Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751785AbXBOXnB (ORCPT ); Thu, 15 Feb 2007 18:43:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751796AbXBOXnB (ORCPT ); Thu, 15 Feb 2007 18:43:01 -0500 Received: from smtp-outbound-1.vmware.com ([65.113.40.141]:59209 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751785AbXBOXnA (ORCPT ); Thu, 15 Feb 2007 18:43:00 -0500 Message-ID: <45D4F003.4030502@vmware.com> Date: Thu, 15 Feb 2007 15:42:59 -0800 From: Zachary Amsden User-Agent: Thunderbird 1.5.0.9 (X11/20061206) MIME-Version: 1.0 To: Pavel Machek CC: Alan , Rusty Russell , Andi Kleen , Linux Kernel Mailing List , Andrew Morton , Jeremy Fitzhardinge , Chris Wright Subject: Re: [PATCH 9/11] Panic delay fix References: <200702060353.l163rUmj000771@zach-dev.vmware.com> <20070206122729.GC47229@muc.de> <45C8FA2D.6010706@vmware.com> <20070207123552.GD4481@ucw.cz> <1170880572.11736.4.camel@localhost.localdomain> <20070214125216.2befda78@localhost.localdomain> <45D36B49.5090109@vmware.com> <20070215101713.GK26240@elf.ucw.cz> In-Reply-To: <20070215101713.GK26240@elf.ucw.cz> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1215 Lines: 27 Pavel Machek wrote: > > You know it is ugly. Alan demonstrated it even hurts performance, but > being ugly is the main problem. > No argument with that. Well, we're ok with dropping it. Actually, reverting the entire set of udelay changes now seems wise. The same bug that happened with i8042 can happen with any hardware device driven by the VM in passthrough mode - potentially USB or IDE CDROM or direct SCSI. Since that is per-device and not global, a global udelay disable really is broken in that case, and recompiling individual C files or modules for passthrough vs. non-passthrough is not the answer. So Rusty, Chris, Jeremy, any objections to killing udelay() and friends in paravirt-ops? It would simplify things a bit. The only thing we lose is a slightly faster boot time in the 100% emulated device case. I'm ok with losing that. Even the PIT fast paths don't use udelay, so I don't think we care for runtime performance at all. Zach - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/