From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
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>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <vschneid@redhat.com>,
Tejun Heo <tj@kernel.org>, 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 1/3] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity()
Date: Thu, 18 Aug 2022 07:37:51 -0700 [thread overview]
Message-ID: <58f4533b-6d0e-dc5f-2b8c-986212598125@redhat.com> (raw)
In-Reply-To: <YvymwlTkdsVDtmRB@worktop.programming.kicks-ass.net>
On 8/17/22 04:28, Peter Zijlstra wrote:
> On Tue, Aug 16, 2022 at 03:27:32PM -0400, Waiman Long wrote:
>
>> This will be some changes in behavior for arm64 systems with asymmetric
>> CPUs in some corner cases. For instance, if sched_setaffinity()
>> has never been called and there is a cpuset change before
>> relax_compatible_cpus_allowed_ptr() is called, its subsequent call will
>> follow what the cpuset allows but not what the previous cpu affinity
>> setting allows.
> That's arguably a correctness fix, no? That is, the save/restore should
> not have been allowed to revert to an earlier cpuset state.
Yes, it is a correctness fix in a sense. I just want to highlight that
there will be some slight changes in behavior in some corner cases for
the arm64 arch.
Cheers,
Longman
next prev parent reply other threads:[~2022-08-18 14:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-16 19:27 [PATCH v5 0/3] sched, cgroup/cpuset: Keep user set cpus affinity 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 [this message]
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
2022-08-17 0:13 ` Waiman Long
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