Erlang ring benchmark

ring.erl

-module(ring).
-export([start/2]).

%% Write a ring benchmark. Create N processes in a ring. Send a message round
%% the ring M times so that a total of N * M messages get sent. Time how long
%% this takes for different values of N and M.

start(M, N) ->
    [P|_] = create_ring(N),
    T1 = erlang:monotonic_time(microsecond),
    P ! {self(), M * N},
    receive
        T2 -> io:format("μs elapsed: ~p~n", [T2 - T1])
    end.

create_ring(N) ->
    [P|Ps] = Ring = [spawn(?MODULE, loop, [none]) || _ <- lists:seq(1, N)],
    lists:foreach(fun({Current, Next}) -> Current ! {next, Next} end,
                  lists:zip(Ring, lists:append(Ps, [P]))),
    Ring.

loop(Next) ->
    receive
        {next, New} -> loop(New);
        {Init, 0} ->
            Init ! erlang:monotonic_time(microsecond),
            Next ! stop;
        {Init, N} ->
            Next ! {Init, N-1},
            loop(Next);
        stop -> Next ! stop
    end.