[erlang-questions] SMP for IO-bound applications

Scott Lystig Fritchie <>
Mon Jul 2 14:39:43 CEST 2012


>>> Erisa Dervishi <> wrote:

ed> As part of my studies, I have recently been doing some performance
ed> evaluations on Erlang SMP improvements  for IO-bound applications.
ed> [...]
ed> The tests I run have these parameters:

Hi, Erisa.  Sorry to jump into this email thread so late.  I didn't
see any mention of a couple of parameters in your summary, so I'm
wondering if you've used or studied the effect of these "erl" command
line flags:

	+A n (where N is an integer > 0)
	+K true

The first flag tells the VM to use the asynchronous I/O thread pool
for local disk I/O.  The second uses a different socket ready/activity
mechanism rather than the old-and-frequently-slower select(2) system
call.  (See http://www.erlang.org/doc/man/erl.html for summary.)

-Scott



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