Pystone uses floats

[regebro]

BPO	21634
Nosy	@vstinner, @regebro
Files	pystone.diff pystone12.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2014-06-02.12:19:38.018>
created_at = <Date 2014-06-02.09:27:08.544>
labels = ['performance']
title = 'Pystone uses floats'
updated_at = <Date 2014-06-02.12:31:53.513>
user = 'https://github.com/regebro'

bugs.python.org fields:

activity = <Date 2014-06-02.12:31:53.513>
actor = 'lregebro'
assignee = 'none'
closed = True
closed_date = <Date 2014-06-02.12:19:38.018>
closer = 'vstinner'
components = ['Benchmarks']
creation = <Date 2014-06-02.09:27:08.544>
creator = 'lregebro'
dependencies = []
files = ['35442', '35443']
hgrepos = []
issue_num = 21634
keywords = ['patch']
message_count = 8.0
messages = ['219559', '219560', '219563', '219570', '219571', '219573', '219574', '219577']
nosy_count = 3.0
nosy_names = ['vstinner', 'lregebro', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue21634'
versions = ['Python 3.4', 'Python 3.5']

[regebro]

Pystone uses some floats in Python 3, while in Python 2 it's all integers. And since it is, as far as I can tell, based on Dhrystone, it should be all ints.

After fixing the division in the loop to be a floor division it runs the same as in Python 2. I've verified that after the attached fix the only floats created are time stamps, so this seems to be all that's needed.

This also makes the benchmark run c:a 5% faster, lessening the speed difference in pystone between Python 2 and Python 3, which contributes to the misconception that Python 3 is horribly slow.

[vstinner]

According to the name of variables ("IntLoc2 = IntLoc3 // IntLoc1"), I agree that integers should be used. Since the performances can be different between int and float, you should change the version and explain your change in the changelog (in the top docstring).

[regebro]

Yes, good point, I added this in a new diff.

[vstinner]

+ Unde Python 3 version 1.1 would use the normal division

I guess that it's a typo: "Under Python 3 ..."?

[regebro]

Oups, yes, that's a typo.

[python-dev]

New changeset 1318324aa93a by Victor Stinner in branch '3.4':
Issue bpo-21634: Fix pystone micro-benchmark: use floor division instead of true
http://hg.python.org/cpython/rev/1318324aa93a

New changeset 95b7acdc0f24 by Victor Stinner in branch 'default':
(Merge 3.4) Issue bpo-21634: Fix pystone micro-benchmark: use floor division
http://hg.python.org/cpython/rev/95b7acdc0f24

[vstinner]

Thanks the patch, I fixed pystone in Python 3.4 and 3.5.

[regebro]

Awesome, thanks!