On 12 Jan 2017, at 21:22, Roland Haas <[email protected]> wrote: > Hello Frank, > > thanks. That is somewhat reassuring. I also did some experiments and > consulted the PAPI thorns source code (its clocks file) and it seems as > if it always accumulates counter values over all threads when reading > out PAPI counters so things do in fact work as hoped for (namely the > flop counter counts all flops in a MPI rank and not just on thread > zero). My threads were bound to kernel level threads (and cores for > that matter) since I ran my tests on Blue Waters.
Hi Roland, I have never been able to get anything like realistic FLOPS numbers from PAPI. I have not tried recently. I think I heard that the hardware counter interfaces were only ever originally intended as debugging tools to be used by the processor manufacturers themselves, and were quite unreliable. This might have changed in recent CPUs. Do you get numbers consistent with what you expect? BlueWaters doesn't use very recent CPUs. I didn't know that the PAPI thorn tests this; that is nice! -- Ian Hinder http://members.aei.mpg.de/ianhin
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