From: Curt Wohlgemuth Subject: Re: Question on block group allocation Date: Wed, 29 Apr 2009 15:29:55 -0700 Message-ID: <6601abe90904291529o5aaab638i73bd34c1a6d54c74@mail.gmail.com> References: <20090423190817.GN3209@webber.adilger.int> <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> <20090429215032.GC24749@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Andreas Dilger , ext4 development To: Theodore Tso Return-path: Received: from smtp-out.google.com ([216.239.45.13]:32246 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755400AbZD2WaB convert rfc822-to-8bit (ORCPT ); Wed, 29 Apr 2009 18:30:01 -0400 Received: from spaceape24.eur.corp.google.com (spaceape24.eur.corp.google.com [172.28.16.76]) by smtp-out.google.com with ESMTP id n3TMTwB0008843 for ; Wed, 29 Apr 2009 15:29:59 -0700 Received: from wa-out-1112.google.com (wahv27.prod.google.com [10.114.248.27]) by spaceape24.eur.corp.google.com with ESMTP id n3TMTu2X028525 for ; Wed, 29 Apr 2009 15:29:56 -0700 Received: by wa-out-1112.google.com with SMTP id v27so552217wah.22 for ; Wed, 29 Apr 2009 15:29:55 -0700 (PDT) In-Reply-To: <20090429215032.GC24749@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi Ted: On Wed, Apr 29, 2009 at 2:50 PM, Theodore Tso wrote: > Oh --- one more question. =A0You did these tests on your 2.6.26-based > kernel with ext4 backports, right? =A0Not 2.6.30 mainline kernel? =A0= Did > you backport the changes to the block and inode allocators? =A0i.e., > this patch (plus a 1 or 2 subsequent bug fixes)? > > > commit a4912123b688e057084e6557cef8924f7ae5bbde > Author: Theodore Ts'o > Date: =A0 Thu Mar 12 12:18:34 2009 -0400 > > =A0 =A0ext4: New inode/block allocation algorithms for flex_bg filesy= stems Yes, we have this patch. I'm not sure if we have the "1 or 2" bug fixes you refer to above; do you have commits for these? I'm regen'ing the e2fsck and debugfs output for the 3 "dd" sequence above, for our stock kernel and for this + Andreas' patch. Thanks, Curt > > =A0 =A0The find_group_flex() inode allocator is now only used if the > =A0 =A0filesystem is mounted using the "oldalloc" mount option. =A0It= is > =A0 =A0replaced with the original Orlov allocator that has been updat= ed for > =A0 =A0flex_bg filesystems (it should behave the same way if flex_bg = is > =A0 =A0disabled). =A0The inode allocator now functions by taking into= account > =A0 =A0each flex_bg group, instead of each block group, when deciding= whether > =A0 =A0or not it's time to allocate a new directory into a fresh flex= _bg. > > =A0 =A0The block allocator has also been changed so that the first bl= ock > =A0 =A0group in each flex_bg is preferred for use for storing directo= ry > =A0 =A0blocks. =A0This keeps directory blocks close together, which i= s good for > =A0 =A0speeding up e2fsck since large directories are more likely to = look > =A0 =A0like this: > > =A0 =A0debugfs: =A0stat /home/tytso/Maildir/cur > =A0 =A0Inode: 1844562 =A0 Type: directory =A0 =A0Mode: =A00700 =A0 Fl= ags: 0x81000 > =A0 =A0Generation: 1132745781 =A0 =A0Version: 0x00000000:0000ad71 > =A0 =A0User: 15806 =A0 Group: 15806 =A0 Size: 1060864 > =A0 =A0File ACL: 0 =A0 =A0Directory ACL: 0 > =A0 =A0Links: 2 =A0 Blockcount: 2072 > =A0 =A0Fragment: =A0Address: 0 =A0 =A0Number: 0 =A0 =A0Size: 0 > =A0 =A0 ctime: 0x499c0ff4:164961f4 -- Wed Feb 18 08:41:08 2009 > =A0 =A0 atime: 0x499c0ff4:00000000 -- Wed Feb 18 08:41:08 2009 > =A0 =A0 mtime: 0x49957f51:00000000 -- Fri Feb 13 09:10:25 2009 > =A0 =A0crtime: 0x499c0f57:00d51440 -- Wed Feb 18 08:38:31 2009 > =A0 =A0Size of extra inode fields: 28 > =A0 =A0BLOCKS: > =A0 =A0(0):7348651, (1-258):7348654-7348911 > =A0 =A0TOTAL: 259 > > =A0 =A0Signed-off-by: "Theodore Ts'o" > > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 =A0 =A0 =A0- 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