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- Improve memory manager to allocate small blocks quickly.

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This commit is contained in:
Andi Gutmans 2002-06-24 12:39:08 +00:00
parent 3d799b5db4
commit 15d7936601
2 changed files with 52 additions and 14 deletions
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61
Zend/zend_mm.c
View File

@ -18,6 +18,7 @@
*/
#include <stdlib.h>
#include <string.h>
#include "zend_mm.h"
#if WIN32|WINNT
@ -48,6 +49,17 @@ typedef union _mm_align_test {
#define ZEND_MM_ALIGNMENT_MASK ~(ZEND_MM_ALIGNMENT-1)
#define ZEND_MM_BUCKET_INDEX(true_size) (true_size >> 3)
#define ZEND_MM_GET_FREE_LIST_BUCKET(index, free_list_bucket) \
if (index < ZEND_MM_NUM_BUCKETS) { \
free_list_bucket = &heap->free_buckets[index]; \
} else { \
/* This size doesn't exist */ \
free_list_bucket = &heap->free_buckets[0]; \
}
/* Aligned header size */
#define ZEND_MM_ALIGNED_SIZE(size) ((size + ZEND_MM_ALIGNMENT - 1) & ZEND_MM_ALIGNMENT_MASK)
#define ZEND_MM_ALIGNED_HEADER_SIZE ZEND_MM_ALIGNED_SIZE(sizeof(zend_mm_block))
@ -66,9 +78,14 @@ typedef union _mm_align_test {
static inline void zend_mm_add_to_free_list(zend_mm_heap *heap, zend_mm_free_block *mm_block)
{
mm_block->next_free_block = heap->free_list;
zend_mm_free_block **free_list_bucket;
size_t index = ZEND_MM_BUCKET_INDEX(mm_block->size);
ZEND_MM_GET_FREE_LIST_BUCKET(index, free_list_bucket);
mm_block->next_free_block = *free_list_bucket;
mm_block->prev_free_block = NULL;
heap->free_list = mm_block;
*free_list_bucket = mm_block;
if (mm_block->next_free_block) {
mm_block->next_free_block->prev_free_block = mm_block;
@ -81,7 +98,12 @@ static inline void zend_mm_remove_from_free_list(zend_mm_heap *heap, zend_mm_fre
if (mm_block->prev_free_block) {
mm_block->prev_free_block->next_free_block = mm_block->next_free_block;
} else {
heap->free_list = mm_block->next_free_block;
zend_mm_free_block **free_list_bucket;
size_t index = ZEND_MM_BUCKET_INDEX(mm_block->size);
ZEND_MM_GET_FREE_LIST_BUCKET(index, free_list_bucket);
*free_list_bucket = mm_block->next_free_block;
}
if (mm_block->next_free_block) {
@ -162,8 +184,8 @@ zend_bool zend_mm_add_memory_block(zend_mm_heap *heap, size_t block_size)
zend_bool zend_mm_startup(zend_mm_heap *heap, size_t block_size)
{
heap->block_size = block_size;
heap->free_list = NULL;
heap->segments_list = NULL;
memset(heap->free_buckets, 0, sizeof(heap->free_buckets));
return zend_mm_add_memory_block(heap, block_size);
}
@ -186,10 +208,27 @@ void *zend_mm_alloc(zend_mm_heap *heap, size_t size)
{
size_t true_size;
zend_mm_free_block *p, *best_fit=NULL;
zend_mm_free_block **free_list_bucket;
size_t index;
/* The max() can probably be optimized with an if() which checks more specific cases */
true_size = MAX(ZEND_MM_ALIGNED_SIZE(size)+ZEND_MM_ALIGNED_HEADER_SIZE, ZEND_MM_ALIGNED_FREE_HEADER_SIZE);
for (p = heap->free_list; p; p = p->next_free_block) {
index = ZEND_MM_BUCKET_INDEX(true_size);
if (index < ZEND_MM_NUM_BUCKETS) {
ZEND_MM_GET_FREE_LIST_BUCKET(index, free_list_bucket);
while (free_list_bucket != &heap->free_buckets[ZEND_MM_NUM_BUCKETS]) {
if (*free_list_bucket) {
best_fit = *free_list_bucket;
goto zend_mm_finished_searching_for_block;
}
free_list_bucket++;
}
}
for (p = heap->free_buckets[0]; p; p = p->next_free_block) {
if (p->size == true_size) {
best_fit = p;
break;
@ -198,6 +237,8 @@ void *zend_mm_alloc(zend_mm_heap *heap, size_t size)
best_fit = p;
}
}
zend_mm_finished_searching_for_block:
if (!best_fit) {
if (true_size > (heap->block_size - ZEND_MM_ALIGNED_SEGMENT_SIZE - ZEND_MM_ALIGNED_FREE_HEADER_SIZE)) {
/* Make sure we add a memory block which is big enough */
@ -224,22 +265,21 @@ void zend_mm_free(zend_mm_heap *heap, void *p)
{
zend_mm_block *mm_block = ZEND_MM_HEADER_OF(p);
zend_mm_block *prev_block, *next_block;
int in_free_list=0;
if (mm_block->type!=ZEND_MM_USED_BLOCK) {
/* error */
return;
}
next_block = ZEND_MM_BLOCK_AT(mm_block, mm_block->size);
/* merge with previous block if empty */
if (mm_block->prev_size != 0
&& (prev_block=ZEND_MM_BLOCK_AT(mm_block, -(int)mm_block->prev_size))->type == ZEND_MM_FREE_BLOCK) {
zend_mm_remove_from_free_list(heap, (zend_mm_free_block *) prev_block);
prev_block->size += mm_block->size;
mm_block = prev_block;
next_block->prev_size = mm_block->size;
in_free_list = 1; /* linked two ways */
}
/* merge with the next block if empty */
@ -251,9 +291,7 @@ void zend_mm_free(zend_mm_heap *heap, void *p)
}
mm_block->type = ZEND_MM_FREE_BLOCK;
if (!in_free_list) {
zend_mm_add_to_free_list(heap, (zend_mm_free_block *) mm_block);
}
zend_mm_add_to_free_list(heap, (zend_mm_free_block *) mm_block);
}
void *zend_mm_realloc(zend_mm_heap *heap, void *p, size_t size)
@ -286,7 +324,6 @@ void *zend_mm_realloc(zend_mm_heap *heap, void *p, size_t size)
ZEND_MM_BLOCK_AT(mm_block, mm_block->size)->prev_size = mm_block->size;
zend_mm_create_new_free_block(heap, mm_block, true_size);
/* We don't yet merge this free block with the following one */
return p;
}

5
Zend/zend_mm.h
View File

@ -46,11 +46,12 @@ typedef struct _zend_mm_segment {
struct _zend_mm_segment *next_segment;
} zend_mm_segment;
#define ZEND_MM_NUM_BUCKETS 64
typedef struct _zend_mm_heap {
/* Head of free list */
zend_mm_free_block *free_list;
zend_mm_segment *segments_list;
size_t block_size;
zend_mm_free_block *free_buckets[ZEND_MM_NUM_BUCKETS];
} zend_mm_heap;
zend_bool zend_mm_startup(zend_mm_heap *heap, size_t block_size);