linux-ext4 - Re: [PATCH 2/5] mm: pagevec: Defer deciding what LRU to add a page to until pagevec drain time

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Message-ID: <20130517203744.GA15721@cmpxchg.org>
Date:	Fri, 17 May 2013 16:37:44 -0400
From:	Johannes Weiner <hannes@...xchg.org>
To:	Mel Gorman <mgorman@...e.de>
Cc:	Alexey Lyahkov <alexey.lyashkov@...il.com>,
	Andrew Perepechko <anserper@...ru>,
	Robin Dong <sanbai@...bao.com>, Theodore Tso <tytso@....edu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Rik van Riel <riel@...hat.com>,
	Bernd Schubert <bernd.schubert@...tmail.fm>,
	David Howells <dhowells@...hat.com>,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	Linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linux-ext4 <linux-ext4@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux-mm <linux-mm@...ck.org>
Subject: Re: [PATCH 2/5] mm: pagevec: Defer deciding what LRU to add a page
 to until pagevec drain time

On Fri, May 17, 2013 at 10:48:04AM +0100, Mel Gorman wrote:
> mark_page_accessed cannot activate an inactive page that is located on
> an inactive LRU pagevec. Hints from filesystems may be ignored as a
> result. In preparation for fixing that problem, this patch removes the
> per-LRU pagevecs and leaves just one pagevec. The final LRU the page is
> added to is deferred until the pagevec is drained.
> 
> This means that fewer pagevecs are available and potentially there is
> greater contention on the LRU lock. However, this only applies in the case
> where there is an almost perfect mix of file, anon, active and inactive
> pages being added to the LRU. In practice I expect that we are adding
> stream of pages of a particular time and that the changes in contention
> will barely be measurable.
> 
> Signed-off-by: Mel Gorman <mgorman@...e.de>
> Acked-by: Rik van Riel <riel@...hat.com>

Acked-by: Johannes Weiner <hannes@...xchg.org>
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