linux-kernel - Re: [PATCH 2/2 v2] sched: use load

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Date:   Mon, 5 Dec 2016 13:35:46 +0000
From:   Matt Fleming <matt@...eblueprint.co.uk>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Brendan Gregg <brendan.d.gregg@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, Morten.Rasmussen@....com,
        dietmar.eggemann@....com, kernellwp@...il.com, yuyang.du@...el.com,
        umgwanakikbuti@...il.com, Mel Gorman <mgorman@...hsingularity.net>
Subject: Re: [PATCH 2/2 v2] sched: use load_avg for selecting idlest group

On Mon, 05 Dec, at 10:27:36AM, Vincent Guittot wrote:
> 
> Hi Matt,
> 
> Thanks for the results.
> 
> During the review, it has been pointed out by Morten that the test condition
> (100*this_avg_load < imbalance_scale*min_avg_load) makes more sense than
> (100*min_avg_load > imbalance_scale*this_avg_load). But i see lower
> performances with this change. Coud you run tests with the change below on
> top of the patchset ?
> 
> ---
>  kernel/sched/fair.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index e8d1ae7..0129fbb 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5514,7 +5514,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
>  	if (!idlest ||
>  	    (min_runnable_load > (this_runnable_load + imbalance)) ||
>  	    ((this_runnable_load < (min_runnable_load + imbalance)) &&
> -			(100*min_avg_load > imbalance_scale*this_avg_load)))
> +			(100*this_avg_load < imbalance_scale*min_avg_load)))
>  		return NULL;
>  	return idlest;
>  }

Queued for testing.