[Python-Dev] memcmp performance (original) (raw)

Stefan Behnel stefan_ml at behnel.de
Fri Oct 21 08:24:44 CEST 2011

Antoine Pitrou, 20.10.2011 23:08:

I have been doing some performance experiments with memcmp, and I was surprised that memcmp wasn't faster than it was in Python. I did a whole, long analysis and came up with some very simple results. Thanks for the analysis. Non-bugfix work now happens on Python 3, where the str type is Python 2's unicode type. Your recommendations would have to be revisited under that light.

Well, Py3 is quite a bit different now that PEP393 is in. It appears to use memcmp() or strcmp() a lot less than before, but I think unicode_compare() should actually receive an optimisation to use a fast memcmp() if both string kinds are equal, at least when their character unit size is less than 4 (i.e. especially for ASCII strings). Funny enough, tailmatch() has such an optimisation.

Stefan

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