From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.43) id 1EKgsg-00075a-S1 for garchives@archives.gentoo.org; Wed, 28 Sep 2005 18:42:15 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.13.5/8.13.5) with SMTP id j8SIY793028565; Wed, 28 Sep 2005 18:34:07 GMT Received: from smtp102.mail.sc5.yahoo.com (smtp102.mail.sc5.yahoo.com [216.136.174.140]) by robin.gentoo.org (8.13.5/8.13.5) with SMTP id j8SIUO9w012356 for ; Wed, 28 Sep 2005 18:30:25 GMT Received: (qmail 92813 invoked from network); 28 Sep 2005 18:37:38 -0000 Received: from unknown (HELO ?192.168.2.100?) (richard?j?fish@68.230.97.177 with plain) by smtp102.mail.sc5.yahoo.com with SMTP; 28 Sep 2005 18:37:38 -0000 Message-ID: <433AE2F3.4080205@asmallpond.org> Date: Wed, 28 Sep 2005 11:37:39 -0700 From: Richard Fish User-Agent: Mozilla Thunderbird 1.0.6 (X11/20050807) X-Accept-Language: en-us, en Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gentoo-user@lists.gentoo.org Subject: Reiserfs speed (Was: Re: [gentoo-user] Re: Size of portage tree) References: <87oe6d5q8s.fsf@newsguy.com> <200509281552.17882.shrdlu@unlimitedmail.org> <877jd15mal.fsf@newsguy.com> In-Reply-To: <877jd15mal.fsf@newsguy.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Archives-Salt: c8279cd4-19c2-47cd-9ea2-4942ab850fbf X-Archives-Hash: 971f794bf64d0bee729712689cf266c0 Harry Putnam wrote: >I am using reiserfs but only on trial basis. I've noticed what >appears to be quite a large increase in time needed for fs intensive >things like du or rm -rf as compared to ext3 but I've done no real >comparison testing. > >Have you noticed that too? > > This is normal, and it's a feature. Reiserfs uses hash values to speed the lookup of single files, and as a result the readdir() system call in reiserfs (which is what find, rm -rf, and du use to walk a directory tree) returns file names in order of their hash value, which probably does not match the order of the files on disk. On the other hand, ext3 readdir() returns files in inode order. This means the disk will typically have to do more seeking for these operations on reiserfs than ext3, which returns file names in inode order. Actually, you can see similar performance differences between ext3 filesystems formatted with "-O dir_index" and those without. You can 'fix' this by tar'ing, reformatting, and restoring the filesystem, which will have the effect of ordering files on disk according to their hash value. Cheers, -Richard -- gentoo-user@gentoo.org mailing list