Re: [RFC PATCH] perf: Add PERF_RECORD_SWITCH to indicate context switches

[Pawel Moll <pawel.moll@arm.com>]

On Fri, 2015-06-12 at 14:28 +0100, Pawel Moll wrote:
> On Fri, 2015-06-12 at 14:15 +0100, Adrian Hunter wrote:
> > >>>> all 3 are already part of sample_id.
> > >>>
> > >>> You have to decide whether you expect to be able to use an event without
> > >>> sample_id. MMAP and MMAP2 both have pid, tid which are in sample_id, LOST
> > >>> has id, EXIT and FORK have time, all of the THROTTLE/UNTHROTTLE members are
> > >>> in sample_id etc. So it currently looks like we expect to be able to use an
> > >>> event without requiring sample_id.
> > > 
> > > The fact that there is this duplication is because sample_id_all came
> > > after those events, but this new one being proposed doesn't have to do
> > > it :-)
> > 
> > Thanks, that's clear then.  There will just need to be a flag to indicate
> > whether it is scheduling in or out.
> 
> Just a thought: wouldn't it be good to know what CPU have we been
> scheduled from/to? This kind of information would be especially valuable
> in heterogeneous systems.

Of course, cpu is a part of sample_id as well. I'm sorted out then :-)

Pawel