From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933271AbXHASpu (ORCPT ); Wed, 1 Aug 2007 14:45:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761459AbXHASpk (ORCPT ); Wed, 1 Aug 2007 14:45:40 -0400 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:46625 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1762281AbXHASpk (ORCPT ); Wed, 1 Aug 2007 14:45:40 -0400 Date: Wed, 1 Aug 2007 11:45:39 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Andi Kleen cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/7] Simple Performance Counters: x86_64 support In-Reply-To: <20070801184026.GC20713@one.firstfloor.org> Message-ID: References: <11859243121617-git-send-email-clameter@sgi.com> <20070801182611.GB20713@one.firstfloor.org> <20070801184026.GC20713@one.firstfloor.org> 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 On Wed, 1 Aug 2007, Andi Kleen wrote: > > It is certainly interesting to compare alternative ways of handling the > > instruction streams by various processors or models of processors. > > Well you have to do a lot more work then to handle instable TSCs then. I have been using this for 2 years. It works fine for my purposes. > In particular the frequencies can be different between CPUs, they > change (which you can catch with cpufreq notifiers) and during the > cpufreq change period they're instable (as in you can't tell for > some time which frequency they're currently running at and they > might be running immediate frequencies) Well then simply make sure that they do not change while you measure.