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Message-ID: <1342102029.28010.3.camel@twins>
Subject: Re: [PATCH] sched: remove useless code in yield_to
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Michael Wang <wangyun@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
        Mike Galbraith <efault@gmx.de>
Date: Thu, 12 Jul 2012 16:07:09 +0200
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On Tue, 2012-07-03 at 14:34 +0800, Michael Wang wrote:
> From: Michael Wang <wangyun@linux.vnet.ibm.com>
> 
> it's impossible to enter else branch if we have set skip_clock_update
> in task_yield_fair(), as yield_to_task_fair() will directly return
> true after invoke task_yield_fair().

It helps if you CC the guy who wrote the code.. I think you're right,
although getting that skip_clock_update crap wrong is annoying.

Mike?


> Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
> ---
>  kernel/sched/core.c |    7 -------
>  1 files changed, 0 insertions(+), 7 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 9bb7d28..77c14aa 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -4737,13 +4737,6 @@ again:
>  		 */
>  		if (preempt && rq != p_rq)
>  			resched_task(p_rq->curr);
> -	} else {
> -		/*
> -		 * We might have set it in task_yield_fair(), but are
> -		 * not going to schedule(), so don't want to skip
> -		 * the next update.
> -		 */
> -		rq->skip_clock_update = 0;
>  	}
>  
>  out: