[Python-Dev] Tuning Python dicts

[Antoine Pitrou]

Reid Kleckner <rnk <at> mit.edu> writes:
> 
> I think you're right about the number of collisions, though.  CPython
> dicts use a pretty low load factor (2/3) to keep collision counts
> down.  One of the major benefits cited in the paper is the ability to
> maintain performance in the face of higher load factors, so I may be
> able to bump up the load factor to save memory.  This would increase
> collisions, but then that wouldn't matter, because resolving them
> would only require looking within two consecutive cache lines.

Why wouldn't it matter? Hash collisions still involve more CPU work, even though
if you're not access memory a lot.


Antoine.