Re: I.2 - Grouping

From: stephane eranian
Date: Tue Jun 23 2009 - 04:31:10 EST


On Tue, Jun 23, 2009 at 10:26 AM, Paul Mackerras<paulus@xxxxxxxxx> wrote:
> stephane eranian writes:
>
>> What happens if I do:
>> Â Âfd0 = perf_counter_open(&hwc1, getpid(), -1, -1, 0);
>> Â Âfd1 = perf_counter_open(&hwc2, getpid(), -1, fd0, 0);
>>
>> And then:
>> Â Âfd2 = 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?
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