From: Peter Zijlstra <peterz@infradead.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Qian Cai <cai@redhat.com>,
Vincent Donnefort <vincent.donnefort@arm.com>,
Dexuan Cui <decui@microsoft.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Steven Rostedt <rostedt@goodmis.org>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 8/8] sched: Relax the set_cpus_allowed_ptr() semantics
Date: Sat, 16 Jan 2021 16:19:39 +0100 [thread overview]
Message-ID: <YAMECwEi93cWZ1W2@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAJhGHyB7fNvxyKwnMgWicvZN7oTnGYLBNH8cUjLg2EcKQ4YMMg@mail.gmail.com>
On Sat, Jan 16, 2021 at 10:39:03PM +0800, Lai Jiangshan wrote:
> On Sat, Jan 16, 2021 at 7:43 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > Now that we have KTHREAD_IS_PER_CPU to denote the critical per-cpu
> > tasks to retain during CPU offline, we can relax the warning in
> > set_cpus_allowed_ptr(). Any spurious kthread that wants to get on at
> > the last minute will get pushed off before it can run.
> >
> > While during CPU online there is no harm, and actual benefit, to
> > allowing kthreads back on early, it simplifies hotplug code.
> >
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
>
> Thanks!
>
> Relaxing set_cpus_allowed_ptr() was also one of the choices I listed,
> which can really simplify hotplug code in the workqueue and may be
> other hotplug code.
Indeed you did. Having that KTHREAD_IS_PER_CPU for the offline side of
things made it possible to relax (as per the Changelog above).
> Reviewed-by: Lai jiangshan <jiangshanlai@gmail.com>
Thanks!
next prev parent reply other threads:[~2021-01-16 17:13 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-16 11:30 [PATCH 0/8] sched: Fix hot-unplug regressions Peter Zijlstra
2021-01-16 11:30 ` [PATCH 1/8] sched/core: Print out straggler tasks in sched_cpu_dying() Peter Zijlstra
2021-01-16 11:30 ` [PATCH 2/8] workqueue: Use cpu_possible_mask instead of cpu_active_mask to break affinity Peter Zijlstra
2021-01-16 11:30 ` [PATCH 3/8] sched: Dont run cpu-online with balance_push() enabled Peter Zijlstra
2021-01-16 15:27 ` Peter Zijlstra
2021-01-16 11:30 ` [PATCH 4/8] kthread: Extract KTHREAD_IS_PER_CPU Peter Zijlstra
2021-01-16 11:30 ` [PATCH 5/8] workqueue: Tag bound workers with KTHREAD_IS_PER_CPU Peter Zijlstra
2021-01-16 11:30 ` [PATCH 6/8] workqueue: Restrict affinity change to rescuer Peter Zijlstra
2021-01-16 11:30 ` [PATCH 7/8] sched: Fix CPU hotplug / tighten is_per_cpu_kthread() Peter Zijlstra
2021-01-17 16:57 ` Valentin Schneider
2021-01-18 9:30 ` Peter Zijlstra
2021-01-16 11:30 ` [PATCH 8/8] sched: Relax the set_cpus_allowed_ptr() semantics Peter Zijlstra
2021-01-16 14:39 ` Lai Jiangshan
2021-01-16 15:19 ` Peter Zijlstra [this message]
2021-01-16 15:25 ` [PATCH 0/8] sched: Fix hot-unplug regressions Peter Zijlstra
2021-01-16 15:45 ` Paul E. McKenney
2021-01-16 18:51 ` Peter Zijlstra
2021-01-16 15:48 ` Paul E. McKenney
2021-01-18 5:28 ` Paul E. McKenney
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