Eugene Loh wrote:
> Sangamesh B wrote:
>> The job is run on 2 nodes - 8 cores.
>> OpenMPI - 25 m 39 s.
>> MPICH2 - 15 m 53 s.
> I don't understand MPICH very well, but it seemed as though some of
> the flags used in building MPICH are supposed to be added in
> automatically to the mpicc/etc compiler wrappers.
Again, this may not apply to your case, but I found out some more
details on my theory.
If you build MPICH2 like this:
% configure CFLAGS=-O2
then when you use "mpicc" to build your application, you automatically
get that optimization flag built in.
What had confused me was that I tried confirming the theory by building
MPICH2 like this:
% configure --enable-fast
That does *NOT* up the mpicc optimization level (despite their