From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262256AbTEIA0A (ORCPT ); Thu, 8 May 2003 20:26:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262254AbTEIA0A (ORCPT ); Thu, 8 May 2003 20:26:00 -0400 Received: from holomorphy.com ([66.224.33.161]:9884 "EHLO holomorphy") by vger.kernel.org with ESMTP id S262256AbTEIAZ7 (ORCPT ); Thu, 8 May 2003 20:25:59 -0400 Date: Thu, 8 May 2003 17:38:25 -0700 From: William Lee Irwin III To: Davide Libenzi Cc: Chris Friesen , Linux Kernel Mailing List Subject: Re: how to measure scheduler latency on powerpc? realfeel doesn't work due to /dev/rtc issues Message-ID: <20030509003825.GR8978@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Davide Libenzi , Chris Friesen , Linux Kernel Mailing List References: <3EBAD63C.4070808@nortelnetworks.com> <20030509001339.GQ8978@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 08, 2003 at 06:12:12PM -0400, Chris Friesen wrote: >>> I'm trying to test the scheduler latency on a powerpc platform. It appears >>> that a realfeel type of program won't work since you can't program /dev/rtc >>> to generated interrupts on powerpc. Is there anything similar which could >>> be done? On Thu, 8 May 2003, William Lee Irwin III wrote: > > Why would you want to use an interrupt? Just count jiffies in sched.c On Thu, May 08, 2003 at 05:38:23PM -0700, Davide Libenzi wrote: > I don't know what he does mean for scheduler latency, but if it is the ctx > switch one something like get_cycles() will be better instead of jiffies. True, if you're looking for performance tweaks and not pathologies (which I was) you'll need something that accurate. -- wli