Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261353AbUJXBlI (ORCPT ); Sat, 23 Oct 2004 21:41:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261354AbUJXBlI (ORCPT ); Sat, 23 Oct 2004 21:41:08 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:37533 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S261353AbUJXBlE (ORCPT ); Sat, 23 Oct 2004 21:41:04 -0400 Subject: Re: How is user space notified of CPU speed changes? From: Lee Revell To: jonathan@jonmasters.org Cc: Alan Cox , Linux Kernel Mailing List , Robert Love In-Reply-To: <35fb2e5904102316177420f6a9@mail.gmail.com> References: <1098399709.4131.23.camel@krustophenia.net> <1098444170.19459.7.camel@localhost.localdomain> <1098508238.13176.17.camel@krustophenia.net> <1098566366.24804.8.camel@localhost.localdomain> <1098571334.29081.21.camel@krustophenia.net> <35fb2e5904102316177420f6a9@mail.gmail.com> Content-Type: text/plain Date: Sat, 23 Oct 2004 21:40:56 -0400 Message-Id: <1098582057.29081.157.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1334 Lines: 32 On Sun, 2004-10-24 at 00:17 +0100, Jon Masters wrote: > On Sat, 23 Oct 2004 18:42:13 -0400, Lee Revell wrote: > > > Does anyone know how OSX/CoreAudio handles the situation? Apparently > > realtime apps work flawlessly on speed scaling laptops under OSX. > > The difference in implementation between the Intel TSC and PowerPC > TB[LU] has been mentioned previously in this thread. Well, it was mentioned that there is a difference... http://www-106.ibm.com/developerworks/eserver/pdfs/archpub2.pdf pg. 39, "Non-constant update frequency". "Each time the update frequency changes, the system software is notified of the change via an interrupt, or the change was instigated by the system software itself. At each such change, the system software must compute the current time of day using the old update frequency, compute a new value of ticks_per_sec for the new frequency, and save the time of day, Time Base value, and the tick rate" This was what I wanted to know: does Linux and/or the x86 have a similar mechanism? Looks like the answer is no... Lee - 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/