[New-bugs-announce] [issue4128] Performance regression in long division in 2.6

[Fredrik Johansson]

New submission from Fredrik Johansson <fredrik.johansson at gmail.com>:

On my laptop (Windows XP, 32-bit), long division is about 15% slower in
2.6 compared to 2.5. See the attached .txt for timings.

I noticed this when comparing the unit tests for mpmath
(http://code.google.com/p/mpmath/) under 2.5 and 2.6. It appears that
most tests run 10-20% faster under 2.6 (good work all Python
developers!), but the tests performing very high precision arithmetic
run noticeably slower.

>From some quick benchmarking, addition and multiplication are not the
culprits (they both actually seem to be quite a bit faster in 2.6). 

There could be other factors involved, but from what I've found out so
far, it is only division that has become slower in 2.6.

Division in Python 2.4 is also the same speed as 2.5.

----------
components: Interpreter Core
files: division_speed.txt
messages: 74798
nosy: fredrikj
severity: normal
status: open
title: Performance regression in long division in 2.6
versions: Python 2.6
Added file: http://bugs.python.org/file11804/division_speed.txt

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<http://bugs.python.org/issue4128>
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