEN) [  337.819080] Xen stack trace from rsp=ffff83081cc8fda0:
> (XEN) [  337.824713]    ffff83081cc72000 ffff83081cc72000 0000000000000000 ffff83081cc615b0
> (XEN) [  337.832772]    ffff83081cc8fe00 ffff82d0802404e0 0000000000000082 ffff83081ccb0e98
> (XEN) [  337.840832]    0000000000000001 ffff83081ccb0e98 0000000000000001 ffff82d080602628
> (XEN) [  337.848895]    ffff83081cc8fe60 ffff82d080240aca 0000004d873bd669 0000000000000001
> (XEN) [  337.856952]    ffff83081cc72000 0000004d873bdc1c ffff8308000000ff ffff82d0805bba00
> (XEN) [  337.865012]    ffff82d0805bb980 ffffffffffffffff ffff83081cc8ffff 0000000000000001
> (XEN) [  337.873072]    ffff83081cc8fe90 ffff82d080242315 0000000000000080 ffff82d0805bb980
> (XEN) [  337.881132]    0000000000000001 ffff82d0806026f0 ffff83081cc8fea0 ffff82d08024236a
> (XEN) [  337.889196]    ffff83081cc8fef0 ffff82d08027a151 ffff82d080242315 000000010665f000
> (XEN) [  337.897256]    ffff83081cc72000 ffff83081cc72000 ffff83080665f000 ffff83081cc63000
> (XEN) [  337.905313]    0000000000000001 ffff830806684000 ffff83081cc8fd78 ffff88809ee08000
> (XEN) [  337.913373]    ffff88809ee08000 0000000000000000 0000000000000000 0000000000000003
> (XEN) [  337.921434]    ffff88809ee08000 0000000000000246 aaaaaaaaaaaaaaaa 0000000000000000
> (XEN) [  337.929497]    0000000096968abe 0000000000000000 ffffffff810013aa ffffffff8203c190
> (XEN) [  337.937554]    deadbeefdeadf00d deadbeefdeadf00d 0000010000000000 ffffffff810013aa
> (XEN) [  337.945615]    000000000000e033 0000000000000246 ffffc900400afeb0 000000000000e02b
> (XEN) [  337.953674]    000000000000beef 000000000000beef 000000000000beef 000000000000beef
> (XEN) [  337.961736]    0000e01000000001 ffff83081cc72000 000000379c66db80 00000000001526e0
> (XEN) [  337.969797]    0000000000000000 0000000000000000 0000060000000000 0000000000000000
> (XEN) [  337.977856] Xen call trace:
> (XEN) [  337.981152]    [<ffff82d08024041c>] sched_context_switched+0xaf/0x101
> (XEN) [  337.988083]    [<ffff82d0802404e0>] schedule.c#sched_context_switch+0x72/0x151
> (XEN) [  337.995796]    [<ffff82d080240aca>] schedule.c#sched_slave+0x2a3/0x2b2
> (XEN) [  338.002817]    [<ffff82d080242315>] softirq.c#__do_softirq+0x85/0x90
> (XEN) [  338.009664]    [<ffff82d08024236a>] do_softirq+0x13/0x15
> (XEN) [  338.015471]    [<ffff82d08027a151>] domain.c#idle_loop+0xb2/0xc9
> (XEN) [  338.021970]
> (XEN) [  338.023965] CPU7 @ e008:ffff82d080242f94 (stop_machine.c#stopmachine_action+0x30/0xa0)
> (XEN) [  338.032372] CPU5 @ e008:ffff82d080242f94 (stop_machine.c#stopmachine_action+0x30/0xa0)
> (XEN) [  338.040776] CPU4 @ e008:ffff82d080242f94 (stop_machine.c#stopmachine_action+0x30/0xa0)
> (XEN) [  338.049182] CPU2 @ e008:ffff82d080242f9a (stop_machine.c#stopmachine_action+0x36/0xa0)
> (XEN) [  338.057591] CPU6 @ e008:ffff82d080242f9a (stop_machine.c#stopmachine_action+0x36/0xa0)
> (XEN) [  338.065999] CPU3 @ e008:ffff82d080242f9a (stop_machine.c#stopmachine_action+0x36/0xa0)
> (XEN) [  338.074406] CPU0 @ e008:ffff82d0802532d1 (ns16550.c#ns_read_reg+0x21/0x42)
> (XEN) [  338.081773]
> (XEN) [  338.083764] ****************************************
> (XEN) [  338.089226] Panic on CPU 1:
> (XEN) [  338.092521] FATAL TRAP: vector = 2 (nmi)
> (XEN) [  338.096940] [error_code=0000]
> (XEN) [  338.100491] ****************************************
> (XEN) [  338.105951]
> (XEN) [  338.107946] Reboot in five seconds...
> (XEN) [  338.112105] Executing kexec image on cpu1
> (XEN) [  338.117383] Shot down all CPUs
> 
> And since Igor managed to fix kdump, I can now post backtraces from
> all CPUs as well: https://paste.debian.net/1092609/

Thanks for the test (and report).

