[Numpy-discussion] strange sin/cos performance

Scott Sinclair scott.sinclair.za@gmail....
Wed Aug 5 10:26:39 CDT 2009


> 2009/8/5 Andrew Friedley <afriedle@indiana.edu>:
>
>> Is anyone with this problem *not* running ubuntu?
>
> Me - RHEL 5.2 opteron:
>
> Python 2.6.1 (r261:67515, Jan  5 2009, 10:19:01)
> [GCC 4.1.2 20071124 (Red Hat 4.1.2-42)] on linux2
>
> Fedora 9 PS3/PPC:
>
> Python 2.5.1 (r251:54863, Jul 17 2008, 13:25:23)
> [GCC 4.3.1 20080708 (Red Hat 4.3.1-4)] on linux2
>
>
> Actually I now have some interesting results that indicate the issue isn't
> in Python or NumPy at all.  I just wrote a C program to try to reproduce the
> error, and was able to do so (actually the difference is even larger).
>
> Opteron:
>
> float (32) time in usecs: 179698
> double (64) time in usecs: 13795
>
> PS3/PPC:
>
> float (32) time in usecs: 614821
> double (64) time in usecs: 37163
>
> I've attached the code for others to review and/or try out.  I guess this is
> worth showing to the libc people?

For whatever it's worth, not much difference on my machine 32-bit
Ubuntu, GCC 4.3.3.

float (32) time in usecs: 13804
double (64) time in usecs: 15394

Cheers,
Scott


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