[erlang-questions] VM not able to use available cores
Sun Jan 20 06:32:45 CET 2008
On a somewhat random lark, I decided to fire up the "big.erl"
exerciser on a new box (8 cores, Xeon, Mac OS 10.5, R12B) that
replaced an old box (4 cores, PPC G5, Mac OS 10.4, R11B), and the
initial returns were surprising -- the 8-core box exhibited more or
less equivalent performance to the 4-core... (Pretty graphs, links to
big.erl source I used, etc., are here - http://mult.ifario.us/p/use-the-cores-erl
A little more digging, and it turned out that the VM was only able to
use the equivalent of 3 cores worth of CPU cycles, no matter how many
schedulers I ran from the command line. Two VMs does a reasonable job
of using all 8 cores worth of cycles, but I'm left with the question
of why a single VM couldn't use more cores.
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