The fix is a one-liner. :-)

diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index f0bc5b3161..da9efb147f 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -2207,6 +2207,7 @@ static struct sched_unit 
*sched_wait_rendezvous_in(struct sched_unit *prev,
          if ( unlikely(!scheduler_active) )
          {
              ASSERT(is_idle_unit(prev));
+            atomic_set(&prev->next_task->rendezvous_out_cnt, 0);
              prev->rendezvous_in_cnt = 0;
          }
      }


Juergen
Sergey Dyasli July 24, 2019, 2:54 p.m. UTC | #16
On 24/07/2019 10:13, Juergen Gross wrote:
> The fix is a one-liner. :-)
> 
> diff --git a/xen/common/schedule.c b/xen/common/schedule.c
> index f0bc5b3161..da9efb147f 100644
> --- a/xen/common/schedule.c
> +++ b/xen/common/schedule.c
> @@ -2207,6 +2207,7 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
>          if ( unlikely(!scheduler_active) )
>          {
>              ASSERT(is_idle_unit(prev));
> +            atomic_set(&prev->next_task->rendezvous_out_cnt, 0);
>              prev->rendezvous_in_cnt = 0;
>          }
>      }

Even with that applied, I'm still seeing it :(

(XEN) [  311.223780] Watchdog timer detects that CPU1 is stuck!

(XEN) [  311.229413] ----[ Xen-4.13.0  x86_64  debug=y   Not tainted ]----

(XEN) [  311.236002] CPU:    1

(XEN) [  311.238774] RIP:    e008:[<ffff82d0802408a8>] sched_context_switched+0x92/0x101

(XEN) [  311.246575] RFLAGS: 0000000000000202   CONTEXT: hypervisor

(XEN) [  311.252556] rax: 0000000000000002   rbx: ffff83081cc635b0   rcx: 0000000000000001

(XEN) [  311.260530] rdx: ffff83081cc63634   rsi: ffff83081cc8f000   rdi: ffff83081cc8f000

(XEN) [  311.268502] rbp: ffff83081cc87df0   rsp: ffff83081cc87dd0   r8:  0000000000000000

(XEN) [  311.276474] r9:  ffff83081cc62000   r10: ffff83081cc62000   r11: ffff83081cc6b000

(XEN) [  311.284448] r12: ffff83081cc8f000   r13: ffff83081cc8f000   r14: ffff83081cc61e80

(XEN) [  311.292422] r15: ffff82d0805e2260   cr0: 000000008005003b   cr4: 00000000001526e0

(XEN) [  311.300395] cr3: 00000000dd4ac000   cr2: 0000559b05a94048

(XEN) [  311.306288] fsb: 0000000000000000   gsb: ffff8880a3940000   gss: 0000000000000000

(XEN) [  311.314262] ds: 002b   es: 002b   fs: 0000   gs: 0000   ss: e010   cs: e008

(XEN) [  311.321716] Xen code around <ffff82d0802408a8> (sched_context_switched+0x92/0x101):

(XEN) [  311.329862]  85 c0 74 08 f3 90 8b 02 <85> c0 75 f8 49 8b 44 24 10 66 81 38 ff 7f 75 05

(XEN) [  311.338269] Xen stack trace from rsp=ffff83081cc87dd0:

(XEN) [  311.343904]    ffff83081cc8f000 ffff83081cc8f000 0000000000000000 ffff83081cc635b0

(XEN) [  311.351963]    ffff83081cc87e28 ffff82d080240996 ffff83081cc61e98 ffff82d08060a4a8

(XEN) [  311.360022]    ffff83081cc61e98 ffff82d08060a4a8 ffff83081cc635b0 ffff83081cc87e80

(XEN) [  311.368083]    ffff82d080240f7a 0000000000000001 ffff83081cc8f000 00000047588837ec

(XEN) [  311.376142]    000000011cc87ec0 ffff82d0805c3a00 ffff82d0805c3980 ffffffffffffffff

(XEN) [  311.384205]    ffff82d0805d3980 ffff82d0805e2260 ffff83081cc87eb0 ffff82d08024274a

(XEN) [  311.392263]    0000000000000001 ffff82d0805c3a00 0000000000000001 0000000000000001

(XEN) [  311.400324]    ffff83081cc87ec0 ffff82d0802427bf ffff83081cc87ef0 ffff82d080279a1d

