linux-kernel - Re: [PATCH 24/27] mm, page_alloc: Remove fair zone allocation policy

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Message-ID: <9f30977a-ff07-d783-4c21-e13bd2478aa3@suse.cz>
Date:	Fri, 17 Jun 2016 13:27:09 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Mel Gorman <mgorman@...hsingularity.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>
Cc:	Rik van Riel <riel@...riel.com>,
	Johannes Weiner <hannes@...xchg.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Michal Hocko <mhocko@...nel.org>
Subject: Re: [PATCH 24/27] mm, page_alloc: Remove fair zone allocation policy

On 06/09/2016 08:04 PM, Mel Gorman wrote:
> The fair zone allocation policy interleaves allocation requests between
> zones to avoid an age inversion problem whereby new pages are reclaimed
> to balance a zone. Reclaim is now node-based so this should no longer be
> an issue and the fair zone allocation policy is not free. This patch
> removes it.

I wonder if fair zone allocation had the side effect of preventing e.g. a small 
Normal zone to be almost fully occupied by long-lived unreclaimable allocations 
early in the kernel lifetime. So that might be one thing to watch out for. But 
otherwise I would agree it should be no longer needed with node-based reclaim.

> Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>

Acked-by: Vlastimil Babka <vbabka@...e.cz>