[erlang-questions] Tilera 64-core chip - let's help them help us!

Matthias Lang <>
Tue Sep 11 09:36:52 CEST 2007


Hugh Perkins writes:

 > Yes, exactly: you need to calculate the number of available cores for
 > the algorithm to be efficient, so the program is not independent of
 > the number of cores.

Which is a problem because...? (Sean already pointed out that having a
loose upper bound on the number of cores is sufficient.)

 > Automatic threading really ought to be dynamic, 

Erlang automatically distributes Erlang processes across OS
threads. That's uncontroversial in a language which isn't attempting
hard real time. But you seem to want more things hidden.

 > Going back to my earlier question ;-), I get the impression that
 > Erlang runs in a VM?

Correct.

 > What documentation is available on how this works?  

Very little, apart from full source code. Everything I know of is
collected in the FAQ, here:

  http://www.erlang.org/faq/faq.html#AEN271

Historically, few people have been brave enough to modify the VM.

 > And, the ten thousand dollar question: to what extent could it be
 > feasible to modify the VM to automatically split maps across available
 > processor cores?

The million dollar question is "is the VM the right place to do
this". And the billion dollar question is "can you come up with an
automatic way of doing it which is significantly better than Sean's
approach---which has the great virtue of being simple"? 

Matthias



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