From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 65EC66006B4 for ; Mon, 19 Jul 2010 10:26:39 -0400 (EDT) Date: Mon, 19 Jul 2010 15:26:22 +0100 From: Mel Gorman Subject: Re: [PATCH 4/8] vmscan: Do not writeback filesystem pages in direct reclaim Message-ID: <20100719142621.GP13117@csn.ul.ie> References: <1279545090-19169-1-git-send-email-mel@csn.ul.ie> <1279545090-19169-5-git-send-email-mel@csn.ul.ie> <20100719141934.GB12510@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20100719141934.GB12510@infradead.org> Sender: owner-linux-mm@kvack.org To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Chris Mason , Nick Piggin , Rik van Riel , Johannes Weiner , Wu Fengguang , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Andrew Morton , Andrea Arcangeli List-ID: On Mon, Jul 19, 2010 at 10:19:34AM -0400, Christoph Hellwig wrote: > On Mon, Jul 19, 2010 at 02:11:26PM +0100, Mel Gorman wrote: > > As the call-chain for writing anonymous pages is not expected to be deep > > and they are not cleaned by flusher threads, anonymous pages are still > > written back in direct reclaim. > > While it is not quite as deep as it skips the filesystem allocator and > extent mapping code it can still be quite deep for swap given that it > still has to traverse the whole I/O stack. Probably not worth worrying > about now, but we need to keep an eye on it. > Agreed that we need to keep an eye on it. If this ever becomes a problem, we're going to need to consider a flusher for anonymous pages. If you look at the figures, we are still doing a lot of writeback of anonymous pages. Granted, the layout of swap sucks anyway but it's something to keep at the back of the mind. > The patch looks fine to me anyway. > Thanks. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org