Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758742AbZF2K0Z (ORCPT ); Mon, 29 Jun 2009 06:26:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752749AbZF2K0Q (ORCPT ); Mon, 29 Jun 2009 06:26:16 -0400 Received: from mail-ew0-f210.google.com ([209.85.219.210]:59700 "EHLO mail-ew0-f210.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751073AbZF2K0P convert rfc822-to-8bit (ORCPT ); Mon, 29 Jun 2009 06:26:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=XJKjgQ/jH7IcA7TV4Kt/lj2sgZBf6jzaQmTgxGuDG59PJLKD6/s+cyWEaGkT0Vp4qq ZL/eOwh78UuIg/M70zI2fYD1mjVcXAKvxEJ6K2UUmEv+wM5Anbcgin463NzI2MSGKXDB D4higTfgW54Z63RP3mgtgrXKF3I54zKJ993hw= MIME-Version: 1.0 In-Reply-To: <20090629093423.GB1315@localhost> References: <6.0.0.20.2.20090601095926.06ee98d8@172.19.0.2> <4A2936A7.9070309@gmail.com> <20090606233056.7B9F.A69D9226@jp.fujitsu.com> <20090606224538.GA6173@localhost> <20090618120436.ad3196e3.akpm@linux-foundation.org> <20090620035504.GA19516@localhost> <4A3CD62B.1020407@vlnb.net> <20090629093423.GB1315@localhost> Date: Mon, 29 Jun 2009 12:26:16 +0200 Message-ID: Subject: Re: [RESEND] [PATCH] readahead:add blk_run_backing_dev From: Ronald Moesbergen To: Wu Fengguang Cc: Vladislav Bolkhovitin , Andrew Morton , "kosaki.motohiro@jp.fujitsu.com" , "Alan.Brunelle@hp.com" , "hifumi.hisashi@oss.ntt.co.jp" , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "jens.axboe@oracle.com" , "randy.dunlap@oracle.com" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5161 Lines: 108 2009/6/29 Wu Fengguang : > On Sat, Jun 20, 2009 at 08:29:31PM +0800, Vladislav Bolkhovitin wrote: >> >> Wu Fengguang, on 06/20/2009 07:55 AM wrote: >> > On Fri, Jun 19, 2009 at 03:04:36AM +0800, Andrew Morton wrote: >> >> On Sun, 7 Jun 2009 06:45:38 +0800 >> >> Wu Fengguang wrote: >> >> >> >>>>> Do you have a place where the raw blktrace data can be retrieved for >> >>>>> more in-depth analysis? >> >>>> I think your comment is really adequate. In another thread, Wu Fengguang pointed >> >>>> out the same issue. >> >>>> I and Wu also wait his analysis. >> >>> And do it with a large readahead size :) >> >>> >> >>> Alan, this was my analysis: >> >>> >> >>> : Hifumi, can you help retest with some large readahead size? >> >>> : >> >>> : Your readahead size (128K) is smaller than your max_sectors_kb (256K), >> >>> : so two readahead IO requests get merged into one real IO, that means >> >>> : half of the readahead requests are delayed. >> >>> >> >>> ie. two readahead requests get merged and complete together, thus the effective >> >>> IO size is doubled but at the same time it becomes completely synchronous IO. >> >>> >> >>> : >> >>> : The IO completion size goes down from 512 to 256 sectors: >> >>> : >> >>> : before patch: >> >>> : ? 8,0 ? ?3 ? 177955 ? ?50.050313976 ? ? 0 ?C ? R 8724991 + 512 [0] >> >>> : ? 8,0 ? ?3 ? 177966 ? ?50.053380250 ? ? 0 ?C ? R 8725503 + 512 [0] >> >>> : ? 8,0 ? ?3 ? 177977 ? ?50.056970395 ? ? 0 ?C ? R 8726015 + 512 [0] >> >>> : ? 