[sac-user] with-loop parallelization

Juhasz David juhda at inf.elte.hu
Tue Jan 11 14:05:05 CET 2011


Hi Clemens,

Clemens Grelck wrote:
[...]
> So far, all real world examples and benchmarks we have come across so far
> did not question the design to only parallelise a single level of with-loops.
> It boils down to the qestion whether the outermost with-loop provides
> sufficient concurrency wrt the target architecture. If you provide with
> some realistic example where this is not the case I'm happy to look into
> this. Of course, it is easy to construct examples that fool the SAC
> compiler, but are these really representative of production code? That
> is my point.
I see your point. The question was only theoretical, so I don't know any 
real world problem to this issue. But I will think about it. ;)

> Also take into account the following: Any more flexible parallelisation
> scheme (which I personally would love to see materialise) must not
> create more overhead in the simple bread-and-butter examples of
> parallelisation.
This is absolutely right. The general purpose parallelisation must not be 
less efficient. That's why I suggested to keep the current parallelisation 
and give hints for special cases, when the programmer is really sure about 
what he/she does.

David



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