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 3/4] workqueue: Tag bound workers with KTHREAD_IS_PER_CPU
Date: Wed, 13 Jan 2021 12:43:56 +0100 [thread overview]
Message-ID: <X/7c/PZbzFCO8tfe@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAJhGHyDWn91eH7-ZPj-utuaugz3UEdGXSKgLYHkdwBr5op=8iA@mail.gmail.com>
On Wed, Jan 13, 2021 at 12:36:55AM +0800, Lai Jiangshan wrote:
> On Tue, Jan 12, 2021 at 10:51 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > Mark the per-cpu workqueue workers as KTHREAD_IS_PER_CPU.
> >
> > Workqueues have unfortunate semantics in that per-cpu workers are not
> > default flushed and parked during hotplug, however a subset does
> > manual flush on hotplug and hard relies on them for correctness.
> >
> > Therefore play silly games..
> >
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > Tested-by: Paul E. McKenney <paulmck@kernel.org>
> > ---
>
> Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
>
> I like this patchset in that the scheduler takes care of the
> affinities of the tasks when we don't want it to be per-cpu.
Thanks! A possibly even simpler approach would be to have
rebind_workers() kill all workers and have create_worker() spawn us new
ones.
That avoids ever having to use set_cpus_allowed_ptr() on per-cpu
kthreads.... with the exception of rescuer.. still pondering that.
next prev parent reply other threads:[~2021-01-13 11:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 14:43 [PATCH 0/4] sched: Fix hot-unplug regressions Peter Zijlstra
2021-01-12 14:43 ` [PATCH 2/4] kthread: Extract KTHREAD_IS_PER_CPU Peter Zijlstra
2021-01-12 14:43 ` [PATCH 3/4] workqueue: Tag bound workers with KTHREAD_IS_PER_CPU Peter Zijlstra
2021-01-12 16:36 ` Lai Jiangshan
2021-01-13 11:43 ` Peter Zijlstra [this message]
2021-01-12 17:57 ` Valentin Schneider
2021-01-13 13:28 ` Lai Jiangshan
2021-01-13 14:16 ` Valentin Schneider
2021-01-13 17:52 ` Paul E. McKenney
2021-01-13 18:43 ` Valentin Schneider
2021-01-13 18:59 ` Paul E. McKenney
2021-01-14 13:12 ` Peter Zijlstra
2021-01-14 13:21 ` Valentin Schneider
2021-01-14 15:34 ` Peter Zijlstra
2021-01-16 6:27 ` Lai Jiangshan
2021-01-16 12:45 ` Peter Zijlstra
2021-01-16 14:45 ` Lai Jiangshan
2021-01-16 15:16 ` Peter Zijlstra
2021-01-16 16:14 ` Lai Jiangshan
2021-01-16 18:46 ` Peter Zijlstra
2021-01-17 9:54 ` Peter Zijlstra
2021-01-16 15:13 ` Peter Zijlstra
2021-01-12 14:43 ` [PATCH 4/4] sched: Fix CPU hotplug / tighten is_per_cpu_kthread() Peter Zijlstra
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