From: Eric Sandeen Subject: Re: [PATCH 1/2] ext2: speed up file creates by optimizing rec_len functions Date: Wed, 08 Dec 2010 20:13:46 -0600 Message-ID: <4D003B5A.5060807@redhat.com> 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> <63DB7A38-7D0F-406E-8ACD-9CE5DB977DD9@dilger.ca> <4CFFF394.1020303@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Andrew Morton , ext4 development , Jan Kara To: Andreas Dilger Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53738 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754890Ab0LICOA (ORCPT ); Wed, 8 Dec 2010 21:14:00 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On 12/8/10 3:44 PM, Andreas Dilger wrote: > On 2010-12-08, at 14:07, Eric Sandeen wrote: >> On 12/08/2010 01:01 PM, Andreas Dilger wrote: >>> 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. >> >> Yep, I ran oprofile. >> >> samples % app name symbol name 1140046 >> 41.8702 ext2.ko ext2_find_entry 1052117 38.6408 >> ext2.ko ext2_add_link 98424 3.6148 vmlinux >> native_safe_halt 40461 1.4860 vmlinux >> wait_on_page_read 29084 1.0682 vmlinux >> find_get_page >> >> pretty slammed on those 2 ext2 functions! I think it's pretty >> overwhelmed by the linear search. > > Can you test ext4 with nojournal mode, but with dir_index enabled? I > suspect that testing ext2 for directory performance is pointless. Oh, I agree. I just had a report of a regression in a certain distro, which is frowned upon... :) I'm positive ext4 nojournal would beat the pants off it due to dir_index. > My personal threshold for ext2 directories was 10k files before I > considered it a lost cause, and all of your tests are with 10k+ files > per directory. Agreed, it's not very realistic but then it was a simple fix too. Still took time though... > Just another log on the fire beneath getting rid of ext2 (and > eventually ext3) in favour of ext4, IMHO. I'd be surprised if there > are many benchmarks that ext2 can beat ext4 in nojournal mode, if > allowed to enable "reversible" format changes like dir_index, > uninit_bg, etc. Hey, I wouldn't complain. -Eric > Cheers, Andreas > > > > > > -- To unsubscribe from this list: send the line "unsubscribe > linux-ext4" in the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html