[Beowulf] Re: Stroustrup regarding multicore

David Mathog mathog at caltech.edu
Tue Aug 26 16:36:16 EDT 2008


Alan Louis Scheinine <alscheinine at tuffmail.us> wrote:

> I forgot to mention, function calls in Fortran, C or C++ seem to kill
efficiency,

That's pretty much true for any language when those calls are inside
inner loops.  There are exceptions though - inlined functions in C with
a "good" compiler will not have the call overhead because the compiler
will just replicate the code in place and compile it there.  It is not a
good thing to depend on though, since some other compiler may not be
able to pull off the same trick.  So in general it is usually best, if
your goal is to have the code run fast everywhere, to locate such
compute intensive loops (with valgrind, or whatever) and squeeze the
function overhead out of them.

Regards,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech
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