Re: ncl performance

Multithreading or multiprocessing or parallel processing??

AFAIK multithreading is more system level. I don't think this
is user controllable.

Multiprocessing: It is not done from the NCL level. The
user can spawn multiple jobs to run on different CPUs from
(say) a C-shell script. Of course, if you have only one
data channel per cpu to a common memory, the different processes
will still have IO 'conflicts' when reading/writing to a common
(shared) memory.

Parallel processing: Requires 'load balancing'' to work well.
Some algorithms [eg: eigenvector conputations] could be set
up to use this and (possibly) some graphics
calculations but, currently, NCL does not include this capability.

D

Micah Sklut wrote:
> Dennis,
>
> Can NCL utilize multi threading? or is it only going to use one
> processor?
>
>
> On Fri, Jun 12, 2009 at 6:47 PM, Dennis Shea <shea_at_ucar.edu
> <mailto:shea_at_ucar.edu>> wrote:
>
> IMHO ... memory is always good to have ...
>
> Often mhz are emphasized ... not that important in and of
> itself. Overlooked issues are data movement from memory and cache.
>
> You can have lots of memory and a fast cpu but if the data
> movement is slow then the code will run slowly. I do not
> just mean reading from memory ... writing takes time also.
> If you have intertwined read/write tasks then performance
> could be even slower.
>
> D
>
> Micah Sklut wrote:
>
> Hi NCL,
>
> Its been a while, since my last questions, but I believe I
> have a straight forward one here.
>
> What is the best way to increase performance for ncl scripts.
> I have batch jobs where I read in large grib files, and output
> lots of images.
>
> Will performance improve by increasing RAM ?
> Will performance improve by increasing Processor Speed?
>
> My guess, is that the memory is going to be the biggest
> factor, and then processor speed second.
>
> Thanks for your help!
>
> Micah
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> --
> ======================================================
> Dennis J. Shea tel: 303-497-1361 |
> P.O. Box 3000 fax: 303-497-1333 |
> Climate Analysis Section |
> Climate & Global Dynamics Div. |
> National Center for Atmospheric Research |
> Boulder, CO 80307 |
> USA email: shea 'at' ucar.edu
> <http://ucar.edu> |
> ======================================================
>
>

-- 
======================================================
Dennis J. Shea                  tel: 303-497-1361    |
P.O. Box 3000                   fax: 303-497-1333    |
Climate Analysis Section                             |
Climate & Global Dynamics Div.                       |
National Center for Atmospheric Research             |
Boulder, CO  80307                                   |
USA                        email: shea 'at' ucar.edu |
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