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

From	Mel Gorman <mgorman@techsingularity.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH 24/27] mm, page_alloc: Remove fair zone allocation policy
Date	2016-06-17 14:10 +0200
Message-ID	<rL0L0-6mx-29@gated-at.bofh.it> (permalink)
References	<rIcyZ-1vR-3@gated-at.bofh.it> <rIcIF-1zJ-17@gated-at.bofh.it> <rL08i-5Sp-21@gated-at.bofh.it>
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On Fri, Jun 17, 2016 at 01:27:09PM +0200, Vlastimil Babka wrote:
> 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.

It's a marginal corner case and the zonelist scan is slightly inefficient
as the first zone is always skipped but the impact is light.

> But otherwise I would agree it should be no longer needed
> with node-based reclaim.
> 
> >Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> 
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> 

Thanks.

-- 
Mel Gorman
SUSE Labs

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Re: [PATCH 24/27] mm, page_alloc: Remove fair zone allocation policy Vlastimil Babka <vbabka@suse.cz> - 2016-06-17 13:30 +0200
  Re: [PATCH 24/27] mm, page_alloc: Remove fair zone allocation policy Mel Gorman <mgorman@techsingularity.net> - 2016-06-17 14:10 +0200

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