[Yt-dev] Projection speed improvement patch

[John Wise]

On 6 Nov 2009, at 10:35, Matthew Turk wrote:

> Hi john,
>
>> Thanks so much for taking a look at my data and examining the  
>> memory usage
>> of analyzing a dataset of this size.  I'll have to give it another  
>> shot on
>> ranger.  I can also see how I/O performance is on the Altix here at
>> Princeton, which has a local RAID (just like red).
>
> Awesome.  This is all with the hierarchy-opt branch in mercurial, but
> I think I am going to port it back to trunk in the very near future,
> now that I have tested it on a number of different datasets.

The parallel projections work well on ranger now.  I ran on 32 cores  
just like you did on triton.  I projected density, temperature, and  
electron fraction, all weighted by density for the same dataset I gave  
you.

yt was using slightly more memory on ranger at 2.1GB/core, which isn't  
bad at all.  This pushed me over the 2GB/core limit on ranger, so I  
had to use 8 cores/node instead of 16.

However, it was slower by a factor of 2.5.  It took 1084 seconds from  
start to finish (including all of the overhead).  I had already  
created a binary hierarchy beforehand.  Ranger in general is slow (I  
suspect its interconnect), so maybe it's just a "feature" of ranger.

Somewhat related but -- The Alltoallv call was failing when I compiled  
mpi4py with openmpi, but this went away when I compiled it with  
mvapich.  If you want to see where it failed, I put the trackback at

http://paste.enzotools.org/show/253/

Once I get mpi4py working on the Altix here, I'll post some timings  
from that, as well.

Cheers,
John