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

Sean Hinde <>
Fri Sep 7 10:39:15 CEST 2007


On 6 Sep 2007, at 23:51, Hugh Perkins wrote:

> On 9/7/07, Sean Hinde <> wrote:
>> You don't need to care about how many cores you have to make a
>> parallel map function in erlang, you only need to care about cores
>> when you start the emulator.
>>
>
> Well... this will spawn a process for every item in the map.  How
> efficient would that be if there are, say, 10 million elements in the
> map and only 64 processor cores?

If your problem domain really produces Erlang lists with 10 million  
elements, and you want to run a map, you could sensibly change the  
algorithm to manage pool of erlang processes and handle the list in  
chunks. Mostly so you don't run out of memory.

In a more realistic case, with say 1000 elements in the list there is  
no significant penalty to spawning 1000 erlang processes over 64  
cores instead of 64 erlang processes. The erlang scheduler will  
distribute the load among its pool of OS threads.

It might actually be more efficient, because the VM will have a  
chance to spread more load to CPUs (OS threads) that are less busy.

Sean



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