From: Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 2/5] mm: pagevec: Defer deciding what LRU to add a page
 to until pagevec drain time
Date: Fri, 17 May 2013 16:37:44 -0400
Message-ID: <20130517203744.GA15721@cmpxchg.org>
References: <1368784087-956-1-git-send-email-mgorman@suse.de>
 <1368784087-956-3-git-send-email-mgorman@suse.de>
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Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com>,
	Andrew Perepechko <anserper@ya.ru>, Robin Dong <sanbai@taobao.com>,
	Theodore Tso <tytso@mit.edu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
	Bernd Schubert <bernd.schubert@fastmail.fm>,
	David Howells <dhowells@redhat.com>,
	Trond Myklebust <Trond.Myklebust@netapp.com>,
	Linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux-ext4 <linux-ext4@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, Linux-mm <linux-mm@kvack.org>
To: Mel Gorman <mgorman@suse.de>
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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@suse.de>
> Acked-by: Rik van Riel <riel@redhat.com>

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

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