Re: [eigen] Performance difference icc <-> gcc, EIGEN_STRONG_INLINE

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We could easily remove EIGEN_COMP_ICC from the cases where EIGEN_STRONG_INLINE is a __force_inline:

But I don't know the history of this, i.e., if it was necessary for older ICC versions. Or if it is necessary at other places.

Did you try to reduce your code to a minimal example where the performance drop occurs?

Regarding mbsolve: Sure, please give us a small description text and tell which category you want to get listed in.


On 13/03/2019 03.10, Michael Riesch wrote:
Hello all,

Thank you very much for your work on Eigen. We found it very useful for our simulation software mbsolve [1] (BTW maybe you would like to add it to the projects list that uses the Eigen library).

The code I am working on at the moment consists mostly of dense matrix-matrix and matrix-vector multiplications. I compiled the code with both Intel compiler 19 and gcc 6.3.0 and found that there is a strange performance difference. Unless I define


the binary compiled by icc is ~13x slower. The gcc binary performance remains the same, as inline seems to be the standard setting of this macro for gcc.

Why can this behavior occur? Or, alternatively, which possible anti-pattern could be the cause of this performance difference?

Any hints are welcome. If you need more information, please let me know.

Thanks in advance and best regards,


 Dr.-Ing. Christoph Hertzberg

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