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
% make
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
% make
That does *NOT* up the mpicc optimization level (despite their
documentation).
