linux-kernel - Re: [PATCH] sched/fair: Dequeue sched_delayed tasks when waking to a busy CPU

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <915eab00325f2bf608bcb2bd43665ccf663d4084.camel@gmx.de>
Date: Wed, 20 Nov 2024 19:37:39 +0100
From: Mike Galbraith <efault@....de>
To: Phil Auld <pauld@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>, mingo@...hat.com, 
 juri.lelli@...hat.com, vincent.guittot@...aro.org,
 dietmar.eggemann@....com,  rostedt@...dmis.org, bsegall@...gle.com,
 mgorman@...e.de, vschneid@...hat.com,  linux-kernel@...r.kernel.org,
 kprateek.nayak@....com, wuyun.abel@...edance.com, 
 youssefesmat@...omium.org, tglx@...utronix.de
Subject: Re: [PATCH] sched/fair: Dequeue sched_delayed tasks when waking to
 a busy CPU

On Tue, 2024-11-19 at 12:51 +0100, Mike Galbraith wrote:
> On Tue, 2024-11-19 at 06:30 -0500, Phil Auld wrote:
> >
> > This, below, by itself, did not do help and caused a small slowdown on some
> > other tests.  Did this need to be on top of the wakeup change?
>
> No, that made a mess.

Rashly speculating that turning mobile kthread component loose is what
helped your write regression...

You could try adding (p->flags & PF_KTHREAD) to the wakeup patch to
only turn hard working kthreads loose to try to dodge service latency.
Seems unlikely wakeup frequency * instances would combine to shred fio
the way turning tbench loose did.

	-Mike