On Wed, 01 Jan 2014 15:21:00 -0600 Rob Landley <r...@landley.net> wrote:
> On 01/01/14 06:41, Martin Schwidefsky wrote: > > On Tue, 31 Dec 2013 22:17:39 -0600 > > Rob Landley <r...@landley.net> wrote: > > > >> On 12/30/13 09:26, Martin Schwidefsky wrote: > >>> On Mon, 30 Dec 2013 16:11:10 +0100 > >>> Oleg Nesterov <o...@redhat.com> wrote: > >>>> Not sure I understand... except that timekeeping_resume() does > >>>> __timekeeping_inject_sleeptime(). > >>> > >>> Hmm, you are right. The sleeptime is added to the monotonic boottime. > >>> So the first value of /proc/uptime is the wall-time since boot. > >>> And the second value is combined idle time over all cpus. > >> > >> Is there an obvious way to query the non-suspend uptime from userspace? > > > > clock_gettime with CLOCK_MONOTONIC gives you the uptime minus without the > > suspend time. > > Given that the clock_gettime man page says: > > CLOCK_MONOTONIC > Clock that cannot be set and represents monotonic time since > some unspecified starting point. > > Can I rely on it _continuing_ to do so in future, and if so should the > man page be clarified? Good point. CLOCK_MONOTONIC is implemented in a specific way now and I doubt that this will change any time soon, but you have no guarantee that it will keep the property 'monotonic-time = uptime - suspend-time'. You can not use the values in /proc/stat either as you can set any CPU offline, which means that no CPU line contains all ticks since boot. Without the CLOCK_MONOTONIC option I do not see a way how to get the non-suspend uptime from user space. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
