linux-kernel - Re: [PATCH 2/3] mm, slub: count freed pages via rcu as this task's reclaimed

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Date:	Tue, 9 Apr 2013 14:28:06 +0000
From:	Christoph Lameter <cl@...ux.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Mel Gorman <mgorman@...e.de>, Hugh Dickins <hughd@...gle.com>,
	Rik van Riel <riel@...hat.com>,
	Minchan Kim <minchan@...nel.org>,
	Pekka Enberg <penberg@...nel.org>,
	Matt Mackall <mpm@...enic.com>
Subject: Re: [PATCH 2/3] mm, slub: count freed pages via rcu as this task's
 reclaimed_slab

On Tue, 9 Apr 2013, Joonsoo Kim wrote:

> Currently, freed pages via rcu is not counted for reclaimed_slab, because
> it is freed in rcu context, not current task context. But, this free is
> initiated by this task, so counting this into this task's reclaimed_slab
> is meaningful to decide whether we continue reclaim, or not.
> So change code to count these pages for this task's reclaimed_slab.

slab->reclaim_state guides the reclaim actions in vmscan.c. With this
patch slab->reclaim_state could get quite a high value without new pages being
available for allocation. slab->reclaim_state will only be updated
when the RCU period ends.

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