linux-kernel - Re: [PATCH v4 24/25] memcg/slub: shrink dead caches

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Message-ID: <5009D8D8.6040509@parallels.com>
Date:	Fri, 20 Jul 2012 19:16:56 -0300
From:	Glauber Costa <glommer@...allels.com>
To:	Christoph Lameter <cl@...ux.com>
CC:	<linux-mm@...ck.org>, Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	<cgroups@...r.kernel.org>, <devel@...nvz.org>,
	<kamezawa.hiroyu@...fujitsu.com>, <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Suleiman Souhlal <suleiman@...gle.com>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Michal Hocko <mhocko@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH v4 24/25] memcg/slub: shrink dead caches

On 07/06/2012 12:16 PM, Christoph Lameter wrote:
> On Mon, 18 Jun 2012, Glauber Costa wrote:
> 
>> In the slub allocator, when the last object of a page goes away, we
>> don't necessarily free it - there is not necessarily a test for empty
>> page in any slab_free path.
> 
> This is the same btw in SLAB which keeps objects in per cpu caches and
> keeps empty slab pages on special queues.
> 
>> This patch marks all memcg caches as dead. kmem_cache_shrink is called
>> for the ones who are not yet dead - this will force internal cache
>> reorganization, and then all references to empty pages will be removed.
> 
> You need to call this also for slab to drain the caches and free the pages
> on the empty list.
> 
Doesn't the SLAB have a time-based reaper for that?

That's why I was less concerned with the SLAB, but I can certainly call
it for both.

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