From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@redhat.com, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
vschneid@redhat.com, clm@meta.com, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 2/5] sched: Optimize ttwu() / select_task_rq()
Date: Fri, 13 Jun 2025 12:20:56 +0200 [thread overview]
Message-ID: <b638eb73e6da733afd6eb758cc144bf119e1b600.camel@gmx.de> (raw)
In-Reply-To: <20250613094052.GF2278213@noisy.programming.kicks-ass.net>
On Fri, 2025-06-13 at 11:40 +0200, Peter Zijlstra wrote:
> On Mon, Jun 09, 2025 at 07:01:47AM +0200, Mike Galbraith wrote:
>
> Right; so the problem being that we can race with
> migrate_disable_switch().
Yeah. Most of the time when we do fallback saves us, but we can and do
zip past it, and that turns box various shades of sad.
>
> Does something like this help?
It surely will, but I'll testdrive it. No news is good news.
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3593,7 +3593,7 @@ int select_task_rq(struct task_struct *p
> cpu = p->sched_class->select_task_rq(p, cpu,
> *wake_flags);
> *wake_flags |= WF_RQ_SELECTED;
> } else {
> - cpu = cpumask_any(p->cpus_ptr);
> + cpu = task_cpu(p);
> }
>
> /*
next prev parent reply other threads:[~2025-06-13 10:21 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-20 9:45 [RFC][PATCH 0/5] sched: Try and address some recent-ish regressions Peter Zijlstra
2025-05-20 9:45 ` [RFC][PATCH 1/5] sched/deadline: Less agressive dl_server handling Peter Zijlstra
2025-06-03 16:03 ` Juri Lelli
2025-06-13 9:43 ` Peter Zijlstra
2025-05-20 9:45 ` [RFC][PATCH 2/5] sched: Optimize ttwu() / select_task_rq() Peter Zijlstra
2025-06-09 5:01 ` Mike Galbraith
2025-06-13 9:40 ` Peter Zijlstra
2025-06-13 10:20 ` Mike Galbraith [this message]
2025-05-20 9:45 ` [RFC][PATCH 3/5] sched: Split up ttwu_runnable() Peter Zijlstra
2025-05-20 9:45 ` [RFC][PATCH 4/5] sched: Add ttwu_queue controls Peter Zijlstra
2025-05-20 9:45 ` [RFC][PATCH 5/5] sched: Add ttwu_queue support for delayed tasks Peter Zijlstra
2025-06-06 15:03 ` Vincent Guittot
2025-06-06 15:38 ` Peter Zijlstra
2025-06-06 16:55 ` Vincent Guittot
2025-06-11 9:39 ` Peter Zijlstra
2025-06-16 12:39 ` Vincent Guittot
2025-06-06 16:18 ` Phil Auld
2025-06-16 12:01 ` Peter Zijlstra
2025-06-16 16:37 ` Peter Zijlstra
2025-06-13 7:34 ` Dietmar Eggemann
2025-06-13 9:51 ` Peter Zijlstra
2025-06-13 10:46 ` Peter Zijlstra
2025-06-16 8:16 ` Dietmar Eggemann
2025-05-28 19:59 ` [RFC][PATCH 0/5] sched: Try and address some recent-ish regressions Peter Zijlstra
2025-05-29 1:41 ` Chris Mason
2025-06-14 10:04 ` Peter Zijlstra
2025-06-16 0:35 ` Chris Mason
2025-05-29 10:18 ` Beata Michalska
2025-05-30 9:00 ` Peter Zijlstra
2025-05-30 10:04 ` Chris Mason
2025-06-02 4:44 ` K Prateek Nayak
2025-06-13 3:28 ` K Prateek Nayak
2025-06-14 10:15 ` Peter Zijlstra
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