linux-kernel - Re: [PATCH] mm-slab: allocate kmem_cache with __GFP

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Date:	Wed, 20 Jul 2011 20:09:33 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	Christoph Lameter <cl@...ux.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Matt Mackall <mpm@...enic.com>
Subject: Re: [PATCH] mm-slab: allocate kmem_cache with __GFP_REPEAT

On Wed, Jul 20, 2011 at 08:41:12PM +0300, Pekka Enberg wrote:
> On Wed, 20 Jul 2011, Pekka Enberg wrote:
> >>On Wed, 20 Jul 2011, Eric Dumazet wrote:
> >>>>[PATCH v2] slab: shrinks sizeof(struct kmem_cache)
> >>
> >>On Wed, 20 Jul 2011, Christoph Lameter wrote:
> >>>This will solve the issue for small nr_cpu_ids but those with 4k cpus will
> >>>still have the issue.
> >>>
> >>>Acked-by: Christoph Lameter <cl@...ux.com>
> >>
> >>Applied, thanks! Do we still want the __GFP_REPEAT patch from Konstantin
> >>though?
> 
> On Wed, 20 Jul 2011, Christoph Lameter wrote:
> >Those with 4k cpus will be thankful I guess.
> 
> OTOH, I'm slightly worried that it might mask a real problem with
> GFP_KERNEL not being aggressive enough. Mel?
> 

The reproduction case was while memory was under heavy pressure
(swapout was active) and even then only 1 in a 1000 containers were
failing to create due to an order-4 allocation failure. I'm not
convinced we need to increase how aggressive the allocator is for
PAGE_ALLOC_COSTLY_ORDER in general based on this.

-- 
Mel Gorman
SUSE Labs
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