Re: [PATCH 2/3] sched/fair: Move hot load_avg into its own cacheline

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/3] sched/fair: Move hot load_avg into its own cacheline
Date	2015-11-30 11:30 +0100
Message-ID	<qAtSx-2jv-7@gated-at.bofh.it> (permalink)
References	<qyNLH-1Zv-7@gated-at.bofh.it> <qyNLH-1Zv-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Nov 25, 2015 at 02:09:39PM -0500, Waiman Long wrote:
> +++ b/kernel/sched/sched.h
> @@ -248,7 +248,12 @@ struct task_group {
>  	unsigned long shares;
>  
>  #ifdef	CONFIG_SMP
> -	atomic_long_t load_avg;
> +	/*
> +	 * load_avg can be heavily contended at clock tick time, so put
> +	 * it in its own cacheline separated from the fields above which
> +	 * will also be accessed at each tick.
> +	 */
> +	atomic_long_t load_avg ____cacheline_aligned;

Same as with the other patch; this only works if the structure itself is
cacheline aligned, which I don't think it is.

>  #endif
>  #endif
>  
> -- 
> 1.7.1
> 
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[PATCH 2/3] sched/fair: Move hot load_avg into its own cacheline Waiman Long <Waiman.Long@hpe.com> - 2015-11-25 20:20 +0100
  Re: [PATCH 2/3] sched/fair: Move hot load_avg into its own cacheline Peter Zijlstra <peterz@infradead.org> - 2015-11-30 11:30 +0100

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