[XviD-devel] Re: OpenMP parallelization

[Felix von Leitner]

Thus spake Christoph Lampert (chl at math.uni-bonn.de):
> what would you think of OpenMP parallelism instead of
> pthread-Multithreading?

Why "instead of"?  Is there reason to believe that openmp could scale
better than the pthread stuff?

> Does VisualC++ suport this (yeah, I know, of course not).
> There is something call Omni OpenMP for cygwin and other projects, I never
> heard of.

> icc for Linux does support openMP, so maybe Windows version does, too. 
> And there might be some modification of gcc that does, but I didn't find
> it.

Just a few days ago, a gcc cvs branch was created for openmp, but AFAIK
no actual code is in it yet.

I'm not involved, I just saw it on the mailing list.

> For those who haven't met openMP: It's a "trick" to tell the compiler
> which parts of a program can be multithreaded by  #pragma  's in the code.
> If the compiler doesn't know about openMP, it ignores the statements.

I wonder how this can me more efficient than pthread on any CPU you can
buy today.  I haven't actually see it used yet, but I understand it is
mainly important to scientists on NUMA architectures.  Does anyone here
have a NUMA box at his disposal?

Felix