| Message ID | 1590714370-67182-4-git-send-email-feng.tang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | make vm_committed_as_batch aware of vm overcommit policy | expand |
On Fri, May 29, 2020 at 09:06:09AM +0800, Feng Tang wrote: > As is explained by Michal Hocko: > > : Looking at the history, this has been added by 82f71ae4a2b8 > : ("mm: catch memory commitment underflow") to have a safety check > : for issues which have been fixed. There doesn't seem to be any bug > : reports mentioning this splat since then so it is likely just > : spending cycles for a hot path (yes many people run with DEBUG_VM) > : without a strong reason. Hmm, it looks like the warning is still useful to catch issues in, https://lore.kernel.org/linux-mm/20140624201606.18273.44270.stgit@zurg https://lore.kernel.org/linux-mm/54BB9A32.7080703@oracle.com/ After read the whole discussion in that thread, I actually disagree with Michal. In order to get ride of this existing warning, it is rather someone needs a strong reason that could prove the performance hit is noticeable with some data. > > Signed-off-by: Feng Tang <feng.tang@intel.com> > Cc: Konstantin Khlebnikov <koct9i@gmail.com> > Cc: Qian Cai <cai@lca.pw> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Andi Kleen <andi.kleen@intel.com> > --- > mm/util.c | 8 -------- > 1 file changed, 8 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index 3c7a08c..fe63271 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -814,14 +814,6 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) > { > long allowed; > > - /* > - * A transient decrease in the value is unlikely, so no need > - * READ_ONCE() for vm_committed_as.count. > - */ > - VM_WARN_ONCE(data_race(percpu_counter_read(&vm_committed_as) < > - -(s64)vm_committed_as_batch * num_online_cpus()), > - "memory commitment underflow"); > - > vm_acct_memory(pages); > > /* > -- > 2.7.4 >
On Thu, May 28, 2020 at 10:49:28PM -0400, Qian Cai wrote: > On Fri, May 29, 2020 at 09:06:09AM +0800, Feng Tang wrote: > > As is explained by Michal Hocko: > > > > : Looking at the history, this has been added by 82f71ae4a2b8 > > : ("mm: catch memory commitment underflow") to have a safety check > > : for issues which have been fixed. There doesn't seem to be any bug > > : reports mentioning this splat since then so it is likely just > > : spending cycles for a hot path (yes many people run with DEBUG_VM) > > : without a strong reason. > > Hmm, it looks like the warning is still useful to catch issues in, > > https://lore.kernel.org/linux-mm/20140624201606.18273.44270.stgit@zurg > https://lore.kernel.org/linux-mm/54BB9A32.7080703@oracle.com/ > > After read the whole discussion in that thread, I actually disagree with > Michal. In order to get ride of this existing warning, it is rather > someone needs a strong reason that could prove the performance hit is > noticeable with some data. One problem with current check is percpu_counter_read(&vm_committed_as) is not accurate, and percpu_counter_sum() is way too heavy. Thanks, Feng
