From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269097AbUIBUpT (ORCPT ); Thu, 2 Sep 2004 16:45:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269090AbUIBUpM (ORCPT ); Thu, 2 Sep 2004 16:45:12 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:58862 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id S269021AbUIBUkY (ORCPT ); Thu, 2 Sep 2004 16:40:24 -0400 Message-ID: <4137851D.5050406@mvista.com> Date: Thu, 02 Sep 2004 13:39:57 -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: john stultz CC: Tim Schmielau , 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> <4134D11B.7050800@mvista.com> <1093985817.14662.155.camel@cog.beaverton.ibm.com> In-Reply-To: <1093985817.14662.155.camel@cog.beaverton.ibm.com> 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 john stultz wrote: > On Tue, 2004-08-31 at 12:27, George Anzinger wrote: > >>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... > > > Hmmm. Well, I may be starting to lean in Tim's direction of pulling the > clock_monotonic based uptime and going back to the jiffies based uptime. > Atleast until we can make all the /proc/ output consistent. > > I just worry that it actually fixed a problem for someone, and backing > it out would just reopen that. > > Thoughts? Well, it was done in reaction to some complaint. I don't, at this point, recall who or why. If it is done with the correct values (i.e. NOT 1/HZ, but what the wall clock uses) I think it will not reopen that complaint. -- 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