From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264577AbUGZUOv (ORCPT ); Mon, 26 Jul 2004 16:14:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265305AbUGZUOv (ORCPT ); Mon, 26 Jul 2004 16:14:51 -0400 Received: from mail.convergence.de ([212.84.236.4]:18580 "EHLO mail.convergence.de") by vger.kernel.org with ESMTP id S264577AbUGZT3F (ORCPT ); Mon, 26 Jul 2004 15:29:05 -0400 Date: Mon, 26 Jul 2004 21:29:39 +0200 From: Johannes Stezenbach To: Lee Revell Cc: Rudo Thomas , linux-kernel Subject: Re: max request size 1024KiB by default? Message-ID: <20040726192939.GA3689@convergence.de> Mail-Followup-To: Johannes Stezenbach , Lee Revell , Rudo Thomas , linux-kernel References: <20040712205917.47d1d58b.akpm@osdl.org> <1089705440.20381.14.camel@mindpipe> <20040719104837.GA9459@elte.hu> <1090301906.22521.16.camel@mindpipe> <20040720061227.GC27118@elte.hu> <20040720121905.GG1651@suse.de> <1090642050.2871.6.camel@mindpipe> <1090647952.1006.7.camel@mindpipe> <20040724112706.GA31077@ss1000.ms.mff.cuni.cz> <1090709881.1194.28.camel@mindpipe> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1090709881.1194.28.camel@mindpipe> User-Agent: Mutt/1.5.6+20040523i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 24, 2004 at 06:58:02PM -0400, Lee Revell wrote: > On Sat, 2004-07-24 at 07:27, Rudo Thomas wrote: > > > HD info: > > > /dev/hdc: > > > > > > Model=Maxtor 6Y160P0, FwRev=YAR41BW0, SerialNo=Y44K8TZE > > > Config={ Fixed } > > > RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57 > > > BuffType=DualPortCache, BuffSize=7936kB, MaxMultSect=16, MultSect=16 > > > CurCHS=4047/16/255, CurSects=16511760, LBA=yes, LBAsects=268435455 > > > IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} > > > PIO modes: pio0 pio1 pio2 pio3 pio4 > > > DMA modes: mdma0 mdma1 mdma2 > > > UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 > > > AdvancedPM=yes: disabled (255) WriteCache=enabled > > > Drive conforms to: (null): > > > > Your disk controller must not support that. It looks like the default > is 1024KiB or whatever the max your controller supports is: For drives smaller than 128GiB the "48-bit Address feature set" is optional, hence many older drives do not support it (since the old 28-bit LBA addressing is suffient). With 28-bit addressing the number sectors which can be transferred in one request is limited to 256. Linux 2.4 limited this further to 128 (i.e. 64KiB). With 48-bit addressing up to 2^16 sectors could be transferred in one request, but Linux 2.6 puts an arbitrarily chosen limit of 1024KiB on it. 'hdparm -I /dev/hda' will tell you whether your drive supports 48-bit addressing: Commands/features: Enabled Supported: * 48-bit Address feature set For full details see the ATA/ATAPI-7 spec at http://www.t13.org/. Johannes