Hi Qian, On Thu, May 28, 2020 at 10:49:28PM -0400, Qian Cai wrote: > On Fri, May 29, 2020 at 09:06:09AM +0800, Feng Tang wrote: > > As is explained by Michal Hocko: > > > > : Looking at the history, this has been added by 82f71ae4a2b8 > > : ("mm: catch memory commitment underflow") to have a safety check > > : for issues which have been fixed. There doesn't seem to be any bug > > : reports mentioning this splat since then so it is likely just > > : spending cycles for a hot path (yes many people run with DEBUG_VM) > > : without a strong reason. > > Hmm, it looks like the warning is still useful to catch issues in, > > https://lore.kernel.org/linux-mm/20140624201606.18273.44270.stgit@zurg > https://lore.kernel.org/linux-mm/54BB9A32.7080703@oracle.com/ > > After read the whole discussion in that thread, I actually disagree with > Michal. In order to get ride of this existing warning, it is rather > someone needs a strong reason that could prove the performance hit is > noticeable with some data. I re-run the same benchmark with v5.7 and 5.7+remove_warning kernels, the overall performance change is trivial (which is expected) 1330147 +0.1% 1331032 will-it-scale.72.processes But the perf stats of "self" shows big change for __vm_enough_memory() 0.27 -0.3 0.00 pp.self.__vm_enough_memory I post the full compare result in the end. Thanks, Feng ========================================================================================= tbox_group/testcase/rootfs/kconfig/compiler/nr_task/mode/test/cpufreq_governor/ucode: lkp-skl-2sp7/will-it-scale/debian-x86_64-20191114.cgz/x86_64-rhel-7.6-vm-debug/gcc-7/100%/process/mmap2/performance/0x2000065 commit: v5.7 af3eca72dc43078e1ee4a38b0ecc0225b659f345 v5.7 af3eca72dc43078e1ee4a38b0ec ---------------- --------------------------- fail:runs %reproduction fail:runs | | | 850:3 -12130% 486:2 dmesg.timestamp:last 2:3 -67% :2 kmsg.Firmware_Bug]:the_BIOS_has_corrupted_hw-PMU_resources(MSR#is#bb) :3 33% 1:2 kmsg.Firmware_Bug]:the_BIOS_has_corrupted_hw-PMU_resources(MSR#is#e08) 5:3 -177% :2 kmsg.timestamp:Firmware_Bug]:the_BIOS_has_corrupted_hw-PMU_resources(MSR#is#bb) :3 88% 2:2 kmsg.timestamp:Firmware_Bug]:the_BIOS_has_corrupted_hw-PMU_resources(MSR#is#e08) 398:3 -4444% 265:2 kmsg.timestamp:last %stddev %change %stddev \ | \ 1330147 +0.1% 1331032 will-it-scale.72.processes 0.02 +0.0% 0.02 will-it-scale.72.processes_idle 18474 +0.1% 18486 will-it-scale.per_process_ops 301.18 -0.0% 301.16 will-it-scale.time.elapsed_time 