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Date:   Mon, 4 Jun 2018 16:12:31 +0800
From:   Aaron Lu <aaron.lu@...el.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     kernel test robot <xiaolong.ye@...el.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>, lkp@...org
Subject: Re: [LKP] [lkp-robot] [tracing/x86] 1c758a2202:
 aim9.disk_rr.ops_per_sec -12.0% regression

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@...el.com> 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
> 
> _______________________________________________
> LKP mailing list
> LKP@...ts.01.org
> https://lists.01.org/mailman/listinfo/lkp

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