linux-kernel - Re: Bug in scheduler when using rt

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Date:	Wed, 19 Jan 2011 14:09:28 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	Mike Galbraith <efault@....de>
Cc:	Peter Zijlstra <peterz@...radead.org>, samu.p.onkalo@...ia.com,
	mingo@...e.hu,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	tglx <tglx@...utronix.de>
Subject: Re: Bug in scheduler when using rt_mutex

On Wed, Jan 19, 2011 at 1:40 PM, Mike Galbraith <efault@....de> wrote:
> On Wed, 2011-01-19 at 12:35 +0800, Yong Zhang wrote:
>
>> cfs_rq->curr != se is always true.
>
> If that were always true, we'd illegally enqueue a running task.

I'm sorry that I'm not express myself correctly.

The conclusion of (cfs_rq->curr != se is always true) is not
self-contained. IOW, it's based on one condition which is
(task_of(se) != rq->curr). So what I want to say is:
task_of(se) != rq->curr    ==>   cfs_rq_of(se)->curr != se
So,
         !running                   ==>   cfs_rq_of(se)->curr != se

Is this more clear?

Thanks,
Yong

-- 
Only stand for myself
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