Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754493AbZCYUxB (ORCPT ); Wed, 25 Mar 2009 16:53:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751645AbZCYUww (ORCPT ); Wed, 25 Mar 2009 16:52:52 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:59727 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750830AbZCYUwv (ORCPT ); Wed, 25 Mar 2009 16:52:51 -0400 Date: Wed, 25 Mar 2009 13:45:43 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Theodore Tso cc: Jan Kara , Andrew Morton , Ingo Molnar , Alan Cox , Arjan van de Ven , Peter Zijlstra , Nick Piggin , Jens Axboe , David Rees , Jesper Krogh , Linux Kernel Mailing List Subject: Re: Linux 2.6.29 In-Reply-To: <20090325185824.GO32307@mit.edu> Message-ID: References: <49C87B87.4020108@krogh.cc> <72dbd3150903232346g5af126d7sb5ad4949a7b5041f@mail.gmail.com> <20090324091545.758d00f5@lxorguk.ukuu.org.uk> <20090324093245.GA22483@elte.hu> <20090324101011.6555a0b9@lxorguk.ukuu.org.uk> <20090324103111.GA26691@elte.hu> <20090324041249.1133efb6.akpm@linux-foundation.org> <20090325123744.GK23439@duck.suse.cz> <20090325150041.GM32307@mit.edu> <20090325185824.GO32307@mit.edu> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 950 Lines: 27 On Wed, 25 Mar 2009, Theodore Tso wrote: > > Now, there are three ways of solving this problem. You seem to disregard the "write in the right order" approach. Or is that your: > The third potential solution we can try doing is to make some tuning > adjustments to the VM so that we start pushing out these data blocks > much more aggressively out to the disk. Yes. but at least one problem is, as mentioned, that when the VM calls writepage[s]() to start async writeback, many filesystems do seem to just _block_ on it. So the VM has a really hard time doing anything sanely early - the filesystems seem to take a perverse pleasure in synchronizing things using blocking semaphores. Linus -- 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/