Re: [PATCH 6/6] numa,sched: do statistics calculation using localvariables only

From: Mel Gorman
Date: Tue Jan 21 2014 - 11:15:30 EST

On Mon, Jan 20, 2014 at 02:21:07PM -0500, riel@xxxxxxxxxx wrote:
> From: Rik van Riel <riel@xxxxxxxxxx>
> The current code in task_numa_placement calculates the difference
> between the old and the new value, but also temporarily stores half
> of the old value in the per-process variables.
> The NUMA balancing code looks at those per-process variables, and
> having other tasks temporarily see halved statistics could lead to
> unwanted numa migrations. This can be avoided by doing all the math
> in local variables.
> This change also simplifies the code a little.
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Chegu Vinod <chegu_vinod@xxxxxx>
> Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>

Acked-by: Mel Gorman <mgorman@xxxxxxx>

Mel Gorman
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