From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261308AbVFNCUP (ORCPT ); Mon, 13 Jun 2005 22:20:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261399AbVFNCUP (ORCPT ); Mon, 13 Jun 2005 22:20:15 -0400 Received: from web30707.mail.mud.yahoo.com ([68.142.200.140]:15468 "HELO web30707.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S261308AbVFNCUD (ORCPT ); Mon, 13 Jun 2005 22:20:03 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Reply-To:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=1QnbgoAlK6CrfRZHWJbbOE/HBMwzTtKV43II8XKmwLL0tJV6a47QHxh8eMUz377xLVrakPVAc5x96eI2UyYsEUO2jFDNJbGA94/5xdnDflLdtGvGXxuB60J6ioeUAZTxWgUFRK6tj87fMbPPjgncPnTZYb+hWjEr1Wb29gpJ7dQ= ; Message-ID: <20050614021959.99775.qmail@web30707.mail.mud.yahoo.com> Date: Mon, 13 Jun 2005 19:19:59 -0700 (PDT) From: Reply-To: spaminos-ker@yahoo.com Subject: Re: cfq misbehaving on 2.6.11-1.14_FC3 To: Andrew Morton Cc: linux-kernel@vger.kernel.org In-Reply-To: <20050611022959.3954ff6b.akpm@osdl.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --- Andrew Morton wrote: > It might be useful to test 2.6.12-rc6-mm1 - it has a substantially > rewritten CFQ implementation. > Just did, and while things seem to be a little better, cfq still gets performance even worst than noop. For this type of load, I think that cfq should get latencies much lower than noop. I ran an automated vi "write to file", to get a more persistant test, on the different i/o scheduler. while true ; do time vi -c '%s/a/aa/g' -c '%s/aa/a/g' -c 'x' /root/somefile > /dev/null ; sleep 1m ; done For some reason, doing a "cp" or appending to files is very fast. I suspect that vi's mmap calls are the reason for the latency problem. the times I got (to save a 200 bytes file on ext3) in seconds: cfq 13,19,23,19,23,15,14,16,14 = 17.3 avg deadline 7,12,11,15,15,8,17,14,16,11 = 12.6 avg noop 23,12,14,12,12,13,14,14,14 = 14.2 avg anticipatory 9,13,13,15,19,15,23,15,12 = 14.8 avg Here is the memory status top - 17:07:44 up 1:42, 1 user, load average: 3.74, 3.62, 3.29 Tasks: 55 total, 2 running, 53 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0% us, 0.0% sy, 0.0% ni, 0.0% id, 99.0% wa, 1.0% hi, 0.0% si Mem: 1035156k total, 1019344k used, 15812k free, 30092k buffers Swap: 4192956k total, 0k used, 4192956k free, 671724k cached and the disk activity (as you can see, mostly writes at this point, as I think most of the data is cached in memory). # vmstat 1 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 1 0 20368 30320 670780 0 0 45 1189 498 201 26 2 20 52 0 3 0 19376 30320 671916 0 0 128 1052 512 211 77 5 0 18 0 3 0 19376 30320 671960 0 0 0 1220 543 231 3 0 0 97 0 3 0 19128 30320 672136 0 0 0 2284 658 250 13 1 0 86 0 3 0 19128 30320 672220 0 0 0 1160 535 222 7 0 0 93 1 2 0 18880 30320 672376 0 0 0 1040 509 204 13 0 0 87 0 3 0 18756 30320 672496 0 0 0 1076 514 210 11 1 0 88 0 3 0 18260 30320 672680 0 0 0 1052 559 356 18 3 0 79 1 1 0 19376 30328 671692 0 0 0 876 529 187 64 3 0 33 1 3 0 18384 30340 672620 0 0 128 2856 515 197 64 5 0 31 0 4 0 18136 30340 672856 0 0 0 1204 546 234 21 0 0 79 0 4 0 18136 30340 672916 0 0 0 1124 530 231 5 2 0 93 0 4 0 18136 30340 672976 0 0 0 2212 627 255 7 1 0 92 0 4 0 18012 30340 673064 0 0 0 1092 523 235 7 1 0 92 0 4 0 17888 30340 673228 0 0 0 1188 545 239 12 0 0 88 1 3 0 17640 30340 673500 0 0 0 1092 515 229 26 0 0 74 0 4 0 17392 30340 673684 0 0 0 1032 515 236 15 1 0 84 1 1 0 17888 30348 672480 0 0 0 1560 568 249 41 4 0 55 1 3 0 16896 30360 673524 0 0 128 1976 586 223 74 3 0 23 0 4 0 16524 30360 673800 0 0 0 1112 522 233 25 1 0 74 0 4 0 16524 30360 673844 0 0 0 1600 588 257 4 1 0 95