From: Mike Galbraith <efault@gmx.de>
To: Francesco Nigro <nigro.fra@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
Valentin Schneider <vschneid@redhat.com>,
K Prateek Nayak <kprateek.nayak@amd.com>,
Mario Limonciello <mario.limonciello@amd.com>,
Huang Rui <ray.huang@amd.com>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [REPORT] sched: ITMT + DELAY_DEQUEUE: woken task waits ~1 ms behind another task on the preferred CPU while allowed CPUs are idle
Date: Tue, 03 Nov 2026 18:27:15 +0100 [thread overview]
Message-ID: <25edb6cd36cb77b82b40826b97232438f1443516.camel@gmx.de> (raw)
In-Reply-To: <20261103154603.1893325-1-nigro.fra@gmail.com>
On Tue, 2026-11-03 at 16:46 +0100, Francesco Nigro wrote:
>
> Related, not tested here
>
> - Mike Galbraith, "sched/fair: Dequeue sched_delayed tasks when waking
> to a busy CPU" (tip sched/urgent, 2024-11-11; not in 7.1.13 or
> 7.4-rc1) and its V2 thread:
> https://lore.kernel.org/all/bf4f50886c462ee1f33cc404843944fea4817616.camel@gmx.de/
Mmm, that's a be careful what you wish for thing. I flushed that one
down the toilet because while lowest possible service latency always
sounds super sexy, it has down sides. Rabid migration does not do great
things for throughput, for instance, that patch slagged the throughput
gain for tbench that put DELAY_DEQUEUE equipped kernels back on par
with pre-EEVDF kernels. Not a keeper.
-Mike
prev parent reply other threads:[~2026-11-03 17:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-03 15:46 Francesco Nigro
2026-11-03 17:27 ` Mike Galbraith [this message]
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