Re: [lkp] [sched/fair] e210bffd39: perf-stat.cpu-migrations -36.0% decrease

From: Peter Zijlstra
Date: Thu Aug 04 2016 - 05:01:48 EST


On Thu, Aug 04, 2016 at 01:24:23PM +0800, kernel test robot wrote:
>
> FYI, we noticed perf-stat.cpu-migrations -36.0% decrease due to commit:
>
> commit e210bffd39d01b649c94b820c28ff112673266dd ("sched/fair: Fix and optimize the fork() path")
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>
> in testcase: unixbench
> on test machine: 16 threads Broadwell-DE with 8G memory
> with following parameters:
>
> runtime: 300s
> nr_task: 1
> test: shell8
> cpufreq_governor: performance
>
>

Urgh, I so hate these reports. They're near useless :/

It took me 3 readings to realize it was the unixbench testcase (why
isn't that in the subject!?). But then I still haven't found the primary
performance metric. Does the test improve, degrade or not change
overall?