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

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Message-ID: <CAERHkrsaXAgE4MyE6ZehZ8cSq0bVrjc5uJnE9GwLCk4dp1hS9g@mail.gmail.com>
Date:   Thu, 16 Jan 2020 09:45:29 +0800
From:   Aubrey Li <aubrey.intel@...il.com>
To:     Tim Chen <tim.c.chen@...ux.intel.com>
Cc:     Aubrey Li <aubrey.li@...ux.intel.com>,
        Vineeth Remanan Pillai <vpillai@...italocean.com>,
        Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...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>,
        Aaron Lu <aaron.lwe@...il.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 Thu, Jan 16, 2020 at 3:33 AM Tim Chen <tim.c.chen@...ux.intel.com> wrote:
>
> On 1/14/20 7:43 PM, Li, Aubrey wrote:
> > On 2020/1/14 23:40, Vineeth Remanan Pillai wrote:
> >> On Mon, Jan 13, 2020 at 8:12 PM Tim Chen <tim.c.chen@...ux.intel.com> wrote:
> >>
> >>> I also encountered kernel panic with the v4 code when taking cpu offline or online
> >>> when core scheduler is running.  I've refreshed the previous patch, along
> >>> with 3 other patches to fix problems related to CPU online/offline.
> >>>
> >>> As a side effect of the fix, each core can now operate in core-scheduling
> >>> mode or non core-scheduling mode, depending on how many online SMT threads it has.
> >>>
> >>> Vineet, are you guys planning to refresh v4 and update it to v5?  Aubrey posted
> >>> a port to the latest kernel earlier.
> >>>
> >> Thanks for the updated patch Tim.
> >>
> >> We have been testing with v4 rebased on 5.4.8 as RC kernels had given us
> >> trouble in the past. v5 is due soon and we are planning to release v5 when
> >> 5.5 comes out. As of now, v5 has your crash fixes and Aubrey's changes
> >> related to load balancing.
> >
> > It turns out my load balancing related changes need to be refined.
> > For example, we don't migrate task if the task's core cookie does not match
> > with CPU's core cookie, but if the entire core is idle, we should allow task
> > migration, something like the following:
> >
> > I plan to do this after my Chinese New Year holiday(Feb 3rd).
> >
> > Thanks,
> > -Aubrey
> >
>
> Aubrey's attached patch should replace his previous patch
> sched/fair: don't migrate task if cookie not match
>
> I've also added a fix below for Aubrey's patch
> sched/fair: find cookie matched idlest CPU.
>
> Aubrey, can you merge this fix into that patch when you update
> your patches?

Thanks Tim, I'll include your fix when I update my patches.

-Aubrey