Thoughts on parallel programming?

[Fawzi Mohamed]

On 11-nov-10, at 15:16, Fawzi Mohamed wrote:

> On 11-nov-10, at 09:58, Russel Winder wrote:
>
>> MPI and all the SPMD approaches have a severely limited future, but I
>> bet the HPC codes are still using Fortran and MPI in 50 years time.
>
> well whole array operations are a generalization of the SPMD  
> approach, so I this sense you said that that kind of approach will  
> have a future (but with a more difficult optimization as the  
> hardware is more complex.

sorry I translated that as SIMD, not SPMD, but the answer below still  
holds in my opinion, if one has a complex parallel problem mpi is a  
worthy contender, the thing is that in many occasions one doesn't need  
all its power.
If a client server, a distributed or a map/reduce approach work, then  
simpler and more flexible solutions are superior.
That (and its reliability problem, that PGAS also shares) is, in my  
opinion, the reason MPI is not very used outside the computational  
community.
Being able to tackle also MPMD in a good way can be useful, and that  
is what the rpc level does between computers, and the event based  
scheduling within a single computer (ensuring that one processor can  
do meaningful work while the other waits.

> About MPI I think that many don't see what MPI really does, mpi  
> offers a simplified parallel model.
> The main weakness of this model is that it assumes some kind of  
> reliability, but then it offers
> a clear computational model with processors ordered in a linear of  
> higher dimensional structure and efficient collective communication  
> primitives.
> Yes MPI is not the right choice for all problems, but when usable it  
> is very powerful, often superior to the alternatives, and  
> programming with it is *simpler* than thinking about a generic  
> distributed system.
> So I think that for problems that are not trivially parallel, or  
> easily parallelizable MPI will remain as the best choice.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puremagic.com/pipermail/digitalmars-d/attachments/20101111/c4ac2043/attachment.html>