Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030422AbVKWWXB (ORCPT ); Wed, 23 Nov 2005 17:23:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030334AbVKWWXA (ORCPT ); Wed, 23 Nov 2005 17:23:00 -0500 Received: from mx2.suse.de ([195.135.220.15]:51106 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S964782AbVKWWWZ (ORCPT ); Wed, 23 Nov 2005 17:22:25 -0500 Date: Wed, 23 Nov 2005 23:22:13 +0100 From: Andi Kleen To: Linus Torvalds Cc: Andi Kleen , Alan Cox , "H. Peter Anvin" , Gerd Knorr , Dave Jones , Zachary Amsden , Pavel Machek , Andrew Morton , Linux Kernel Mailing List , Zwane Mwaikambo , Pratap Subrahmanyam , Christopher Li , "Eric W. Biederman" , Ingo Molnar Subject: Re: [patch] SMP alternatives Message-ID: <20051123222212.GV20775@brahms.suse.de> References: <1132764133.7268.51.camel@localhost.localdomain> <20051123163906.GF20775@brahms.suse.de> <1132766489.7268.71.camel@localhost.localdomain> <4384AECC.1030403@zytor.com> <1132782245.13095.4.camel@localhost.localdomain> <20051123214344.GU20775@brahms.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1234 Lines: 34 On Wed, Nov 23, 2005 at 02:15:24PM -0800, Linus Torvalds wrote: > > > On Wed, 23 Nov 2005, Andi Kleen wrote: > > > > > THAT is what I'd like to have CPU support for. Not for UP (it's going > > > away), and not for the kernel (it's never single-threaded). > > > > There is one reasonly interesting special case that will probably stay > > around: single CPU guest in a virtualized environment. > > .. and then the _virtualizer_ should just set the bit. That wouldn't work if it's limited limited to ring 3. Also currently at least the Xen the driver interfaces seem to rely on lock, but perhaps that can be changed. > However, quite frankly, virtualization is overhyped, in my opinion. And if > it forces people to run UP because of performance issues, it's simply not > acceptable for a lot of loads. I don't think it'll force them to that, it will just be a common use case. e.g. you start a separate VM to run your firewall in. Do you really need it multithreaded? -Andi - 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/