Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758623AbXEYITP (ORCPT ); Fri, 25 May 2007 04:19:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752182AbXEYITG (ORCPT ); Fri, 25 May 2007 04:19:06 -0400 Received: from holomorphy.com ([66.93.40.71]:35338 "EHLO holomorphy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751982AbXEYITE (ORCPT ); Fri, 25 May 2007 04:19:04 -0400 Date: Fri, 25 May 2007 01:19:44 -0700 From: William Lee Irwin III To: Ingo Molnar Cc: Andi Kleen , Satyam Sharma , Andrew Morton , linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: [patch] i386, numaq: enable TSCs again Message-ID: <20070525081944.GZ31925@holomorphy.com> References: <20070525071005.GA6431@elte.hu> <20070525073158.GB8094@one.firstfloor.org> <20070525073957.GA15207@elte.hu> <20070525074316.GA16821@elte.hu> <20070525074915.GA18400@elte.hu> <20070525075446.GA20140@elte.hu> <20070525080827.GA22399@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070525080827.GA22399@elte.hu> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1113 Lines: 25 On Fri, May 25, 2007 at 10:08:27AM +0200, Ingo Molnar wrote: > Andi, Andrew, do you remember why we disabled TSCs on NUMAQ? It was > slightly async between CPUs, right? In that case we should try the patch > below. I remember. It was far beyond "slightly async;" they would drift minutes apart during reasonable amounts of uptime, though it would take at least several days to drift so far (I don't recall how long it took). TSC synchronization is uniformly impossible on NUMA-Q. Bootlogs showing the results of the attempts are still extant. They shouldn't end up too far apart right after booting, but I don't have even ballpark estimates. I'd hazard a guess of a few seconds. NUMA-Q's also supported mixed CPU models in hardware, though that's not really expected to be handled by Linux. I suspect DYNIX/ptx would be used by anyone interested in that. -- wli - 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/