From: Peter Zijlstra <peterz@infradead.org>
To: Valentin Schneider <valentin.schneider@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, vincent.guittot@linaro.org,
mgorman@suse.de, Oleg Nesterov <oleg@redhat.com>,
david@fromorbit.com
Subject: Re: [RFC][PATCH] sched: Better document ttwu()
Date: Fri, 3 Jul 2020 13:36:03 +0200 [thread overview]
Message-ID: <20200703113603.GL117543@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200703083012.GU4800@hirez.programming.kicks-ass.net>
On Fri, Jul 03, 2020 at 10:30:12AM +0200, Peter Zijlstra wrote:
> On Thu, Jul 02, 2020 at 07:39:16PM +0100, Valentin Schneider wrote:
> > > @@ -3134,8 +3274,12 @@ static inline void prepare_task(struct task_struct *next)
> > > /*
> > > * Claim the task as running, we do this before switching to it
> > > * such that any running task will have this set.
> > > + *
> > > + * __schedule()'s rq->lock and smp_mb__after_spin_lock() orders this
> > > + * store against prior state change of @next, also see
> > > + * try_to_wake_up(), specifically smp_load_acquire(&p->on_cpu).
> >
> > smp_*cond*_load_acquire(&p->on_cpu, <blah>)
>
> Both, but yeah.. arguably the cond one is the more important one.
Ah no, this one really want to match the WF_ON_CPU case. I'll clarify
non-the-less.
next prev parent reply other threads:[~2020-07-03 11:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 12:52 [RFC][PATCH] sched: Better document ttwu() Peter Zijlstra
2020-07-02 13:13 ` Phil Auld
2020-07-02 15:23 ` Peter Zijlstra
2020-07-02 18:39 ` Valentin Schneider
2020-07-03 8:30 ` Peter Zijlstra
2020-07-03 11:36 ` Peter Zijlstra [this message]
2020-07-03 10:12 ` Dietmar Eggemann
2020-07-03 12:39 ` Vincent Guittot
2020-07-22 9:12 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
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