Re: [LKP] [lkp-robot] [tracing/x86] 1c758a2202: aim9.disk_rr.ops_per_sec -12.0% regression

From: Aaron Lu
Date: Mon Jun 04 2018 - 04:12:40 EST

On Fri, Jun 01, 2018 at 05:43:19PM -0400, Steven Rostedt wrote:
> On Mon, 28 May 2018 19:34:19 +0800
> kernel test robot <xiaolong.ye@xxxxxxxxx> wrote:
>
> > Greeting,
> >
> > FYI, we noticed a -12.0% regression of aim9.disk_rr.ops_per_sec due to commit:
> >
> >
> > commit: 1c758a2202a6b4624d0703013a2c6cfa6e7455aa ("tracing/x86: Update syscall trace events to handle new prefixed syscall func names")
>
> How can this commit cause a run time regression. It changes code
> in an __init call (that gets removed after boot)??

Sorry for the noise.

We actually enabled the syscall trace events for a duration of 10s
during many tests to hopefully capture syscall "noise", i.e. does some
syscall start to take more time etc. for a workload?

We failed to notice this monitor has stopped running due to commit
d5a00528b58c ("syscalls/core, syscalls/x86: Rename struct pt_regs-based
sys_*() to __x64_sys_*()") as you pointed out in your commit's
changelog. And with your fix commit, syscall trace event starts to work
again, and I believe it is the 10s trace that caused some overhead
during the test that it triggered a bisect and ultimately sent out this
misleading report.

