Performance of int/long in Python 3

[Chris Angelico]

On Wed, Mar 27, 2013 at 3:41 AM, Cousin Stanley <cousinstanley at gmail.com> wrote:
>
> Chris Angelico wrote:
>
>> Once again, Py3 is slower on small integers than Py2.
>
>   Chris Angelico
>   Ubuntu Karmic.
>   Pentium(R) Dual-Core  CPU E6500  @ 2.93GHz.
>
>   python  inline  range_sum  forloop  forloop_offset
>
>   2.6.4   2.7050  2.6492      6.5877  16.5168
>
>   3.1.1   4.4453  4.3731     12.4834  13.5001
>
>   You do seem to have a slight py3 improvement
>   under ubuntu for the  forloop_offset  case ....

Yes, that's correct. The forloop_offset one is using long integers in
all cases. (Well, on Py2 it's adding a series of ints to a long, but
the arithmetic always has to be done with longs.) Python 3 has had
some improvements done, but the main thing is that there's a massive
spike in the Py2 time, while Py3 has _already paid_ that cost - as
evidenced by the closeness of the forloop and forloop_offset times on
Py3.

ChrisA