From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: NCQ general question Date: Wed, 01 Mar 2006 13:34:38 -0500 Message-ID: <4405E93E.3010307@rtr.ca> References: <5d96567b0602282304o558fb564jd72784bafdd289f5@mail.gmail.com> <440561CB.30201@yahoo.de> <4405A656.1030602@rtr.ca> <4405C41F.5060504@yahoo.de> <20060301160554.GD4816@suse.de> <4405D040.8000700@yahoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rtr.ca ([64.26.128.89]:53156 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S1751074AbWCASeV (ORCPT ); Wed, 1 Mar 2006 13:34:21 -0500 In-Reply-To: <4405D040.8000700@yahoo.de> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Gentoopower Cc: "linux-ide@vger.kernel.org" Gentoopower wrote: > Jens Axboe wrote: >> On Wed, Mar 01 2006, Gentoopower wrote: .. >>> I can defintely feel the speed difference between the two drives. >>> >> Well that can't be because of NCQ, since it isn't active :-) > > Got ya:-) > > Who said this box is running only linux? You did, by posting to the *Linux-IDE* kernel mailing list. All bets are off for other OSs, especially those that really *need* NCQ for half-decent performance. Linux doesn't, but it's definitely nice to wish for. I've implemented host-queuing support for NCQ and TCQ on several controllers (for Linux), and it almost always produces only a tiny *measureable* effect on desktop systems. Busy servers, with lots of teensy random read requests, benefit most from it, as do benchmark programs that do a lot of seeking. But normal system use -- running OO.org, rebuilding kernels, etc.. no significant measurable difference. Maybe by fiddling with the IO scheduler code (which defeats NCQ/TCQ to a degree).. But I'd happily enable it on my own systems anyway! Cheers