From: Tejun Heo <tj@kernel.org>
To: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: phasta@kernel.org, dri-devel@lists.freedesktop.org,
Boris Brezillon <boris.brezillon@collabora.com>,
Steven Price <steven.price@arm.com>,
Liviu Dudau <liviu.dudau@arm.com>, Chia-I Wu <olvaffe@gmail.com>,
Danilo Krummrich <dakr@kernel.org>,
Matthew Brost <matthew.brost@intel.com>,
kernel-dev@igalia.com
Subject: Re: [RFC 0/8] DRM scheduler kthread_worker for submission latency improvements
Date: Mon, 6 Jul 2026 09:36:59 -1000 [thread overview]
Message-ID: <akwD28ihbzn1FB-P@slm.duckdns.org> (raw)
In-Reply-To: <b76ea01c-ead3-4eaf-86a7-5bf91bfdb9cb@igalia.com>
Hello,
On Mon, Jul 06, 2026 at 01:20:49PM +0100, Tvrtko Ursulin wrote:
...
> > So the first question I would like to see considered is whether
> > workqueue could be improved in any way to address said latency issues.
> >
> > Have you already considered that, Tvrtko?
>
> Yes, priority inheritance was justifiably rejected for generic workqueues.
> There is WQ_HIGHPRI, but the idea here is to go one step further and allow
> tracking realtime scheduling policies.
If deciding at work item boundaries is granular enough, it's not
unconscionable to support RT worker pools. The main reason for resisting
that is because it can be too easy to abuse. A couple RT threads may solve
immediate problems but with a bunch of them you just don't have a working
scheduler in the system. In general, it's pretty suspicious if there's
intersection of "I need a bunch of worker threads in a flexible way" and "I
want RT".
How big a hit is WQ_HIGHPRI vs. RT?
Thanks.
--
tejun
next prev parent reply other threads:[~2026-07-06 19:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-02 14:37 [RFC 0/8] DRM scheduler kthread_worker for submission latency improvements Tvrtko Ursulin
2026-07-02 14:37 ` [RFC 1/8] drm/panthor: Remove redundant drm_sched_job_cleanup() from the .free_job callback Tvrtko Ursulin
2026-07-03 15:00 ` Steven Price
2026-07-02 14:37 ` [RFC 2/8] drm/panthor: Use separate workqueue for DRM scheduler Tvrtko Ursulin
2026-07-02 15:31 ` Boris Brezillon
2026-07-06 12:03 ` Tvrtko Ursulin
2026-07-06 14:18 ` Boris Brezillon
2026-07-02 14:37 ` [RFC 3/8] drm/sched: Use generic naming for workqueue helpers Tvrtko Ursulin
2026-07-02 14:37 ` [RFC 4/8] drm/xe: Convert to per gt scheduler workers Tvrtko Ursulin
2026-07-03 9:06 ` Matthew Brost
2026-07-06 12:27 ` Tvrtko Ursulin
2026-07-06 23:14 ` Matthew Brost
2026-07-02 14:37 ` [RFC 5/8] drm: Wrap DRM scheduler worker in own abstraction Tvrtko Ursulin
2026-07-02 14:37 ` [RFC 6/8] drm/sched: Convert the scheduler job submission to kthread_worker Tvrtko Ursulin
2026-07-02 14:37 ` [RFC 7/8] drm/sched: Add ability to change drm_sched_worker priority Tvrtko Ursulin
2026-07-02 14:37 ` [RFC 8/8] drm/sched: Notify worker of the entity submission priority Tvrtko Ursulin
2026-07-03 8:52 ` [RFC 0/8] DRM scheduler kthread_worker for submission latency improvements Philipp Stanner
2026-07-06 12:20 ` Tvrtko Ursulin
2026-07-06 19:36 ` Tejun Heo [this message]
2026-07-03 9:22 ` Matthew Brost
2026-07-06 12:41 ` Tvrtko Ursulin
2026-07-06 22:54 ` Matthew Brost
2026-07-07 7:12 ` Matthew Brost
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