From owner-freebsd-hackers Thu Sep 26 19:10:16 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1AA4737B401 for ; Thu, 26 Sep 2002 19:10:15 -0700 (PDT) Received: from out8.mx.nwbl.wi.voyager.net (out8.mx.nwbl.wi.voyager.net [169.207.3.117]) by mx1.FreeBSD.org (Postfix) with ESMTP id A3CAF43E65 for ; Thu, 26 Sep 2002 19:10:14 -0700 (PDT) (envelope-from silby@silby.com) Received: from pop1.nwbl.wi.voyager.net (pop1.nwbl.wi.voyager.net [169.207.2.115]) by out8.mx.nwbl.wi.voyager.net (Postfix) with ESMTP id BD1013C24D; Thu, 26 Sep 2002 21:10:13 -0500 (CDT) Received: from [10.1.1.6] (d5.as13.nwbl0.wi.voyager.net [169.207.135.133]) by pop1.nwbl.wi.voyager.net (8.10.2/8.10.2) with ESMTP id g8R2ABU89521; Thu, 26 Sep 2002 21:10:12 -0500 (CDT) Date: Thu, 26 Sep 2002 21:14:26 -0500 (CDT) From: Mike Silbersack To: Sean Farley Cc: freebsd-hackers@freebsd.org Subject: Re: Slow I/O responsiveness with UDMA133 In-Reply-To: <20020926075207.U295-100000@thor.farley.org> Message-ID: <20020926211102.Q9440-100000@patrocles.silby.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Thu, 26 Sep 2002, Sean Farley wrote: > I just do not understand how a 5400 RPM UDMA 33 drive can beat a 7200 > RPM UDMA 133 drive by 33% on sequential output blocks. Rumor has it that newer drives cannot write a single sector at a time, and instead must read a whole cluster of sectors, add in the new sector, and write back the whole cluster. That behavior sounds like it would hurt sequentual performance substantially, as it would become a lot of read-modify-write operations. > > Does the drive support tagged queueing? That should give you the > > benefits of write caching with a little bit more safety. > > I thought only IBM had IDE drives which supported tags. No. The specs > do not mention tags. Hm, I thought other vendors had started to support them, I guess they decided not to. :| I have no idea on what BIOS settings would be optimal. I doubt that they'll make a real performance difference. Mike "Silby" Silbersack To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message