linux-kernel - Re: [PATCH v5 02/14] memcg: Reclaim when more than one page needed.

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Message-ID: <alpine.DEB.2.00.1210171445010.20712@chino.kir.corp.google.com>
Date:	Wed, 17 Oct 2012 14:46:44 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Glauber Costa <glommer@...allels.com>
cc:	linux-mm@...ck.org, cgroups@...r.kernel.org,
	Mel Gorman <mgorman@...e.de>, Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>,
	kamezawa.hiroyu@...fujitsu.com, Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>, devel@...nvz.org,
	linux-kernel@...r.kernel.org,
	Suleiman Souhlal <suleiman@...gle.com>
Subject: Re: [PATCH v5 02/14] memcg: Reclaim when more than one page
 needed.

On Tue, 16 Oct 2012, Glauber Costa wrote:

> From: Suleiman Souhlal <ssouhlal@...eBSD.org>
> 
> mem_cgroup_do_charge() was written before kmem accounting, and expects
> three cases: being called for 1 page, being called for a stock of 32
> pages, or being called for a hugepage.  If we call for 2 or 3 pages (and
> both the stack and several slabs used in process creation are such, at
> least with the debug options I had), it assumed it's being called for
> stock and just retried without reclaiming.
> 
> Fix that by passing down a minsize argument in addition to the csize.
> 
> And what to do about that (csize == PAGE_SIZE && ret) retry?  If it's

I think you're referring to the (nr_pages == 1 && ret) retry, csize is 
only used for interfacing with res_counter.

> needed at all (and presumably is since it's there, perhaps to handle
> races), then it should be extended to more than PAGE_SIZE, yet how far?
> And should there be a retry count limit, of what?  For now retry up to
> COSTLY_ORDER (as page_alloc.c does) and make sure not to do it if
> __GFP_NORETRY.
> 
> [v4: fixed nr pages calculation pointed out by Christoph Lameter ]
> 
> Signed-off-by: Suleiman Souhlal <suleiman@...gle.com>
> Signed-off-by: Glauber Costa <glommer@...allels.com>
> Acked-by: Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> Acked-by: Michal Hocko <mhocko@...e.cz>
> Acked-by: Johannes Weiner <hannes@...xchg.org>
> CC: Tejun Heo <tj@...nel.org>

Acked-by: David Rientjes <rientjes@...gle.com>
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