From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent CORBES Subject: Re: [dm-devel] Re: Ext3 sequential read performance drop 2.6.29 -> 2.6.30,2.6.31,... Date: Tue, 3 Nov 2009 11:55:05 +0100 Message-ID: <20091103115505.3d6e096d@smartjog.com> References: <20091013120955.6bd5844b@smartjog.com> <20091102135554.b10ece3e.akpm@linux-foundation.org> <20091103100645.GA13118@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "device-mapper development" , akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org To: "NeilBrown" Return-path: Received: from fw.fr.smartjog.net ([91.197.165.186]:54819 "EHLO mx.fr.smartjog.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752660AbZKCKyg convert rfc822-to-8bit (ORCPT ); Tue, 3 Nov 2009 05:54:36 -0500 In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hi all, > >> > Hi all, > >> > > >> > While benchmarking some systems I discover a big sequential read > >> performance > >> > drop using ext3 on ~ big files. The drop seems to be introduced = in > >> 2.6.30. I'm > >> > testing with 2.6.28.6 -> 2.6.29.6 -> 2.6.30.4 -> 2.6.31.3. > >> > >> Seems that large performance regressions aren't of interest to thi= s > >> list :( Or +200MB/s is enough for a lot of people :) > > No sure which list you mean, but dm-devel is for dm, not md. We're= also > > seeing similarly massive performance drops with md and ext3/xfs as > > already reported on the list. Someone tracked it down to writeback > > changes as usual, but there it got stuck. >=20 > I'm still looking - running some basic tests on 4 filesystems over > half a dozen recent kernels to see what has been happening. >=20 > I have a suspicion that there a multiple problems. > In particular, XFS has a strange degradation which was papered over > by commit c8a4051c3731b. > I'm beginning to wonder if it was caused by commit 17bc6c30cf6bf > but I haven't actually tested that yet. What is really strange is that from all the tests I did the raw md perf= s never dropped. only a few MB of diff between kernel (~2%). This is maybe rela= ted to the way upper FS write datas on the md layer. I'll make the tests on raw disks to see if there is some troubles here = also. I can also test with other raid layers. Is there any tuning/debug I can make for you ? I can also setup a remote access to this system if n= eeded. Thanks. --=20 Laurent Corbes - laurent.corbes@smartjog.com SmartJog SAS | Phone: +33 1 5868 6225 | Fax: +33 1 5868 6255 | www.smar= tjog.com 27 Blvd Hippolyte Marqu=E8s, 94200 Ivry-sur-Seine, France A TDF Group company -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html