linux-kernel - Re: [PATCH] sched/fair: Do not decay new task load on first enqueue

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Date:   Tue, 11 Oct 2016 11:27:47 +0100
From:   Matt Fleming <matt@...eblueprint.co.uk>
To:     Wanpeng Li <kernellwp@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mike Galbraith <umgwanakikbuti@...il.com>,
        Yuyang Du <yuyang.du@...el.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>
Subject: Re: [PATCH] sched/fair: Do not decay new task load on first enqueue

On Mon, 10 Oct, at 06:09:14PM, Wanpeng Li wrote:
> 2016-10-10 18:01 GMT+08:00 Matt Fleming <matt@...eblueprint.co.uk>:
> > On Sun, 09 Oct, at 11:39:27AM, Wanpeng Li wrote:
> >>
> >> The difference between this patch and Peterz's is your patch have a
> >> delta since activate_task()->enqueue_task() does do update_rq_clock(),
> >> so why don't have the delta will cause low cpu machines (4 or 8) to
> >> regress against your another reply in this thread?
> >
> > Both my patch and Peter's patch cause issues with low cpu machines. In
> > <20161004201105.GP16071@...eblueprint.co.uk> I said,
> >
> >  "This patch causes some low cpu machines (4 or 8) to regress. It turns
> >   out they regress with my patch too."
> >
> > Have I misunderstood your question?
> 
> I compare this one https://marc.info/?l=linux-kernel&m=147446511924571
> with Peterz's patch.

Oh. Low cpu machines probably do regress with my patch. At least, I
can't find the notes to prove that they don't.