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Added a slab allocator

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A slab-allocator can now be used as the back-end for all memory allocations by setting __slab_max_size to a value > 0. This controls the slab size used for allocations and should be a power of 2, such as 2048 or 4096 bytes.

This change still needs testing.
This commit is contained in:
Olaf Barthel
2016-11-17 11:45:59 +01:00
parent ac6d131dc3
commit 8051da3c9a
7 changed files with 566 additions and 22 deletions
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1
library/GNUmakefile.68k
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@ -368,6 +368,7 @@ C_LIB = \
stdlib_set_process_window.o \
stdlib_shell_escape.o \
stdlib_showerror.o \
stdlib_slab_max_size.o \
stdlib_srand.o \
stdlib_stacksize.o \
stdlib_stack_usage.o \

1
library/libc.gmk
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@ -255,6 +255,7 @@ C_LIB := \
stdlib_shared_objs.o \
stdlib_shell_escape.o \
stdlib_showerror.o \
stdlib_slab_max_size.o \
stdlib_srand.o \
stdlib_stacksize.o \
stdlib_stack_usage.o \

1
library/smakefile
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@ -546,6 +546,7 @@ STDLIB_OBJ = \
stdlib_set_process_window.o \
stdlib_shell_escape.o \
stdlib_showerror.o \
stdlib_slab_max_size.o \
stdlib_srand.o \
stdlib_arg.o \
stdlib_stack_usage.o \

103
library/stdlib_free.c
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@ -367,10 +367,111 @@ remove_and_free_memory_node(struct MemoryNode * mn)
}
#endif /* __MEM_DEBUG */
if(__memory_pool != NULL)
/* Are we using the slab allocator? */
if (__slab_data.sd_InUse)
{
assert( __slab_data.sd_MaxSlabSize > 0 );
/* Number of bytes to allocate exceeds the slab size?
* Then the chunk was allocated separately.
*/
if(allocation_size > __slab_data.sd_MaxSlabSize)
{
Remove((struct Node *)&mn[-1]);
__slab_data.sd_NumSingleAllocations--;
}
/* Otherwise the allocation should have come from a slab. */
else
{
struct MinList * slab_list = NULL;
size_t entry_size;
ULONG chunk_size;
int slab_index;
/* Chunks must be at least as small as a MinNode, because
* that's what we use for keeping track of the chunks which
* are available for allocation within each slab.
*/
entry_size = allocation_size;
if(entry_size < sizeof(struct MinNode))
entry_size = sizeof(struct MinNode);
/* Find a slab which keeps track of chunks that are no
* larger than the amount of memory which needs to be
* released. We end up picking the smallest chunk
* size that still works.
*/
for(slab_index = 0, chunk_size = (1UL << slab_index) ;
slab_index < 31 ;
slab_index++, chunk_size += chunk_size)
{
assert( (chunk_size % sizeof(LONG)) == 0);
if(entry_size <= chunk_size)
{
slab_list = &__slab_data.sd_Slabs[slab_index];
break;
}
}
/* Find the slab which contains the memory chunk. */
if(slab_list != NULL)
{
struct SlabNode * sn;
BYTE * first_byte;
BYTE * last_byte;
for(sn = (struct SlabNode *)slab_list->mlh_Head ;
sn->sn_MinNode.mln_Succ != NULL ;
sn = (struct SlabNode *)sn->sn_MinNode.mln_Succ)
{
assert( sn->sn_ChunkSize == chunk_size );
first_byte = (BYTE *)&sn[1];
last_byte = &first_byte[__slab_data.sd_MaxSlabSize - chunk_size];
/* Is this where the chunk belongs? */
if(first_byte <= (BYTE *)mn && (BYTE *)mn <= last_byte)
{
AddTail((struct List *)&sn->sn_FreeList, (struct Node *)mn);
assert( sn->sn_UseCount > 0 );
sn->sn_UseCount--;
/* If this slab is empty, mark it as unused and
* allow it to be purged.
*/
if(sn->sn_UseCount == 0)
{
AddTail((struct List *)&__slab_data.sd_EmptySlabs,(struct Node *)&sn->sn_EmptyLink);
sn->sn_EmptyDecay = 1;
}
/* This slab now has room. Move it to front of the list
* so that searching for a free chunk will pick it
* first.
*/
if(sn != (struct SlabNode *)slab_list->mlh_Head)
{
Remove((struct Node *)sn);
AddHead((struct List *)slab_list, (struct Node *)sn);
}
break;
}
}
}
}
}
else if (__memory_pool != NULL)
{
FreePooled(__memory_pool,mn,allocation_size);
}
else
{
FreeMem(mn,allocation_size);
}
__current_memory_allocated -= allocation_size;
__current_num_memory_chunks_allocated--;

