From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263286AbVFXTy3 (ORCPT ); Fri, 24 Jun 2005 15:54:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262919AbVFXTyJ (ORCPT ); Fri, 24 Jun 2005 15:54:09 -0400 Received: from mx2.elte.hu ([157.181.151.9]:49819 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S263385AbVFXTxA (ORCPT ); Fri, 24 Jun 2005 15:53:00 -0400 Date: Fri, 24 Jun 2005 21:52:48 +0200 From: Ingo Molnar To: "Martin J. Bligh" Cc: Andrew Morton , linux-kernel@vger.kernel.org, Con Kolivas Subject: Re: 2.6.12-mm1 boot failure on NUMA box. Message-ID: <20050624195248.GA9663@elte.hu> References: <20050621130344.05d62275.akpm@osdl.org> <51900000.1119622290@[10.10.2.4]> <20050624170112.GD6393@elte.hu> <320710000.1119632967@flay> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <320710000.1119632967@flay> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Martin J. Bligh wrote: > > - /* > > - * In the NUMA case we dont use the TSC as they are not > > - * synchronized across all CPUs. > > - */ > > -#ifndef CONFIG_NUMA > > - if (!use_tsc) > > -#endif > > + if (!cpu_has_tsc) > > /* no locking but a rare wrong value is not a big deal */ > > return jiffies_64 * (1000000000 / HZ); > > Humpf. That does look dangerous on a NUMA-Q. The TSCs aren't synced, > and we can't use them .... have to use PIT, whether the CPUs have TSC > or not. is the only problem the unsyncedness? That should be fine as far as the scheduler is concerned. (we compensate for per-CPU drifts) Ingo