From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756148Ab3L3PKd (ORCPT ); Mon, 30 Dec 2013 10:10:33 -0500 Received: from mx1.redhat.com ([209.132.183.28]:4206 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756116Ab3L3PKc (ORCPT ); Mon, 30 Dec 2013 10:10:32 -0500 Date: Mon, 30 Dec 2013 16:11:10 +0100 From: Oleg Nesterov To: Martin Schwidefsky Cc: Rob Landley , linux-kernel@vger.kernel.org, Frederic Weisbecker Subject: Re: Question about /proc/uptime Message-ID: <20131230151110.GA29636@redhat.com> References: <1388025009.1176.17@driftwood> <20131227144504.GA17192@redhat.com> <20131230095656.4c78dd98@mschwide> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131230095656.4c78dd98@mschwide> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/30, Martin Schwidefsky wrote: < > On Fri, 27 Dec 2013 15:45:04 +0100 > Oleg Nesterov wrote: > > > Add Frederic, I am not sure I understand this correctly. > > > > On 12/25, Rob Landley wrote: > > > > > > There are two values here, the first is seconds since boot time (which > > > is just elapsed time; at one point it was ajusted for suspend and that > > > was revered as confusing). > > > > Hmm, uptime_proc_show() still uses get_monotonic_boottime(), this should > > include suspend time? > > The first value of /proc/uptime is the amount of time the system has been > running, the sum of the suspend time is not included. Hmm. It uses get_monotonic_boottime() and this helper adds timekeeper->total_sleep_time to the returned value? Even the comment says * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also * includes the time spent in suspend. > timekeeping_resume() > is supposed to take care of that. Not sure I understand... except that timekeeping_resume() does __timekeeping_inject_sleeptime(). > > > The second value isn't documented but looking at fs/proc/uptime.c I > > > think it's idle time? > > > > And this cpustat[CPUTIME_IDLE] doesn't match get_idle_time(), I guess > > it only counts ticks. > > The second value of /proc/uptime is the sum of the idle time of all cpus. > The value should roughly match the sum over get_idle_time() for all cpus. > The difference is that get_idle_time() uses arch_idle_time to add the > time for the currently running idle period as well (at least for s390). Only if defined(arch_idle_time) ? Otherwise get_idle_time() uses get_cpu_idle_time_us() and CONFIG_NO_HZ_COMMON makes a difference. > That does make a difference if the cpus stay idle for long periods of > time. Yes. Oleg.