Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757723AbZC3D4S (ORCPT ); Sun, 29 Mar 2009 23:56:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755674AbZC3D4D (ORCPT ); Sun, 29 Mar 2009 23:56:03 -0400 Received: from wf-out-1314.google.com ([209.85.200.169]:11811 "EHLO wf-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755434AbZC3D4B convert rfc822-to-8bit (ORCPT ); Sun, 29 Mar 2009 23:56:01 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=jCd0V9av0eCY5x86K47J3H/hf+kydMQsIMVZkagprVDPqMBc55Do6FsqWtVIxujji2 3/gxaAVzqaHbNAtFsi0gTO9DrX8XnCF7O/t4vUb6J11dTPCNps9CphQJcPyBIzsOoc7a KvMtOOB2CiGNO3Z9J7FGtxGnfwbeMtsPcFO+A= MIME-Version: 1.0 In-Reply-To: <20090330032827.GD13356@mit.edu> References: <49CD7B10.7010601@garzik.org> <49CD9047.4060500@garzik.org> <49CE2633.2000903@s5r6.in-berlin.de> <49CE3186.8090903@garzik.org> <49CE35AE.1080702@s5r6.in-berlin.de> <49CE3F74.6090103@rtr.ca> <20090329231451.GR26138@disturbed> <20090330003948.GA13356@mit.edu> <9b1675090903291829u7a69df36m65b6698290773859@mail.gmail.com> <20090330032827.GD13356@mit.edu> Date: Sun, 29 Mar 2009 21:55:59 -0600 Message-ID: <9b1675090903292055q6f0f5126we47d853b96a385f6@mail.gmail.com> Subject: Re: Linux 2.6.29 From: "Trenton D. Adams" To: Theodore Tso , Trenton Adams , Mark Lord , Stefan Richter , Jeff Garzik , Linus Torvalds , Matthew Garrett , Alan Cox , Andrew Morton , David Rees , Jesper Krogh , Linux Kernel Mailing List Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2086 Lines: 43 On Sun, Mar 29, 2009 at 9:28 PM, Theodore Tso wrote: > On Sun, Mar 29, 2009 at 07:29:09PM -0600, Trenton Adams wrote: >> I am slightly confused by the "data=ordered" thing that everyone is >> mentioning of late. ?In theory, it made sense to me before I tried it. >> ?I switched to mounting my ext3 as ext4, and I'm still seeing >> seriously delayed fsyncs. ?Theodore, I used a modified version of your >> fsync-tester.c to bench 1M writes, while doing a dd, and I'm still >> getting *almost* as bad of "fsync" performance as I was on ext3. ?On >> ext3, the fsync would usually not finish until the dd was complete. > > How much memory do you have? ?On my 4gig X61 laptop, using a 5400 rpm > laptop drive, I see typical times of 1 to 1.5 seconds, with a few > outliers at 4-5 seconds. ?With ext3, the fsync times immediately > jumped up to 6-8 seconds, with the outliers in the 13-15 second range. 2G, and I believe 5400rpm > > (This is with a filesystem formated as ext3, and mounted as either > ext3 or ext4; if the filesystem is formatted using "mke2fs -t ext4", > what you see is a very smooth 1.2-1.5 seconds fsync latency, indirect > blocks for very big files end up being quite inefficient.) Oh. I thought I had read somewhere that mounting ext4 over ext3 would solve the problem. Not sure where I read that now. Sorry for wasting your time. > > So I'm seeing a definite difference --- but also please remember that > "dd if=/dev/zero of=bigzero.img" really is an unfair, worst-case > scenario, since you are dirtying memory as fast as your CPU will dirty > pages. ?Normally, even if you are running distcc, the rate at which > you can dirty pages will be throttled at your local network speed. Yes, I realize that. When trying to find performance problems I try to be as *unfair* as possible. :D Thanks Ted. -- 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/