[Python-Dev] Tunable parameters in dictobject.c (was dictnotes.txt out of date?) (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Mon Jun 18 17:04:10 CEST 2012

On Mon, 18 Jun 2012 15:28:24 +0100 Mark Shannon <mark at hotpy.org> wrote:

But do they? The results of benchmarking would seem to suggest (at least on my test machine) that overly-sparse dicts are slower. Possibly due to increased cache misses.

Or, at least, they are not faster. See the synthetic experiments in http://bugs.python.org/issue10408

That said, Raymond might have witnessed different results at the time. Hardware evolves quickly and the parameters change (memory latency today is at least 50+ CPU cycles, which is quite a lot of wasted work on a pipelined superscalar CPU).

Regards

Antoine.

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