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Improving detail of design.mps.bootstrap.land.sol and cross-referencing from source code.

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Richard Brooksby 2016-02-25 23:43:50 +00:00
parent b26e5cc27d
commit 2de01f7d2d
3 changed files with 26 additions and 11 deletions
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4
mps/code/arena.c
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@ -758,7 +758,7 @@ void ArenaChunkRemoved(Arena arena, Chunk chunk)
* This is a primitive allocator used to allocate pages for the arena
* Land. It is called rarely and can use a simple search. It may not
* use the Land or any pool, because it is used as part of the
* bootstrap.
* bootstrap. See design.mps.bootstrap.land.sol.alloc.
*/
static Res arenaAllocPageInChunk(Addr *baseReturn, Chunk chunk, Pool pool)
@ -866,7 +866,7 @@ static void arenaExcludePage(Arena arena, Range pageRange)
* The arena's free land can't get memory for its block pool in the
* usual way (via ArenaAlloc), because it is the mechanism behind
* ArenaAlloc! So we extend the block pool via a back door (see
* arenaExtendCBSBlockPool).
* arenaExtendCBSBlockPool). See design.mps.bootstrap.land.sol.pool.
*
* Only fails if it can't get a page for the block pool.
*/

3
mps/code/poolmfs.c
View file

@ -249,7 +249,8 @@ static Res MFSAlloc(Addr *pReturn, Pool pool, Size size,
if(f == NULL)
{
Addr base;
/* See design.mps.bootstrap.land.sol.pool. */
if (!mfs->extendSelf)
return ResLIMIT;

30
mps/design/bootstrap.txt
View file

@ -67,13 +67,23 @@ Arena's free land
_`.land`: Before the arena can allocate memory, a range of addresses
must be inserted into the arena's free land (so that the free land can
hand out memory from this range). But before addresses can be inserted
into the arena's free land, the arena must be able to allocate memory
(to store the nodes in the tree representing those addresses).
into the arena's free land, the free land's block pool must have
memory from the arena to store the nodes in the tree representing
those addresses.
_`.land.sol`: The arena has two "back door" mechanisms and uses them
in combination. First, there is a mechanism for allocating a block of
memory directly from a chunk, bypassing the free land; second, the MFS
pool class has a mechanism for extending it with a block of memory.
in combination.
_`.land.sol.alloc`: First, there is a mechanism for allocating a
page of memory directly from a chunk, bypassing the free land.
_`.land.sol.pool`: Second, the free land's block pool has an option to
prevent it extending itself by allocating memory from the arena.
Instead, it fails allocations with ``ResLIMIT``. The free land's
block pool also has a mechanism, ``MFSExtend`` to extend it with a
block of memory. When the free land fails with ``ResLIMIT`` the arena
uses `.land.sol.alloc`_ to provide it with memory.
Document History
@ -81,15 +91,19 @@ Document History
- 2015-09-01 GDR_ Initial draft.
- 2016-02-25 RB_ Improving description of arena free land bootstrap
and cross-referencing from source code.
.. _GDR: http://www.ravenbrook.com/consultants/gdr/
.. _RB: http://www.ravenbrook.com/consultants/rb/
Copyright and License
---------------------
Copyright © 2015 Ravenbrook Limited. All rights reserved.
<http://www.ravenbrook.com/>. This is an open source license. Contact
Ravenbrook for commercial licensing options.
Copyright © 2015-2016 Ravenbrook Limited
<http://www.ravenbrook.com/>. All rights reserved. This is an open
source license. Contact Ravenbrook for commercial licensing options.
Redistribution and use in source and binary forms, with or without
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