8,0 ? ?3 ? 177988 ? ?50.060326743 ? ? 0 ?C ? R 8726527 + 512 [0] >> >>> : ? 8,0 ? ?3 ? 177999 ? ?50.063922341 ? ? 0 ?C ? R 8727039 + 512 [0] >> >>> : >> >>> : after patch: >> >>> : ? 8,0 ? ?3 ? 257297 ? ?50.000760847 ? ? 0 ?C ? R 9480703 + 256 [0] >> >>> : ? 8,0 ? ?3 ? 257306 ? ?50.003034240 ? ? 0 ?C ? R 9480959 + 256 [0] >> >>> : ? 8,0 ? ?3 ? 257307 ? ?50.003076338 ? ? 0 ?C ? R 9481215 + 256 [0] >> >>> : ? 8,0 ? ?3 ? 257323 ? ?50.004774693 ? ? 0 ?C ? R 9481471 + 256 [0] >> >>> : ? 8,0 ? ?3 ? 257332 ? ?50.006865854 ? ? 0 ?C ? R 9481727 + 256 [0] >> >>> >> >> I haven't sent readahead-add-blk_run_backing_dev.patch in to Linus yet >> >> and it's looking like 2.6.32 material, if ever. >> >> >> >> If it turns out to be wonderful, we could always ask the -stable >> >> maintainers to put it in 2.6.x.y I guess. >> > >> > Agreed. The expected (and interesting) test on a properly configured >> > HW RAID has not happened yet, hence the theory remains unsupported. >> >> Hmm, do you see anything improper in the Ronald's setup (see >> http://sourceforge.net/mailarchive/forum.php?thread_name=a0272b440906030714g67eabc5k8f847fb1e538cc62%40mail.gmail.com&forum_name=scst-devel)? >> It is HW RAID based. > > No. Ronald's HW RAID performance is reasonably good. ?I meant Hifumi's > RAID performance is too bad and may be improved by increasing the > readahead size, hehe. > >> As I already wrote, we can ask Ronald to perform any needed tests. > > Thanks! ?Ronald's test results are: > > 231 ? MB/s ? HW RAID > ?69.6 MB/s ? HW RAID + SCST > ?89.7 MB/s ? HW RAID + SCST + this patch > > So this patch seem to help SCST, but again it would be better to > improve the SCST throughput first - it is now quite sub-optimal. > (Sorry for the long delay: currently I have not got an idea on > ?how to measure such timing issues.) > > And if Ronald could provide the HW RAID performance with this patch, > then we can confirm if this patch really makes a difference for RAID. I just tested raw HW RAID throughput with the patch applied, same readahead setting (512KB), and it doesn't look promising: ./blockdev-perftest -d -r /dev/cciss/c0d0 blocksize W W W R R R 67108864 -1 -1 -1 5.59686 5.4098 5.45396 33554432 -1 -1 -1 6.18616 6.13232 5.96124 16777216 -1 -1 -1 7.6757 7.32139 7.4966 8388608 -1 -1 -1 8.82793 9.02057 9.01055 4194304 -1 -1 -1 12.2289 12.6804 12.19 2097152 -1 -1 -1 13.3012 13.706 14.7542 1048576 -1 -1 -1 11.7577 12.3609 11.9507 524288 -1 -1 -1 12.4112 12.2383 11.9105 262144 -1 -1 -1 7.30687 7.4417 7.38246 131072 -1 -1 -1 7.95752 7.95053 8.60796 65536 -1 -1 -1 10.1282 10.1286 10.1956 32768 -1 -1 -1 9.91857 9.98597 10.8421 16384 -1 -1 -1 10.8267 10.8899 10.8718 8192 -1 -1 -1 12.0345 12.5275 12.005 4096 -1 -1 -1 15.1537 15.0771 15.1753 2048 -1 -1 -1 25.432 24.8985 25.4303 1024 -1 -1 -1 45.2674 45.2707 45.3504 512 -1 -1 -1 87.9405 88.5047 87.4726 It dropped down to 189 MB/s. :( Ronald. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/