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Default value for mps_key_arena_size makes it easier to create arenas.

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This commit is contained in:
Gareth Rees 2014-04-11 21:15:09 +01:00
parent 2f50660fcf
commit 2ef0e22c55
3 changed files with 21 additions and 18 deletions
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6
mps/code/arenavm.c
View file

@ -480,7 +480,7 @@ ARG_DEFINE_KEY(arena_contracted, Fun);
static Res VMArenaInit(Arena *arenaReturn, ArenaClass class, ArgList args)
{
Size userSize; /* size requested by user */
Size userSize = VM_ARENA_SIZE_DEFAULT; /* size requested by user */
Size chunkSize; /* size actually created */
Size vmArenaSize; /* aligned size of VMArenaStruct */
Res res;
@ -495,8 +495,8 @@ static Res VMArenaInit(Arena *arenaReturn, ArenaClass class, ArgList args)
AVER(class == VMArenaClassGet());
AVERT(ArgList, args);
ArgRequire(&arg, args, MPS_KEY_ARENA_SIZE);
userSize = arg.val.size;
if (ArgPick(&arg, args, MPS_KEY_ARENA_SIZE))
userSize = arg.val.size;
AVER(userSize > 0);

2
mps/code/config.h
View file

@ -366,6 +366,8 @@
pool to be very heavily used. */
#define CONTROL_EXTEND_BY 4096
#define VM_ARENA_SIZE_DEFAULT ((Size)1 << 20)
/* Stack configuration */

31
mps/manual/source/topic/arena.rst
View file

@ -233,18 +233,18 @@ Virtual memory arenas
more efficient.
When creating a virtual memory arena, :c:func:`mps_arena_create_k`
requires one :term:`keyword argument`:
accepts one :term:`keyword argument` on all platforms:
* :c:macro:`MPS_KEY_ARENA_SIZE` (type :c:type:`size_t`). is the
initial amount of virtual address space, in :term:`bytes (1)`,
that the arena will reserve (this space is initially reserved so
that the arena can subsequently use it without interference from
other parts of the program, but most of it is not committed, so
it doesn't require any RAM or backing store). The arena may
allocate more virtual address space beyond this initial
reservation as and when it deems it necessary. The MPS is most
efficient if you reserve an address space that is several times
larger than your peak memory usage.
* :c:macro:`MPS_KEY_ARENA_SIZE` (type :c:type:`size_t`, default
2\ :superscript:`20`) is the initial amount of virtual address
space, in :term:`bytes (1)`, that the arena will reserve (this
space is initially reserved so that the arena can subsequently
use it without interference from other parts of the program, but
most of it is not committed, so it doesn't require any RAM or
backing store). The arena may allocate more virtual address
space beyond this initial reservation as and when it deems it
necessary. The MPS is most efficient if you reserve an address
space that is several times larger than your peak memory usage.
.. note::
@ -252,8 +252,8 @@ Virtual memory arenas
more times it has to extend its address space, the less
efficient garbage collection will become.
An optional :term:`keyword argument` may be passed, but is
only used on the Windows operating system:
A second optional :term:`keyword argument` may be passed, but it
only has any effect on the Windows operating system:
* :c:macro:`MPS_KEY_VMW3_TOP_DOWN` (type :c:type:`mps_bool_t`). If
true, the arena will allocate address space starting at the
@ -273,8 +273,9 @@ Virtual memory arenas
If the MPS fails to allocate memory for the internal arena
structures, :c:func:`mps_arena_create_k` returns
:c:macro:`MPS_RES_MEMORY`. Either ``size`` was far too small or
the operating system refused to provide enough memory.
:c:macro:`MPS_RES_MEMORY`. Either :c:macro:`MPS_KEY_ARENA_SIZE`
was far too small or the operating system refused to provide
enough memory.
For example::