Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759575AbXEYIX0 (ORCPT ); Fri, 25 May 2007 04:23:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760490AbXEYIXD (ORCPT ); Fri, 25 May 2007 04:23:03 -0400 Received: from one.firstfloor.org ([213.235.205.2]:50745 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760535AbXEYIXA (ORCPT ); Fri, 25 May 2007 04:23:00 -0400 Date: Fri, 25 May 2007 10:22:59 +0200 From: Andi Kleen To: William Lee Irwin III Cc: Ingo Molnar , Andi Kleen , Satyam Sharma , Andrew Morton , linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: [patch] i386, numaq: enable TSCs again Message-ID: <20070525082259.GH8094@one.firstfloor.org> 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> <20070525081944.GZ31925@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070525081944.GZ31925@holomorphy.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1174 Lines: 26 On Fri, May 25, 2007 at 01:19:44AM -0700, William Lee Irwin III wrote: > 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). sched_clock should handle that. > 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. You should mark_tsc_instable(), but not tsc disable. In a release or two hopefully even that will be obsolete. -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/