Messages in this thread | | | Date | Mon, 28 Jul 2014 05:36:29 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH v3 6/9] perf, x86: handle multiple records in PEBS buffer |
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> I don't think this method works for interrupt threshold > 1 case. When collision > happens, the hardware only create one PEBS record. The status in next record has > nothing to do with the collision record. > Not even for the threshold == 1 case, because the same could happen with a different PEBS event. Of course in any case it's very unlikely ...
> > > So typically we'd have one event set and no problem, but in case there's > > more we can reconstruct with such a backwards pass from a known good > > state. > > > > But when in doubt, we should drop the record, its the safest choice. > > The problem is that, in some cases, each PEBS record has more than one events > set, so we will drop all records.
Just dropping is fine imho, this should be rare.
-Andi
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