[Python-Dev] Slowdown in Python CVS

[M.-A. Lemburg]

Raymond Hettinger wrote:
>>>My nightly run of pybench went up from the usual 7590ms per
>>>run to around 8200ms between Monday night and today. Can anyone
>>>explain this ?
>>
>>Did you compare the outputs?  There could be importants hint there!
>>:-)
>>
>>Maybe this checkin to ceval.c backfired?
>>
>>----------------------------
>>revision 2.351
>>date: 2003/02/26 18:11:50;  author: rhettinger;  state: Exp;  lines: +18 -4
>>Micro-optimizations.
>>* List/Tuple checkexact is faster for the common case.
>>* Testing for Py_True and Py_False can be inlined for faster looping.
>>----------------------------
> 
> 
> That would be a bummer.  It looked like a pure win.
> 
> I timed the changes with PyStone with N=200000 and got:
> Base Code:      12.379   12.2716   12.2716
> + CheckExact: 12.2746  12.2278   12.3165
> + T/F inlined:  12.108    12.1697   12.1259
> 
> Since PyStone does weird things to booleans and uses
> "while 1", I ran a separate test on "while 1" vs. "while True"
> showed a speedup of "while True" and no measurable
> change to "while 1".
> 
> If your timings show a different result, let me know and
> I'll back it out.

Ok, I reran the tests using the CVS time machine and the results
indicate that this was a false alarm. I am not exactly sure
what is causing it though: both figures for the Monday checkout
and todays checkout hover around 8200ms per run on average,
while most historical figures from last month are in the
7590-7950ms range.

Oh, BTW, your patch does not result in any significant
change in pybench results.

Nevermind,
-- 
Marc-Andre Lemburg
eGenix.com

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