PAPI and OpenMP

[Henrique Rennó]

Hello, I'm trying to read hardware counters with PAPI for OpenMP threads. The following C code does not seem to work as the values for the first thread are fine, but for the second thread are not. What is the right use of PAPI and OpenMP? Code is attached. I'd appreciate any help. Thanks in advance.

This code is compiled with (for a PAPI default installation): icc -I/usr/local/include -L/usr/local/lib -lpapi -qopenmp -o teste_papith.xc teste_papith.c

Output:

84279296 84279296

0 0

id = 0, time = 0.000067, event[0] = 105, x = 24975000

id = 0, time = 0.000067, event[1] = 165, x = 24975000

id = 1, time = 0.000058, event[0] = 140419991043152, x = 99950000

id = 1, time = 0.000058, event[1] = 140420010960080, x = 99950000

[Frank Winkler]

Hi Henrique,

You need an event set for each thread!

With "PAPI_start_counters" you created an event set for the main thread.

You could try to call "PAPI_start_counters()" inside your parallel region or just use the low-level API.

BTW:

There will be a new high-level API soon that makes this kind of PAPI instrumentation much easier.

I will test it with your example and come back to you soon!

Thanks,

Frank

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<teste_papith.c>

__________________________________________________________

Frank Winkler, M.Sc.

Technische Universität Dresden
Center for Information Services and
High Performance Computing (ZIH)
01062 Dresden, Germany

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