Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964936AbVKOQx1 (ORCPT ); Tue, 15 Nov 2005 11:53:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964924AbVKOQx1 (ORCPT ); Tue, 15 Nov 2005 11:53:27 -0500 Received: from smtp.osdl.org ([65.172.181.4]:29064 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S964951AbVKOQxZ (ORCPT ); Tue, 15 Nov 2005 11:53:25 -0500 Date: Tue, 15 Nov 2005 08:52:58 -0800 (PST) From: Linus Torvalds To: Zachary Amsden cc: Arjan van de Ven , Gerd Knorr , Dave Jones , Pavel Machek , Andrew Morton , Linux Kernel Mailing List , "H. Peter Anvin" , Zwane Mwaikambo , Pratap Subrahmanyam , Christopher Li , "Eric W. Biederman" , Ingo Molnar Subject: Re: [PATCH 1/10] Cr4 is valid on some 486s In-Reply-To: <437A0BC3.3060909@vmware.com> Message-ID: References: <200511100032.jAA0WgUq027712@zach-dev.vmware.com> <20051111103605.GC27805@elf.ucw.cz> <4374F2D5.7010106@vmware.com> <4374FB89.6000304@vmware.com> <20051113074241.GA29796@redhat.com> <4378A7F3.9070704@suse.de> <4379ECC1.20005@suse.de> <437A0649.7010702@suse.de> <437A0710.4020107@vmware.com> <1132070764.2822.27.camel@laptopd505.fenrus.org> <437A0BC3.3060909@vmware.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 882 Lines: 23 On Tue, 15 Nov 2005, Zachary Amsden wrote: > > It's not overkill in the virtualization context, and there are (struggling, > but infinite possibilities) opportunities for native here as well. No, there are almost no opportunities for native. Especially with SMP, doing on-line code switching is really really nasty. You basically have to shut down all CPU's to make sure there are no races with other CPU's executing the code while it's being rewritten. I'd be very very nervous about it. It would have to be some major performance feature for it to make sense over a simple "switch function pointers around" approach. Linus - 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/