From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764366AbXK3SqT (ORCPT ); Fri, 30 Nov 2007 13:46:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763739AbXK3Spx (ORCPT ); Fri, 30 Nov 2007 13:45:53 -0500 Received: from iriserv.iradimed.com ([72.242.190.170]:10009 "EHLO iradimed.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1764039AbXK3Spv (ORCPT ); Fri, 30 Nov 2007 13:45:51 -0500 Message-ID: <47505A63.8070507@cfl.rr.com> Date: Fri, 30 Nov 2007 13:45:55 -0500 From: Phillip Susi User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) MIME-Version: 1.0 To: Tejun Heo CC: Pavel Machek , Alan Cox , noah , Linux Kernel Mailing List , linux-ide@vger.kernel.org Subject: Re: Possibly SATA related freeze killed networking and RAID References: <20071120220512.46b9e975@the-village.bc.nu> <20071126120649.GC4701@ucw.cz> <474CCA82.7030000@gmail.com> <474F3A4B.3080304@cfl.rr.com> <474F530D.8090302@gmail.com> In-Reply-To: <474F530D.8090302@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 30 Nov 2007 18:46:02.0901 (UTC) FILETIME=[41DF4C50:01C83381] X-TM-AS-Product-Ver: SMEX-7.5.0.1243-5.0.1023-15578.000 X-TM-AS-Result: No--12.354000-5.000000-31 X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Tejun Heo wrote: > Because SFF ATA controller don't have IRQ pending bit. You don't know > whether IRQ is raised or not. Plus, accessing the status register which > clears pending IRQ can be very slow on PATA machines. It has to go > through the PCI and ATA bus and come back. So, unconditionally trying > to clear IRQ by accessing Status can incur noticeable overhead if the > IRQ is shared with devices which raise a lot of IRQs. There HAS to be a way to determine if that device generated the interrupt, or the interrupt can not be shared. Since the kernel said nobody cared about the interrupt, that indicates that the sata driver checked the status register and realized the sata chip didn't generate the interrupt, and returned to the kernel letting it know that the interrupt was not for it.