[issue18771] Reduce the cost of hash collisions for set objects
Raymond Hettinger
report at bugs.python.org
Sun Aug 18 18:54:55 CEST 2013
Raymond Hettinger added the comment:
> Instead of only a second lookup, could you try for example 4 lookup
> and align j to fit in a cache line?
Accessing 4 entries per probe is a tempting line of development, but will be subject to diminishing returns (second and third collisions aren't frequent).
I like the idea of aligning j to fit in a cache line, but the computation would need to be cheap and portable (standard C with no pointer tricks that rely on non-guaranteed behavior).
Have you had a chance to run the benchmarks on your machine? I'm curious how this works out on other processors and with other compilers.
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