linux-kernel - Re: [PATCH 4/6] sched,idle: Clear polling before descheduling the idle thread

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Message-ID: <20140604075324.GI30445@twins.programming.kicks-ass.net>
Date:	Wed, 4 Jun 2014 09:53:24 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	umgwanakikbuti@...il.com, mingo@...nel.org, tglx@...utronix.de,
	nicolas.pitre@...aro.org, daniel.lezcano@...aro.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] sched,idle: Clear polling before descheduling the
 idle thread

On Tue, Jun 03, 2014 at 05:29:50PM -0700, Andy Lutomirski wrote:
> @@ -229,6 +234,8 @@ static void cpu_idle_loop(void)
>  		 */
>  		preempt_set_need_resched();
>  		tick_nohz_idle_exit();
> +		__current_clr_polling();
> +		smp_mb__after_clear_bit();

barriers always need a comment, and I'm not entirely sure why you put
this one here.

Merging the NR set and POLLING tests into a single atomic made the
entire barrier situation somewhat more complicated and I really need to
rethink that.

>  		schedule_preempt_disabled();
>  	}
>  }
> -- 
> 1.9.3
> 

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