(XEN) [  311.408385]    ffff83081cc8f000 ffff83081cc8f000 0000000000000001 ffff83081cc635b0

(XEN) [  311.416443]    ffff83081cc87df0 ffff88809ee1ba00 ffff88809ee1ba00 0000000000000000

(XEN) [  311.424504]    0000000000000000 0000000000000005 ffff88809ee1ba00 0000000000000246

(XEN) [  311.432563]    aaaaaaaaaaaaaaaa 0000000000000000 000000000001ca00 0000000000000000

(XEN) [  311.440625]    ffffffff810013aa ffffffff8203c190 deadbeefdeadf00d deadbeefdeadf00d

(XEN) [  311.448685]    0000010000000000 ffffffff810013aa 000000000000e033 0000000000000246

(XEN) [  311.456747]    ffffc900400bfeb0 000000000000e02b 000000000000beef 000000000000beef

(XEN) [  311.464807]    000000000000beef 000000000000beef 0000e01000000001 ffff83081cc8f000

(XEN) [  311.472864]    000000379c665d00 00000000001526e0 0000000000000000 0000000000000000

(XEN) [  311.480926]    0000060000000000 0000000000000000

(XEN) [  311.486041] Xen call trace:

(XEN) [  311.489332]    [<ffff82d0802408a8>] sched_context_switched+0x92/0x101

(XEN) [  311.496266]    [<ffff82d080240996>] schedule.c#sched_context_switch+0x7f/0x160

(XEN) [  311.503980]    [<ffff82d080240f7a>] schedule.c#sched_slave+0x28f/0x2b5

(XEN) [  311.510999]    [<ffff82d08024274a>] softirq.c#__do_softirq+0x61/0x8c

(XEN) [  311.517846]    [<ffff82d0802427bf>] do_softirq+0x13/0x15

(XEN) [  311.523653]    [<ffff82d080279a1d>] domain.c#idle_loop+0x52/0xa7

(XEN) [  311.530152]

(XEN) [  311.532144] CPU0 @ e008:ffff82d08024334d (stop_machine.c#stopmachine_wait_state+0x19/0x24)

(XEN) [  311.540899] CPU5 @ e008:ffff82d080243398 (stop_machine.c#stopmachine_action+0x40/0x93)

(XEN) [  311.549307] CPU3 @ e008:ffff82d08024339e (stop_machine.c#stopmachine_action+0x46/0x93)

(XEN) [  311.557712] CPU4 @ e008:ffff82d08024339e (stop_machine.c#stopmachine_action+0x46/0x93)

(XEN) [  311.566119] CPU7 @ e008:ffff82d08024339e (stop_machine.c#stopmachine_action+0x46/0x93)

(XEN) [  311.574526] CPU2 @ e008:ffff82d080243398 (stop_machine.c#stopmachine_action+0x40/0x93)

(XEN) [  311.582931] CPU6 @ e008:ffff82d080243398 (stop_machine.c#stopmachine_action+0x40/0x93)

(XEN) [  311.591919]

(XEN) [  311.593914] ****************************************

(XEN) [  311.599374] Panic on CPU 1:

(XEN) [  311.602669] FATAL TRAP: vector = 2 (nmi)

(XEN) [  311.607088] [error_code=0000]

(XEN) [  311.610641] ****************************************

(XEN) [  311.616101]

(XEN) [  311.618095] Reboot in five seconds...

(XEN) [  311.622254] Executing kexec image on cpu1

(XEN) [  311.627534] Shot down all CPUs
Jürgen Groß July 24, 2019, 3:11 p.m. UTC | #17
On 24.07.19 16:54, Sergey Dyasli wrote:
> On 24/07/2019 10:13, Juergen Gross wrote:
>> The fix is a one-liner. :-)
>>
>> diff --git a/xen/common/schedule.c b/xen/common/schedule.c
>> index f0bc5b3161..da9efb147f 100644
>> --- a/xen/common/schedule.c
>> +++ b/xen/common/schedule.c
>> @@ -2207,6 +2207,7 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
>>           if ( unlikely(!scheduler_active) )
>>           {
>>               ASSERT(is_idle_unit(prev));
>> +            atomic_set(&prev->next_task->rendezvous_out_cnt, 0);
>>               prev->rendezvous_in_cnt = 0;
>>           }
>>       }
> 
> Even with that applied, I'm still seeing it :(

Interesting, for me it was gone.

Time for more tests and some debug code...


