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Date: Mon, 12 Dec 2016 14:25:04 +0100
From: Vincent Guittot <vincent.guittot@...aro.org>
To: kernel test robot <ying.huang@...ux.intel.com>
Cc: Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <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 <lkp@...org>,
Andi Kleen <ak@...ux.intel.com>,
Tim Chen <tim.c.chen@...ux.intel.com>,
Dave Hansen <dave.hansen@...el.com>
Subject: Re: [lkp-developer] [sched/fair] 4e5160766f: +149% ftq.noise.50% regression
Hi Ying,
On 12 December 2016 at 06:43, kernel test robot
<ying.huang@...ux.intel.com> wrote:
> 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
Why using powersave ? Are you testing every governors ?
>
> 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
It's a bit difficult to understand exactly what is measured and what
is ftq.noise.50% because this result is not part of the bench which
seems to only record a log of data in a file and ftq.noise.50% seems
to be lkp specific
I have tried to reproduce the lkp test on a debian jessie then a
ubuntu server 16.10 but lkp doesn't seems to install cleanly as there
are some errors:
sudo bin/lkp run job.yaml
IPMI BMC is not supported on this machine, skip bmc-watchdog setup!
2016-12-12 13:58:39 ./ftq_cache -f 20 -n 6000 -t 8 -a 524288
Start 5088418680237 end 5438443372098 elapsed 350024691861
cyclestart 14236344834332 cycleend 15214154208877 elapsed 977809374545
Avg Cycles(ticks) per ns. is 2.793544; nspercycle is 0.357968
Pre-computed ticks per ns: 2.793541
Sample frequency is 20.000000
ticks per ns 2.79354
chown: utilisateur incorrect: «lkp.lkp»
chown: utilisateur incorrect: «lkp.lkp»
wait for background monitors: 9405 9407 oom-killer nfs-hang
curl: (6) Could not resolve host: ftq.time
>
> 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
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