From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: Bad ext4 sync performance on 16 TB GPT partition Date: Fri, 26 Feb 2010 11:49:54 -0600 Message-ID: <4B8809C2.2000300@redhat.com> References: <87ljegb4ow.fsf@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Dmitry Monakhov , "linux-ext4@vger.kernel.org" To: Karsten Weiss Return-path: Received: from mx1.redhat.com ([209.132.183.28]:54564 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965499Ab0BZRuC (ORCPT ); Fri, 26 Feb 2010 12:50:02 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: Karsten Weiss wrote: > Hi Dmitry! > > On Fri, 26 Feb 2010, Dmitry Monakhov wrote: > ... >>> * I did not try a vanilla kernel so far. >> IMHO It would be really good to know vanilla kernel's stats. > > I did a quick&dirty compilation of vanilla kernel 2.6.33 and repeated the > test: > > # /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, 50.044 seconds, 210 MB/s > 0.01user 13.76system 1:04.75elapsed 21%CPU (0avgtext+0avgdata 6224maxresident)k > 0inputs+0outputs (0major+1049minor)pagefaults 0swaps > > => 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. 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. -Eric