From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269045AbUHaTbL (ORCPT ); Tue, 31 Aug 2004 15:31:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269020AbUHaT3S (ORCPT ); Tue, 31 Aug 2004 15:29:18 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:34798 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id S269005AbUHaT1s (ORCPT ); Tue, 31 Aug 2004 15:27:48 -0400 Message-ID: <4134D11B.7050800@mvista.com> Date: Tue, 31 Aug 2004 12:27:23 -0700 From: George Anzinger Reply-To: george@mvista.com Organization: MontaVista Software User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20030225 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Tim Schmielau CC: john stultz , Andrew Morton , Petri Kaukasoina , albert@users.sourceforge.net, hirofumi@mail.parknet.co.jp, lkml , voland@dmz.com.pl, nicolas.george@ens.fr, david+powerix@blue-labs.org Subject: Re: [PATCH] Re: boot time, process start time, and NOW time References: <87smcf5zx7.fsf@devron.myhome.or.jp> <20040816124136.27646d14.akpm@osdl.org> <412285A5.9080003@mvista.com> <1092782243.2429.254.camel@cog.beaverton.ibm.com> <1092787863.2429.311.camel@cog.beaverton.ibm.com> <1092781172.2301.1654.camel@cube> <1092791363.2429.319.camel@cog.beaverton.ibm.com> <20040819191537.GA24060@elektroni.ee.tut.fi> <20040826040436.360f05f7.akpm@osdl.org> <1093916047.14662.144.camel@cog.beaverton.ibm.com> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Tim Schmielau wrote: > On Mon, 30 Aug 2004, john stultz wrote: > > >>On Mon, 2004-08-30 at 16:00, Tim Schmielau wrote: >> >>>George, please excuse my lack of understanding. What again where the >>>precise reasons to have an ntp-corrected uptime? >> >>Ah, here's the thread with the first mention of it that I could find. >> >>http://www.uwsg.iu.edu/hypermail/linux/kernel/0306.1/1471.html As I recall the problem was that jiffies since boot was being converted to get uptime base on 1/HZ = 1 jiffie. Since it is really not quite that, there was an error. Using clock_monotonic seemed like the right answer as it eliminated the error AND made the result consistant with get_clock(CLOCK_MONOTONIC,..). The alternate answer is, of course, to directly convert the elapsed jiffies. The main problem with this is that this can be a BIG number and, therefor, the math needs to be carefully. And, of course, it is inconsistant with get_clock(), but that is a new interface... George > > > Ah, it seems George indeed did the patch because of these problems: > > http://www.uwsg.iu.edu/hypermail/linux/kernel/0306.1/1641.html > > However, the actual reason were just missing wall_to_monotonic > initializations: > > http://www.uwsg.iu.edu/hypermail/linux/kernel/0306.2/1330.html > > This was fixed in mainline: > > http://linus.bkbits.net:8080/linux-2.5/cset%403f0e60dcpIosK3b5_uJ-aD9Mare17w > > Tim > -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml