[erlang-questions] Strange observation running in an SMP environment.

Jesper Louis Andersen <>
Wed Jun 13 11:12:26 CEST 2012

On Tue Jun 12 22:39:02 2012, Ronny Meeus wrote:

> Does the issue that I had (pure message passing without extra load)
> have anything to do with the fact that I'm running on Linux?
> I sometimes have the impression (not in the context of my Erlang
> playing) that the scheduler does not always makes the right decision
> during the migration of processes between cores?

No, it has not. I ran your examples on an Apple OSX 10.7.4,

tiefling:~ jlouis$ uname -a
Darwin tiefling.issuu.com 11.4.0 Darwin Kernel Version 11.4.0: Mon Apr  
9 19:32:15 PDT 2012; root:xnu-1699.26.8~1/RELEASE_X86_64 x86_64

and I got roughly the same results as yours. The problem is that really 
good parallelism speedup requires you to do very specific things upon 
your data in order to achieve that parallel speedup. Erlang is built 
for concurrency more than parallelism - if you want that I'd suggest 
looking into Haskell :)

Jesper Louis Andersen
  Erlang Solutions Ltd., Copenhagen, DK

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