linux-kernel - Re: [RFC PATCH v4 00/19] Core scheduling v4

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Message-ID: <CAERHkrsNYnJOdhb1ecgwXHfWMNEU5CkS7CcuS-X9Wo6gE=KgHQ@mail.gmail.com>
Date:   Tue, 25 Feb 2020 21:41:28 +0800
From:   Aubrey Li <aubrey.intel@...il.com>
To:     Aaron Lu <aaron.lwe@...il.com>
Cc:     Tim Chen <tim.c.chen@...ux.intel.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Vineeth Remanan Pillai <vpillai@...italocean.com>,
        Nishanth Aravamudan <naravamudan@...italocean.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul Turner <pjt@...gle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Dario Faggioli <dfaggioli@...e.com>,
        Frédéric Weisbecker <fweisbec@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Greg Kerr <kerrnel@...gle.com>, Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [RFC PATCH v4 00/19] Core scheduling v4

On Tue, Feb 25, 2020 at 7:22 PM Aaron Lu <aaron.lwe@...il.com> wrote:
>
> On Tue, Feb 25, 2020 at 06:40:02PM +0800, Aubrey Li wrote:
> > On Tue, Feb 25, 2020 at 3:34 PM Aaron Lu <aaron.lwe@...il.com> wrote:
> > >
> > > On Tue, Feb 25, 2020 at 01:32:35PM +0800, Aubrey Li wrote:
> > > > Aaron - did you test this before? In other words, if you reset repo to your
> > > > last commit:
> > >
> > > I did this test only recently when I started to think if I can use
> > > coresched to boost main workload's performance in a colocated
> > > environment.
> > >
> > > >
> > > > - 5bd3c80 sched/fair : Wake up forced idle siblings if needed
> > > >
> > > > Does the problem remain? Just want to check if this is a regression
> > > >  introduced by the subsequent patchset.
> > >
> > > The problem isn't there with commit 5bd3c80 as the head, so yes, it
> > > looks like indeed a regression introduced by subsequent patchset.
> > >
> > > P.S. I will need to take a closer look if each cgA's task is running
> > > on a different core later but the cpu usage of cgA is back to 800% with
> > > commit 5bd3c80.
> >
> > Hmm..., I went through the subsequent patches, and I think this one
> >
> > - 4041eeb8f3 sched/fair: don't migrate task if cookie not match
> >
> > is probably the major cause, can you please revert this one to see
> > if the problem is gone?
>
> Yes, reverting this one fixed the problem.

okay, but this patch also contributed the improvement of a few benchmarks
on my side. So we need a way to fix your case, my quick thought is allowing
task migration in this case(sounds like a workaround). Need take a deep look
at CPU resource controlled code path when core scheduling enabled.

Any ideas?

Thanks,
-Aubrey