Re: [PATCH] sched: Reduce the rate of needless idle load balancing

[Peter Zijlstra]

On Tue, May 20, 2014 at 02:39:27PM -0700, Tim Chen wrote:
> From: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> Subject: [PATCH v2] sched: Reduce the rate of needless idle load balancing
> 
> 
> The current no_hz idle load balancer do load balancing for *all* idle cpus,
> even though the time due to load balance for a particular
> idle cpu could be still a while in the future.  This introduces a much
> higher load balancing rate than what is necessary.  The patch
> changes the behavior by only doing idle load balancing on
> behalf of an idle cpu only when it is due for load balancing.
> 
> On SGI's systems with over 3000 cores, the cpu responsible for idle balancing
> got overwhelmed with idle balancing, and introduces a lot of OS noise
> to workloads.  This patch fixes the issue.
> 
> Acked-by: Russ Anderson <rja@xxxxxxx>
> Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
> Reviewed-by: Jason Low <jason.low2@xxxxxx>
> Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> ---

Thanks!

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