From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [linux-usb-devel] 2.6.0-test1: random errors for USB disk Date: Thu, 17 Jul 2003 12:58:08 -0700 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <3F16FFD0.9070905@pacbell.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mta4.rcsntx.swbell.net ([151.164.30.28]:24246 "EHLO mta4.rcsntx.swbell.net") by vger.kernel.org with ESMTP id S268822AbTGQTky (ORCPT ); Thu, 17 Jul 2003 15:40:54 -0400 In-Reply-To: List-Id: linux-scsi@vger.kernel.org To: Alan Stern Cc: Harald Dunkel , USB Storage List , SCSI development list Alan Stern wrote: > The information in your system logs is very clear. Your USB drive worked > just great until it received a big data transfer. > > Under 2.4, the largest WRITE transfer was 130048 bytes and it worked fine. > Under 2.6, the largest attempted WRITE transfer was 524288 bytes and it > crashed the drive. The two commands were otherwise identical. Just to clarify: there's another difference, and that's that 2.4 does doing that smaller write one page at a time (write, wait, write, wait,...) while 2.6 does it all at once (write, write, write, write, ... wait). That difference is how I've seen usb-storage top 30 MByte/sec on USB with 2.6 kernels, when 2.4 may not reach 10 MB/sec on the same hardware. - Dave > Presumably differences in the block I/O systems account for the difference > in buffer sizes. But I don't know of any way to tell Linux that the drive > is unable to accept data transfers larger than some fixed limit. > > Can anyone else suggest a way to solve this? > > Alan Stern > >