From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: Issue with AHCI driver Date: Fri, 01 Aug 2008 13:06:54 +0900 Message-ID: <48928BDE.9050806@kernel.org> References: <29493114.1215703025597.JavaMail.root@elwamui-lapwing.atl.sa.earthlink.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:58250 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750812AbYHAEHa (ORCPT ); Fri, 1 Aug 2008 00:07:30 -0400 In-Reply-To: <29493114.1215703025597.JavaMail.root@elwamui-lapwing.atl.sa.earthlink.net> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: the4hoffmans@earthlink.net Cc: jgarzik@pobox.com, linux-ide@vger.kernel.org, blward@micron.com the4hoffmans@earthlink.net wrote: > Sorry about the multiple e-mails Jeff, but our IT group has seen fit > to deny me the ability to send e-mail to vger.kernel.org so I'm > trying again from my own personal account. > ------------------------------------------------------------------- > > > My name is Bob Hoffman. I am a software engineer for Micron > Technology in Minneapolis. I have been working on AHCI drivers. We > recently installed kernel build 2.6.19.0 (unpatched) of Linux on an > Intel motherboard system which includes the ICH9 SATA controller. We > have been running some benchmarks and found that the SATA harddrives > looked slow. When I attached a SATA analyzer it shows that we are > only getting one command "in flight" or "outstanding" at a time, and > it is always slot (or tag) zero. The AHCI driver doesn't seem to be > taking advantage of the 32 deep queue. > > I checked the queue depth using the info at > http://linux-ata.org/faq.html#io32 and it shows "NCQ (depth 31/32)". > I'm wondering if there is something else I need to know. > > I've copied our "Linux guru", Bob Ward, who knows more about the > kernel stuff than I do. > > Thank you for any help you can provide. Bob (Hoffman) ; ) -- To > unsubscribe from this list: send the line "unsubscribe linux-ide" in > the body of a message to majordomo@vger.kernel.org More majordomo > info at http://vger.kernel.org/majordomo-info.html > What kind of workload are you testing? If you're doing multiple random IOs, using deadline io scheduler will give you a better result. Can't say whether that would help on any realistic workload tho. -- tejun