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randomize free slabs reuse

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This commit is contained in:
Daniel Micay 2018-10-13 13:55:44 -04:00
parent 83df37436d
commit 65a7014b48
2 changed files with 16 additions and 5 deletions
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1
config.h
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@ -12,5 +12,6 @@
#define REGION_QUARANTINE_RANDOM_SIZE 128
#define REGION_QUARANTINE_QUEUE_SIZE 1024
#define REGION_QUARANTINE_SKIP_THRESHOLD (32 * 1024 * 1024)
#define FREE_SLABS_QUARANTINE_RANDOM_SIZE 32
#endif

20
malloc.c
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@ -144,6 +144,7 @@ static struct size_class {
// FIFO singly-linked list
struct slab_metadata *free_slabs_head;
struct slab_metadata *free_slabs_tail;
struct slab_metadata *free_slabs_quarantine[FREE_SLABS_QUARANTINE_RANDOM_SIZE];
struct libdivide_u32_t size_divisor;
struct libdivide_u64_t slab_size_divisor;
@ -425,12 +426,21 @@ static size_t slab_usable_size(void *p) {
static void enqueue_free_slab(struct size_class *c, struct slab_metadata *metadata) {
metadata->next = NULL;
if (c->free_slabs_tail != NULL) {
c->free_slabs_tail->next = metadata;
} else {
c->free_slabs_head = metadata;
static_assert(FREE_SLABS_QUARANTINE_RANDOM_SIZE < (u16)-1, "free slabs quarantine too large");
size_t index = get_random_u16_uniform(&c->rng, FREE_SLABS_QUARANTINE_RANDOM_SIZE);
struct slab_metadata *substitute = c->free_slabs_quarantine[index];
c->free_slabs_quarantine[index] = metadata;
if (substitute == NULL) {
return;
}
c->free_slabs_tail = metadata;
if (c->free_slabs_tail != NULL) {
c->free_slabs_tail->next = substitute;
} else {
c->free_slabs_head = substitute;
}
c->free_slabs_tail = substitute;
}
static inline void deallocate_small(void *p, size_t *expected_size) {