[Python-Dev] Tunable parameters in dictobject.c (was dictnotes.txt out of date?)

[Maciej Fijalkowski]

On Mon, Jun 18, 2012 at 5:04 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:

> 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.
>
>
More like 200-500 CPU cycles on modern CPUs.
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