Regards,
Aaron

> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> >
> > in testcase: aim9
> > on test machine: 144 threads Intel(R) Xeon(R) CPU E7-8890 v3 @ 2.50GHz with 512G memory
> > with following parameters:
> >
> > testtime: 300s
> > test: disk_rr
> > cpufreq_governor: performance
> >
> > test-description: Suite IX is the "AIM Independent Resource Benchmark:" the famous synthetic benchmark.
> > test-url: https://sourceforge.net/projects/aimbench/files/aim-suite9/
> >
> >
> > Details are as below:
> > -------------------------------------------------------------------------------------------------->
> > =========================================================================================
> > compiler/cpufreq_governor/kconfig/rootfs/tbox_group/test/testcase/testtime:
> > gcc-7/performance/x86_64-rhel-7.2/debian-x86_64-2016-08-31.cgz/lkp-hsx04/disk_rr/aim9/300s
> >
> > commit:
> > 1cdae042fc ("tracing: Add missing forward declaration")
> > 1c758a2202 ("tracing/x86: Update syscall trace events to handle new prefixed syscall func names")
> >
> > 1cdae042fc63dd98 1c758a2202a6b4624d0703013a
> > ---------------- --------------------------
> > %stddev %change %stddev
> > \ | \
> > 633310 -12.0% 557268 aim9.disk_rr.ops_per_sec
> > 244.24 +2.2% 249.57 aim9.time.system_time
> > 55.76 -9.6% 50.43 aim9.time.user_time
> > 8135 ± 39% +73.2% 14091 ± 33% numa-meminfo.node0.Shmem
> > 1328 -11.9% 1171 pmeter.performance_per_watt
> > 450606 ± 3% -9.5% 407878 ± 5% meminfo.Committed_AS
> > 406.75 ±173% +300.1% 1627 meminfo.Mlocked
> > 20124 ± 4% +8.4% 21819 ± 6% softirqs.NET_RX
> > 8237636 ± 6% -15.4% 6965294 ± 2% softirqs.RCU
> > 2033 ± 39% +73.0% 3518 ± 33% numa-vmstat.node0.nr_shmem
> > 21.25 ±173% +378.8% 101.75 ± 27% numa-vmstat.node2.nr_mlock
> > 21.25 ±173% +378.8% 101.75 ± 27% numa-vmstat.node3.nr_mlock
> > 9.408e+08 ± 6% +53.3% 1.442e+09 ± 20% perf-stat.dTLB-load-misses
> > 47.39 ± 17% -10.4 36.99 ± 8% perf-stat.iTLB-load-miss-rate%
> > 1279 ± 27% +63.4% 2089 ± 21% perf-stat.instructions-per-iTLB-miss
> > 46.73 ± 5% -5.4 41.33 ± 5% perf-stat.node-store-miss-rate%
> > 19240 +1.2% 19474 proc-vmstat.nr_indirectly_reclaimable
> > 18868 +4.0% 19628 proc-vmstat.nr_slab_reclaimable
> > 48395423 -11.8% 42700849 proc-vmstat.numa_hit
> > 48314997 -11.8% 42620296 proc-vmstat.numa_local
> > 3153408 -12.0% 2775642 proc-vmstat.pgactivate
> > 48365477 -11.8% 42678780 proc-vmstat.pgfree
> > 3060 +38.9% 4250 slabinfo.ftrace_event_field.active_objs
> > 3060 +38.9% 4250 slabinfo.ftrace_event_field.num_objs
> > 2748 ± 3% -8.9% 2502 ± 3% slabinfo.sighand_cache.active_objs
> > 2763 ± 3% -8.9% 2517 ± 3% slabinfo.sighand_cache.num_objs
> > 4125 ± 4% -10.3% 3700 ± 2% slabinfo.signal_cache.active_objs
> > 4125 ± 4% -10.3% 3700 ± 2% slabinfo.signal_cache.num_objs
> > 1104 +57.3% 1736 slabinfo.trace_event_file.active_objs
> > 1104 +57.3% 1736 slabinfo.trace_event_file.num_objs
> > 0.78 ± 4% -0.1 0.67 ± 5% perf-profile.calltrace.cycles-pp.rcu_process_callbacks.__softirqentry_text_start.irq_exit.smp_apic_timer_interrupt.apic_timer_interrupt
> > 2.10 ± 2% -0.1 2.00 perf-profile.calltrace.cycles-pp.tick_sched_timer.__hrtimer_run_queues.hrtimer_interrupt.smp_apic_timer_interrupt.apic_timer_interrupt
> > 1.89 -0.1 1.79 perf-profile.calltrace.cycles-pp.tick_sched_handle.tick_sched_timer.__hrtimer_run_queues.hrtimer_interrupt.smp_apic_timer_interrupt
> > 1.71 ± 2% -0.1 1.60 perf-profile.calltrace.cycles-pp.update_process_times.tick_sched_handle.tick_sched_timer.__hrtimer_run_queues.hrtimer_interrupt
> > 0.53 ± 12% -0.1 0.44 ± 4% perf-profile.children.cycles-pp._raw_spin_lock_irqsave
> > 0.17 ± 7% -0.0 0.15 ± 4% perf-profile.children.cycles-pp.leave_mm
> > 0.09 ± 8% -0.0 0.08 ± 11% perf-profile.children.cycles-pp.cpu_load_update_active
> > 0.17 ± 8% +0.0 0.19 ± 4% perf-profile.children.cycles-pp.irq_work_needs_cpu
> > 0.43 ± 14% -0.1 0.38 ± 3% perf-profile.self.cycles-pp._raw_spin_lock_irqsave
> > 0.17 ± 7% -0.0 0.15 ± 4% perf-profile.self.cycles-pp.leave_mm
> > 0.30 +0.0 0.32 ± 2% perf-profile.self.cycles-pp.get_next_timer_interrupt
> > 0.17 ± 8% +0.0 0.19 ± 4% perf-profile.self.cycles-pp.irq_work_needs_cpu
> > 0.06 ± 9% +0.0 0.08 ± 15% perf-profile.self.cycles-pp.sched_clock
> > 4358 ± 15% +25.0% 5446 ± 7% sched_debug.cfs_rq:/.exec_clock.avg
> > 24231 ± 7% +12.3% 27202 ± 3% sched_debug.cfs_rq:/.exec_clock.stddev
> > 23637 ± 17% +33.3% 31501 ± 14% sched_debug.cfs_rq:/.load.avg
> > 73299 ± 9% +19.8% 87807 ± 8% sched_debug.cfs_rq:/.load.stddev
> > 35584 ± 7% +13.2% 40294 ± 5% sched_debug.cfs_rq:/.min_vruntime.stddev
> > 0.09 ± 10% +27.8% 0.12 ± 15% sched_debug.cfs_rq:/.nr_running.avg
> > 17.10 ± 18% +36.5% 23.33 ± 18% sched_debug.cfs_rq:/.runnable_load_avg.avg
> > 63.20 ± 10% +18.9% 75.11 ± 7% sched_debug.cfs_rq:/.runnable_load_avg.stddev
> > 23618 ± 17% +33.3% 31477 ± 14% sched_debug.cfs_rq:/.runnable_weight.avg
> > 73217 ± 9% +19.9% 87751 ± 8% sched_debug.cfs_rq:/.runnable_weight.stddev
> > 35584 ± 7% +13.2% 40294 ± 5% sched_debug.cfs_rq:/.spread0.stddev
> > 95.02 ± 9% +14.5% 108.82 ± 7% sched_debug.cfs_rq:/.util_avg.avg
> > 19.44 ± 9% +23.0% 23.91 ± 10% sched_debug.cfs_rq:/.util_est_enqueued.avg
> > 323.02 ± 3% -6.4% 302.21 ± 4% sched_debug.cpu.ttwu_local.avg
> >
> >
> >
> > aim9.disk_rr.ops_per_sec
> >
> > 650000 +-+----------------------------------------------------------------+
> > 640000 +-+ .+.. |
> > | .+.+..+..+..+..+ +.. .+.. .+.. .+..+..|
> > 630000 +-++. +..+..+ +..+..+.+. +..+..+ |
> > 620000 +-+ |
> > | |
> > 610000 +-+ |
> > 600000 +-+ |
> > 590000 +-+ |
> > | |
> > 580000 +-+ |
> > 570000 +-+ |
> > O O O O O O O O O O |
> > 560000 +-+O O O O O O O O O O O O O |
> > 550000 +-+----------------------------------------------------------------+
> >
> >
> > aim9.time.user_time
> >
> > 57 +-+--------------------------------------------------------------------+
> > | .+..+.. .+. .+.. .|
> > 56 +-+ .+..+.. .+..+..+. +..+. +.. .+..+. +.. .+.. .+..+. |
> > 55 +-++. +. +. +. +. |
> > | |
> > 54 +-+ |
> > | |
> > 53 +-+ |
> > | |
> > 52 +-+ O |
> > 51 +-+ |
> > | O O O O O O O O O |
> > 50 O-+O O O O O O O O |
> > | O O O O |
> > 49 +-+--------------------------------------------------------------------+
> >
> >
> > aim9.time.system_time
> >
> > 251 +-+-------------------------------------------------------------------+
> > | O O O O |
> > 250 O-+O O O O O O O O |
> > 249 +-+ O O O O O O O O O |
> > | |
> > 248 +-+ O |
> > | |
> > 247 +-+ |
> > | |
> > 246 +-+ |
> > 245 +-+ |
> > | .+.. .+.. .+.. .+.. .+.. |
> > 244 +-+ +..+. +..+.+.. .+..+..+..+. +..+..+..+ +. +..+..|
> > | +..+. |
> > 243 +-+-------------------------------------------------------------------+
> >
> >
> >
> > [*] bisect-good sample
> > [O] bisect-bad sample
> >
> >
> > Disclaimer:
> > Results have been estimated based on internal Intel analysis and are provided
> > for informational purposes only. Any difference in system hardware or software
> > design or configuration may affect actual performance.
> >
> >
> > Thanks,
> > Xiaolong
>
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