On Wed, May 28, 2014 at 09:51:44AM -0700, Andi Kleen wrote: > > The only part I don't quite follow here is this: > > if (__test_and_set_bit(bit, (unsigned long *)&status)) > > continue; > > > > Which seems to indicate the code is making sure each counter is > > processed only once. But it can only be processed once, if you have > > only one record. And if you have multiple, you want to be able to > > handle the same counter multiple times, at least once perf PEBS > > record. So I am a bit confused about this test. > > Each PEBS record is only for a single counter overflow. So it > always should only be a single perf event.
OK, so what Stephane said, that two counter's having their assist on the exact same cycle results in but a single record is false? That would be good.
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