Comments on: Struggling with pyrex http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/ games, tech, web, stuff, biz, and bilge Wed, 03 Dec 2008 07:26:52 +0000 http://wordpress.org/?v=2.5.1 By: philhassey http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-233 philhassey Tue, 04 Dec 2007 18:21:41 +0000 http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-233 Okay - that change got the speed similar to PyPy/Rpython and Shed-skin. Okay - that change got the speed similar to PyPy/Rpython and Shed-skin.

]]> By: Allefant http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-232 Allefant Tue, 04 Dec 2007 18:02:18 +0000 http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-232 It should have been: a=(<float>x/SW) * 4.0 - 2.0 b=(<float>y/SH) * 4.0 - 2.0 It should have been:
a=(<float>x/SW) * 4.0 - 2.0
b=(<float>y/SH) * 4.0 - 2.0

]]> By: Allefant http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-231 Allefant Tue, 04 Dec 2007 18:01:32 +0000 http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-231 Hm, somehow < and > got eaten in my comment? Hm, somehow < and > got eaten in my comment?

]]> By: Allefant http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-230 Allefant Tue, 04 Dec 2007 17:59:54 +0000 http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-230 Sorry, I didn' have a runnable version yet when I looked at the code yesterday, so didn't try to pinpoint the speed problem. The mistake is one pyrex peculiarity - to get C style casts you need to use not float(). Now what happens in your code is, you perform lots of calls to the Python function float() where you meant to do a cast - killing any performance. Replace this: a=(float(x/SW) * 4.0 - 2.0) b=(float(y/SH) * 4.0 - 2.0) with this: a=(x/SW) * 4.0 - 2.0 b=(y/SH) * 4.0 - 2.0 And the per-frame time should drop by a factor of 10 or 20 :) Sorry, I didn’ have a runnable version yet when I looked at the code yesterday, so didn’t try to pinpoint the speed problem. The mistake is one pyrex peculiarity - to get C style casts you need to use not float(). Now what happens in your code is, you perform lots of calls to the Python function float() where you meant to do a cast - killing any performance.

Replace this:
a=(float(x/SW) * 4.0 - 2.0)
b=(float(y/SH) * 4.0 - 2.0)
with this:
a=(x/SW) * 4.0 - 2.0
b=(y/SH) * 4.0 - 2.0

And the per-frame time should drop by a factor of 10 or 20 :)

]]> By: Mark Dufour http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-229 Mark Dufour Tue, 04 Dec 2007 17:17:00 +0000 http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-229 doesn't that kind of defeat the purpose of pyrex? btw, JIT compilers are similarly intransparent. with Psyco, it's hard to tell when and why something will go much faster or not. doesn’t that kind of defeat the purpose of pyrex?

btw, JIT compilers are similarly intransparent. with Psyco, it’s hard to tell when and why something will go much faster or not.

]]> By: oleastre http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-227 oleastre Tue, 04 Dec 2007 08:34:31 +0000 http://www.philhassey.com/blog/2007/12/03/struggling-with-pyrex/#comment-227 For m, pyrex is usefulle to interface C code with python one, not for directly implementing stuff. You may write time consuming parts of your code in C and interface it with pyrex to be callable from python. For m, pyrex is usefulle to interface C code with python one, not for directly implementing stuff.

You may write time consuming parts of your code in C and interface it with pyrex to be callable from python.

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