On Wed, 12 Mar 2014, Alen Stojanov wrote: > So just to summarize (since I did not get any reply) - the final conclusion is > that I can not simply obtain proper flop counts with linux perf, because of > hardware limitations ?
Performance counters are tricky things. You shouldn't take my word for it, you should either run tests or contact people inside Intel. But yes, "flop count" has always been a tricky quantity to measure (what constitutes a flop? Is a fused multiply-add one flop or two? etc.) And in recent Intel processors the floating point events are notriously hard to use, and for a while Intel even stopped documenting that they existed until the HPC community complained enough that Intel has brought them back but with a lot of warnings about accuracy. This doesn't mean you can't get useful results out of the events, it just means that it's probably never going to be possible to get "exact flop counts", whatever that means. Vince -- To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
