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Overhead of using OpenMP?

Tony_Garratt
Beginner
‎12-16-2011 03:10 PM
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We build an application using v11 of your Fortran compiler which makes use of OpenMP. We run the exe with 1 thread and it takes around 6 mins. We re-compile and remove /QopenMP and re-run it and it takes around 6 mins. So, the use of OpenMP has a large overhead in the case when the code is run a single core machine. Is this expected?

Thanks!
Tony
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IanH
Honored Contributor III
‎12-16-2011 04:54 PM
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You've got "6 mins" twice, which implies no overhead. Is this what you intended?
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Tony_Garratt
Beginner
‎12-19-2011 08:07 AM
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Oh - sorry about that - here is what I meant to say:

We build an application using v11 of your Fortran compiler which makes use of OpenMP. We run the exe with 1 thread and it takes around9 mins. We re-compile and remove /QopenMP and re-run it and it takes around 6 mins. So, the use of OpenMP has a large overhead in the case when the code is run a single core machine. Is this expected?
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