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Asked: 2026-05-20T06:28:32+00:00

I am learning about OpenMP concurrency, and tried my hand at some existing code

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I am learning about OpenMP concurrency, and tried my hand at some existing code I have. In this code, I tried to make all the for loops parallel. However, this seems to make the program MUCH slower, at least 10x slower, or even more than the single threaded version.

Here is the code: http://pastebin.com/zyLzuWU2

I also used pthreads, which turns out to be faster than the single threaded version.

Now the question is, what am I doing wrong in my OpenMP implementation that is causing this slowdown?

Thanks!

edit: the single threaded version is just the one without all the #pragmas

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  1. Editorial Team

    One problem I see with your code is that you are using OpenMP across loops that are very small (8 or 64 iterations, for example). This will not be efficient due to overheads. If you want to use OpenMP for the n-queens problem, look at OpenMP 3.0 tasks and thread parallelism for branch-and-bound problems.

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