From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760983AbXGDBUQ (ORCPT ); Tue, 3 Jul 2007 21:20:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756420AbXGDBUF (ORCPT ); Tue, 3 Jul 2007 21:20:05 -0400 Received: from nz-out-0506.google.com ([64.233.162.231]:51807 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755744AbXGDBUA (ORCPT ); Tue, 3 Jul 2007 21:20:00 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:x-enigmail-version:content-type:content-transfer-encoding; b=TwY+EvAxCqqC/pvBsXIg+ojI9OTdH910EQirUO+gy4k8dSWXO9FUQr0Ptw3ZT6RVunDU13iWKXW9jzoQIX/G2scMrxAYsVWSosL732y/nbjUbJ66K+7Xt+6M26sChAkpIuKp6s4ctdsu4onR96BZKqs4cWlQ3fq1++738EhnoUs= Message-ID: <468AF5BB.10005@gmail.com> Date: Wed, 04 Jul 2007 10:19:55 +0900 From: Tejun Heo User-Agent: Icedove 1.5.0.10 (X11/20070307) MIME-Version: 1.0 To: Michael Tokarev CC: Kernel Mailing List , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org Subject: Re: Some NCQ numbers... References: <468392CE.6010206@msgid.tls.msk.ru> <468A06A0.1020802@gmail.com> <468AB1A7.9010201@msgid.tls.msk.ru> In-Reply-To: <468AB1A7.9010201@msgid.tls.msk.ru> X-Enigmail-Version: 0.94.2.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, Michael Tokarev wrote: > Well. It looks like the results does not depend on the > elevator. Originally I tried with deadline, and just > re-ran the test with noop (hence the long delay with > the answer) - changing linux elevator changes almost > nothing in the results - modulo some random "fluctuations". I see. Thanks for testing. > In any case, NCQ - at least in this drive - just does > not work. Linux with its I/O elevator may help to > speed things up a bit, but the disk does nothing in > this area. NCQ doesn't slow things down either - it > just does not work. > > The same's for ST3250620NS "enterprise" drives. > > By the way, Seagate announced Barracuda ES 2 series > (in range 500..1200Gb if memory serves) - maybe with > those, NCQ will work better? No one would know without testing. > Or maybe it's libata which does not implement NCQ > "properly"? (As I shown before, with almost all > ol'good SCSI drives TCQ helps alot - up to 2x the > difference and more - with multiple I/O threads) Well, what the driver does is minimal. It just passes through all the commands to the harddrive. After all, NCQ/TCQ gives the harddrive more responsibility regarding request scheduling. -- tejun