linux-kernel - Re: [PATCH 0/4] sched/fair: Improve fairness between cfs tasks

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Message-ID: <20200918163928.GG55398@lorien.usersys.redhat.com>
Date:   Fri, 18 Sep 2020 12:39:28 -0400
From:   Phil Auld <pauld@...hat.com>
To:     peterz@...radead.org
Cc:     Vincent Guittot <vincent.guittot@...aro.org>, mingo@...hat.com,
        juri.lelli@...hat.com, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        linux-kernel@...r.kernel.org, valentin.schneider@....com,
        Jirka Hladky <jhladky@...hat.com>
Subject: Re: [PATCH 0/4] sched/fair: Improve fairness between cfs tasks

Hi Peter,

On Mon, Sep 14, 2020 at 01:42:02PM +0200 peterz@...radead.org wrote:
> On Mon, Sep 14, 2020 at 12:03:36PM +0200, Vincent Guittot wrote:
> > Vincent Guittot (4):
> >   sched/fair: relax constraint on task's load during load balance
> >   sched/fair: reduce minimal imbalance threshold
> >   sched/fair: minimize concurrent LBs between domain level
> >   sched/fair: reduce busy load balance interval
> 
> I see nothing objectionable there, a little more testing can't hurt, but
> I'm tempted to apply them.
> 
> Phil, Mel, any chance you can run them through your respective setups?
> 

Sorry for the delay. Things have been backing up...

We tested with tis series and found there was no performance change in
our test suites. (We don't have a good way to share the actual numbers
outside right now, but since they aren't really different it probably
doesn't matter much here.)

The difference we did see was a slight decrease in the number of tasks
moved around at higher loads.  That seems to be a good thing even though
it didn't directly show time-based performance benefits (and was pretty
minor).

So if this helps other use cases we've got no problems with it.

Thanks,
Phil

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