From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261502AbVFAXoE (ORCPT ); Wed, 1 Jun 2005 19:44:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261499AbVFAXnS (ORCPT ); Wed, 1 Jun 2005 19:43:18 -0400 Received: from ylpvm12-ext.prodigy.net ([207.115.57.43]:33192 "EHLO ylpvm12.prodigy.net") by vger.kernel.org with ESMTP id S261453AbVFAXkd (ORCPT ); Wed, 1 Jun 2005 19:40:33 -0400 X-ORBL: [69.107.40.98] From: David Brownell To: Rene Herman Subject: Re: External USB2 HDD affects speed hda Date: Wed, 1 Jun 2005 16:40:14 -0700 User-Agent: KMail/1.7.1 Cc: Petr Vandrovec , Mark Lord , Bartlomiej Zolnierkiewicz , Linux Kernel References: <429BA001.2030405@keyaccess.nl> <200506011337.29656.david-b@pacbell.net> <429E359D.8090701@keyaccess.nl> In-Reply-To: <429E359D.8090701@keyaccess.nl> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200506011640.15147.david-b@pacbell.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 01 June 2005 3:24 pm, Rene Herman wrote: > I see. Well, sort of at least. "Even if the HDD were using periodic > transfers, which it isn't, it would be DMAing 32-bits 8x per msec while > idle, which certainly isn't going to cost 8MB/s bus bandwidth". Right? Well, "certainly" is hard to say without the kind of PCI-bus level logic analyser thing. Flakey PCI implementations could chew up lots of bandwidth. It _should_ not take 8 MB/s bandwidth. But if it's chewing up bandwidth, and you're already near the limit in terms of throughput on that hardware (doesn't need to be at the theoretical ceiling!) then regular small demands could conceivably chew up more bandwidth than you'd like. - Dave