349
library/stdlib_malloc.c
View File

@ -72,6 +72,47 @@ struct MinList NOCOMMON __memory_list;
/****************************************************************************/
struct SlabData NOCOMMON __slab_data;
/****************************************************************************/
/* Free all currently unused slabs, regardless of whether they
* are ready to be purged (SlabNode.sn_EmptyDecay == 0).
*/
void
__free_unused_slabs(void)
{
struct MinNode * free_node;
struct MinNode * free_node_next;
struct SlabNode * sn;
__memory_lock();
for(free_node = (struct MinNode *)__slab_data.sd_EmptySlabs.mlh_Head ;
free_node->mln_Succ != NULL ;
free_node = free_node_next)
{
free_node_next = (struct MinNode *)free_node->mln_Succ;
/* free_node points to SlabNode.sn_EmptyLink, which
* directly follows the SlabNode.sn_MinNode.
*/
sn = (struct SlabNode *)&free_node[-1];
/* Unlink from list of empty slabs. */
Remove((struct Node *)free_node);
/* Unlink from list of slabs of the same size. */
Remove((struct Node *)sn);
FreeVec(sn);
}
__memory_unlock();
}
/****************************************************************************/
size_t
__get_allocation_size(size_t size)
{
@ -142,7 +183,195 @@ __allocate_memory(size_t size,BOOL never_free,const char * UNUSED unused_file,in
}
#endif /* __MEM_DEBUG */
if(__memory_pool != NULL)
/* Are we using the slab allocator? */
if (__slab_data.sd_InUse)
{
mn = NULL;
assert( __slab_data.sd_MaxSlabSize > 0 );
/* Number of bytes to allocate exceeds the slab size?
* If so, allocate this memory chunk separately and
* keep track of it.
*/
if(allocation_size > __slab_data.sd_MaxSlabSize)
{
struct MinNode * single_allocation;
#if defined(__amigaos4__)
{
single_allocation = AllocVec(sizeof(*single_allocation) + allocation_size,MEMF_PRIVATE);
}
#else
{
single_allocation = AllocVec(sizeof(*single_allocation) + allocation_size,MEMF_ANY);
}
#endif /* __amigaos4__ */
if(single_allocation != NULL)
{
AddTail((struct List *)&__slab_data.sd_SingleAllocations,(struct Node *)single_allocation);
__slab_data.sd_NumSingleAllocations++;
mn = (struct MemoryNode *)&single_allocation[1];
}
}
/* Otherwise allocate a chunk from a slab. */
else
{
struct MinList * slab_list = NULL;
ULONG entry_size;
ULONG chunk_size;
int slab_index;
/* Chunks must be at least as small as a MinNode, because
* that's what we use for keeping track of the chunks which
* are available for allocation within each slab.
*/
entry_size = allocation_size;
if(entry_size < sizeof(struct MinNode))
entry_size = sizeof(struct MinNode);
/* Find a slab which keeps track of chunks that are no
* larger than the amount of memory which needs to be
* allocated. We end up picking the smallest chunk
* size that still works.
*/
for(slab_index = 0, chunk_size = (1UL << slab_index) ;
slab_index < 31 ;
slab_index++, chunk_size += chunk_size)
{
assert( (chunk_size % sizeof(LONG)) == 0);
if(entry_size <= chunk_size)
{
slab_list = &__slab_data.sd_Slabs[slab_index];
break;
}
}
if(slab_list != NULL)
{
struct SlabNode * sn;
/* Find the first slab which has a free chunk and use it. */
for(sn = (struct SlabNode *)slab_list->mlh_Head ;
sn->sn_MinNode.mln_Succ != NULL ;
