overhead on openmp

General OpenMP discussion

overhead on openmp

Postby cluster1321 » Tue Jan 08, 2008 12:35 pm

hi all,
I begin to use openmp , I compared the time that openmp and sequentail program use to execute ( the same program ) the result of that is the sequentail program is faster than the openmp program so that I would like to know about the general cuase of overhead on openmp.


thanks
diakala
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Re: overhead on openmp

Postby lfm » Tue Jan 15, 2008 9:03 am

You can measure overhead with the EPCC microbenchmarks. In general, there needs to be enough work in the parallel code to overcome the overhead. Also, other issues such as memory bandwidth and false sharing can drastically affect performance.
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