Juergen
Sergey Dyasli July 25, 2019, 4:01 p.m. UTC | #18
Hi Juergen,

I've found another regression that happens only with sched-gran=core.
CentOS 5.11 (PV, CPUs: 32; RAM: 6GB) kernel hangs during suspend attempt.
The last kernel messages are:

    CPU 1 offline: Remove Rx thread
    CPU 2 offline: Remove Rx thread

Kernel: Linux localhost 2.6.18-398.el5xen #1 SMP Tue Sep 16 21:31:50 EDT 2014 x86_64 x86_64 x86_64 GNU/Linux

xl top shows 100% CPU utilization for the hanged VM. And here's its state:

(XEN) [ 1907.976356] *** Dumping CPU14 guest state (d1v0): ***

(XEN) [ 1907.982558] ----[ Xen-4.13.0-8.0.6-d  x86_64  debug=y   Not tainted ]----

(XEN) [ 1907.990704] CPU:    14

(XEN) [ 1907.993901] RIP:    e033:[<ffffffff80264a7b>]

(XEN) [ 1907.999333] RFLAGS: 0000000000000286   EM: 1   CONTEXT: pv guest (d1v0)

(XEN) [ 1908.007282] rax: 0000000000000001   rbx: ffffffff80522b80   rcx: 0000000000000000

(XEN) [ 1908.016203] rdx: ffffffff80522b90   rsi: 0000000000000079   rdi: ffffffff8052a980

(XEN) [ 1908.025121] rbp: ffffffff80522980   rsp: ffff88017106dcf8   r8:  ffff88017106c000

(XEN) [ 1908.034040] r9:  0000000000000000   r10: 0000000000000000   r11: ffff880176fad8c0

(XEN) [ 1908.042962] r12: 0000000000000001   r13: 0000000000000000   r14: ffffffff80522980

(XEN) [ 1908.051881] r15: 0000000000000003   cr0: 000000008005003b   cr4: 0000000000142660

(XEN) [ 1908.060800] cr3: 000000801d8c0000   cr2: 00002b5400970000

(XEN) [ 1908.067393] fsb: 0000000000000000   gsb: ffffffff80639000   gss: 0000000000000000

(XEN) [ 1908.076311] ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: e02b   cs: e033

(XEN) [ 1908.084650] Guest stack trace from rsp=ffff88017106dcf8:

(XEN) [ 1908.091147]    ffffffff802c3dd4 0000000001168460 ffffffff80522b90 0000000000000079

(XEN) [ 1908.100164]    ffffffff80522b80 ffffffff80522980 0000000000000001 0000000000000000

(XEN) [ 1908.109179]    0000000000000003 0000000000000003 ffffffff802c4041 ffff88017d68b040

(XEN) [ 1908.118197]    0000000000000003 0000000000000003 0000000000000007 0000000000000003

(XEN) [ 1908.127213]    00000000ffffffea ffffffff8029f0ad ffffffff802c4092 ffffffff8050ff90

(XEN) [ 1908.136229]    ffffffff80268111 0000000000000003 0000000000000000 ffff88017d68b040

(XEN) [ 1908.145245]    ffffffff802a408b 0000000000000000 ffff8800011d3860 fffffffffffffff7

(XEN) [ 1908.154263]    ffffffffffffffff ffffffffffffffff 7fffffffffffffff 0000000000000001

(XEN) [ 1908.163278]    0000000000000000 0000000000000000 0000000000000000 0000000000000000

(XEN) [ 1908.172296]    0000000000000003 0000000000000003 0000000000000000 ffff88017f5ebce0

(XEN) [ 1908.181312]    0000000000000000 ffff88017f5ebcd0 ffffffff803be1a6 0000000000000001

(XEN) [ 1908.190328]    0000000000000000 ffffffff803be9dd ffffffff803bea43 ffff88017106deb0

(XEN) [ 1908.199345]    ffffffff80289495 0000000300000000 ffff88017f5ebce0 ffff88017f5ebce8

(XEN) [ 1908.208362]    0000000000000000 ffff88017f5ebcd0 ffffffff8029f0ad ffff88017106dee0

(XEN) [ 1908.217379]    0000000000000000 ffff88017f5ebce0 0000000000000000 ffff88017f5ebcd0

(XEN) [ 1908.226396]    ffffffff8029f0ad 0000000000000000 ffffffff80233ee4 0000000000000000

(XEN) [ 1908.235413]    ffff88017d8687f0 ffffffffffffffff ffffffffffffffff ffffffffffffffff

(XEN) [ 1908.244427]    7fffffffffffffff ffffffffffffffff ffff8800011d3860 ffff88017f5ebcd0

(XEN) [ 1908.253444]    ffff88017f5ebc78 ffff88017f5ce6c0 ffffffff80260b2c 0000000000000000

(XEN) [ 1908.262461]    ffffffff8029f0ad ffff88017f5ebcd0 0000000000000000 ffff88017f5ce6c0



Thanks,
Sergey