Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg

From: Vincent Guittot
Date: Thu May 04 2017 - 15:03:11 EST

Hi Tejun,

On 4 May 2017 at 19:43, Tejun Heo <tj@xxxxxxxxxx> wrote:
> Hello,
> On Thu, May 04, 2017 at 10:19:46AM +0200, Vincent Guittot wrote:
>> > schbench inside a cgroup and have some base load, it is actually
>> > expected to show worse latency. You need to give higher weight to the
>> > cgroup matching the number of active threads (to be accruate, scaled
>> > by duty cycle but shouldn't matter too much in practice).
>> I don't have to change anything cgroup weight with mainline to get
>> good number which means that the base load which is quite close to
>> null, is probably not the problem
> So, while that *could* be the case, it could also be the baseline
> incorrectly favoring the nested cfs_rqs over other tasks because of
> the nested runnables being inflated with blocked load avgs. I think
> it'd be a good idea to test with matching weight to put things on the
> even ground.

In the trace i have uploaded, you will see that regressions happen
whereas there is no other runnable threads around so it's not a matter
of background activities that disturbs schbench


> Thanks.
> --
> tejun