[Speed] External sources of noise changing call_simple "performance"

[Victor Stinner]

2016-05-30 10:14 GMT+02:00 Antoine Pitrou <solipsis at pitrou.net>:
>> I'm still (!) investigating the reasons why the benchmark call_simple
>> (ok, let's be honest: the *micro*benchmark) gets different results for
>> unknown reasons.
>
> Try to define MCACHE_STATS in Objects/typeobject.c and observe the
> statistics from run to run. It might give some hints.

call_simple only uses regular functions, not methods, so the type
cache should not have any effect on it. No?

I already noticed that the exact layout of items in globals() dict
matters. Depending on the PYTHONHASHSEED, you get or not hash
collision, the effect is visible on such microbenchmark.

Victor