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CUDA-x86.

May not be beneficial

 
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THX 1138



Joined: 30 Jun 2011
Posts: 102

PostPosted: Thu Nov 01, 2012 12:34 pm    Post subject: May not be beneficial Reply with quote

When a loop in a function that you are trying to compile renders the output:

Loop not parallelized: may not be beneficial

What is it basing its criteria for that response on? It seems a little arbitrary to me.

Also, is there a pgcc command to tell the pgcc compiler to not parallelize a loop if the intensity is below a certain value: say 5.00?

Any help appreciated. Thanks in advance.

Newport_j
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mkcolg



Joined: 30 Jun 2004
Posts: 5952
Location: The Portland Group Inc.

PostPosted: Mon Nov 05, 2012 2:50 pm    Post subject: Reply with quote

Quote:
What is it basing its criteria for that response on?
It's generally based on the number of instructions plus other heuristics. There's overhead required to set-up and tear-down threads so if there isn't enough work in a loop, parallelization can hurt performance due to this overhead.

- Mat
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