From: Tejun Heo <tj@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
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>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <vschneid@redhat.com>,
Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Will Deacon <will@kernel.org>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v5 3/3] cgroup/cpuset: Keep user set cpus affinity
Date: Tue, 16 Aug 2022 12:19:07 -1000 [thread overview]
Message-ID: <YvwX24GXadKQNp6V@slm.duckdns.org> (raw)
In-Reply-To: <c10e4f69-9951-6c38-6e28-fafcaec00d89@redhat.com>
Hello,
On Tue, Aug 16, 2022 at 06:11:03PM -0400, Waiman Long wrote:
> It is hard to synchronize different subsystems atomically without running
> into locking issue. Let me think about what can be done in this case.
I have a hard time seeing why this would be particularly difficult. cpuset
just needs to make the latest cpumask available to sched core in an easily
accessible form and whenever that changes, trigger a set_cpus_allowed call.
There's no need to entangle operations across the whole subsystems. All
that's needed to be communicated is the current cpumask.
> Is using a sequence number to check for race with retry good enough?
It seems unnecessarily fragile and complicated to me. If we're gonna change
it, let's change it right.
Thanks.
--
tejun
next prev parent reply other threads:[~2022-08-16 22:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-16 19:27 [PATCH v5 0/3] sched, " Waiman Long
2022-08-16 19:27 ` [PATCH v5 1/3] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity() Waiman Long
2022-08-17 8:28 ` Peter Zijlstra
2022-08-18 14:37 ` Waiman Long
2022-08-17 8:41 ` Peter Zijlstra
2022-08-18 15:31 ` Waiman Long
2022-08-17 8:46 ` Peter Zijlstra
2022-08-16 19:27 ` [PATCH v5 2/3] sched: Provide copy_user_cpus_mask() to copy out user mask Waiman Long
2022-08-16 19:27 ` [PATCH v5 3/3] cgroup/cpuset: Keep user set cpus affinity Waiman Long
2022-08-16 20:15 ` Tejun Heo
2022-08-16 22:11 ` Waiman Long
2022-08-16 22:19 ` Tejun Heo [this message]
2022-08-17 0:13 ` Waiman Long
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