linux-kernel - Re: [RHEL-ALT-7.4 PATCH 1/2] numa,sched: slow down scan rate if shared faults dominate

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Message-ID: <20170802070139.qsfo5ydcafdlomso@suse.de>
Date:   Wed, 2 Aug 2017 08:01:39 +0100
From:   Mel Gorman <mgorman@...e.de>
To:     riel@...hat.com
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...nel.org, jhladky@...hat.com, lvenanci@...hat.com
Subject: Re: [RHEL-ALT-7.4 PATCH 1/2] numa,sched: slow down scan rate if
 shared faults dominate

On Mon, Jul 31, 2017 at 03:28:46PM -0400, Rik van Riel wrote:
> From: Rik van Riel <riel@...hat.com>
> 
> The comment above update_task_scan_period says the scan period should
> be increased (scanning slows down) if the majority of memory accesses
> are on the local node, or if the majority of the page accesses are
> shared with other tasks.
> 
> However, with the current code, all a high ratio of shared accesses
> does is slow down the rate at which scanning is made faster.
> 
> This patch changes things so either lots of shared accesses or
> lots of local accesses will slow down scanning, and numa scanning
> is sped up only when there are lots of private faults on remote
> memory pages.
> 
> Signed-off-by: Rik van Riel <riel@...hat.com>

Acked-by: Mel Gorman <mgorman@...e.de>

-- 
Mel Gorman
SUSE Labs