Re: [lkp] [x86/platform/UV] 71854cb812: will-it-scale.per_thread_ops -2.3% regression

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [lkp] [x86/platform/UV] 71854cb812: will-it-scale.per_thread_ops -2.3% regression
Date	2016-10-28 01:10 +0200
Message-ID	<sx1Y6-8mn-17@gated-at.bofh.it> (permalink)
References	<sw3IB-1ZK-9@gated-at.bofh.it> <sw7Cx-4uH-9@gated-at.bofh.it> <swI93-3vr-3@gated-at.bofh.it>
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On Thu, 27 Oct 2016, Ye Xiaolong wrote:
> Yes, this is weird, the per_thread_ops change is small and should be run
> to run variation, the actual significant change is will-it-scale.time.user_time
> -27% decrease, but the patch seems not relevant, we can't interpret it. :(
> 
> We've tried to queue the jobs (4 times) for
> 71854cb812ec23bfe5f63d52217e6b9e6cb901f5 and v4.9-rc1 with new kconfig
> (added CONFIG_DEBUG_INFO_REDUCED), and result shows user_time change is
> quite stable.

>         v4.9-rc1 71854cb812ec23bfe5f63d5221
> ---------------- -------------------------- 
>          %stddev     %change         %stddev
>              \          |                \
>    1670068 ±  0%      -3.8%    1606650 ±  1%  will-it-scale.per_thread_ops
>       9749 ±  2%   +1328.0%     139222 ±105%  will-it-scale.time.involuntary_context_switches

	     	     		  ^^^^^^ This is massive

I have no explanation for this either, but you really should try to figure
out what's going on here.

The only difference between plain rc1 and rc + this patch is the resulting
text size and therefor some other unrelated stuff moving to different
places in memory which has some yet to figure out side effects.

Thanks,

	tglx

Thread

Re: [lkp] [x86/platform/UV] 71854cb812: will-it-scale.per_thread_ops  -2.3% regression Ye Xiaolong <xiaolong.ye@intel.com> - 2016-10-27 04:00 +0200
  Re: [lkp] [x86/platform/UV] 71854cb812: will-it-scale.per_thread_ops  -2.3% regression Thomas Gleixner <tglx@linutronix.de> - 2016-10-28 01:10 +0200
    Re: [LKP] [lkp] [x86/platform/UV] 71854cb812:  will-it-scale.per_thread_ops -2.3% regression Fengguang Wu <fengguang.wu@intel.com> - 2016-10-31 06:50 +0100
      Re: [LKP] [lkp] [x86/platform/UV] 71854cb812: will-it-scale.per_thread_ops  -2.3% regression Thomas Gleixner <tglx@linutronix.de> - 2016-10-31 19:30 +0100

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