Hey Intel folks,
anyone out there who tested/used the vmdexp function in fortran code with Intel AVX extensions enabled at
compiling time via the command line switch -mavx ???
I just implemted the vmdexp function in a library function of a fortran combustion simulation code, but unfortunately
the wall time spend in the function (measured with omp_get_wtime) raised by a factor of 3 to 3.5 running (compared to
code relying completely on calls to the exp function from the Intel compiler math lib ) on a sandy bridge machine with
a processor implementing the Intel AVX extensions. :-(
Did anyone encounter the same/similar problem(s) using the vmdexp function in a C++/Fortran program?
I do not think that misalignment of the elements of the hand-written vector with 156 double precision elements should
cause such a massive performance loss when using the vmdexp function.
But I've just to test for this in near future (being just a tedious task ;-} )...
I also experimented with a vector generated by a do-loop, but the problem get even worse... :-(
@ Intel programmes: Did you implement any support for AVX in vmdexp or does the function completely lack from
support for (Intel) AVX ???
Thanks in advance for your replies and help, Sebastian.