Re: Why is PERF_FORMAT_GROUP incompatible with inherited events?

[Peter Zijlstra]

On Sun, 2010-02-14 at 22:33 +1100, Paul Mackerras wrote:
> 
> But we don't go and collect the count delta from children without
> PERF_FORMAT_GROUP, so why would we with it? 

Yes we do, see perf_event_read_value().

But now that I look at it we don't seem to do so in
perf_output_read_one()... I guess we should fix that.

There is of course the lock inversion in the .read() code reported by
stephane, but other than that is seems to actually support inherited &&
group just fine.

So I think if we fix that lock inversion and make the PERF_SAMPLE_READ
code look like the .read() code it should all work out.



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