Re: I.2 - Grouping

[Corey Ashford <cjashfor@linux.vnet.ibm.com>]

stephane eranian wrote:
> On Tue, Jun 23, 2009 at 10:26 AM, Paul Mackerras<paulus@samba.org> wrote:
>> stephane eranian writes:
>>
>>> What happens if I do:
>>>    fd0 = perf_counter_open(&hwc1, getpid(), -1, -1, 0);
>>>    fd1 = perf_counter_open(&hwc2, getpid(), -1, fd0, 0);
>>>
>>> And then:
>>>    fd2 = perf_counter_open(&hwc2, getpid(), -1, fd1, 0);
>> That perf_counter_open call will fail with an EINVAL error because fd1
>> is not a group leader.
>>
> Okay. Thanks.
> 
> But that leads me to another question related to grouping
> which was hinted for by Peter's comment about IBS.
> 
> Can you have multiple sampling events in a group?

There's a PAPI ctest which exercises this - profile_two_events - and it 
does work with the PCL substrate.

- Corey