linux-kernel - Re: [RFC][PATCH 4/6] sched: Fold sched_class::switch{ing,ed}

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Message-ID: <20241030213735.GS14555@noisy.programming.kicks-ass.net>
Date: Wed, 30 Oct 2024 22:37:35 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Tejun Heo <tj@...nel.org>
Cc: mingo@...nel.org, juri.lelli@...hat.com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
	mgorman@...e.de, vschneid@...hat.com, void@...ifault.com,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 4/6] sched: Fold
 sched_class::switch{ing,ed}_{to,from}() into the change pattern

On Wed, Oct 30, 2024 at 11:29:09AM -1000, Tejun Heo wrote:
> On Wed, Oct 30, 2024 at 10:15:06PM +0100, Peter Zijlstra wrote:
> ...
> > > > +		if (!(queue_flags & DEQUEUE_CLASS))
> > > > +			check_prio_changed(task_rq(p), p, p->prio);
> > > 
> > > Maybe prio_changed can be moved into scoped_guard?
> > 
> > It wasn't before -- do you have need for it to be inside?
> 
> No, was just wondering whether that'd make things a bit more compact. Either
> way is fine.

Oh, did you perhaps mean into sched_change_end() ? I suppose that's
possible indeed. Initially I thought that would require yet another
flags, but looking at it again, that doesn't seem to be the case. All
sched_change users lacking it never change the prio anyway.

I'll have a look at doing that tomorrow, with a slightly fresher brain.

I also think that adding flags to the switch*() methods isn't at all
needed, but perhaps it makes sense anyway.