[hcoop/debian/mlton.git] / doc / guide / src / MLtonRusage.adoc

MLtonRusage
===========

[source,sml]
----
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
<:RunTimeOptions: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).
Commit	Line	Data
7f918cf1 CE	1	MLtonRusage
	2	===========
	3
	4	[source,sml]
	5	----
	6	signature MLTON_RUSAGE =
	7	sig
	8	type t = {utime: Time.time, (* user time *)
	9	stime: Time.time} (* system time *)
	10
	11	val measureGC: bool -> unit
	12	val rusage: unit -> {children: t, gc: t, self: t}
	13	end
	14	----
	15
	16	* `type t`
	17	+
	18	corresponds to a subset of the C `struct rusage`.
	19
	20	* `measureGC b`
	21	+
	22	controls whether garbage collection time is separately measured during
	23	program execution. This affects the behavior of both `rusage` and
	24	`Timer.checkCPUTimes`, both of which will return gc times of zero with
	25	`measureGC false`. Garbage collection time is always measured when
	26	either `gc-messages` or `gc-summary` is given as a
	27	<:RunTimeOptions:runtime system option>.
	28
	29	* `rusage ()`
	30	+
	31	corresponds to the C `getrusage` function. It returns the resource
	32	usage of the exited children, the garbage collector, and the process
	33	itself. The `self` component includes the usage of the `gc`
	34	component, regardless of whether `measureGC` is `true` or `false`. If
	35	`rusage` is used in a program, either directly, or indirectly via the
	36	`Timer` structure, then `measureGC true` is automatically called at
	37	the start of the program (it can still be disable by user code later).