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Rename full_position to low_bound in cache_bin.h.

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This commit is contained in:
Qi Wang 2021-12-28 13:38:12 -08:00 committed by Qi Wang
parent dfdd7562f5
commit eabe889162
1 changed files with 24 additions and 12 deletions
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36
include/jemalloc/internal/cache_bin.h
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@ -66,6 +66,17 @@ struct cache_bin_info_s {
/* /*
* Responsible for caching allocations associated with a single size. * Responsible for caching allocations associated with a single size.
*
* Several pointers are used to track the stack. To save on metadata bytes,
* only the stack_head is a full sized pointer (which is dereferenced on the
* fastpath), while the others store only the low 16 bits -- this is correct
* because a single stack never takes more space than 2^16 bytes, and at the
* same time only equality checks are performed on the low bits.
*
* (low addr) (high addr)
* |------stashed------|------available------|------cached-----|
* ^ ^ ^ ^
* low_bound(derived) low_bits_full stack_head low_bits_empty
*/ */
typedef struct cache_bin_s cache_bin_t; typedef struct cache_bin_s cache_bin_t;
struct cache_bin_s { struct cache_bin_s {
@ -94,11 +105,12 @@ struct cache_bin_s {
/* /*
* The low bits of the value that stack_head will take on when the array * The low bits of the value that stack_head will take on when the array
* is full. (But remember that stack_head always points to a valid item * is full (of cached & stashed items). But remember that stack_head
* when the array is nonempty -- this is in the array). * always points to a valid item when the array is nonempty -- this is
* in the array.
* *
* Recall that since the stack grows down, this is the lowest address in * Recall that since the stack grows down, this is the lowest available
* the array. Only adjusted when stashing items. * address in the array for caching. Only adjusted when stashing items.
*/ */
uint16_t low_bits_full; uint16_t low_bits_full;
@ -246,7 +258,7 @@ cache_bin_empty_position_get(cache_bin_t *bin) {
* A pointer to the position with the lowest address of the backing array. * A pointer to the position with the lowest address of the backing array.
*/ */
static inline void ** static inline void **
cache_bin_full_position_get(cache_bin_t *bin, cache_bin_info_t *info) { cache_bin_low_bound_get(cache_bin_t *bin, cache_bin_info_t *info) {
cache_bin_sz_t ncached_max = cache_bin_info_ncached_max(info); cache_bin_sz_t ncached_max = cache_bin_info_ncached_max(info);
void **ret = cache_bin_empty_position_get(bin) - ncached_max; void **ret = cache_bin_empty_position_get(bin) - ncached_max;
assert(ret <= bin->stack_head); assert(ret <= bin->stack_head);
@ -429,14 +441,14 @@ JEMALLOC_ALWAYS_INLINE cache_bin_sz_t
cache_bin_nstashed_get_internal(cache_bin_t *bin, cache_bin_info_t *info, cache_bin_nstashed_get_internal(cache_bin_t *bin, cache_bin_info_t *info,
bool racy) { bool racy) {
cache_bin_sz_t ncached_max = cache_bin_info_ncached_max(info); cache_bin_sz_t ncached_max = cache_bin_info_ncached_max(info);
void **full = cache_bin_full_position_get(bin, info); void **low_bound = cache_bin_low_bound_get(bin, info);
cache_bin_sz_t n = cache_bin_diff(bin, (uint16_t)(uintptr_t)full, cache_bin_sz_t n = cache_bin_diff(bin, (uint16_t)(uintptr_t)low_bound,
bin->low_bits_full) / sizeof(void *); bin->low_bits_full) / sizeof(void *);
assert(n <= ncached_max); assert(n <= ncached_max);
/* Below are for assertions only. */ /* Below are for assertions only. */
void *stashed = *(full + n - 1); void *stashed = *(low_bound + n - 1);
bool aligned = cache_bin_nonfast_aligned(stashed); bool aligned = cache_bin_nonfast_aligned(stashed);
#ifdef JEMALLOC_JET #ifdef JEMALLOC_JET
/* Allow arbitrary pointers to be stashed in tests. */ /* Allow arbitrary pointers to be stashed in tests. */
@ -564,17 +576,17 @@ cache_bin_init_ptr_array_for_stashed(cache_bin_t *bin, szind_t binind,
assert(nstashed > 0); assert(nstashed > 0);
assert(cache_bin_nstashed_get_local(bin, info) == nstashed); assert(cache_bin_nstashed_get_local(bin, info) == nstashed);
void **full = cache_bin_full_position_get(bin, info); void **low_bound = cache_bin_low_bound_get(bin, info);
arr->ptr = full; arr->ptr = low_bound;
assert(*arr->ptr != NULL); assert(*arr->ptr != NULL);
} }
static inline void static inline void
cache_bin_finish_flush_stashed(cache_bin_t *bin, cache_bin_info_t *info) { cache_bin_finish_flush_stashed(cache_bin_t *bin, cache_bin_info_t *info) {
void **full = cache_bin_full_position_get(bin, info); void **low_bound = cache_bin_low_bound_get(bin, info);
/* Reset the bin local full position. */ /* Reset the bin local full position. */
bin->low_bits_full = (uint16_t)(uintptr_t)full; bin->low_bits_full = (uint16_t)(uintptr_t)low_bound;
assert(cache_bin_nstashed_get_local(bin, info) == 0); assert(cache_bin_nstashed_get_local(bin, info) == 0);
} }