From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Mel Gorman <mel@csn.ul.ie>
Subject: Re: [PATCH 2/3] Properly account for the number of page cache pages zone_reclaim() can reclaim
Cc: kosaki.motohiro@jp.fujitsu.com, Wu Fengguang <fengguang.wu@intel.com>,
       Rik van Riel <riel@redhat.com>,
       Christoph Lameter <cl@linux-foundation.org>,
       "Zhang, Yanmin" <yanmin.zhang@intel.com>,
       "linuxram@us.ibm.com" <linuxram@us.ibm.com>,
       linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <20090609082728.GF18380@csn.ul.ie>
References: <20090609022549.GB6740@localhost> <20090609082728.GF18380@csn.ul.ie>
Message-Id: <20090609175211.DD85.A69D9226@jp.fujitsu.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Date: Tue,  9 Jun 2009 17:55:03 +0900 (JST)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1232
Lines: 29

> > > The ideal would be that the number of tmpfs pages would also be known
> > > and account for like NR_FILE_MAPPED as swap is required to discard them.
> > > A means of working this out quickly was not obvious but a comment is added
> > > noting the problem.
> > 
> > I'd rather prefer it be accounted separately than to muck up NR_FILE_MAPPED :)
> > 
> 
> Maybe I used a poor choice of words. What I meant was that the ideal would
> be we had a separate count for tmpfs pages. As tmpfs pages and mapped pages
> both have to be unmapped and potentially, they are "like" each other with
> respect to the zone_reclaim_mode and how it behaves. We would end up
> with something like
> 
> 	pagecache_reclaimable -= zone_page_state(zone, NR_FILE_MAPPED);
> 	pagecache_reclaimable -= zone_page_state(zone, NR_FILE_TMPFS);

Please see shmem_writepage(). tmpfs writeout make swapcache, We also
need to concern swapcache.

note: swapcache also increase NR_FILE_PAGES, see add_to_swap_cache.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/