Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753810AbdCBOZN (ORCPT ); Thu, 2 Mar 2017 09:25:13 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:45754 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753422AbdCBOYk (ORCPT ); Thu, 2 Mar 2017 09:24:40 -0500 Date: Thu, 2 Mar 2017 14:13:34 +0000 From: Russell King - ARM Linux To: =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= Cc: Rabin Vincent , Daniel Lezcano , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Srinivas Kandagatla , tglx@linutronix.de, Patrice Chotard , Hauke Mehrtens , Maxime Coquelin Subject: Re: DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer") Message-ID: <20170302141334.GM21222@n2100.armlinux.org.uk> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1399 Lines: 36 On Thu, Mar 02, 2017 at 02:36:23PM +0100, Rafał Miłecki wrote: > Hi, > > I just updated kernel on my SmartRG SR400ac (bcm4708-smartrg-sr400ac.dts) from > 4.4 to 4.9 and noticed that this part of the log: > [ 0.020820] Calibrating delay loop... 1594.16 BogoMIPS (lpj=7970816) > (...) > [ 0.190806] Brought up 2 CPUs > [ 0.200022] SMP: Total of 2 processors activated (3188.32 BogoMIPS). > > became: > [ 0.027082] Calibrating delay loop (skipped), value calculated using timer frequency.. 800.00 BogoMIPS (lpj=4000000) > (...) > [ 0.078858] Brought up 2 CPUs > [ 0.088254] SMP: Total of 2 processors activated (1600.00 BogoMIPS). > > This is caused by commit bbaa06702719 ("clocksource/drivers/arm_global_timer: > Register delay timer"). > > Is this something expected? Yes. > Or should I be worried about this? I'm aware it's just BogoMIPS, but I > still prefer to ask :) It's *bogus*. Bogomips is the calibration value that the kernel uses to achieve delays. It has nothing to do with the speed of the CPU on modern systems that use a timer instead. (In that case, it's a calibration value for the timer, rather than a calibration value for the number of software loops required to achieve a delay.) -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.