From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753512AbXC3Pua (ORCPT ); Fri, 30 Mar 2007 11:50:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753515AbXC3Pua (ORCPT ); Fri, 30 Mar 2007 11:50:30 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:40192 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753512AbXC3Pu3 (ORCPT ); Fri, 30 Mar 2007 11:50:29 -0400 Subject: Re: exposing FSB clock speed in /sys From: Arjan van de Ven To: eranian@hpl.hp.com Cc: linux-kernel@vger.kernel.org, perfmon@napali.hpl.hp.com In-Reply-To: <20070330153937.GC16059@frankl.hpl.hp.com> References: <20070330153937.GC16059@frankl.hpl.hp.com> Content-Type: text/plain Organization: Intel International BV Date: Fri, 30 Mar 2007 08:49:52 -0700 Message-Id: <1175269792.3360.2.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.8.3 (2.8.3-1.fc6) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2007-03-30 at 07:39 -0800, Stephane Eranian wrote: > Hello, > > It seems that the kernel does not expose the Front-Side Bus (FSN) Clock > speed to user applications and that is a good thing ;) > Knowledge the the FSB speed is very useful to monitoring tools. It is used > to compute certain bus-related metrics. perhaps. > > Looking at the code, it seems that there is no standard way of extracting > the FSB speed. For each processor model, you have different MSRs. I would > think that the routines in the cpufreq code could be moved out and used > as the basis to expose the information somewhere in /sys. ... yet not all CPU's *have* an FSB. Notably AMD ones do not, and I'm sure you've read on a lot of online tech magazines that other vendors may also not have one in the future :-) Exposing a concept that we KNOW does not make sense via a kernel interface (which means we need to keep it around forever) is in my opinion quite a bad mistake to make.... Please lets not do this.