From: "Aneesh Kumar K.V" Subject: Online defragmentation and ext4migrate Date: Fri, 18 May 2007 18:36:53 +0530 Message-ID: <464DA4ED.9040408@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: Takashi Sato Return-path: Received: from ausmtp06.au.ibm.com ([202.81.18.155]:57487 "EHLO ausmtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757420AbXERNHB (ORCPT ); Fri, 18 May 2007 09:07:01 -0400 Received: from sd0109e.au.ibm.com (d23rh905.au.ibm.com [202.81.18.225]) by ausmtp06.au.ibm.com (8.13.8/8.13.8) with ESMTP id l4ID8N4G5390384 for ; Fri, 18 May 2007 23:08:23 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.250.237]) by sd0109e.au.ibm.com (8.13.8/8.13.8/NCO v8.3) with ESMTP id l4IDARU8082862 for ; Fri, 18 May 2007 23:10:27 +1000 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l4ID6tuk020813 for ; Fri, 18 May 2007 23:06:56 +1000 Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Hi Takashi san, While doing online defragmentation do we move the blocks corresponding to extent index ? The reason why i am asking this is to understand the usefulness of doing a ext4migrate followed by defrag. I understand that defragmentation in general will improve the performance. But with respect to ext4migrate we are not touching the data blocks. Instead we build the extent map and if that requires to have an extent index block then we allocate one. I am trying to understand what would be the performance impact of this and whether doing a defrag really improve the performance. Also looking at the version 0.4 I see that defrag ioctl only work if we have EXT4_EXTENTS_FL flag set. What are the plans for making defrag work with indirect block map inode ? -aneesh