linux-kernel - Re: [PATCH] sched/fair: no sync wakeup from interrupt context

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Date:   Thu, 4 Aug 2022 10:51:50 +0100
From:   Mel Gorman <mgorman@...e.de>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Libo Chen <libo.chen@...cle.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        peterz@...radead.org, vincent.guittot@...aro.org,
        tim.c.chen@...ux.intel.com, 21cnbao@...il.com,
        dietmar.eggemann@....com, linux-kernel@...r.kernel.org,
        tglx@...utronix.de
Subject: Re: [PATCH] sched/fair: no sync wakeup from interrupt context

On Thu, Aug 04, 2022 at 10:55:12AM +0200, Ingo Molnar wrote:
> 
> * Libo Chen <libo.chen@...cle.com> wrote:
> 
> > Oh yes, I have no issue with holding the patch back until the regression 
> > is fully understood. I was just a little confused on your reference to 
> > Mel's comments. [...]
> 
> Yeah, that was just me getting confused about which change Mel was 
> referring to, as I was looking for external confirmation saying what I was 
> thinking about the patch: in_task()/in_interrupt() heuristics rarely do 
> well. ;-)
> 

Even though I was referring to something else, the reported regression
is still a regression.  Prateek's report and what I brought up in
https://lore.kernel.org/all/20220715100738.GD3493@suse.de/ are both simply
examples where changes to affine wakeup can have surprising results.

-- 
Mel Gorman
SUSE Labs