[erlang-questions] My frustration with Erlang
Fri Sep 12 17:00:19 CEST 2008
Joel Reymont wrote:
> These are gen_server call timeouts when requests for game information
> take longer than the default 5 seconds. I have an average of 5 players
> per game so this is not because a large number of processes are trying
> to access the game.
> I suppose this is a reflection of the load on the system, although CPU
> usage never goes past 300% which tells me that no more than 3 cores
> are used by Erlang.
We have a system with a completely different workload profile, but our
initial testing has indicated a SMP scaling barrier, such that scaling
beyond 4 cores (on x86-64 linux 2.6.24 w/R12-3) deteriorate quickly.
My very preliminary in investigations indicated a substantial number of
futex system calls (which should happen only on contended locks which
need kernel arbitrartion) as the work scaled toward 4 cores. I had
initially thought that this was related to the amount of work we perform
in linked in drivers via async threads, but some more current
information indicates that this might be more core scheduler related.
Can anyone with experiences running a sufficiently complex system on 8+
core systems share your experiences? I would love to hear from someone
intimate with the SMP implementation on the state of affairs and
possible future directions.
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