1msのtimerをビジーループで実現

busytimer_test.erl

-module(busytimer_test).

-export([test/2]).

-define(MICROSECONDS, 1000000).

test(Wait, Count) ->
    Begin = erlang:timestamp(),
    busywait_repeat(Wait, Count),
    End = erlang:timestamp(),
    DiffUsec = timer:now_diff(End, Begin),
    DiffSec = DiffUsec / 1000 / 1000,
    io:format("~p counts in ~p sec, ~p count/sec~n", [Count, DiffSec, Count/DiffSec]).

busywait_repeat(_Wait, 0) ->
    ok;
busywait_repeat(Wait, N) ->
    busywait(Wait),
    busywait_repeat(Wait, N-1).

busywait(Wait) ->
    Finish = erlang:monotonic_time(?MICROSECONDS) + Wait*1000,
    busywait_until(Finish).

busywait_until(Finish) ->
    Now = erlang:monotonic_time(?MICROSECONDS),
    if Now >= Finish -> ok;
       true -> busywait_until(Finish)
    end.

erl上で以下を実行:

1> c(busytimer_test).
{ok,busytimer_test}
2> busytimer_test:test(1,1000).
1000 counts in 1.003644 sec, 996.3692305239707 count/sec
ok

だいたい秒間1000回になっている。