linux-kernel - Re: [PATCH 2/2] numa,sched: only consider less busy nodes as numa balancing destination

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Message-ID: <20150528110741.GA3370@linux.vnet.ibm.com>
Date:	Thu, 28 May 2015 16:37:41 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	riel@...hat.com
Cc:	linux-kernel@...r.kernel.org, mgorman@...e.de, jhladky@...hat.com,
	peterz@...radead.org, mingo@...nel.org, dedekind1@...il.com
Subject: Re: [PATCH 2/2] numa,sched: only consider less busy nodes as numa
 balancing destination

* riel@...hat.com <riel@...hat.com> [2015-05-27 15:04:28]:

> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index c47bf0dffb34..f655f2ad155d 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1398,6 +1398,30 @@ static void task_numa_find_cpu(struct task_numa_env *env,
>  	}
>  }
>  
> +/* Only move tasks to a NUMA node less busy than the current node. */
> +static bool numa_has_capacity(struct task_numa_env *env)
> +{
> +	struct numa_stats *src = &env->src_stats;
> +	struct numa_stats *dst = &env->dst_stats;
> +
> +	if (src->has_free_capacity && !dst->has_free_capacity)
> +		return false;
> +
> +	/*
> +	 * Only consider a task move if the source has a higher destination
> +	 * than the destination, corrected for CPU capacity on each node.

In the above comment, did you mean source has higher load than the
destination?

> +	 *
> +	 *      src->load                dst->load
> +	 * --------------------- vs ---------------------
> +	 * src->compute_capacity    dst->compute_capacity
> +	 */
> +	if (src->load * dst->compute_capacity >
> +	    dst->load * src->compute_capacity)
> +		return true;
> +
> +	return false;
> +}
> +
> 

-- 
Thanks and Regards
Srikar Dronamraju

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