Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754367Ab0HBSbn (ORCPT ); Mon, 2 Aug 2010 14:31:43 -0400 Received: from cantor.suse.de ([195.135.220.2]:48267 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754029Ab0HBSbm (ORCPT ); Mon, 2 Aug 2010 14:31:42 -0400 Date: Mon, 2 Aug 2010 20:31:10 +0200 From: Jan Kara To: Mel Gorman Cc: Andrew Morton , 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 , Christoph Hellwig , Wu Fengguang , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Andrea Arcangeli Subject: Re: [PATCH 6/6] vmscan: Kick flusher threads to clean pages when reclaim is encountering dirty pages Message-ID: <20100802183109.GJ3278@quack.suse.cz> References: <1280497020-22816-1-git-send-email-mel@csn.ul.ie> <1280497020-22816-7-git-send-email-mel@csn.ul.ie> <20100730150601.199c5618.akpm@linux-foundation.org> <20100731103321.GI3571@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100731103321.GI3571@csn.ul.ie> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1365 Lines: 32 On Sat 31-07-10 11:33:22, Mel Gorman wrote: > On Fri, Jul 30, 2010 at 03:06:01PM -0700, Andrew Morton wrote: > > Sigh. We have sooo many problems with writeback and latency. Read > > https://bugzilla.kernel.org/show_bug.cgi?id=12309 and weep. > > You aren't joking. > > > Everyone's > > running away from the issue and here we are adding code to solve some > > alleged stack-overflow problem which seems to be largely a non-problem, > > by making changes which may worsen our real problems. > > > > As it is, filesystems are beginnning to ignore writeback from direct > reclaim - such as xfs and btrfs. I'm lead to believe that ext3 > effectively ignores writeback from direct reclaim although I don't have > access to code at the moment to double check (am on the road). So either > way, we are going to be facing this problem so the VM might as well be > aware of it :/ Umm, ext3 should be handling direct reclaim just fine. ext4 does however ignore it when a page does not have block already allocated (which is a common case with delayed allocation). Honza -- Jan Kara SUSE Labs, CR -- 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/