linux-kernel - Re: [PATCH RFC] numa,sched: have fbq_classify

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Date:	Thu, 21 May 2015 15:13:43 +0300
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Rik van Riel <riel@...hat.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org,
	mgorman@...e.de, jhladky@...hat.com, mingo@...nel.org
Subject: Re: [PATCH RFC] numa,sched: have fbq_classify_* factor out the
 current task

On Tue, 2015-05-19 at 10:55 -0400, Rik van Riel wrote:
> The load balancer tries to find, through find_busiest_group and
> find_busiest_queue, a busy CPU with tasks that are running on
> the wrong NUMA node.
> 
> However, the load balancer only moves runnable-but-not-running
> tasks in most situations. This fails horribly when the current
> task on a CPU is on the wrong NUMA node, but the other task(s)
> on the run queue are placed correctly.
> 
> In that situation, what started out as one misplaced tasks
> quickly turns into two misplaced tasks.
> 
> Try to avoid that by factoring out the placement of the current
> task, in order to find groups and runqueues with misplaced tasks
> that are not currently running.
> 
> Signed-off-by: Rik van Riel <riel@...hat.com>

This seem to give small improvement for our eCommerce web workload,
average sever response time went down from ~1.4 to ~1.34. I can run the
workload for longer time to get better numbers.

Thanks,
Artem.

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