133 lines
6.5 KiB
OCaml
133 lines
6.5 KiB
OCaml
(***********************************************************************)
|
|
(* *)
|
|
(* Objective Caml *)
|
|
(* *)
|
|
(* Damien Doligez, projet Para, INRIA Rocquencourt *)
|
|
(* *)
|
|
(* Copyright 1996 Institut National de Recherche en Informatique et *)
|
|
(* en Automatique. All rights reserved. This file is distributed *)
|
|
(* under the terms of the GNU Library General Public License. *)
|
|
(* *)
|
|
(***********************************************************************)
|
|
|
|
(* $Id$ *)
|
|
|
|
(* Module [Gc]: memory management control and statistics *)
|
|
|
|
type stat = {
|
|
minor_words : int;
|
|
promoted_words : int;
|
|
major_words : int;
|
|
minor_collections : int;
|
|
major_collections : int;
|
|
heap_words : int;
|
|
heap_chunks : int;
|
|
live_words : int;
|
|
live_blocks : int;
|
|
free_words : int;
|
|
free_blocks : int;
|
|
largest_free : int;
|
|
fragments : int;
|
|
compactions : int
|
|
}
|
|
(* The memory management counters are returned in a [stat] record.
|
|
The fields of this record are:
|
|
- [minor_words] Number of words allocated in the minor heap since
|
|
the program was started.
|
|
- [promoted_words] Number of words allocated in the minor heap that
|
|
survived a minor collection and were moved to the major heap
|
|
since the program was started.
|
|
- [major_words] Number of words allocated in the major heap, including
|
|
the promoted words, since the program was started.
|
|
- [minor_collections] Number of minor collections since the program
|
|
was started.
|
|
- [major_collections] Number of major collection cycles, not counting
|
|
the current cycle, since the program was started.
|
|
- [heap_words] Total number of words in the major heap.
|
|
- [heap_chunks] Number of times the major heap size was increased
|
|
since the program was started.
|
|
- [live_words] Number of words of live data in the major heap, including
|
|
the header words.
|
|
- [live_blocks] Number of live objects in the major heap.
|
|
- [free_words] Number of words in the free list.
|
|
- [free_blocks] Number of objects in the free list.
|
|
- [largest_free] Size (in words) of the largest object in the free list.
|
|
- [fragments] Number of wasted words due to fragmentation. These are
|
|
1-words free blocks placed between two live objects. They
|
|
cannot be inserted in the free list, thus they are not available
|
|
for allocation.
|
|
- [compactions] Number of heap compactions since the program was started.
|
|
|
|
The total amount of memory allocated by the program since it was started
|
|
is (in words) [minor_words + major_words - promoted_words]. Multiply by
|
|
the word size (4 on a 32-bit machine, 8 on a 64-bit machine) to get
|
|
the number of bytes.
|
|
*)
|
|
|
|
type control = {
|
|
mutable minor_heap_size : int;
|
|
mutable major_heap_increment : int;
|
|
mutable space_overhead : int;
|
|
mutable verbose : int;
|
|
mutable max_overhead : int;
|
|
mutable stack_limit : int
|
|
}
|
|
|
|
(* The GC parameters are given as a [control] record. The fields are:
|
|
- [minor_heap_size] The size (in words) of the minor heap. Changing
|
|
this parameter will trigger a minor collection. Default: 32k.
|
|
- [major_heap_increment] The minimum number of words to add to the
|
|
major heap when increasing it. Default: 62k.
|
|
- [space_overhead] The major GC speed is computed from this parameter.
|
|
This is the memory that will be "wasted" because the GC does not
|
|
immediatly collect unreachable objects. It is expressed as a
|
|
percentage of the memory used for live data.
|
|
The GC will work more (use more CPU time and collect
|
|
objects more eagerly) if [space_overhead] is smaller.
|
|
The computation of the GC speed assumes that the amount
|
|
of live data is constant. Default: 42.
|
|
- [max_overhead] Heap compaction is triggered when the estimated amount
|
|
of free memory is more than [max_overhead] percent of the amount
|
|
of live data. If [max_overhead] is set to 0, heap
|
|
compaction is triggered at the end of each major GC cycle
|
|
(this setting is intended for testing purposes only).
|
|
If [max_overhead >= 1000000], compaction is never triggered.
|
|
Default: 1000000.
|
|
- [verbose] This value controls the GC messages on standard error output.
|
|
It is a sum of some of the following flags, to print messages
|
|
on the corresponding events:
|
|
- [1 ] Start of major GC cycle.
|
|
- [2 ] Minor collection and major GC slice.
|
|
- [4 ] Growing and shrinking of the heap.
|
|
- [8 ] Resizing of stacks and memory manager tables.
|
|
- [16] Heap compaction.
|
|
- [32] Change of GC parameters.
|
|
- [64] Computation of major GC slice size.
|
|
Default: 0.
|
|
- [stack_limit] The maximum size of the stack (in words). This is only
|
|
relevant to the byte-code runtime, as the native code runtime
|
|
uses the operating system's stack. Default: 256k.
|
|
*)
|
|
|
|
external stat : unit -> stat = "gc_stat"
|
|
(* Return the current values of the memory management counters in a
|
|
[stat] record. *)
|
|
val print_stat : out_channel -> unit
|
|
(* Print the current values of the memory management counters (in
|
|
human-readable form) into the channel argument. *)
|
|
external get : unit -> control = "gc_get"
|
|
(* Return the current values of the GC parameters in a [control] record. *)
|
|
external set : control -> unit = "gc_set"
|
|
(* [set r] changes the GC parameters according to the [control] record [r].
|
|
The normal usage is: [ Gc.set { (Gc.get()) with Gc.verbose = 13 } ]. *)
|
|
external minor : unit -> unit = "gc_minor"
|
|
(* Trigger a minor collection. *)
|
|
external major : unit -> unit = "gc_major"
|
|
(* Finish the current major collection cycle. *)
|
|
external full_major : unit -> unit = "gc_full_major"
|
|
(* Finish the current major collection cycle and perform a complete
|
|
new cycle. This will collect all currently unreachable objects. *)
|
|
external compact : unit -> unit = "gc_compaction";;
|
|
(* Perform a full major collection and compact the heap. Note that heap
|
|
compaction is a lengthy operation. *)
|