[pooma-dev] simple pooma question

[Richard Guenther]

On Wed, 17 Jul 2002, Garnet Kin-Lic Chan wrote:

>
> Sorry if these are simple questions, but I am having quite a lot of
> difficulty trying to understand what POOMA does during its parallel
> execution. I have done some parallel programming before,
> but here everything is hidden!
>
> If a piece of code has both a serial component and a parallel
> component, and one is executing it in a distributed environment, does
> every copy of the code run the serial component, or does POOMA only make
> one node execute the serial component.

All nodes execute the serial component except you mark the serial section
with something like

  if (Pooma::context() == 0) {
       ... serial part to be executed exclusively on node 0 ...
  }

but you need to be careful to not have non-local engines working in such
sections (or you'll deadlock and get errors).

> Similarly, are arrays which are not
> declared as distributed, then exist as identical copies on each node?

Yes, they exist on each node as identical copies (similar to choosing
ReplicatedTag).

> Also, where can I look to better understand the parallel behaviour of
> POOMA?

Browse through the available documentation - and the source, if necessary.
Parallel behavior ist straight forward except for some surprising
effects...

Richard.

--
Richard Guenther <richard.guenther at uni-tuebingen.de>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/
The GLAME Project: http://www.glame.de/