From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 26 Dec 2002 02:36:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 26 Dec 2002 02:36:01 -0500 Received: from packet.digeo.com ([12.110.80.53]:14252 "EHLO packet.digeo.com") by vger.kernel.org with ESMTP id ; Thu, 26 Dec 2002 02:36:00 -0500 Message-ID: <3E0AB348.7EC3D454@digeo.com> Date: Wed, 25 Dec 2002 23:44:08 -0800 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.5.52 i686) X-Accept-Language: en MIME-Version: 1.0 To: Paolo Ciarrocchi CC: vda@port.imtp.ilyichevsk.odessa.ua, conma@kolivas.net, riel@conectiva.com.br, linux-kernel@vger.kernel.org Subject: Re: Poor performance with 2.5.52, load and process in D state References: <20021226000308.31344.qmail@linuxmail.org> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 26 Dec 2002 07:44:08.0665 (UTC) FILETIME=[92C9CC90:01C2ACB2] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Paolo Ciarrocchi wrote: > > Hi Andrew/Rik/Con/all > > Andrew, I promised you to run a few tests > using osdb (www.osdb.org with 40M of data)against both > 2.4.19 and 2.5.52 booting the kernel with the > mem=XXM paramter. > > I also played with the /proc/sys/vm/swappiness > parameter, I've ran all the tests with the standard > swappiness value (60), with 80 and 100. > > 100 means the 2.4 behaviour, isn't it ? Not really. swappiness=100 is strict LRU, treating pagecache and mapped-into-process-memory pages identically. Smaller values will make the kernel prefer to preserve mapped-into-process-memory. > Looking at the results it seems that the "standard" > value is too low, probably 80 is the best one. > What do you think ? I would agree with that. > ... > > 2.4.19 all x 778.65 seconds (0:12:58.65) > 2.5.52 all 60 768.98 seconds (0:12:48.98) > 2.5.52 all 80 770.43 seconds (0:12:50.43) > 2.5.52 all 100 771.76 seconds (0:12:51.76) Only 1% difference. On my 4xPIII with mem=128M, 2.4.20-pre2 took 1080.55 seconds and 2.5.52-mm3 took 991.03. That's 9% faster, and from the profile: c010a858 system_call 192 4.3636 c011e518 current_kernel_time 201 3.3500 c012cdbc __generic_file_aio_read 214 0.4652 c012bba0 kallsyms_lookup 219 0.8295 c012ccec file_read_actor 230 1.1058 c0145abc fget 318 4.1842 c01d3ed4 radix_tree_lookup 384 3.8400 c0144be0 vfs_read 409 1.3279 c01315f4 check_poison_obj 695 7.8977 c012c964 do_generic_mapping_read 1007 1.1988 c01d7ae0 __copy_user_intel 34130 213.3125 c0108a58 poll_idle 299231 3562.2738 it appears that this benefit came from the special usercopy code. What sort of CPU are you using?