Erlang Scheduler Utilization

scheduler_utilization.ex

¯\_(ツ)_/¯ iex  -S mix
Erlang/OTP 22 [erts-10.4.4] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Interactive Elixir (1.9.1) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> :scheduler.sample() |> :scheduler.utilization()
[
  {:total, 0.081145584725537, '8.1%'},
  {:normal, 1, 0.057692307692307696, '5.8%'},
  {:normal, 2, 0.06521739130434782, '6.5%'},
  {:normal, 3, 0.34545454545454546, '34.5%'},
  {:normal, 4, 0.19148936170212766, '19.1%'},
  {:cpu, 5, 0.0, '0.0%'},
  {:cpu, 6, 0.0, '0.0%'},
  {:cpu, 7, 0.0, '0.0%'},
  {:cpu, 8, 0.0, '0.0%'}
]
iex(2)> doing_work = fn() -> Enum.reduce(1..10_000_000, 1, fn(x, acc) -> x + acc end) end
#Function<21.91303403/0 in :erl_eval.expr/5>
iex(3)> tasks = Enum.map(1..2, fn(_) -> Task.async(doing_work) end)
[
  %Task{
    owner: #PID<0.417.0>,
    pid: #PID<0.423.0>,
    ref: #Reference<0.1046173346.4011851779.128377>
  },
  %Task{
    owner: #PID<0.417.0>,
    pid: #PID<0.424.0>,
    ref: #Reference<0.1046173346.4011851779.128378>
  }
]
iex(4)> :scheduler.sample() |> :scheduler.utilization()
[
  {:total, 0.381139489194499, '38.1%'},
  {:normal, 1, 1.0, '100.0%'},
  {:normal, 2, 1.0, '100.0%'},
  {:normal, 3, 1.0, '100.0%'},
  {:normal, 4, 0.023255813953488372, '2.3%'},
  {:cpu, 5, 0.0, '0.0%'},
  {:cpu, 6, 0.0, '0.0%'},
  {:cpu, 7, 0.0, '0.0%'},
  {:cpu, 8, 0.0, '0.0%'}
]