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To: linux-kernel@vger.kernel.org
From: DM <dm.n9107@gmail.com>
Subject: Re: [PATCH] sched: avoid large irq-latencies in smp-balancing
Date: Fri, 9 Nov 2007 12:41:28 +0000 (UTC)
Message-ID: <loom.20071109T123749-481@post.gmane.org>
References: <1194434956.6289.111.camel@twins> <1194437820.6289.114.camel@twins>
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Peter Zijlstra <peterz <at> infradead.org> writes:
> @@ -2237,7 +2243,7 @@ balance_tasks(struct rq *this_rq, int th
>  	      enum cpu_idle_type idle, int *all_pinned,
>  	      int *this_best_prio, struct rq_iterator *iterator)
>  {
> -	int pulled = 0, pinned = 0, skip_for_load;
> +	int loops = 0, pulled = 0, pinned = 0, skip_for_load;
>  	struct task_struct *p;
>  	long rem_load_move = max_load_move;
> 
> @@ -2251,10 +2257,10 @@ balance_tasks(struct rq *this_rq, int th
>  	 */
>  	p = iterator->start(iterator->arg);
>  next:
> -	if (!p)
> +	if (!p || loops++ > sysctl_sched_nr_migrate)
>  		goto out;

Looks to me like an off-by-one thingy. If sysctl_sched_nr_migrate is zero we 
can still migrate one task. Feature or bug?

/dm


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