Hi James,

The GIZA++ is a very typical EM algorithm and probably you want to
parallelize the e-step since it takes long time then M-Step. You may want to
check out the PGIZA++ and MGIZA++ implementations which you can download in
my homepage:

http://www.cs.cmu.edu/~qing

And you may also be interested in a paper describing the work:

www.aclweb.org/anthology-new/W/W08/W08-0509.pdf

Please let me know if there are anything I can help.

Best,
Qin

On Thu, Feb 19, 2009 at 4:12 PM, James Read <[email protected]> wrote:

> Hi all,
>
> as the title suggest I am involved in a project which may involve
> parallelising the code of Giza++ so that it will run on supercomputers
> scalably on n number of processors. This would have obvious benefits
> to any researchers making regular use of Giza++ who would like it to
> finish in minutes rather than hours.
>
> The first step of such a project was profiling Giza++ to see where the
> executable spends most of its time on a typical run. Such profiling
> indicated a number of candidate functions. One of which was
> model1::em_loop found in the model1.cpp file.
>
> In order to parallelise such a function (using OpenMPI) it is
> necessary to first come up with some kind of data decomposition
> strategy which minimizes the latency of interprocessor communication
> but ensures that the parallelisation has no side effects other than
> running faster on a number of processors up to some optimal number of
> processors where the latency of communication begins to outweigh the
> benefits of throwing more processors at the job.
>
> In order to do this I am trying to gain an understanding of the logic
> in the model1::em_loop function. However, intuitive comments are
> lacking in the code. Does anyone on this list have a good internal
> knowledge of this function? Enough to give a rough outline of the
> logic it contains in some kind of readable pseudocode?
>
> Thanks
>
> P.S. Apologies to anybody to whom this email was not of interest.
>
> --
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
>
>
>
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-- 
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Qin Gao
Language Technology Institution
Carnegie Mellon University
http://geek.kyloo.net
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