linux-kernel - Re: [PATCH] sched/fair: remove 2 early returns

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Message-ID: <20231101085801.GI15024@noisy.programming.kicks-ass.net>
Date:   Wed, 1 Nov 2023 09:58:01 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Peng Liang <tcx4c70@...il.com>
Cc:     mingo@...hat.com, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, linux-kernel@...r.kernel.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com
Subject: Re: [PATCH] sched/fair: remove 2 early returns

On Thu, Oct 26, 2023 at 08:37:20PM +0800, Peng Liang wrote:
> After commit 5e963f2bd465 ("sched/fair: Commit to EEVDF"), the 2 early
> returns in entity_tick can be removed safely.

Right, so I still need to go through the whole hrtick thing. I suspect
there's more to clean up / fix.

For exapmle, I don't think hrtick_update() still makes sense.

As to the patch at hand, since slices are now fully controlled through
update_curr() -> update_deadline(), I suspect we can clear out more.

OTOH, we have the problem where rq-clock and wall-time are not running
at the same rate, so hrtick might come in early, so that's something to
look into.

So I don't mind this patch per-se, but I do think there's far more work
to be done here.