linux-kernel - Re: [PATCH] sched: idle: move need_resched check after function rcu_idle

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Message-ID: <20151123130533.GY3816@twins.programming.kicks-ass.net>
Date:	Mon, 23 Nov 2015 14:05:33 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Lianwei Wang <lianwei.wang@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...ts.linux-foundation.org,
	rjw@...ysocki.net, mingo@...hat.com
Subject: Re: [PATCH] sched: idle: move need_resched check after function
 rcu_idle_enter

On Sat, Nov 21, 2015 at 01:02:02AM -0800, Lianwei Wang wrote:
> The rcu_idle_endter may call wakeup_softirqd to set the need resched
> flag on idle process. But if we don't check it after that, then the
> cpu will enter idle state with RESCHED flag set and can not be woken
> up by wakeup/resched call anymore.

Fair enough; but which cpuidle driver did you observe that with? All the
ones I checked test for need_resched again after this.
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