Message-ID: <4FE2CEB0.7080200@linux.vnet.ibm.com>
Date: Thu, 21 Jun 2012 15:35:12 +0800
From: Michael Wang <wangyun@linux.vnet.ibm.com>
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:12.0) Gecko/20120430 Thunderbird/12.0.1
MIME-Version: 1.0
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: mingo@kernel.org, pjt@google.com, venki@google.com, efault@gmx.de,
        rostedt@goodmis.org, glommer@parallels.com,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 2/4] sched: Push put_prev_task() into pick_next_task()
References: <20120614132902.800827488@chello.nl> <20120614133212.690691207@chello.nl>
In-Reply-To: <20120614133212.690691207@chello.nl>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 995
Lines: 35


> +pick_next_task_fair(struct rq *rq, struct task_struct *prev)
>  {
>  	struct task_struct *p;
>  	struct cfs_rq *cfs_rq = &rq->cfs;
> @@ -2999,6 +3000,9 @@ static struct task_struct *pick_next_tas
>  	if (!cfs_rq->nr_running)
>  		return NULL;
> 
> +	if (prev)
> +		prev->sched_class->put_prev_task(rq, prev);
> +
>  	do {
>  		se = pick_next_entity(cfs_rq);
>  		set_next_entity(cfs_rq, se);
> --- a/kernel/sched/idle_task.c
> +++ b/kernel/sched/idle_task.c
> @@ -22,8 +22,12 @@ static void check_preempt_curr_idle(stru
>  	resched_task(rq->idle);
>  }

Will it cause trouble when the last task on cfs_rq was dequeued before
been putted?

The cfs_rq->nr_running will be 0 and we will miss the chance to put
prev, will we?

Regards,
Michael Wang

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/