From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.theptrgroup.com (mail.theptrgroup.com [71.178.251.9]) by ozlabs.org (Postfix) with ESMTP id BBEB2B7BB1 for ; Wed, 28 Oct 2009 04:03:12 +1100 (EST) Message-ID: <4AE727CD.3020509@theptrgroup.com> Date: Tue, 27 Oct 2009 13:03:09 -0400 From: Jeff Angielski MIME-Version: 1.0 To: luigi.mantellini.ml@gmail.com Subject: Re: Low BogoMips References: <200910271627.06549.luigi.mantellini.ml@gmail.com> In-Reply-To: <200910271627.06549.luigi.mantellini.ml@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Luigi 'Comio' Mantellini wrote: > Hi All, > > my name is Luigi. I'm working on a stripped-down mpc8541 board (that has just > a serian and twe enets). > I have an issue on delay calibration. In fact my at boot time I see the > following on the serial console: > > .... > Calibrating delay loop... 83.20 BogoMIPS (lpj=166400) > .... > > This value seems to be too low and I suspect an error propagated from u-boot. > > Can anyone help me to understand a good way to investigate this problem? which > registers or configuration values I need to check? > > I will post the necessary snips of code or configuration if required. > > Thanks a lot for your help, On the PowerPC, the BogoMIPS is not an estimate of the performance of the CPU, but rather related to the internal timebase register frequency. "With recent kernels, when build with ARCH=powerpc, we now use the hardware timebase instead of bogus processor loops for short timings. Thus our bogomips value is no longer the speed at which the processor runs empty loops, but the actual processor timebase value as obtained after calibration at boot. " - Benjamin Herrenschmidt Google(powerpc, bogomips, timebase)=happiness -- Jeff Angielski The PTR Group www.theptrgroup.com