On 23 Aug 2010 00:33:39 -0700, Tobias Burnus wrote:
> While I do like coarrays, I do not see them as being "an enormous
> leap forward"; they make Fortran more attractive, they offer some
> nice features and integrate nicely into the language, but one has to
> do the same effort as with MPI to parallelize the code. (The coarray
> syntax seems to be easier, but the structure of the program is the
> same as with MPI.)
There are some crucial differences between Co-Array Fortran and MPI:
While it is indeed true that MPI2 supports one-sided parallelism,
(1) It is much easier and clearer to implement one-sided parallelism
with CAF. Ease of code maintenance should not be dismissed
lightly :-).
(2) MPI2 support for one-sided parallelism is not
integrated with the compiler and is less reliably supported. Many
codes still use MPI1.
(3) If OpenMP and Co-Array Fortran are both being handled in the
compiler rather than putting distributed parallelism into a
separate library, one has more confidence that threading and
parallel memory allocation will be handled appropriately. Getting
mixed mode OpenMP + MPI to work can be a nightmare.
Ted
--
Frango ut patefaciam -- I break so that I may reveal
