[Yt-dev] parallelism when ngrids < nprocs

John Wise jwise at astro.princeton.edu
Sun Feb 20 15:09:55 PST 2011


> The mpi_catarray function has caused some problems lately.  We had to
> change a few things around to get it to work with inline in a
> particular way, but the specifics escape me now.  I think that it was
> this change that broke the ngrids<ncpu issue that you bring up; I'm
> sorry it caused you an issue!  Your fix looks fine to me.

Thanks for letting me know how this bug possibly arose.  I'll go ahead 
and push the change.

> Nope!  As of right now, Enzo's the only code that implements preload.
> I suspect that any fix would have to be applied specific to each code,
> but my gut feeling is that the only reason it came up in Enzo is
> because of carelessness on my part; for some reason the IO Handler
> instance doesn't know about its parent parameter file or hierarchy.  I
> think that a longer-term fix would be to avoid this ignorance, and
> simply give unto the IOHandler a reference to the parameter file.  I
> think that if we removed the grids[0] call, otherwise preload() should
> succeed.  Your fix is great, thought.

Good to know.  I just didn't want to push a change that could've been 
extended to other formats :)

Thanks again,
John



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