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Added a slab allocator

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Added a slab allocator which replaces the use of memory pools or the plain AllocMem() operations, respectively. In order to activate the slab allocator, choose a slab size (e.g. 2048 bytes or 4096 bytes) and declare a global variable like this:

   ULONG __slab_max_size = 2048;

Memory allocations smaller than the slab size will be made from "slabs", i.e. large chunks of memory of the given size. Larger allocations will be managed separately.
This commit is contained in:
obarthel
2016-11-18 17:22:21 +01:00
parent eb223f269d
commit fbc8694c49
22 changed files with 786 additions and 495 deletions
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453
library/stdlib_malloc.c
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@ -72,47 +72,6 @@ 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)
{
@ -183,255 +142,50 @@ __allocate_memory(size_t size,BOOL never_free,const char * UNUSED unused_file,in
}
#endif /* __MEM_DEBUG */
/* Are we using the slab allocator? */
if (__slab_data.sd_InUse)
#if defined(__USE_SLAB_ALLOCATOR)
{
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)
/* Are we using the slab allocator? */
if (__slab_data.sd_InUse)
{
mn = __slab_allocate(allocation_size);
}
else if (__memory_pool != NULL)
{
mn = AllocPooled(__memory_pool,allocation_size);
}
else
{
struct MinNode * single_allocation;
#if defined(__amigaos4__)
{
single_allocation = AllocVec(sizeof(*single_allocation) + allocation_size,MEMF_PRIVATE);
mn = AllocMem(allocation_size,MEMF_PRIVATE);
}
#else
{
single_allocation = AllocVec(sizeof(*single_allocation) + allocation_size,MEMF_ANY);
mn = AllocMem(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
{
if(__memory_pool != NULL)
{
mn = AllocPooled(__memory_pool,allocation_size);
}
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)
#if defined(__amigaos4__)
{
assert( (chunk_size % sizeof(LONG)) == 0);
if(entry_size <= chunk_size)
{
slab_list = &__slab_data.sd_Slabs[slab_index];
break;
}
mn = AllocMem(allocation_size,MEMF_PRIVATE);
}
if(slab_list != NULL)
#else
{
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++;
/* Is this slab now fully utilized? Move it to the
* end of the queue so that it will not be checked
* before other slabs of the same size have been
* tested. Those at the front of the queue should
* still have room left.
*/
if(sn->sn_UseCount == sn->sn_Count && sn != (struct SlabNode *)slab_list->mlh_TailPred)
{
Remove((struct Node *)sn);
AddTail((struct List *)slab_list, (struct Node *)sn);
}
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);
}
/* Mark unused slabs for purging, and purge those which
* are ready to be purged.
*/
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 purged? */
if(sn->sn_EmptyDecay == 0)
{
/* 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);
}
/* Give it another chance. */
else
{
sn->sn_EmptyDecay--;
}
}
}
mn = AllocMem(allocation_size,MEMF_ANY);
}
#endif /* __amigaos4__ */
}
}
else if (__memory_pool != NULL)
{
mn = AllocPooled(__memory_pool,allocation_size);
}
else
{
#if defined(__amigaos4__)
{
mn = AllocMem(allocation_size,MEMF_PRIVATE);
}
#else
{
mn = AllocMem(allocation_size,MEMF_ANY);
}
#endif /* __amigaos4__ */
}
#endif /* __USE_SLAB_ALLOCATOR */
if(mn == NULL)
{
@ -626,67 +380,63 @@ STDLIB_DESTRUCTOR(stdlib_memory_exit)
}
#endif /* __MEM_DEBUG */
/* Is the slab memory allocator enabled? */
if (__slab_data.sd_InUse)
#if defined(__USE_SLAB_ALLOCATOR)
{
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++)
/* Is the slab memory allocator enabled? */
if (__slab_data.sd_InUse)
{
for(sn = (struct SlabNode *)__slab_data.sd_Slabs[i].mlh_Head ;
sn->sn_MinNode.mln_Succ != NULL ;
sn = sn_next)
__slab_exit();
}
else
{
if (__memory_pool != NULL)
{
sn_next = (struct SlabNode *)sn->sn_MinNode.mln_Succ;
NewList((struct List *)&__memory_list);
FreeVec(sn);
DeletePool(__memory_pool);
__memory_pool = NULL;
}
else if (__memory_list.mlh_Head != NULL)
{
#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 */
}
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)
#else
{
NewList((struct List *)&__memory_list);
if (__memory_pool != NULL)
{
NewList((struct List *)&__memory_list);
DeletePool(__memory_pool);
__memory_pool = NULL;
}
else if (__memory_list.mlh_Head != NULL)
{
#ifdef __MEM_DEBUG
{
while(NOT IsListEmpty((struct List *)&__memory_list))
__free_memory_node((struct MemoryNode *)__memory_list.mlh_Head,__FILE__,__LINE__);
DeletePool(__memory_pool);
__memory_pool = NULL;
}
#else
else if (__memory_list.mlh_Head != NULL)
{
while(NOT IsListEmpty((struct List *)&__memory_list))
__free_memory_node((struct MemoryNode *)__memory_list.mlh_Head,NULL,0);
#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 */
}
#endif /* __MEM_DEBUG */
}
#endif /* __USE_SLAB_ALLOCATOR */
#if defined(__THREAD_SAFE)
{
@ -722,42 +472,46 @@ STDLIB_CONSTRUCTOR(stdlib_memory_init)
NewList((struct List *)&__memory_list);
/* Enable the slab memory allocator? */
if(__slab_max_size > 0)
#if defined(__USE_SLAB_ALLOCATOR)
{
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)
/* ZZZ this is just for the purpose of testing */
#if 0
{
int i;
TEXT slab_size_var[20];
assert( size <= __slab_max_size );
if(GetVar("SLAB_SIZE", slab_size_var, sizeof(slab_size_var), 0) > 0)
{
LONG value;
/* Start with an empty slab list. */
for(i = 0 ; i < 31 ; i++)
NewList((struct List *)&__slab_data.sd_Slabs[i]);
if(StrToLong(slab_size_var,&value) > 0 && value > 0)
__slab_max_size = (size_t)value;
}
}
#endif
NewList((struct List *)&__slab_data.sd_SingleAllocations);
NewList((struct List *)&__slab_data.sd_EmptySlabs);
__slab_data.sd_MaxSlabSize = size;
__slab_data.sd_InUse = TRUE;
/* Enable the slab memory allocator? */
if(__slab_max_size > 0)
{
__slab_init(__slab_max_size);
}
else
{
#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__ */
}
}
else
#else
{
#if defined(__amigaos4__)
{
@ -773,6 +527,7 @@ STDLIB_CONSTRUCTOR(stdlib_memory_init)
}
#endif /* __amigaos4__ */
}
#endif /* __USE_SLAB_ALLOCATOR) */
success = TRUE;