Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755653AbZIJNDY (ORCPT ); Thu, 10 Sep 2009 09:03:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755634AbZIJNDX (ORCPT ); Thu, 10 Sep 2009 09:03:23 -0400 Received: from smtp-vbr14.xs4all.nl ([194.109.24.34]:4041 "EHLO smtp-vbr14.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753220AbZIJNDX (ORCPT ); Thu, 10 Sep 2009 09:03:23 -0400 Message-ID: <2f08a48107b19501ffa2c1570483544f.squirrel@webmail.xs4all.nl> In-Reply-To: <20090908225858.04d56dce.akpm@linux-foundation.org> References: <20090908225858.04d56dce.akpm@linux-foundation.org> Date: Thu, 10 Sep 2009 15:02:53 +0200 Subject: Re: [PATCH] Re: /proc/uptime idle counter remains at 0 From: "Johan van Baarlen" To: "Andrew Morton" Cc: "Michael Abbott" , "Jan Engelhardt" , "Martin Schwidefsky" , "Linux Kernel Mailing List" , "Johan van Baarlen" User-Agent: SquirrelMail/1.4.18 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2300 Lines: 65 Andrew, with this patch the idle-time in /proc/uptime makes a lot more sense - but it runs about a factor of 4 too fast (I'm thinking this is not coincidence - I've got 4 cpu's in this box, and simply adding 4 idle timers means you are going 4 times too fast). Can we just add idletime /= (i+1) after the foreachcpu loop, or am I thinking too easy? Regards, Johan > On Fri, 14 Aug 2009 13:18:08 +0100 (BST) Michael Abbott > wrote: > >> Reviving this: >> >> On Sat, 9 May 2009, Jan Engelhardt wrote: >> > starting from v2.6.28-4930-g79741dd lasting thru at least v2.6.29.1, >> > the second field of /proc/uptime always shows 0.00. This happens for >> > both the typical i386 (my case) and on an ARM (according to Michael, >> > cc'ed). >> > >> > >From the commit log of 79741dd: >> > >> > """The cpu time spent by the idle process actually doing >> > something is currently accounted as idle time. This is plain >> > wrong, the architectures that support VIRT_CPU_ACCOUNTING=y >> > can do better: distinguish between the time spent doing >> > nothing and the time spent by idle doing work. The first is >> > accounted with account_idle_time and the second with >> > account_system_time.""" >> > >> > Citing Michael from our irc conversation: >> > >> > """the writer[committer] [says] that [the] idle process time >> > isn't really idle time ... but that's all that /proc/uptime >> > looks at. I guess fs/proc/uptime.c needs to catch up.""" >> > >> > So, were the updates to uptime.c missed, or do we now live on with >> > /proc/uptime constantly having 0? >> >> My previous patch seems to have run into the sand. It every so nearly >> got >> pulled into mainstream as far as I can tell, but didn't seem to make it; >> no idea what happened. >> >> So here we go again: >> > > Imagine my surprise to find a version of this patch lurking in Martin's > tree since June 22. It's a regression fix! > > Johan, does this patch help with the regression you reported in > http://bugzilla.kernel.org/show_bug.cgi?id=14131 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/