301.18 -0.0% 301.16 will-it-scale.time.elapsed_time.max 1.00 ± 81% +100.0% 2.00 will-it-scale.time.involuntary_context_switches 9452 +0.0% 9452 will-it-scale.time.maximum_resident_set_size 5925 +0.1% 5932 will-it-scale.time.minor_page_faults 4096 +0.0% 4096 will-it-scale.time.page_size 0.01 ± 35% +12.5% 0.01 ± 33% will-it-scale.time.system_time 0.03 ± 14% +5.0% 0.04 ± 14% will-it-scale.time.user_time 83.33 +0.2% 83.50 will-it-scale.time.voluntary_context_switches 1330147 +0.1% 1331032 will-it-scale.workload 0.45 ± 29% +0.0 0.50 ± 28% mpstat.cpu.all.idle% 98.41 -0.1 98.34 mpstat.cpu.all.sys% 1.14 +0.0 1.16 mpstat.cpu.all.usr% 200395 ± 18% +11.9% 224282 ± 14% cpuidle.C1.time 4008 ± 38% -2.1% 3924 ± 15% cpuidle.C1.usage 1.222e+08 ± 19% -29.2% 86444161 cpuidle.C1E.time 254203 ± 19% -23.2% 195198 ± 4% cpuidle.C1E.usage 8145747 ± 31% +339.9% 35830338 ± 72% cpuidle.C6.time 22878 ± 9% +288.2% 88823 ± 70% cpuidle.C6.usage 8891 ± 7% -7.4% 8229 cpuidle.POLL.time 3111 ± 18% -11.1% 2766 cpuidle.POLL.usage 0.00 -100.0% 0.00 numa-numastat.node0.interleave_hit 314399 ± 2% -1.0% 311244 ± 3% numa-numastat.node0.local_node 322209 +2.4% 329909 numa-numastat.node0.numa_hit 7814 ± 73% +138.9% 18670 ± 24% numa-numastat.node0.other_node 0.00 -100.0% 0.00 numa-numastat.node1.interleave_hit 343026 ± 2% -0.3% 341980 numa-numastat.node1.local_node 358632 -3.3% 346708 numa-numastat.node1.numa_hit 15613 ± 36% -69.7% 4728 ± 98% numa-numastat.node1.other_node 301.18 -0.0% 301.16 time.elapsed_time 301.18 -0.0% 301.16 time.elapsed_time.max 1.00 ± 81% +100.0% 2.00 time.involuntary_context_switches 9452 +0.0% 9452 time.maximum_resident_set_size 5925 +0.1% 5932 time.minor_page_faults 4096 +0.0% 4096 time.page_size 0.01 ± 35% +12.5% 0.01 ± 33% time.system_time 0.03 ± 14% +5.0% 0.04 ± 14% time.user_time 83.33 +0.2% 83.50 time.voluntary_context_switches 0.33 ±141% +50.0% 0.50 ±100% vmstat.cpu.id 97.00 +0.0% 97.00 vmstat.cpu.sy 1.00 +0.0% 1.00 vmstat.cpu.us 0.00 -100.0% 0.00 vmstat.io.bi 4.00 +0.0% 4.00 vmstat.memory.buff 1391751 +0.1% 1392746 vmstat.memory.cache 1.294e+08 -0.0% 1.294e+08 vmstat.memory.free 71.00 +0.0% 71.00 vmstat.procs.r 1315 -0.7% 1305 vmstat.system.cs 147433 -0.0% 147369 vmstat.system.in 0.00 -100.0% 0.00 proc-vmstat.compact_isolated 85060 +0.4% 85431 proc-vmstat.nr_active_anon 37.00 -1.4% 36.50 proc-vmstat.nr_active_file 71111 +0.1% 71200 proc-vmstat.nr_anon_pages 77.33 ± 17% +12.5% 87.00 proc-vmstat.nr_anon_transparent_hugepages 54.00 +1.9% 55.00 proc-vmstat.nr_dirtied 5.00 +0.0% 5.00 proc-vmstat.nr_dirty 3215506 -0.0% 3215471 proc-vmstat.nr_dirty_background_threshold 6438875 -0.0% 6438805 proc-vmstat.nr_dirty_threshold 327936 +0.1% 328237 proc-vmstat.nr_file_pages 50398 +0.0% 50398 proc-vmstat.nr_free_cma 32356721 -0.0% 32356374 