From mboxrd@z Thu Jan 1 00:00:00 1970 From: 914059751@qq.com (rocky) Date: Fri, 22 Jan 2010 09:11:29 +0800 Subject: =?gb2312?B?tPC4tDogUXVlcnkgYWJvdXQgbG9vcHNfcGVyX2ppZmZ5?= In-Reply-To: References: Message-ID: <6134FC3AD99C4CA8A47F7E3D5E71C470@dufan> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Green hand apology for the unintended CC, I should make this query personal. _____ ???: linux-arm-kernel-bounces at lists.infradead.org [mailto:linux-arm-kernel-bounces at lists.infradead.org] ?? ??? ????: 2010?1?19? 21:38 ???: Alessandro Rubini ??: linux-arm-kernel ??: Re: Query about loops_per_jiffy Are you Alessandro Rubini of LINUX DEVICE DRIVER? ------------------ Original ------------------ From: "Alessandro Rubini"; Date: Tue, Jan 19, 2010 04:21 PM To: "914059751"<914059751@qq.com>; Cc: "linux-arm-kernel"; Subject: Re: Query about loops_per_jiffy > (loops_per_jiffy * HZ)/1000,000 will give a BogoMips value. No, it will give a BogoLips (loops per second). A loop is two instructions, in ./arch/arm/lib/delay.S (function __delay) called by init/calibrate.c .. To have bogomips you need to multiply by two. > then why calibrate_delay do it like the following: > printk(KERN_CONT "%lu.%02lu BogoMIPS (lpj=%lu)\n", > loops_per_jiffy/(500000/HZ), > (loops_per_jiffy/(5000/HZ)) % 100, loops_per_jiffy); It's correct, using normal integer aritmetics care. /alessandro -------------- next part -------------- An HTML attachment was scrubbed... URL: