From: Theodore Tso Subject: Re: Question on block group allocation Date: Wed, 29 Apr 2009 17:50:32 -0400 Message-ID: <20090429215032.GC24749@mit.edu> References: <20090423190817.GN3209@webber.adilger.int> <6601abe90904231502y393155dbrf8913b728c704320@mail.gmail.com> <20090427021411.GA9059@mit.edu> <6601abe90904262229w602e17d8s51ceae05c2895ce5@mail.gmail.com> <20090427224052.GC22104@mit.edu> <20090429191646.GF14264@mit.edu> <6601abe90904291138r6e24c04dj4b2efcdba22bf84@mail.gmail.com> <20090429193744.GA17797@mit.edu> <6601abe90904291321u3f13d8b0p88b9a9eba5bc03a1@mail.gmail.com> <20090429212043.GB24749@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andreas Dilger , ext4 development To: Curt Wohlgemuth Return-path: Received: from thunk.org ([69.25.196.29]:41228 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752280AbZD2Vuh (ORCPT ); Wed, 29 Apr 2009 17:50:37 -0400 Content-Disposition: inline In-Reply-To: <20090429212043.GB24749@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: Oh --- one more question. You did these tests on your 2.6.26-based kernel with ext4 backports, right? Not 2.6.30 mainline kernel? Did you backport the changes to the block and inode allocators? i.e., this patch (plus a 1 or 2 subsequent bug fixes)? commit a4912123b688e057084e6557cef8924f7ae5bbde Author: Theodore Ts'o Date: Thu Mar 12 12:18:34 2009 -0400 ext4: New inode/block allocation algorithms for flex_bg filesystems The find_group_flex() inode allocator is now only used if the filesystem is mounted using the "oldalloc" mount option. It is replaced with the original Orlov allocator that has been updated for flex_bg filesystems (it should behave the same way if flex_bg is disabled). The inode allocator now functions by taking into account each flex_bg group, instead of each block group, when deciding whether or not it's time to allocate a new directory into a fresh flex_bg. The block allocator has also been changed so that the first block group in each flex_bg is preferred for use for storing directory blocks. This keeps directory blocks close together, which is good for speeding up e2fsck since large directories are more likely to look like this: debugfs: stat /home/tytso/Maildir/cur Inode: 1844562 Type: directory Mode: 0700 Flags: 0x81000 Generation: 1132745781 Version: 0x00000000:0000ad71 User: 15806 Group: 15806 Size: 1060864 File ACL: 0 Directory ACL: 0 Links: 2 Blockcount: 2072 Fragment: Address: 0 Number: 0 Size: 0 ctime: 0x499c0ff4:164961f4 -- Wed Feb 18 08:41:08 2009 atime: 0x499c0ff4:00000000 -- Wed Feb 18 08:41:08 2009 mtime: 0x49957f51:00000000 -- Fri Feb 13 09:10:25 2009 crtime: 0x499c0f57:00d51440 -- Wed Feb 18 08:38:31 2009 Size of extra inode fields: 28 BLOCKS: (0):7348651, (1-258):7348654-7348911 TOTAL: 259 Signed-off-by: "Theodore Ts'o" - Ted