proc-vmstat.nr_free_pages 4640 -0.1% 4636 proc-vmstat.nr_inactive_anon 82.67 ± 2% -0.8% 82.00 ± 2% proc-vmstat.nr_inactive_file 13256 -0.3% 13211 proc-vmstat.nr_kernel_stack 8057 -0.5% 8017 proc-vmstat.nr_mapped 134.00 ±141% +49.3% 200.00 ±100% proc-vmstat.nr_mlock 2229 +0.2% 2234 proc-vmstat.nr_page_table_pages 18609 ± 3% +1.6% 18898 ± 3% proc-vmstat.nr_shmem 19964 -0.3% 19901 proc-vmstat.nr_slab_reclaimable 34003 +0.1% 34025 proc-vmstat.nr_slab_unreclaimable 309227 +0.0% 309249 proc-vmstat.nr_unevictable 0.00 -100.0% 0.00 proc-vmstat.nr_writeback 53.00 +0.0% 53.00 proc-vmstat.nr_written 85060 +0.4% 85431 proc-vmstat.nr_zone_active_anon 37.00 -1.4% 36.50 proc-vmstat.nr_zone_active_file 4640 -0.1% 4636 proc-vmstat.nr_zone_inactive_anon 82.67 ± 2% -0.8% 82.00 ± 2% proc-vmstat.nr_zone_inactive_file 309227 +0.0% 309249 proc-vmstat.nr_zone_unevictable 5.00 +0.0% 5.00 proc-vmstat.nr_zone_write_pending 2181 ±124% -68.6% 685.50 ± 80% proc-vmstat.numa_hint_faults 37.67 ±109% +77.9% 67.00 ± 91% proc-vmstat.numa_hint_faults_local 702373 +0.7% 707116 proc-vmstat.numa_hit 35.33 ± 85% -70.3% 10.50 ± 4% proc-vmstat.numa_huge_pte_updates 0.00 -100.0% 0.00 proc-vmstat.numa_interleave 678938 +0.7% 683714 proc-vmstat.numa_local 23435 -0.1% 23401 proc-vmstat.numa_other 4697 ± 68% -86.8% 618.50 ± 98% proc-vmstat.numa_pages_migrated 25844 ± 52% -79.1% 5406 ± 4% proc-vmstat.numa_pte_updates 20929 ± 4% +1.9% 21332 ± 5% proc-vmstat.pgactivate 0.00 -100.0% 0.00 proc-vmstat.pgalloc_dma32 760325 -0.4% 756908 proc-vmstat.pgalloc_normal 801566 -0.5% 797832 proc-vmstat.pgfault 714690 -0.2% 713286 proc-vmstat.pgfree 4697 ± 68% -86.8% 618.50 ± 98% proc-vmstat.pgmigrate_success 0.00 -100.0% 0.00 proc-vmstat.pgpgin 103.00 +0.5% 103.50 proc-vmstat.thp_collapse_alloc 5.00 +0.0% 5.00 proc-vmstat.thp_fault_alloc 0.00 -100.0% 0.00 proc-vmstat.thp_zero_page_alloc 41.00 ± 98% +35.4% 55.50 ± 80% proc-vmstat.unevictable_pgs_culled 183.00 ±141% +50.0% 274.50 ±100% proc-vmstat.unevictable_pgs_mlocked 2.59 +0.5% 2.60 perf-stat.i.MPKI 4.854e+09 +0.0% 4.856e+09 perf-stat.i.branch-instructions 0.45 -0.0 0.43 perf-stat.i.branch-miss-rate% 21296577 -2.3% 20817170 perf-stat.i.branch-misses 39.98 -0.2 39.81 perf-stat.i.cache-miss-rate% 21372778 +0.0% 21380457 perf-stat.i.cache-misses 53441942 +0.5% 53705724 perf-stat.i.cache-references 1285 -0.7% 1277 perf-stat.i.context-switches 10.67 -0.0% 10.67 perf-stat.i.cpi 71998 -0.0% 71998 perf-stat.i.cpu-clock 2.21e+11 +0.0% 2.21e+11 perf-stat.i.cpu-cycles 117.36 +0.3% 117.71 perf-stat.i.cpu-migrations 10322 -0.0% 10321 perf-stat.i.cycles-between-cache-misses 0.05 +0.0 0.05 perf-stat.i.dTLB-load-miss-rate% 2709233 +0.1% 2712427 perf-stat.i.dTLB-load-misses 5.785e+09 +0.0% 5.787e+09 perf-stat.i.dTLB-loads 0.00 +0.0 0.00 ± 2% perf-stat.i.dTLB-store-miss-rate% 8967 -3.0% 8701 perf-stat.i.dTLB-store-misses 1.97e+09 +0.1% 1.971e+09 perf-stat.i.dTLB-stores 94.02 +0.2 94.24 perf-stat.i.iTLB-load-miss-rate% 2732366 -1.4% 2694372 perf-stat.i.iTLB-load-misses 173049 -5.7% 163172 ± 2% perf-stat.i.iTLB-loads 2.07e+10 +0.0% 2.071e+10 perf-stat.i.instructions 7671 +1.0% 7747 perf-stat.i.instructions-per-iTLB-miss 0.10 +0.1% 0.10 perf-stat.i.ipc 3.07 +0.0% 3.07 perf-stat.i.metric.GHz 0.42 +0.5% 0.43 perf-stat.i.metric.K/sec 175.98 +0.1% 176.08 perf-stat.i.metric.M/sec 2565 -0.7% 2547 perf-stat.i.minor-faults 99.55 -0.0 99.53 perf-stat.i.node-load-miss-rate% 5949351 +0.3% 5969805 perf-stat.i.node-load-misses 22301 ± 6% +5.6% 23543 ± 8% perf-stat.i.node-loads 99.73 -0.0 99.72 perf-stat.i.node-store-miss-rate% 5314673 -0.1% 5310449 perf-stat.i.node-store-misses 4704 ± 4% -1.8% 4619 perf-stat.i.node-stores 2565 -0.7% 2547 perf-stat.i.page-faults 71998 -0.0% 71998 perf-stat.i.task-clock 2.58 +0.5% 2.59 perf-stat.overall.MPKI 0.44 -0.0 0.43 perf-stat.overall.branch-miss-rate% 39.99 -0.2 39.81 perf-stat.overall.cache-miss-rate% 10.67 -0.0% 10.67 perf-stat.overall.cpi 10340 -0.0% 10337 perf-stat.overall.cycles-between-cache-misses 0.05 +0.0 0.05 perf-stat.overall.dTLB-load-miss-rate% 0.00 -0.0 0.00 perf-stat.overall.dTLB-store-miss-rate% 94.04 +0.2 94.29 perf-stat.overall.iTLB-load-miss-rate% 7577 +1.4% 7686 perf-stat.overall.instructions-per-iTLB-miss 0.09 +0.0% 0.09 perf-stat.overall.ipc 99.62 -0.0 99.60 perf-stat.overall.node-load-miss-rate% 99.91 +0.0 99.91 perf-stat.overall.node-store-miss-rate% 4691551 +0.0% 4693151 perf-stat.overall.path-length 4.838e+09 +0.0% 4.84e+09 perf-stat.ps.branch-instructions 21230930 -2.3% 20750859 perf-stat.ps.branch-misses 21302195 +0.0% 21309444 perf-stat.ps.cache-misses 53273375 +0.5% 53531696 perf-stat.ps.cache-references 1281 -0.7% 1273 perf-stat.ps.context-switches 71760 -0.0% 71759 perf-stat.ps.cpu-clock 2.203e+11 +0.0% 2.203e+11 perf-stat.ps.cpu-cycles 117.02 +0.3% 117.33 perf-stat.ps.cpu-migrations 2702184 +0.1% 2704689 perf-stat.ps.dTLB-load-misses 5.766e+09 +0.0% 5.767e+09 perf-stat.ps.dTLB-loads 9028 -3.2% 8736 perf-stat.ps.dTLB-store-misses 1.963e+09 +0.1% 1.965e+09 perf-stat.ps.dTLB-stores 2723237 -1.4% 2685365 perf-stat.ps.iTLB-load-misses 172573 -5.7% 162735 ± 2% perf-stat.ps.iTLB-loads 2.063e+10 +0.0% 2.064e+10 perf-stat.ps.instructions 2559 -0.7% 2540 perf-stat.ps.minor-faults 5929506 +0.3% 5949863 perf-stat.ps.node-load-misses 22689 ± 5% +4.7% 23766 ± 8% perf-stat.ps.node-loads 5296902 -0.1% 5292690 perf-stat.ps.node-store-misses 4724 ± 4% -2.2% 4622 perf-stat.ps.node-stores 2559 -0.7% 2540 perf-stat.ps.page-faults 71760 -0.0% 71759 perf-stat.ps.task-clock 6.24e+12 +0.1% 6.247e+12 perf-stat.total.instructions 47.20 -0.2 47.05 pp.bt.percpu_counter_add_batch.