linux-kernel - Re: [RFC PATCHSET v2] sched/fair: fix load balancer behavior when cgroup is in use

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Date:   Fri, 5 May 2017 15:32:26 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Tejun Heo <tj@...nel.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Galbraith <efault@....de>, Paul Turner <pjt@...gle.com>,
        Chris Mason <clm@...com>, kernel-team@...com
Subject: Re: [RFC PATCHSET v2] sched/fair: fix load balancer behavior when
 cgroup is in use

On 5 May 2017 at 15:28, Tejun Heo <tj@...nel.org> wrote:
> Hello, Vincent.
>
> On Fri, May 05, 2017 at 10:46:53AM +0200, Vincent Guittot wrote:
>> schbench results looks better with this version
>> Latency percentiles (usec)
>> 50.0000th: 212
>> 75.0000th: 292
>> 90.0000th: 385
>> 95.0000th: 439
>> *99.0000th: 671
>> 99.5000th: 7992
>> 99.9000th: 12176
>> min=0, max=14855
>>
>> p99 is back to a normal value but p99.5 stays higher than mainline
>
> By how much and is that with the weight adjustment on the cgroup?  I
> can't get reliable numbers on p99.5 and beyond on my test setup.  I
> ordered the hikey board and will try to replicate your setup once it
> arrives.

This is the results that I got when i tested you 1st version last week:

With v4.11-rc8. I have run 10 times the test and get consistent results
schbench -m 2 -t 4 -s 10000 -c 15000 -r 30
Latency percentiles (usec)
50.0000th: 255
75.0000th: 350
90.0000th: 454
95.0000th: 489
*99.0000th: 539
99.5000th: 585
99.9000th: 10224
min=0, max=13567

>
>> I have also checked load_avg and runnable_load_avg value and there is
>> something incorrect. I will provide details on the related patch
>
> Sure, will respond there.
>
> Thanks.
>
> --
> tejun