signature MLTON_RUSAGE =
   sig
      type t = {utime: Time.time, (* user time *)
                stime: Time.time} (* system time *)

      val measureGC: bool -> unit         
      val rusage: unit -> {children: t, gc: t, self: t}
   end

• type t
  corresponds to a subset of the C struct rusage.

• measureGC b
  controls whether garbage collection time is separately measured during program execution. This affects the behavior of both rusage and Timer.checkCPUTimes, both of which will return gc times of zero with measureGC false. Garbage collection time is always measured when either gc-messages or gc-summary is given as a runtime system option.

• rusage ()
  corresponds to the C getrusage function. It returns the resource usage of the exited children, the garbage collector, and the process itself. The self component includes the usage of the gc component, regardless of whether measureGC is true or false. If rusage is used in a program, either directly, or indirectly via the Timer structure, then measureGC true is automatically called at the start of the program (it can still be disable by user code later).