[Python-Dev] insertdict slower?

[Tim Peters]

[MAL]
> It doesn't have anything to do with icache conflicts or
> other esoteric magic at dye-level. The reason for the slowdown
> is that the benchmark uses integers as keys and these have to
> go through the whole rich compare machinery to find their way into
> the dictionary.

But insertdict doesn't do any compares at all (besides C pointer comparison
to NULL).  There's more than one mystery here.  The one I was addressing is
why the profiler said *insertdict* got slower.  Jeremy's profile did not
give any reason to suspect that lookdict got slower (which is where the
compares are); to the contrary, it said lookdict got 4.5% *faster* in 2.1.

> Please see my other post on the subject -- I think we need
> an optimized API especially for checking for equality.

Quite possibly, but if Jeremy remains keen to help with investigating timing
puzzles, he needs to figure out why his profiling approach is pointing him
at the wrong functions.  That has long-term value far beyond patching the
regression du jour.

it's-not-either/or-it's-both-ly y'rs  -tim