From: Theodore Tso Subject: Re: bigalloc and max file size Date: Mon, 31 Oct 2011 06:15:23 -0400 Message-ID: References: <51BECC2B-2EBC-4FCB-B708-8431F7CB6E0D@dilger.ca> <5846CEDC-A1ED-4BB4-8A3E-E726E696D3E9@mit.edu> <97D9C5CC-0F22-4BC7-BDFA-7781D33CA7F3@whamcloud.com> <4EAA2217.5020002@tao.ma> Mime-Version: 1.0 (Apple Message framework v1251.1) Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Theodore Tso , Andreas Dilger , linux-ext4 development , Alex Zhuravlev , "hao.bigrat@gmail.com" To: Tao Ma Return-path: Received: from DMZ-MAILSEC-SCANNER-4.MIT.EDU ([18.9.25.15]:58285 "EHLO dmz-mailsec-scanner-4.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932508Ab1JaKP1 convert rfc822-to-8bit (ORCPT ); Mon, 31 Oct 2011 06:15:27 -0400 In-Reply-To: <4EAA2217.5020002@tao.ma> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Oct 27, 2011, at 11:31 PM, Tao Ma wrote: > Forget to say, if we increase the extent length to be cluster, there = are > also a good side effect. ;) Current bigalloc has a severe performance > regression in the following test case: > mount -t ext4 /dev/sdb1 /mnt/ext4 > cp linux-3.0.tar.gz /mnt/ext4 > cd /mnt/ext4 > tar zxvf linux-3.0.tar.gz > umount /mnt/ext4 I've been traveling, so I haven't had a chance to test this, but it mak= es no sense that changing the encoding fro the extent length would chan= ge the performance of the forced writeback caused by amount. There ma= y be a performance bug that we should fix, or may have been fixed by ac= cident with the extent encoding change.=20 Have you investigated why this got better when you changed the meaning = of the extent length field? It makes no sense that such a format chan= ge would have such an impact=85. -- Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html