schedstat.erl

-module(schedstat).
-export([run/0,run/1]).

run() ->
    run(1000).

run(Samples) ->
    spawn(fun() ->
                  erlang:trace(all, true, [running,scheduler_id]),
                  Tid = ets:new(?MODULE, [private]),
                  [ets:insert(Tid, {S, 0}) || S <- lists:seq(1, erlang:system_info(schedulers))],
                  loop(Tid, Samples)
          end).


loop(Tid, 0) ->
    io:format("=== in scheduler count===\n~p\n", [lists:sort(ets:tab2list(Tid))]);
loop(Tid, Times) ->
    receive
        {trace,_Pid,in,Sched,_MFArity} ->
            ets:update_counter(Tid, Sched, {2, 1}),
            loop(Tid, Times - 1);
        _ ->
            loop(Tid, Times - 1)
    after
        5000 ->
            loop(Tid, 0)
    end.