Re: [generalized cache events] Re: [PATCH 1/1] perf tools: Addmissing user space support for config1/config2

[Andi Kleen]

> 
> That is what Andi is referring to. The issue causes bias and thus impacts
> the quality of the samples. On SNB, there is a new INST_RETIRED:PREC_DIST
> event. PREC_DIST=precise distribution. It tries to correct for the skid
> on this event on INST_RETIRED with PEBS (look at Vol3b).

Unfortunately even PDIST doesn't completely fix the problem, but
it only makes it somewhat better. Also it's only statistical,
so you won't get a guaranteed answer for every sample.

-Andi
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