sn = (struct SlabNode *)sn->sn_MinNode.mln_Succ)
{
assert( sn->sn_ChunkSize == chunk_size );
mn = (struct MemoryNode *)RemHead((struct List *)&sn->sn_FreeList);
if(mn != NULL)
{
/* Was this slab empty before we began using it again? */
if(sn->sn_UseCount == 0)
{
/* Mark it as no longer empty. */
Remove((struct Node *)&sn->sn_EmptyLink);
sn->sn_EmptyDecay = 0;
}
sn->sn_UseCount++;
break;
}
}
/* There is no slab with a free chunk? Then we might have to
* allocate a new one.
*/
if(mn == NULL)
{
struct MinNode * free_node;
struct MinNode * free_node_next;
struct SlabNode * new_sn = NULL;
/* Try to recycle an empty (unused) slab, if possible. */
for(free_node = (struct MinNode *)__slab_data.sd_EmptySlabs.mlh_Head ;
free_node->mln_Succ != NULL ;
free_node = free_node_next)
{
free_node_next = (struct MinNode *)free_node->mln_Succ;
/* free_node points to SlabNode.sn_EmptyLink, which
* directly follows the SlabNode.sn_MinNode.
*/
sn = (struct SlabNode *)&free_node[-1];
/* Is this empty slab ready to be reused? */
if(sn->sn_EmptyDecay == 0)
{
/* Unlink from list of empty slabs. */
Remove((struct Node *)free_node);
/* Unlink from list of slabs which keep chunks
* of the same size.
*/
Remove((struct Node *)sn);
new_sn = sn;
break;
}
}
/* We couldn't reuse an empty slab? Then we'll have to allocate
* memory for another one.
*/
if(new_sn == NULL)
{
#if defined(__amigaos4__)
{
new_sn = (struct SlabNode *)AllocVec(sizeof(*sn) + __slab_data.sd_MaxSlabSize,MEMF_PRIVATE);
}
#else
{
new_sn = (struct SlabNode *)AllocVec(sizeof(*sn) + __slab_data.sd_MaxSlabSize,MEMF_ANY);
}
#endif /* __amigaos4__ */
}
if(new_sn != NULL)
{
struct MinNode * free_chunk;
ULONG num_free_chunks = 0;
BYTE * first_byte;
BYTE * last_byte;
/* Split up the slab memory into individual chunks
* of the same size and keep track of them
* in the free list. The memory managed by
* this slab immediately follows the
* SlabNode header.
*/
first_byte = (BYTE *)&new_sn[1];
last_byte = &first_byte[__slab_data.sd_MaxSlabSize - chunk_size];
for(free_chunk = (struct MinNode *)first_byte ;
free_chunk <= (struct MinNode *)last_byte;
free_chunk = (struct MinNode *)(((BYTE *)free_chunk) + chunk_size))
{
AddTail((struct List *)&new_sn->sn_FreeList, (struct Node *)free_chunk);
num_free_chunks++;
}
/* Grab the first free chunk (there has to be one). */
mn = (struct MemoryNode *)RemHead((struct List *)&new_sn->sn_FreeList);
assert( mn != NULL );
/* Set up the new slab and put it where it belongs. */
new_sn->sn_EmptyDecay = 0;
new_sn->sn_UseCount = 1;
new_sn->sn_Count = num_free_chunks;
new_sn->sn_ChunkSize = chunk_size;
AddHead((struct List *)slab_list,(struct Node *)&new_sn);
}
}
}
}
}
else if (__memory_pool != NULL)
{
mn = AllocPooled(__memory_pool,allocation_size);
}
@ -352,29 +581,66 @@ STDLIB_DESTRUCTOR(stdlib_memory_exit)
}
#endif /* __MEM_DEBUG */
if(__memory_pool != NULL)
/* Is the slab memory allocator enabled? */
if (__slab_data.sd_InUse)
{
struct SlabNode * sn;
struct SlabNode * sn_next;
struct MinNode * mn;
struct MinNode * mn_next;
int i;
/* Free the memory allocated for each slab. */
for(i = 0 ; i < 31 ; i++)
{
for(sn = (struct SlabNode *)__slab_data.sd_Slabs[i].mlh_Head ;
