Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934961Ab0GSO0k (ORCPT ); Mon, 19 Jul 2010 10:26:40 -0400 Received: from gir.skynet.ie ([193.1.99.77]:34003 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933554Ab0GSO0i (ORCPT ); Mon, 19 Jul 2010 10:26:38 -0400 Date: Mon, 19 Jul 2010 15:26:22 +0100 From: Mel Gorman 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 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> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1359 Lines: 32 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 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/