From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757869AbYEJUkE (ORCPT ); Sat, 10 May 2008 16:40:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754715AbYEJUjy (ORCPT ); Sat, 10 May 2008 16:39:54 -0400 Received: from yw-out-2324.google.com ([74.125.46.29]:26105 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753387AbYEJUjx (ORCPT ); Sat, 10 May 2008 16:39:53 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=jpHtJlUhyD9l8pA0W4+/WhGQ7yLXKl2yV9//GSgxozSGSWCu12V51OhifHJAVshKppFPk6taZ02WPvMXEbIg7ALxbDOC+gyFlVjI2zrO5023we/4Nn54eXqEePURpKXoZV1IUiaq6X/2XKq905LMN7JHsOalOcguSFfljLo7FVc= Message-ID: Date: Sat, 10 May 2008 22:39:50 +0200 From: Matthew To: "Fabio Checconi" Subject: Re: performance "regression" in cfq compared to anticipatory, deadline and noop Cc: "Linux Kernel Mailing List" , jens.axboe@oracle.com In-Reply-To: <20080510200053.GA78555@gandalf.sssup.it> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080510200053.GA78555@gandalf.sssup.it> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Hi, I'm experiencing some cfq/bfq performance issues too, but I'm > still not able to track down the reasons, so before posting on this > topic on the mailing list I'd ask you a couple of questions. > > 1) Are you running the hdparm performance test under some cpu load? > (Even two hdparm instances ran in parallel could do.) > > 2) Does using a bigger value of slice_idle increase the throughput? > Hi, 1) no it was always in (almost) complete idle 2) a bigger value even made it worse, setting it to "0" however seemingly "fixed" it, I however don't know how the overall effect/impact is, this will need some more real-world testing ;) cat /sys/block/sdd/queue/iosched/slice_idle 0 hdparm -t /dev/sdd /dev/sdd: Timing buffered disk reads: 314 MB in 3.01 seconds = 104.32 MB/sec hdparm -t /dev/sdd /dev/sdd: Timing buffered disk reads: 312 MB in 3.00 seconds = 103.86 MB/sec hdparm -t /dev/sdd /dev/sdd: Timing buffered disk reads: 314 MB in 3.01 seconds = 104.24 MB/sec one side-node / question: will this cause more wakeups on the cpu and/or decrease battery runtime on, e.g. laptops ? > Thank you very much, I'll try hdparm on my test boxes and come back > to the list if I find something on that. > > As a sidenote, Ingo is not the author/maintainer of cfq, maybe the > next time CC: Jens Axboe for that. > oops, didn't know that, thanks - didn't want to give the wrong person the "credits" hi & kudos to Jens ;) here's a nice site which explains all of the settings: http://www.nextre.it/oracledocs/ioscheduler_03.html Regards Mat