sn->sn_MinNode.mln_Succ != NULL ;
sn = sn_next)
{
sn_next = (struct SlabNode *)sn->sn_MinNode.mln_Succ;
FreeVec(sn);
}
NewList((struct List *)&__slab_data.sd_Slabs[i]);
}
/* Free the memory allocated for each allocation which did not
* go into a slab.
*/
for(mn = __slab_data.sd_SingleAllocations.mlh_Head ; mn->mln_Succ != NULL ; mn = mn_next)
{
mn_next = mn->mln_Succ;
FreeVec(mn);
}
NewList((struct List *)&__slab_data.sd_SingleAllocations);
NewList((struct List *)&__slab_data.sd_EmptySlabs);
__slab_data.sd_InUse = FALSE;
}
else if (__memory_pool != NULL)
{
NewList((struct List *)&__memory_list);
DeletePool(__memory_pool);
__memory_pool = NULL;
}
else
else if (__memory_list.mlh_Head != NULL)
{
if(__memory_list.mlh_Head != NULL)
#ifdef __MEM_DEBUG
{
#ifdef __MEM_DEBUG
{
while(NOT IsListEmpty((struct List *)&__memory_list))
__free_memory_node((struct MemoryNode *)__memory_list.mlh_Head,__FILE__,__LINE__);
}
#else
{
while(NOT IsListEmpty((struct List *)&__memory_list))
__free_memory_node((struct MemoryNode *)__memory_list.mlh_Head,NULL,0);
}
#endif /* __MEM_DEBUG */
while(NOT IsListEmpty((struct List *)&__memory_list))
__free_memory_node((struct MemoryNode *)__memory_list.mlh_Head,__FILE__,__LINE__);
}
#else
{
while(NOT IsListEmpty((struct List *)&__memory_list))
__free_memory_node((struct MemoryNode *)__memory_list.mlh_Head,NULL,0);
}
#endif /* __MEM_DEBUG */
}
#if defined(__THREAD_SAFE)
@ -411,16 +677,57 @@ STDLIB_CONSTRUCTOR(stdlib_memory_init)
NewList((struct List *)&__memory_list);
#if defined(__amigaos4__)
/* Enable the slab memory allocator? */
if(__slab_max_size > 0)
{
__memory_pool = CreatePool(MEMF_PRIVATE,(ULONG)__default_pool_size,(ULONG)__default_puddle_size);
size_t size;
/* If the maximum allocation size to be made from the slab
* is not already a power of 2, round it up. We do not
* support allocations larger than 2^31, and the maximum
* allocation size should be much smaller.
*
* Note that the maximum allocation size also defines the
* amount of memory which each slab manages.
*/
size = sizeof(struct MinNode);
while(size < __slab_max_size && (size & 0x80000000) == 0)
size += size;
/* If the slab size looks sound, enable the slab memory allocator. */
if((size & 0x80000000) == 0)
{
int i;
assert( size <= __slab_max_size );
/* Start with an empty slab list. */
for(i = 0 ; i < 31 ; i++)
NewList((struct List *)&__slab_data.sd_Slabs[i]);
NewList((struct List *)&__slab_data.sd_SingleAllocations);
NewList((struct List *)&__slab_data.sd_EmptySlabs);
__slab_data.sd_MaxSlabSize = size;
__slab_data.sd_InUse = TRUE;
}
}
#else
else
{
if(((struct Library *)SysBase)->lib_Version >= 39)
__memory_pool = CreatePool(MEMF_ANY,(ULONG)__default_pool_size,(ULONG)__default_puddle_size);
#if defined(__amigaos4__)
{
__memory_pool = CreatePool(MEMF_PRIVATE,(ULONG)__default_pool_size,(ULONG)__default_puddle_size);
}
#else
{
/* There is no support for memory pools in the operating system
* prior to Kickstart 3.0 (V39).
*/
if(((struct Library *)SysBase)->lib_Version >= 39)
__memory_pool = CreatePool(MEMF_ANY,(ULONG)__default_pool_size,(ULONG)__default_puddle_size);
}
#endif /* __amigaos4__ */
}
#endif /* __amigaos4__ */
success = TRUE;

