[pooma-dev] simple pooma question

[James Crotinger]

> 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!

That was the point. (Hiding parallelism, not causing you difficulty 8-)

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

Under normal operation, POOMA is basically SPMD, so yes, the serial code
runs in every process. If a threaded evaluator is used, then the serial code
runs in the main thread of every process, but not in the worker threads. 

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

I'm not sure what the state of the tutorials are. The nitty-gritty is not
documented anywhere that I'm aware of. We tried to do a good job of
commenting the source, so there is always that. A high level design document
would have been good, especially for an open-source development model. When
this was being developed at the lab, there were 8-10 people working closely
together, having weekly meetings, etc., and some of the stuff that was well
known to all just never got written down. 

	Jim
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