__do_munmap.__vm_munmap.__x64_sys_munmap.do_syscall_64 50.12 -0.2 49.97 pp.bt.entry_SYSCALL_64_after_hwframe.munmap 50.10 -0.1 49.95 pp.bt.do_syscall_64.entry_SYSCALL_64_after_hwframe.munmap 46.75 -0.1 46.60 pp.bt._raw_spin_lock_irqsave.percpu_counter_add_batch.__do_munmap.__vm_munmap.__x64_sys_munmap 49.36 -0.1 49.22 pp.bt.__do_munmap.__vm_munmap.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe 49.78 -0.1 49.64 pp.bt.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe.munmap 49.75 -0.1 49.61 pp.bt.__vm_munmap.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe.munmap 50.48 -0.1 50.34 pp.bt.munmap 46.56 -0.1 46.41 pp.bt.native_queued_spin_lock_slowpath._raw_spin_lock_irqsave.percpu_counter_add_batch.__do_munmap.__vm_munmap 1.88 -0.0 1.88 pp.bt.unmap_region.__do_munmap.__vm_munmap.__x64_sys_munmap.do_syscall_64 1.32 +0.0 1.33 pp.bt.unmap_page_range.unmap_vmas.unmap_region.__do_munmap.__vm_munmap 1.42 +0.0 1.44 pp.bt.unmap_vmas.unmap_region.__do_munmap.__vm_munmap.__x64_sys_munmap 0.51 +0.0 0.53 pp.bt.___might_sleep.unmap_page_range.unmap_vmas.unmap_region.__do_munmap 48.27 +0.1 48.39 pp.bt.mmap_region.do_mmap.vm_mmap_pgoff.ksys_mmap_pgoff.do_syscall_64 48.67 +0.1 48.80 pp.bt.vm_mmap_pgoff.ksys_mmap_pgoff.do_syscall_64.entry_SYSCALL_64_after_hwframe.mmap64 48.51 +0.1 48.65 pp.bt.do_mmap.vm_mmap_pgoff.ksys_mmap_pgoff.do_syscall_64.entry_SYSCALL_64_after_hwframe 47.10 +0.1 47.24 pp.bt.__vm_enough_memory.mmap_region.do_mmap.vm_mmap_pgoff.ksys_mmap_pgoff 48.74 +0.1 48.88 pp.bt.ksys_mmap_pgoff.do_syscall_64.entry_SYSCALL_64_after_hwframe.mmap64 49.08 +0.1 49.23 pp.bt.entry_SYSCALL_64_after_hwframe.mmap64 46.48 +0.1 46.62 pp.bt.native_queued_spin_lock_slowpath._raw_spin_lock_irqsave.percpu_counter_add_batch.__vm_enough_memory.mmap_region 49.06 +0.1 49.21 pp.bt.do_syscall_64.entry_SYSCALL_64_after_hwframe.mmap64 49.46 +0.1 49.61 pp.bt.mmap64 46.66 +0.1 46.80 pp.bt._raw_spin_lock_irqsave.percpu_counter_add_batch.__vm_enough_memory.mmap_region.do_mmap 46.84 +0.4 47.23 pp.bt.percpu_counter_add_batch.__vm_enough_memory.mmap_region.do_mmap.vm_mmap_pgoff 49.78 -0.1 49.64 pp.child.__x64_sys_munmap 50.51 -0.1 50.36 pp.child.munmap 49.76 -0.1 49.61 pp.child.__vm_munmap 49.36 -0.1 49.22 pp.child.__do_munmap 0.45 -0.0 0.41 pp.child.perf_event_mmap 0.03 ± 70% -0.0 0.00 pp.child.strlen 0.02 ±141% -0.0 0.00 pp.child.common_file_perm 0.30 -0.0 0.29 pp.child.free_pgd_range 1.88 -0.0 1.88 pp.child.unmap_region 0.28 -0.0 0.27 pp.child.free_p4d_range 0.28 ± 4% -0.0 0.27 pp.child.apic_timer_interrupt 0.19 ± 4% -0.0 0.18 ± 2% pp.child.hrtimer_interrupt 0.09 -0.0 0.08 ± 5% pp.child.find_vma 0.40 ± 2% -0.0 0.40 ± 3% pp.child.vm_area_alloc 0.35 -0.0 0.34 pp.child.syscall_return_via_sysret 0.35 ± 2% -0.0 0.34 pp.child.up_read 93.41 -0.0 93.41 pp.child._raw_spin_lock_irqsave 0.05 ± 8% -0.0 0.05 pp.child.kmem_cache_alloc_trace 0.11 ± 4% -0.0 0.11 pp.child.d_path 0.11 ± 4% -0.0 0.11 pp.child.perf_iterate_sb 0.08 ± 5% -0.0 0.08 pp.child.prepend_path 99.23 -0.0 99.23 pp.child.entry_SYSCALL_64_after_hwframe 93.04 -0.0 93.04 pp.child.native_queued_spin_lock_slowpath 0.09 -0.0 0.09 pp.child.tick_sched_timer 0.05 -0.0 0.05 pp.child.unlink_file_vma 0.05 -0.0 0.05 pp.child.task_tick_fair 0.05 -0.0 0.05 pp.child.perf_event_mmap_output 99.20 +0.0 99.20 pp.child.do_syscall_64 0.21 ± 3% +0.0 0.21 pp.child.smp_apic_timer_interrupt 0.08 +0.0 0.08 pp.child.update_process_times 0.06 +0.0 0.06 pp.child.down_write_killable 0.15 +0.0 0.15 ± 6% pp.child.rcu_all_qs 0.37 ± 2% +0.0 0.37 ± 5% pp.child.kmem_cache_alloc 0.28 +0.0 0.29 ± 5% pp.child._cond_resched 0.12 ± 3% +0.0 0.12 ± 4% pp.child.vma_link 0.09 ± 5% +0.0 0.10 ± 5% pp.child.security_mmap_file 0.06 ± 7% +0.0 0.07 ± 7% pp.child.scheduler_tick 0.13 ± 3% +0.0 0.14 ± 3% pp.child.__hrtimer_run_queues 0.32 ± 2% +0.0 0.32 pp.child._raw_spin_unlock_irqrestore 0.08 +0.0 0.08 ± 5% pp.child.tick_sched_handle 0.06 +0.0 0.07 ± 7% pp.child.down_write 0.06 +0.0 0.07 ± 7% pp.child.remove_vma 1.43 +0.0 1.44 pp.child.unmap_vmas 0.05 +0.0 0.06 pp.child.__vma_rb_erase 0.08 +0.0 0.09 pp.child.free_pgtables 1.39 +0.0 1.40 pp.child.unmap_page_range 0.35 +0.0 0.36 ± 4% pp.child.entry_SYSCALL_64 0.10 ± 4% +0.0 0.11 pp.child.arch_get_unmapped_area_topdown 0.58 +0.0 0.59 pp.child.___might_sleep 0.06 +0.0 0.08 ± 6% pp.child.shmem_mmap 0.03 ± 70% +0.0 0.05 pp.child.up_write 0.03 ± 70% +0.0 0.05 pp.child.vm_unmapped_area 0.03 ± 70% +0.0 0.05 pp.child.__vma_link_rb 0.15 ± 3% +0.0 0.17 ± 3% pp.child.shmem_get_unmapped_area 0.18 ± 2% +0.0 0.20 ± 2% pp.child.get_unmapped_area 0.00 +0.0 0.03 ±100% pp.child.prepend_name 0.02 ±141% +0.0 0.05 pp.child.touch_atime 48.28 +0.1 48.39 pp.child.mmap_region 47.10 +0.1 47.24 pp.child.__vm_enough_memory 48.51 +0.1 48.65 pp.child.do_mmap 48.74 +0.1 48.88 pp.child.ksys_mmap_pgoff 48.67 +0.1 48.81 pp.child.vm_mmap_pgoff 49.49 +0.1 49.64 pp.child.mmap64 94.04 +0.2 94.28 pp.child.percpu_counter_add_batch 0.27 -0.3 0.00 pp.self.__vm_enough_memory 0.03 ± 70% -0.0 0.00 pp.self.strlen 0.02 ±141% -0.0 0.00 pp.self.prepend_path 0.28 -0.0 0.27 pp.self.free_p4d_range 0.07 -0.0 0.06 pp.self.perf_iterate_sb 0.08 -0.0 0.07 pp.self.perf_event_mmap 0.35 ± 2% -0.0 0.34 ± 5% pp.self.kmem_cache_alloc 0.11 -0.0 0.11 ± 4% pp.self.rcu_all_qs 0.37 -0.0 0.36 pp.self._raw_spin_lock_irqsave 0.35 -0.0 0.34 pp.self.syscall_return_via_sysret 0.35 ± 2% -0.0 0.34 pp.self.up_read 0.14 ± 3% -0.0 0.14 ± 3% pp.self._cond_resched 93.04 -0.0 93.04 pp.self.native_queued_spin_lock_slowpath 0.31 +0.0 0.32 ± 4% pp.self.entry_SYSCALL_64 0.69 +0.0 0.69 pp.self.unmap_page_range 0.10 ± 4% +0.0 0.10 pp.self._raw_spin_unlock_irqrestore 0.06 ± 8% +0.0 0.06 pp.self.find_vma 0.06 ± 8% +0.0 0.06 pp.self.