95
library/stdlib_memory.h
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@ -144,6 +144,10 @@ extern char * __getcwd(char * buffer,size_t buffer_size,const char *file,int lin
/****************************************************************************/
extern void __free_unused_slabs(void);
/****************************************************************************/
struct MemoryNode
{
struct MinNode mn_MinNode;
@ -190,6 +194,97 @@ struct MemoryTree
/****************************************************************************/
/* This keeps track of individual slabs. Each slab begins with this
* header and is followed by the memory it manages. The size of that
* memory "slab" is fixed and matches what is stored in
* SlabData.sd_MaxSlabSize.
*
* Each slab manages allocations of a specific maximum size, e.g. 8, 16, 32,
* 64, etc. bytes. Multiple slabs can exist which manage allocations of the same
* size, in case one such slab is not enough. Allocations are made from chunks,
* and for each slab, all chunks are the same size.
*/
struct SlabNode
{
struct MinNode sn_MinNode;
/* If this slab is empty, it goes into a list of slabs to be
* purged when memory is tight, or if it has stuck around long
* enough without getting purged. This is what the sn_EmptyDecay
* field is for. sn_EmptyDecay is decreased whenever an allocation
* suceeds which did not use this slab, and when sn_EmptyDecay
* reaches 0, the empty slab is purged.
*/
struct MinNode sn_EmptyLink;
ULONG sn_EmptyDecay;
/* How many chunks of memory does this slab contain? */
ULONG sn_Count;
/* How large are the individual chunks? */
ULONG sn_ChunkSize;
/* How many chunks of this slab are currently in use? */
ULONG sn_UseCount;
/* This contains all the chunks of memory which are available
* for allocation.
*/
struct MinList sn_FreeList;
};
/* This is the global bookkeeping information for managing
* memory allocations from the slab data structure.
*/
struct SlabData
{
/* This table contains slabs which manage memory chunks
* which are a power of 2 bytes in size, e.g. 8, 16, 32,
* 64, 128 bytes. Hence, sd_Slabs[3] keeps track of the slabs
* which are 8 bytes in size, sd_Slabs[4] is for 16 byte
* chunks, etc. The minimum chunk size is 8, which is why
* lists 0..2 are not used. Currently, there is an upper limit
* of 2^31 bytes per chunk, but you should not be using slab
* chunks much larger than 4096 bytes.
*/
struct MinList sd_Slabs[31];
/* Memory allocations which are larger than the limit
* found in the sd_MaxSlabSize field are kept in this list.
* They are never associated with a slab.
*/
struct MinList sd_SingleAllocations;
/* All slabs which currently are empty, i.e. none of their
* memory is being used, are registered in this list.
* The list linkage uses the SlabNode.sn_EmptyLink field.
*/
struct MinList sd_EmptySlabs;
/* This is the maximum size of a memory allocation which may
* be made from a slab that can accommodate it. This number
* is initialized from the __slab_max_size global variable,
* if > 0, and unless it already is a power of two, it will
* be rounded up to the next largest power of two.
*/
size_t sd_MaxSlabSize;
/* This field keeps track of how many entries there are in
* the sd_SingleAllocations list.
*/
ULONG sd_NumSingleAllocations;
/* If this is set to TRUE, then memory allocations will be
* be managed through slabs.
*/
BOOL sd_InUse;
};
/****************************************************************************/
extern struct SlabData NOCOMMON __slab_data;
extern ULONG NOCOMMON __slab_max_size;
/****************************************************************************/
extern struct MemoryTree NOCOMMON __memory_tree;
extern struct MinList NOCOMMON __memory_list;
extern APTR NOCOMMON __memory_pool;

38
library/stdlib_slab_max_size.c Normal file
View File

@ -0,0 +1,38 @@
/*
* :ts=4
*
* Portable ISO 'C' (1994) runtime library for the Amiga computer
* Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Neither the name of Olaf Barthel nor the names of contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _STDLIB_HEADERS_H
#include "stdlib_headers.h"
#endif /* _STDLIB_HEADERS_H */
/****************************************************************************/
ULONG NOCOMMON __slab_max_size;