From: Peter Zijlstra <peterz@infradead.org>
To: Andrea Righi <arighi@nvidia.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
K Prateek Nayak <kprateek.nayak@amd.com>,
Tejun Heo <tj@kernel.org>,
Patrick Bellasi <patrick.bellasi@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] sched/deadline: Skip bandwidth accounting with SCHED_FLAG_KEEP_PARAMS
Date: Thu, 30 Jul 2026 12:04:57 +0200 [thread overview]
Message-ID: <20260730100457.GP49951@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20260730055631.2271580-1-arighi@nvidia.com>
On Thu, Jul 30, 2026 at 07:56:31AM +0200, Andrea Righi wrote:
> A sched_setattr() invocation targeting a non-deadline task can specify
> SCHED_DEADLINE together with SCHED_FLAG_KEEP_PARAMS. The flag prevents
> __sched_setscheduler() from applying the requested parameters or class,
> but deadline admission runs before the guarded update and immediately
> accounts the requested bandwidth in the root domain. Repeating the
> invocation can therefore consume bandwidth without creating a deadline
> task capable of releasing it.
>
> Skip deadline bandwidth admission when SCHED_FLAG_KEEP_PARAMS is set,
> since neither the deadline policy nor its parameters will change.
I'm thinking this should be fixed by simply not allowing KEEP_PARAM when
the policy changes, no?
next prev parent reply other threads:[~2026-07-30 10:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-30 5:50 [PATCH 0/2] sched: Fix SCHED_FLAG_KEEP_PARAMS side effects Andrea Righi
2026-07-30 5:50 ` [PATCH 1/2] sched: Skip class callbacks with SCHED_FLAG_KEEP_PARAMS Andrea Righi
2026-07-30 7:29 ` K Prateek Nayak
2026-07-30 8:57 ` Andrea Righi
2026-07-30 9:57 ` Peter Zijlstra
2026-07-30 11:42 ` Andrea Righi
2026-07-30 5:56 ` [PATCH 2/2] sched/deadline: Skip bandwidth accounting " Andrea Righi
2026-07-30 10:04 ` Peter Zijlstra [this message]
2026-07-30 9:32 ` [PATCH 0/2] sched: Fix SCHED_FLAG_KEEP_PARAMS side effects Peter Zijlstra
2026-07-30 9:52 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260730100457.GP49951@noisy.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=arighi@nvidia.com \
--cc=bsegall@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=juri.lelli@redhat.com \
--cc=kprateek.nayak@amd.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mgorman@suse.de \
--cc=mingo@redhat.com \
--cc=patrick.bellasi@arm.com \
--cc=rostedt@goodmis.org \
--cc=tj@kernel.org \
--cc=vincent.guittot@linaro.org \
--cc=vschneid@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.