Re: measuring system wide CPU usage ignoring idle process

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Thu, Nov 23, 2017 at 04:12:05PM +0100, Jiri Olsa escreveu:
> On Thu, Nov 23, 2017 at 11:42:20AM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Nov 23, 2017 at 03:21:00PM +0100, Jiri Olsa escreveu:
> > > On Thu, Nov 23, 2017 at 03:09:31PM +0100, Jiri Olsa wrote:
> > > > On Thu, Nov 23, 2017 at 02:40:36PM +0100, Milian Wolff wrote:
> > > > > > > Sorry for being unclear: I was talking about the task-clock and cpu-clock
> > > > > > > values which you omitted from your measurements below. My example also
> > > > > > > shows that the counts for cycles and instructions are fine. But the
> > > > > > > cpu-clock and task-clock are useless as they always sum up to essentially
> > > > > > > `$nproc*$runtime`. What I'm hoping for are fractional values for the "N
> > > > > > > CPUs utilized".

> > > > > > ugh my bad.. anyway by using -a you create cpu counters
> > > > > > which never unschedule, so those times will be same
> > > > > > as the 'sleep 1' run length

> > Humm, what role perf_event_attr.exclude_idle has here?

> it's used for omiting samples from idle process.. but looks like it's
> enforced for software clock events

looks like it is NOT enforced?
 
> AFAICS it's not used in counting mode

But it should? I think it should, as we see from Milian's use case.

PeterZ sent a patch, I guess we should continue from there :-)

- Arnaldo