[yt-dev] Parallelization & the ART frontend

[Matthew Turk]

Hi Chris,

On Tue, Feb 7, 2012 at 9:30 PM, Christopher Moody <cemoody at ucsc.edu> wrote:
> Hi guys,
>
> I've been working hard on the ART frontend. Lately, I'm to the point where
> I'm playing around with more complex datasets that are taking much longer to
> project - so I'd really like to to start using the parallelization engines.
> I've tried Sam's workshop parallelization demos, and they all work. But
> launching with the ART frontend (http://paste.yt-project.org/show/2152/)
> spawns many independent processes which evidently are not actually splitting
> the projection job, but still taking up lots of processors.

My guess is that parallelism is not enabled for the ART frontend
simply as a matter of how the IO is conducted.  To make it really work
in parallel, the IO needs to be split up so that when process 1 reads
a given grid patch, the rest of the processors don't also need to read
all the data for that grid patch.

Can you lower your loglevel (by setting loglevel = 1 in ~/.yt/config
or by --config yt.loglevel=1 on the command line) and report back with
what it says during a projection job there?

-MAtt

>
> My mpi installation  works:
> yt : [INFO     ] 2012-02-07 18:12:28,207 Global parallel computation
> enabled: 0 / 8yt : [INFO     ] 2012-02-07 18:12:28,207 Global parallel
> computation enabled: 2 / 8
> yt : [INFO     ] 2012-02-07 18:12:28,208 Global parallel computation
> enabled: 1 / 8
> yt : [INFO     ] 2012-02-07 18:12:28,208 Global parallel computation
> enabled: 6 / 8
> yt : [INFO     ] 2012-02-07 18:12:28,208 Global parallel computation
> enabled: 3 / 8
> yt : [INFO     ] 2012-02-07 18:12:28,208 Global parallel computation
> enabled: 4 / 8
> yt : [INFO     ] 2012-02-07 18:12:28,208 Global parallel computation
> enabled: 5 / 8yt : [INFO     ] 2012-02-07 18:12:28,209 Global parallel
> computation enabled: 7 / 8
>
> But the script is just run 8 times, not any faster.
>
> What am I missing here?
>
> Many thanks!
> chris
>
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