From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: Playing with SATA NCQ Date: Mon, 30 May 2005 08:07:50 +0200 Message-ID: <20050530060749.GD7054@suse.de> References: <20050526140058.GR1419@suse.de> <429793C8.8090007@gmail.com> <42979C4F.8020007@pobox.com> <42979FA3.1010106@gmail.com> <20050528121258.GA17869@suse.de> <4299BD23.6010004@gmail.com> <20050529190259.GA29770@suse.de> <429A2238.8010604@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from brick.kernel.dk ([62.242.22.158]:55427 "EHLO nelson.home.kernel.dk") by vger.kernel.org with ESMTP id S261526AbVE3GGr (ORCPT ); Mon, 30 May 2005 02:06:47 -0400 Content-Disposition: inline In-Reply-To: <429A2238.8010604@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Michael Thonke Cc: Jeff Garzik , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org On Sun, May 29 2005, Michael Thonke wrote: > >Nothing, unfortunately NCQ doesn't provided any way of doing ordered > >tags. The only tunable is the queue_depth, you can set that anywhere > >between 1 and 30. > > > > > > > So way my drive got default 30 as queue_depth on AHCI as you mentoined > in the next mail > 2-4 should be suitable and enough/normal? Yes, 30 will be default for basically anyone as ahci now advertises a max depth of 30 and the drives typically all support a depth of 32. The minimum value of those two is used. Whether 2-4 is 'enough' depends on your workload. But usually 2-4 is enough to get a nice speedup on heavier io, while still getting you good latencies on the individual io. -- Jens Axboe