[erlang-bugs] Erlang 18.0-rc1 is behaving slower than 17.4 (and 17.5)

[José Valim]

>
> This is most likely due to multiple timer wheels in 18. We now have one
> wheel per scheduler and a larger wheel to boot. I'm unsure to why it is so
> large though. Rickard? TIW 16x larger?
>
> You can see the size vary with +S <n> switch.
>

Yup, it is the due to the timer wheel. +S 1 reduces it. I believe Lukas
mentioned it would take around 1 word MB per scheduler.

It is likely this higher memory usage is going to cause confusion for folks
jumping into Erlang 18.0 if we don't provide proper disclaimers, even more
for those in the embedded space as I often hear the memory footprint to be
one of Erlang VM benefits.

Maybe one solution is to ship with smaller wheels but allow the size to be
configurable?
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