From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265111AbTL2Tc6 (ORCPT ); Mon, 29 Dec 2003 14:32:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265112AbTL2Tc6 (ORCPT ); Mon, 29 Dec 2003 14:32:58 -0500 Received: from obsidian.spiritone.com ([216.99.193.137]:59563 "EHLO obsidian.spiritone.com") by vger.kernel.org with ESMTP id S265111AbTL2Tc4 (ORCPT ); Mon, 29 Dec 2003 14:32:56 -0500 Date: Mon, 29 Dec 2003 11:32:00 -0800 From: "Martin J. Bligh" To: John Hawkes , Andrew Morton cc: lse-tech@lists.sourceforge.net, mingo@elte.hu, linux-kernel@vger.kernel.org, johnstul@us.ibm.com Subject: Re: [Lse-tech] Re: [RFC][PATCH] 2.6.0-test11 sched_clock() broken for "drifty ITC" Message-ID: <30410000.1072726318@[10.10.2.4]> In-Reply-To: <200312291851.KAA25312@google.engr.sgi.com> References: <200312182044.hBIKiCLY5477429@babylon.engr.sgi.com> <200312291851.KAA25312@google.engr.sgi.com> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> Could you please finalise it, cook up the ia64 and numaq implementations >> and send it over? > > I believe the "ia64 implementation" stands as-is, since it uses the low- > overhead ITC. > > I'm not familiar with NUMAQ issues, but perhaps this timer_tsc.c change > would be appropriate? It allows i386 CONFIG_NUMA platforms to potentially > use the TSC for sched_clock() timings, given that sched_clock() no longer > requires that the TSC be synchronized across all CPUs. It does, however, > require that "use_tsc" be properly initialized for i386 CONFIG_NUMA. Is > that a valid assumption? I don't think there's anything special about use_tsc for NUMA-Q - it's set to 1 AFAICS. I had a patch to force notsc on about 6 months or so ago, but it made the machine crash hard in strange ways I never bothered debugging. Is there any harm in dropping the first part of your patch, ie. > diff -X /home/hawkes/Patches/ignore.dirs -Naur linux-2.6.0/arch/i386/kernel/timers/timer_tsc.c linux-2.6.0-schedclock2/arch/i386/kernel/timers/timer_tsc.c > --- linux-2.6.0/arch/i386/kernel/timers/timer_tsc.c Mon Nov 24 12:18:20 2003 > +++ linux-2.6.0-schedclock2/arch/i386/kernel/timers/timer_tsc.c Sat Dec 13 11:33:04 2003 > @@ -138,9 +138,7 @@ > * In the NUMA case we dont use the TSC as they are not > * synchronized across all CPUs. > */ > -#ifndef CONFIG_NUMA > if (!use_tsc) > -#endif > return (unsigned long long)jiffies * (1000000000 / HZ); > > /* Read the Time Stamp Counter */ and leaving the rest of it? the CONFIG_NUMA affects both NUMA-Q and Summit, BTW, which uses the cyclone timer, so it gets even more complex ;-) M.