From: Andreas Dilger Subject: Re: [PATCH 1/2] ext2: speed up file creates by optimizing rec_len functions Date: Wed, 8 Dec 2010 12:01:51 -0700 Message-ID: <63DB7A38-7D0F-406E-8ACD-9CE5DB977DD9@dilger.ca> References: <4CFE7347.8030807@redhat.com> <4CFE7409.9090609@redhat.com> <20101207130708.71c894e9.akpm@linux-foundation.org> <4CFEA5AF.2000702@redhat.com> <20101207133308.eb2144da.akpm@linux-foundation.org> Mime-Version: 1.0 (Apple Message framework v1082) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: Eric Sandeen , ext4 development , Jan Kara To: Andrew Morton Return-path: Received: from idcmail-mo2no.shaw.ca ([64.59.134.9]:63261 "EHLO idcmail-mo2no.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754171Ab0LHTBw convert rfc822-to-8bit (ORCPT ); Wed, 8 Dec 2010 14:01:52 -0500 In-Reply-To: <20101207133308.eb2144da.akpm@linux-foundation.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2010-12-07, at 14:33, Andrew Morton wrote: > On Tue, 07 Dec 2010 15:22:55 -0600 > Eric Sandeen wrote: >> Retesting at a bunch of different number-of-files in bonnie >> (with a small sample size so probably a little noise) >> >> |files per sec| >> files stock patched delta >> 10,000 12300 14700 +19% >> 20,000 6300 7600 +20% >> 30,000 4200 5000 +20% >> 40,000 3150 3700 +17% >> 50,000 2500 3000 +20% >> >> (again all on a 512MB ramdisk) >> >> *shrug* I'll believe my lyin' eyes, I guess. :) > > I bet other tweaks in there would yield similar goodliness. I think an important factor here is that this is being tested on a ramdisk, and is likely CPU bound, so any CPU reduction will directly be measured as a performance improvement. Probably oprofile is in order to see where other major CPU users are. In the past, ext3_mark_inode_dirty() was a major offender, and I recall that we discussed on the ext4 concall a mechanism to only copy the inode once per transaction so that overhead could be removed. Cheers, Andreas