From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-vbr10.xs4all.nl (smtp-vbr10.xs4all.nl [194.109.24.30]) by ozlabs.org (Postfix) with ESMTP id A664B474E4 for ; Thu, 27 Nov 2008 01:33:02 +1100 (EST) Message-ID: <492D5B38.3080709@aimvalley.nl> Date: Wed, 26 Nov 2008 15:20:40 +0100 From: Norbert van Bolhuis MIME-Version: 1.0 To: linuxppc-embedded@ozlabs.org Subject: Re: too few bogoMips on MPC8313E-RDB ? References: <492D1CA5.2090007@aimvalley.nl> <20081126102042.GA11397@mail.gnudd.com> In-Reply-To: <20081126102042.GA11397@mail.gnudd.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Thanks for the answer, but that's not it. I checked the jiffies variable, it increases about 250 times per second. So the (mpc83xx_defconfig) kernel perception (#define CONFIG_HZ 250) is OK. It must be something else, I still think 83.20 BogoMIPS can't be correct for a MPC8313 running at 333 MHz. Alessandro Rubini wrote: >> This is what a linux-2.6.x reports (for the MPC8313E running at 333 MHz): >> Calibrating delay loop... 83.20 BogoMIPS (lpj=166400) >> >> Which can't be correct. >> >> A MPC870 (running at 133 mhz) has ~ 131.07 BogoMIPS > > Actaully, one-instruction-per-clock leads to BogoMIPS = MHz. > > Your "loop per jiffies" value shows you make 332800 instructions per > jiffy (a loop is two instructions: increment and jump). > > So most liker your timer tick runs at 1000 Hz but Linux is thinking > it's at 250Hz (332800 * 250 = 83.20 millions). > >> Of course it's only a benchmark figure. > > No, it's not a benchmark figure. It's the metric by which udelay() is > calculated. So your udelays (and mdelays) will be 4 times shorter than > required, and some hardware may be misbehaving as a result. > > Hope this help > /alessandro, who however is not runing a powerPC these times >