[Numpy-discussion] performance comparison of C++ vs Numeric (MA) operations.

[Paul F. Dubois]

PS my test was on double precision, failed to notice that too.

-----Original Message-----
From: numpy-discussion-admin at lists.sourceforge.net
[mailto:numpy-discussion-admin at lists.sourceforge.net]On Behalf Of Joe
Van Andel
Sent: Tuesday, June 12, 2001 5:20 PM
To: numpy-discussion
Subject: [Numpy-discussion] performance comparison of C++ vs Numeric
(MA) operations.


I was curious about the relative performance of C++ vs Numeric Python,
for operations on arrays of roughly 400,000 array elements.  I built a
simple array single precision multiplication function in C++, that
performs an element by element multiply, checking whether each element
is "valid" or "missing data".

Then, for comparision, I wrote a similar multiplication routine, using
the Masked Array (MA) package of Numeric Python.

I compiled Numeric Python (20.1.0b2) with '-O3', by modifying setup.py
to contain lines like

OPTIMIZE=['-O3']

ext_modules = 
.
.
 Extension('multiarray', ['Src/multiarraymodule.c'],
                                extra_compile_args=OPTIMIZE
                                ),

---------------------------------------

On an 800 Mhz dual processor Dell Linux box, using gcc 2.95.3,

Software                Performance
------------------------------------------------                 
Numeric Python	        5.0e6 multiplies/second
Numeric Python -03	6.1e6 multiplies/second
C++	               10.3e6 multiplies/second
C++ -O3		       10.3e6 multiplies/second

(I tried using "plain" Numeric arrays, rather than Masked arrays, and it
didn't seem to make much difference.)

Has anyone else benchmarked the relative performance of C/C++ vs Numeric
Python?  

Does anyone know of other optimizations to Numeric Python that could be
implemented?

I know a more realistic benchmark would include I/O, which might tend to
reduce the apparent difference in performance.


I've attached the benchmark modules, in case someone would like to
examine them. 
-- 
Joe VanAndel  	          
National Center for Atmospheric Research
http://www.atd.ucar.edu/~vanandel/
Internet: vanandel at ucar.edu