From mboxrd@z Thu Jan 1 00:00:00 1970 From: Erik Mouw Subject: Re: [PATCH] CPU frequency display in /proc/cpuinfo Date: Mon, 5 Dec 2005 14:02:24 +0100 Message-ID: <20051205130224.GC17993@harddisk-recovery.com> References: <20051202181927.GD9766@wotan.suse.de> <20051202104320.A5234@unix-os.sc.intel.com> <20051204164335.GB32492@isilmar.linta.de> <20051204183239.GE14247@wotan.suse.de> <1133725767.19768.12.camel@mindpipe> <20051205011611.GA12664@redhat.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20051205011611.GA12664@redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cpufreq-bounces@lists.linux.org.uk Errors-To: cpufreq-bounces+glkc-cpufreq=m.gmane.org+glkc-cpufreq=m.gmane.org@lists.linux.org.uk Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Dave Jones , Lee Revell , Andi Kleen , Venkatesh Pallipadi , Andrew Morton , cpufreq , linux-kernel On Sun, Dec 04, 2005 at 08:16:11PM -0500, Dave Jones wrote: > I can't think of a single valid reason why a program would want > to know the MHz rating of a CPU. Given that it's a) approximate, > b) subject to change due to power management, c) completely nonsensical > across CPU vendors, and d) only one of many variables regarding CPU > performance, any program that bases any decision on the values found > by parsing that field of /proc/cpuinfo is utterly broken beyond belief. If you want a userspace governor to change the CPU speed, you need to export the value to userland. There are several papers showing[1] that such speed scheduling should be done by power-aware applications which need to tell the OS what speed they require to run to meet their processing needs. I agree that /proc/cpuinfo shouldn't be used (though it is a nice interface for humans to read about the CPU speed), but the current sysfs interface should do. Erik [1] See for example http://www.pds.twi.tudelft.nl/~pouwelse/energy_priority_scheduling.ps.gz http://www.pds.twi.tudelft.nl/~pouwelse/power_aware_video_decoding.ps -- +-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 -- | Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands