[Python-Dev] Dictionary tuning

[Raymond Hettinger]

[Timbot]
> FYI, for years the dict code had some #ifdef'ed preprocessor gimmick to
> force cache alignment.  I ripped that out a while back because nobody ever
> reported an improvement when using it.

Gee, you mean we're not the first ones to have ever 
thought up dictionary optimizations that didn't pan out?

I've tried square wheels, pentagonal wheels, and gotten
even better results with octagonal wheels.  Each further 
subdivision seems to have less-and-less payoff
so I'm confident that octagonal is close to optimum ;-)

I'm going to write-up an informational PEP to summarize the
results of research to-date.  After the first draft, I'm sure the
other experimenters will each have lessons to share.  In
addition, I'll attach a benchmarking suite and dictionary
simulator (fully instrumented).  That way, future generations
can reproduce the results and pickup where we left-off.  

I've decided that this new process should have a name, 
something pithy, yet magical sounding, so it shall be 
dubbed SCIENCE.


Raymond Hettinger