From: Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 1/3] mm: pagevec: Defer deciding what LRU to add a page
 to until pagevec drain time
Date: Mon, 29 Apr 2013 12:50:40 -0400
Message-ID: <517EA4E0.3020803@redhat.com>
References: <1367253119-6461-1-git-send-email-mgorman@suse.de> <1367253119-6461-2-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>, Johannes Weiner <hannes@cmpxchg.org>,
        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>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <1367253119-6461-2-git-send-email-mgorman@suse.de>
Sender: owner-linux-mm@kvack.org
List-Id: linux-ext4.vger.kernel.org

On 04/29/2013 12:31 PM, 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>


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