[firedrake] cached kernels

[Eike Mueller]

Hi Lawrence,

>> Could there be an overhead from loading the LAPACK library, which
>> is required for the LU solve?

> This isn't how dynamic loading works.  The first time you load the
> .so, in the warmup phase, the symbol is resolved, and the trampoline
> is replaced by a direct call.

Yes, that's what I also thought, just wanted to double check.

> I have effectively no idea what's going on.  Does the LU solve take
> this long on this much data if you just call it from C?

I agree, that seems to be the obvious test to do. Maybe there is something strange going on in the LAPACK. I will have a go at that, and see if I get exactly the same time as if I run it through firedrake.

> IOW, I think it's not "our" fault, unless somehow you're managing to
> get a recompile or similar every time you call _lu_solve.
>
> Lawrence

Thanks,

Eike

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