From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261182AbVFATTY (ORCPT ); Wed, 1 Jun 2005 15:19:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261230AbVFATQo (ORCPT ); Wed, 1 Jun 2005 15:16:44 -0400 Received: from mailgw.cvut.cz ([147.32.3.235]:49833 "EHLO mailgw.cvut.cz") by vger.kernel.org with ESMTP id S261225AbVFATPj (ORCPT ); Wed, 1 Jun 2005 15:15:39 -0400 Message-ID: <429E0965.1090809@vc.cvut.cz> Date: Wed, 01 Jun 2005 21:15:49 +0200 From: Petr Vandrovec User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.8) Gecko/20050513 Debian/1.7.8-1 X-Accept-Language: en MIME-Version: 1.0 To: Rene Herman CC: Mark Lord , Bartlomiej Zolnierkiewicz , Linux Kernel Subject: Re: External USB2 HDD affects speed hda References: <429BA001.2030405@keyaccess.nl> <429DA0A9.6010808@rtr.ca> <429DFEBF.8090908@keyaccess.nl> In-Reply-To: <429DFEBF.8090908@keyaccess.nl> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Rene Herman wrote: > Mark Lord wrote: > >> Look at "cat /proc/interrupts" and see if the USB is sharing >> an IRQ line with ide0. If so, then the best explanation I can >> see is that the USB driver must have a *really slow* interrupt >> handler up to the point where it determines that the interrupt >> is not for it. > > > No, that's not it. Both ide0 (14) and EHCI (3) are on private, unshared > IRQs. rmmodding ehci_hcd as per Pavel's sugestion gets me back my speed. > Exactly _why_ I've no idea though. I've just added you to the CC on that > reply... Because EHCI hardware continuously watches some memory area to find whether there are some transfers from host to your USB devices ready... You just need better memory bandwidth so all your devices transfers fit on your bus. Or maybe EHCI driver could program hardware to not query transfer descriptors that often. But it would increase latency for people who use USB only and do not care about other parts of system. Petr Vandrovec