Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752113AbdCBUbV (ORCPT ); Thu, 2 Mar 2017 15:31:21 -0500 Received: from 10.mo1.mail-out.ovh.net ([178.32.96.102]:54763 "EHLO 10.mo1.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751461AbdCBUbS (ORCPT ); Thu, 2 Mar 2017 15:31:18 -0500 Subject: Re: DIfferent BogoMIPS value after bbaa06702719 ("clocksource/drivers/arm_global_timer: Register delay timer") To: Russell King - ARM Linux References: <20170302141334.GM21222@n2100.armlinux.org.uk> 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 From: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= Message-ID: <8d136a2c-c306-e8c8-780a-f55cb891f6e0@milecki.pl> Date: Thu, 2 Mar 2017 18:46:10 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <20170302141334.GM21222@n2100.armlinux.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Ovh-Tracer-Id: 6515301289328610893 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeelhedrfedvgddutdegucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuqfggjfdpvefjgfevmfevgfenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddm Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1353 Lines: 34 On 03/02/2017 03:13 PM, Russell King - ARM Linux wrote: > 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.) Now I can sleep calm ;) thanks!