linux-kernel - [lkp-developer] [sched/fair] 4e5160766f: +149% ftq.noise.50% regression

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Date:   Mon, 12 Dec 2016 13:43:55 +0800
From:   kernel test robot <ying.huang@...ux.intel.com>
TO:     Vincent Guittot <vincent.guittot@...aro.org>
CC:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra (Intel) <peterz@...radead.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>, lkp@...org,
        Andi Kleen <ak@...ux.intel.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>
Subject: [lkp-developer] [sched/fair]  4e5160766f: +149% ftq.noise.50% regression

Greeting,

FYI, we noticed a 149% regression of ftq.noise.50% due to commit:


commit: 4e5160766fcc9f41bbd38bac11f92dce993644aa ("sched/fair: Propagate asynchrous detach")
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master

in testcase: ftq
on test machine: 8 threads Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz with 8G memory
with following parameters:

	nr_task: 100%
	samples: 6000ss
	test: cache
	freq: 20
	cpufreq_governor: powersave

test-description: The FTQ benchmarks measure hardware and software interference or 'noise' on a node from the applications perspective.
test-url: https://github.com/rminnich/ftq

In addition to that, the commit also has significant impact on the following tests:

+------------------+--------------------------------------------------------------------------------+
| testcase: change | unixbench: unixbench.score 2.7% improvement                                    |
| test machine     | 4 threads Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz with 4G memory               |
| test parameters  | cpufreq_governor=performance                                                   |
|                  | nr_task=100%                                                                   |
|                  | runtime=300s                                                                   |
|                  | test=execl                                                                     |
+------------------+--------------------------------------------------------------------------------+


Details are as below:
-------------------------------------------------------------------------------------------------->


To reproduce:

        git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml

testcase/path_params/tbox_group/run: ftq/100%-6000ss-cache-20-powersave/lkp-hsw-d01

09a43ace1f986b00  4e5160766fcc9f41bbd38bac11  
----------------  --------------------------  
         %stddev      change         %stddev
             \          |                \  
       305 ± 30%       260%       1100 ± 14%  ftq.noise.75%
      1386 ± 19%       149%       3457 ±  7%  ftq.noise.50%
      2148 ± 11%        98%       4257 ±  4%  ftq.noise.25%
   3963589                     3898578        ftq.time.involuntary_context_switches



                                   ftq.noise.50_

  4000 ++------------O------------------------------------------------------+
       |                                                           O      O |
  3500 ++     O             O                        O    O O O             O
       | O  O      O   O      O O  O O O    O O    O   O         O          |
       O        O                         O                          O O    |
  3000 ++                                       O                           |
       |                 O                                                  |
  2500 ++                                                                   |
       |                                                                    |
  2000 ++                                                                   |
       |    *                  .*                                           |
       |   + :     *   *      *  +                                          |
  1500 ++ +  :    + + + +    :    + .*                                      |
       |.*    *. +   *   *.. :     *  +                                     |
  1000 *+-------*-----------*----------*------------------------------------+

	[*] 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,
Ying Huang

View attachment "config-4.9.0-rc5-00198-g4e51607" of type "text/plain" (153626 bytes)

View attachment "job-script" of type "text/plain" (4199 bytes)

View attachment "job.yaml" of type "text/plain" (3412 bytes)

View attachment "reproduce" of type "text/plain" (143 bytes)