| Message ID | 20210611124624.1404010-1-jingzhangos@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM statistics data fd-based binary interface | expand |
On 11/06/21 14:46, Jing Zhang wrote: > This patchset provides a file descriptor for every VM and VCPU to read > KVM statistics data in binary format. > It is meant to provide a lightweight, flexible, scalable and efficient > lock-free solution for user space telemetry applications to pull the > statistics data periodically for large scale systems. The pulling > frequency could be as high as a few times per second. > In this patchset, every statistics data are treated to have some > attributes as below: > * architecture dependent or generic > * VM statistics data or VCPU statistics data > * type: cumulative, instantaneous, > * unit: none for simple counter, nanosecond, microsecond, > millisecond, second, Byte, KiByte, MiByte, GiByte. Clock Cycles > Since no lock/synchronization is used, the consistency between all > the statistics data is not guaranteed. That means not all statistics > data are read out at the exact same time, since the statistics date > are still being updated by KVM subsystems while they are read out. The binary interface itself looks good. Can you do a follow-up patch to remove struct kvm_stats_debugfs_item and avoid the duplication? I'd rather have that too before committing the code. Thanks, Paolo
Hi Paolo, On Fri, Jun 11, 2021 at 8:35 AM Paolo Bonzini <pbonzini@redhat.com> wrote: > > On 11/06/21 14:46, Jing Zhang wrote: > > This patchset provides a file descriptor for every VM and VCPU to read > > KVM statistics data in binary format. > > It is meant to provide a lightweight, flexible, scalable and efficient > > lock-free solution for user space telemetry applications to pull the > > statistics data periodically for large scale systems. The pulling > > frequency could be as high as a few times per second. > > In this patchset, every statistics data are treated to have some > > attributes as below: > > * architecture dependent or generic > > * VM statistics data or VCPU statistics data > > * type: cumulative, instantaneous, > > * unit: none for simple counter, nanosecond, microsecond, > > millisecond, second, Byte, KiByte, MiByte, GiByte. Clock Cycles > > Since no lock/synchronization is used, the consistency between all > > the statistics data is not guaranteed. That means not all statistics > > data are read out at the exact same time, since the statistics date > > are still being updated by KVM subsystems while they are read out. > > The binary interface itself looks good. Can you do a follow-up patch to > remove struct kvm_stats_debugfs_item and avoid the duplication? I'd > rather have that too before committing the code. > > Thanks, > > Paolo > Sure. Will do. Thanks, Jing
This patchset provides a file descriptor for every VM and VCPU to read KVM statistics data in binary format. It is meant to provide a lightweight, flexible, scalable and efficient lock-free solution for user space telemetry applications to pull the statistics data periodically for large scale systems. The pulling frequency could be as high as a few times per second. In this patchset, every statistics data are treated to have some attributes as below: * architecture dependent or generic * VM statistics data or VCPU statistics data * type: cumulative, instantaneous, * unit: none for simple counter, nanosecond, microsecond, millisecond, second, Byte, KiByte, MiByte, GiByte. Clock Cycles Since no lock/synchronization is used, the consistency between all the statistics data is not guaranteed. That means not all statistics data are read out at the exact same time, since the statistics date are still being updated by KVM subsystems while they are read out. --- * v7-> v8 - Rebase to kvm/queue, commit c1dc20e254b4 ("KVM: switch per-VM stats to u64") - Revise code to reflect the per-VM stats type from ulong to u64 - Addressed some other nits * v6 -> v7 - Improve file descriptor allocation function by Krish suggestion - Use "generic stats" instead of "common stats" as Krish suggested - Addressed some other nits from Krish and David Matlack * v5 -> v6 - Use designated initializers for STATS_DESC - Change KVM_STATS_SCALE... to KVM_STATS_BASE... - Use a common function for kvm_[vm|vcpu]_stats_read - Fix some documentation errors/missings - Use TEST_ASSERT in selftest - Use a common function for [vm|vcpu]_stats_test in selftest * v4 -> v5 - Rebase to kvm/queue, commit a4345a7cecfb ("Merge tag 'kvmarm-fixes-5.13-1'") - Change maximum stats name length to 48 - Replace VM_STATS_COMMON/VCPU_STATS_COMMON macros with stats descriptor definition macros. - Fixed some errors/warnings reported by checkpatch.pl * v3 -> v4 - Rebase to kvm/queue, commit 9f242010c3b4 ("KVM: avoid "deadlock" between install_new_memslots and MMU notifier") - Use C-stype comments in the whole patch - Fix wrong count for x86 VCPU stats descriptors - Fix KVM stats data size counting and validity check in selftest * v2 -> v3 - Rebase to kvm/queue, commit edf408f5257b ("KVM: avoid "deadlock" between install_new_memslots and MMU notifier") - Resolve some nitpicks about format * v1 -> v2 - Use ARRAY_SIZE to count the number of stats descriptors - Fix missing `size` field initialization in macro STATS_DESC [1] https://lore.kernel.org/kvm/20210402224359.2297157-1-jingzhangos@google.com [2] https://lore.kernel.org/kvm/20210415151741.1607806-1-jingzhangos@google.com [3] https://lore.kernel.org/kvm/20210423181727.596466-1-jingzhangos@google.com [4] https://lore.kernel.org/kvm/20210429203740.1935629-1-jingzhangos@google.com [5] https://lore.kernel.org/kvm/20210517145314.157626-1-jingzhangos@google.com [6] https://lore.kernel.org/kvm/20210524151828.4113777-1-jingzhangos@google.com [7] https://lore.kernel.org/kvm/20210603211426.790093-1-jingzhangos@google.com --- Jing Zhang (4): KVM: stats: Separate generic stats from architecture specific ones KVM: stats: Add fd-based API to read binary stats data KVM: stats: Add documentation for statistics data binary interface KVM: selftests: Add selftest for KVM statistics data binary interface Documentation/virt/kvm/api.rst | 174 +++++++++++++- arch/arm64/include/asm/kvm_host.h | 9 +- arch/arm64/kvm/guest.c | 46 +++- arch/mips/include/asm/kvm_host.h | 9 +- arch/mips/kvm/mips.c | 71 +++++- arch/powerpc/include/asm/kvm_host.h | 9 +- arch/powerpc/kvm/book3s.c | 72 +++++- arch/powerpc/kvm/book3s_hv.c | 12 +- arch/powerpc/kvm/book3s_pr.c | 2 +- arch/powerpc/kvm/book3s_pr_papr.c | 2 +- arch/powerpc/kvm/booke.c | 67 +++++- arch/s390/include/asm/kvm_host.h | 9 +- arch/s390/kvm/kvm-s390.c | 137 ++++++++++- arch/x86/include/asm/kvm_host.h | 9 +- arch/x86/kvm/x86.c | 75 +++++- include/linux/kvm_host.h | 138 ++++++++++- include/linux/kvm_types.h | 12 + include/uapi/linux/kvm.h | 46 ++++ tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 3 + .../testing/selftests/kvm/include/kvm_util.h | 3 + .../selftests/kvm/kvm_binary_stats_test.c | 218 ++++++++++++++++++ tools/testing/selftests/kvm/lib/kvm_util.c | 12 + virt/kvm/kvm_main.c | 157 ++++++++++++- 24 files changed, 1202 insertions(+), 91 deletions(-) create mode 100644 tools/testing/selftests/kvm/kvm_binary_stats_test.c base-commit: c1dc20e254b421a2463da7f053b37d822788224a