From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263163AbUEBT6Z (ORCPT ); Sun, 2 May 2004 15:58:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263227AbUEBT6Y (ORCPT ); Sun, 2 May 2004 15:58:24 -0400 Received: from [213.171.41.46] ([213.171.41.46]:8979 "EHLO kaamos.homelinux.net") by vger.kernel.org with ESMTP id S263163AbUEBT6O (ORCPT ); Sun, 2 May 2004 15:58:14 -0400 From: Alexey Kopytov To: linux-kernel@vger.kernel.org Subject: Random file I/O regressions in 2.6 Date: Sun, 2 May 2004 23:57:59 +0400 User-Agent: KMail/1.6.2 MIME-Version: 1.0 Content-Disposition: inline Organization: MySQL AB Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <200405022357.59415.alexeyk@mysql.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello! I tried to compare random file I/O performance in 2.4 and 2.6 kernels and found some regressions that I failed to explain. I tested 2.4.25, 2.6.5-bk2 and 2.6.6-rc3 with my own utility SysBench which was written to generate workloads similar to a database under intensive load. For 2.6.x kernels anticipatory, deadline, CFQ and noop I/O schedulers were tested with AS giving the best results for this workload, but it's still about 1.5 times worse than the results for 2.4.25 kernel. The SysBench 'fileio' test was configured to generate the following workload: 16 worker threads are created, each running random read/write file requests in blocks of 16 KB with a read/write ratio of 1.5. All I/O operations are evenly distributed over 128 files with a total size of 3 GB. Each 100 requests, an fsync() operations is performed sequentially on each file. The total number of requests is limited by 10000. The FS used for the test was ext3 with data=ordered. Here are the results (values are number of seconds to complete the test): 2.4.25: 77.5377 2.6.5-bk2(noop): 165.3393 2.6.5-bk2(anticipatory): 118.7450 2.6.5-bk2(deadline): 130.3254 2.6.5-bk2(CFQ): 146.4286 2.6.6-rc3(noop): 164.9486 2.6.6-rc3(anticipatory): 125.1776 2.6.6-rc3(deadline): 131.8903 2.6.6-rc3(CFQ): 152.9280 I have published the results as well as the hardware and kernel setups at the SysBench home page: http://sysbench.sourceforge.net/results/fileio/ Any comments or suggestions would be highly appreciated. -- Alexey Kopytov, Software Developer MySQL AB, www.mysql.com Are you MySQL certified? www.mysql.com/certification