__do_munmap 0.06 ± 7% +0.0 0.07 pp.self.mmap_region 0.61 ± 3% +0.0 0.62 pp.self.do_syscall_64 0.02 ±141% +0.0 0.03 ±100% pp.self.up_write 0.05 +0.0 0.06 pp.self.__vma_rb_erase 0.54 +0.0 0.56 pp.self.___might_sleep 0.03 ± 70% +0.0 0.05 pp.self.vm_unmapped_area 0.03 ± 70% +0.0 0.05 pp.self.shmem_get_unmapped_area 0.03 ± 70% +0.0 0.05 pp.self.__vma_link_rb 0.00 +0.0 0.03 ±100% pp.self.prepend_name 0.00 +0.0 0.03 ±100% pp.self.do_mmap 0.00 +0.0 0.03 ±100% pp.self.arch_get_unmapped_area_topdown 0.02 ±141% +0.0 0.05 pp.self.perf_event_mmap_output 0.32 ± 2% +0.2 0.56 pp.self.percpu_counter_add_batch 552.67 ± 2% -5.2% 524.00 ± 6% softirqs.BLOCK 2.00 +0.0% 2.00 softirqs.HI 911.00 ± 47% -31.4% 625.00 ± 2% softirqs.NET_RX 63.67 ± 3% -5.0% 60.50 ± 4% softirqs.NET_TX 312414 -1.1% 309101 softirqs.RCU 228903 -1.4% 225602 ± 3% softirqs.SCHED 265.67 -1.0% 263.00 softirqs.TASKLET 8777267 +0.1% 8789634 softirqs.TIMER 23504 -0.1% 23472 interrupts.CAL:Function_call_interrupts 144.00 -0.3% 143.50 interrupts.IWI:IRQ_work_interrupts 43641147 -0.0% 43621882 interrupts.LOC:Local_timer_interrupts 0.00 -100.0% 0.00 interrupts.MCP:Machine_check_polls 570736 ± 5% +2.1% 582977 ± 5% interrupts.NMI:Non-maskable_interrupts 570736 ± 5% +2.1% 582977 ± 5% interrupts.PMI:Performance_monitoring_interrupts 45097 +0.7% 45407 interrupts.RES:Rescheduling_interrupts 0.00 -100.0% 0.00 interrupts.RTR:APIC_ICR_read_retries 193.67 ± 26% -21.3% 152.50 ± 29% interrupts.TLB:TLB_shootdowns
diff --git a/mm/util.c b/mm/util.c index 3c7a08c..fe63271 100644 --- a/mm/util.c +++ b/mm/util.c @@ -814,14 +814,6 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) { long allowed; - /* - * A transient decrease in the value is unlikely, so no need - * READ_ONCE() for vm_committed_as.count. - */ - VM_WARN_ONCE(data_race(percpu_counter_read(&vm_committed_as) < - -(s64)vm_committed_as_batch * num_online_cpus()), - "memory commitment underflow"); - vm_acct_memory(pages); /*
As is explained by Michal Hocko: : Looking at the history, this has been added by 82f71ae4a2b8 : ("mm: catch memory commitment underflow") to have a safety check : for issues which have been fixed. There doesn't seem to be any bug : reports mentioning this splat since then so it is likely just : spending cycles for a hot path (yes many people run with DEBUG_VM) : without a strong reason. Signed-off-by: Feng Tang <feng.tang@intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Qian Cai <cai@lca.pw> Cc: Michal Hocko <mhocko@suse.com> Cc: Andi Kleen <andi.kleen@intel.com> --- mm/util.c | 8 -------- 1 file changed, 8 deletions(-)