Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from cfs_rq to its sched_entity

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from cfs_rq to its sched_entity
Date	2017-05-04 13:00 +0200
Message-ID	<tDmEh-2js-9@gated-at.bofh.it> (permalink)
References	(3 earlier) <tD6SS-tq-11@gated-at.bofh.it> <tDajL-2yX-7@gated-at.bofh.it> <tDhXX-7Jm-1@gated-at.bofh.it> <tDir0-8aF-11@gated-at.bofh.it> <tDlId-1IX-1@gated-at.bofh.it>
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On Thu, May 04, 2017 at 10:49:51AM +0100, Dietmar Eggemann wrote:
> On 04/05/17 07:21, Peter Zijlstra wrote:
> > On Thu, May 04, 2017 at 07:51:29AM +0200, Peter Zijlstra wrote:
> > 
> >> Urgh, and my numbers were so pretty :/
> > 
> > Just to clarify on how to run schbench, I limited to a single socket (as
> > that is what you have) and set -t to the number of cores in the socket
> > (not the number of threads).
> > 
> > Furthermore, my machine is _idle_, if I don't do anything, it doesn't do
> > _anything_.
> >
> 
> I can't recreate this problem running 'numactl -N 0 ./schbench -m 2 -t
> 10 -s 10000 -c 15000 -r 30' on my E5-2690 v2 (IVB-EP, 2 sockets, 10
> cores / socket, 2 threads / core)
> 
> I tried tip/sched/core comparing running in 'cpu:/' and 'cpu:/foo' and

I'm running tip/master (I think, possibly with the numa topology fixes
in, which should be no-op on the EP).

Also, I run debian sysvinit, so nobody creating cgroups I don't know about.

> using your patch on top with all the combinations of {NO_}FUDGE,
> {NO_}FUDGE2 with prop_type=shares_avg or prop_type_runnable.
> 
> Where you able to see the issue on tip/sched/core w/o your patch on your
> machine?

I see the 99.5th percentile shoot up when I run it in a cgroup.
With FUDGE2 its all good again like not using cgroups.

But yes, last time I played with schbench (when prodding at
select_idle_sibling) the thing was finicky too, I never quite got the same
numbers Chris did. But in the end we found something that worked
at both ends.

Thread

[PATCH v2 1/2] sched/fair: Fix how load gets propagated from cfs_rq  to its sched_entity Tejun Heo <tj@kernel.org> - 2017-04-24 23:40 +0200
  Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Peter Zijlstra <peterz@infradead.org> - 2017-05-03 20:10 +0200
    Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Tejun Heo <tj@kernel.org> - 2017-05-03 23:50 +0200
      Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Peter Zijlstra <peterz@infradead.org> - 2017-05-04 08:00 +0200
        Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Peter Zijlstra <peterz@infradead.org> - 2017-05-04 08:30 +0200
          Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Dietmar Eggemann <dietmar.eggemann@arm.com> - 2017-05-04 12:00 +0200
            Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Peter Zijlstra <peterz@infradead.org> - 2017-05-04 13:00 +0200
            Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Tejun Heo <tj@kernel.org> - 2017-05-04 19:40 +0200
              Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Dietmar Eggemann <dietmar.eggemann@arm.com> - 2017-05-05 12:40 +0200
    Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from  cfs_rq to its sched_entity Vincent Guittot <vincent.guittot@linaro.org> - 2017-05-04 12:30 +0200

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