From: Karsten Weiss Subject: Re: Bad ext4 sync performance on 16 TB GPT partition Date: Mon, 1 Mar 2010 09:57:31 +0100 (CET) Message-ID: References: <87ljegb4ow.fsf@openvz.org> <4B8809C2.2000300@redhat.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Dmitry Monakhov , "linux-ext4@vger.kernel.org" To: Eric Sandeen Return-path: Received: from smtp2.belwue.de ([129.143.2.15]:64698 "EHLO smtp2.belwue.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750696Ab0CAJMg (ORCPT ); Mon, 1 Mar 2010 04:12:36 -0500 Received: from mx3.science-computing.de (mx3.science-computing.de [193.197.16.20]) by smtp2.belwue.de with ESMTP id o218vcVJ008138 for ; Mon, 1 Mar 2010 09:57:39 +0100 (MET) env-from (prvs=6691a5a41=K.Weiss@science-computing.de) In-Reply-To: <4B8809C2.2000300@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi Eric, On Fri, 26 Feb 2010, Eric Sandeen wrote: > > => The problem shows only with the CentOS / Red Hat 5.4 kernels (including > > RH's test kernel 2.6.18-190.el5). Aadmittedly ext4 is only a technology > > preview in 5.4... > > > > I've also tried the latest CentOS 5.3 kernel-2.6.18-128.7.1.el5 but > > couldn't mount the device (with -t ext4dev). > > > > 2.6.18-164.el5 (the initial CentOS 5.4 kernel) has the bug, too. > > > > I'm willing to test patches if somebody wants to debug the problem. > > Ok, that's interesting. We've not had bona-fide RHEL customers report > the problem, but then maybe it hasn't been tested this way. I think so because, as I mentioned, the issue can be reproduced with the RH test kernel 2.6.18-190.el5 x86_64 (http://people.redhat.com/jwilson/el5/), too. > 2.6.18-178.el5 and beyond is based on the 2.6.32 codebase for ext4. > > Testing generic 2.6.32 might also be interesting as a datapoint, > if you're willing. Sorry for the delay, here's the (good) 2.6.32 result: # /usr/bin/time bash -c "dd if=/dev/zero of=/mnt/large/10GB bs=1M count=10000 && sync" 10000+0 records in 10000+0 records out 10485760000 bytes (10 GB) copied, 46.3369 seconds, 226 MB/s 0.00user 14.17system 0:59.53elapsed 23%CPU (0avgtext+0avgdata 6224maxresident)k 0inputs+0outputs (0major+1045minor)pagefaults 0swaps To summarize: Bad: 2.6.18-164.el5 (CentOS) Bad: 2.6.18-164.11.1el5 (CentOS) Bad: 2.6.18-190.el5 (RH) Good: 2.6.32 Good: 2.6.33 -- Karsten Weiss