Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268132AbUIGQUy (ORCPT ); Tue, 7 Sep 2004 12:20:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268260AbUIGQSH (ORCPT ); Tue, 7 Sep 2004 12:18:07 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:64462 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S268111AbUIGQRV (ORCPT ); Tue, 7 Sep 2004 12:17:21 -0400 Date: Tue, 7 Sep 2004 09:14:39 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Ulrich Windl cc: Dominik Brodowski , lkml , tim@physik3.uni-rostock.de, george anzinger , albert@users.sourceforge.net, Len Brown , David Mosberger , Andi Kleen , paulus@samba.org, schwidefsky@de.ibm.com, jimix@us.ibm.com, keith maanthey , greg kh , Patricia Gaughen , Chris McDermott Subject: Re: [RFC] New Time of day proposal (updated 9/2/04) In-Reply-To: <413C1F21.32130.254827@rkdvmks1.ngate.uni-regensburg.de> Message-ID: References: <1094240482.14662.525.camel@cog.beaverton.ibm.com> <413C1F21.32130.254827@rkdvmks1.ngate.uni-regensburg.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1256 Lines: 26 On Mon, 6 Sep 2004, Ulrich Windl wrote: > On 3 Sep 2004 at 22:26, Dominik Brodowski wrote: > > ... > > What about removing cpu_freq_khz you have in your patch, adding a per-CPU > > value, and just use the value of the boot CPU for the other CPUs if > > !CONFIG_DIFFERENT_CPU_SPEEDS or something like that? > ... > > I would not mention SMP at that stage, but most of the existing code on IA32 > suumes that all CPUs run with the same frequency. I only heared that at least on > Alphas this is not true. Probably you'll need a per-CPU state regarding time. Most > likely resulting in the "local CPU's time" and a global concept of time that > should not be in contradiction with any CPU's time. That might mean that any > process always has to query the global time, involving extra overhead. CPUs in SGI Altix systems may also run at different frequencies. Typically 2 CPUs have a common clock source. For example in a system of 16 CPUs, there may exist 8 clock sources that slightly diverge from one another. - 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/