[Numpy-discussion] numpy ufuncs and COREPY - any info?

Andrew Friedley afriedle@indiana....
Mon May 25 05:59:31 CDT 2009


For some reason the list seems to occasionally drop my messages...

Francesc Alted wrote:
> A Friday 22 May 2009 13:52:46 Andrew Friedley escrigué:
>> I'm the student doing the project.  I have a blog here, which contains
>> some initial performance numbers for a couple test ufuncs I did:
>>
>> http://numcorepy.blogspot.com

>> Another alternative we've talked about, and I (more and more likely) may
>> look into is composing multiple operations together into a single ufunc.
>>   Again the main idea being that memory accesses can be reduced/eliminated.
> 
> IMHO, composing multiple operations together is the most promising venue for 
> leveraging current multicore systems.

Agreed -- our concern when considering for the project was to keep the 
scope reasonable so I can complete it in the GSoC timeframe.  If I have 
time I'll definitely be looking into this over the summer; if not later.

> Another interesting approach is to implement costly operations (from the point 
> of view of CPU resources), namely, transcendental functions like sin, cos or 
> tan, but also others like sqrt or pow) in a parallel way.  If besides, you can 
> combine this with vectorized versions of them (by using the well spread SSE2 
> instruction set, see [1] for an example), then you would be able to achieve 
> really good results for sure (at least Intel did with its VML library ;)
> 
> [1] http://gruntthepeon.free.fr/ssemath/

I've seen that page before.  Using another source [1] I came up with a 
quick/dirty cos ufunc.  Performance is crazy good compared to NumPy 
(100x); see the latest post on my blog for a little more info.  I'll 
look at the source myself when I get time again, but is NumPy using a 
Python-based cos function, a C implementation, or something else?  As I 
wrote in my blog, the performance gain is almost too good to believe.

[1] http://www.devmaster.net/forums/showthread.php?t=5784

Andrew


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