diff options
| -rw-r--r-- | src/extent.c | 71 |
1 files changed, 61 insertions, 10 deletions
diff --git a/src/extent.c b/src/extent.c index bca703f..517780e 100644 --- a/src/extent.c +++ b/src/extent.c @@ -363,6 +363,43 @@ extents_remove_locked(tsdn_t *tsdn, extents_t *extents, extent_t *extent, cur_extents_npages - (size >> LG_PAGE), ATOMIC_RELAXED); } +/* + * Find an extent with size [min_size, max_size) to satisfy the alignment + * requirement. For each size, try only the first extent in the heap. + */ +static extent_t * +extents_fit_alignment(extents_t *extents, size_t min_size, size_t max_size, + size_t alignment) { + pszind_t pind = sz_psz2ind(extent_size_quantize_ceil(min_size)); + pszind_t pind_max = sz_psz2ind(extent_size_quantize_ceil(max_size)); + + for (pszind_t i = (pszind_t)bitmap_ffu(extents->bitmap, + &extents_bitmap_info, (size_t)pind); i < pind_max; i = + (pszind_t)bitmap_ffu(extents->bitmap, &extents_bitmap_info, + (size_t)i+1)) { + assert(i < NPSIZES); + assert(!extent_heap_empty(&extents->heaps[i])); + extent_t *extent = extent_heap_first(&extents->heaps[i]); + uintptr_t base = (uintptr_t)extent_base_get(extent); + size_t candidate_size = extent_size_get(extent); + assert(candidate_size >= min_size); + + uintptr_t next_align = ALIGNMENT_CEILING((uintptr_t)base, + PAGE_CEILING(alignment)); + if (base > next_align || base + candidate_size <= next_align) { + /* Overflow or not crossing the next alignment. */ + continue; + } + + size_t leadsize = next_align - base; + if (candidate_size - leadsize >= min_size) { + return extent; + } + } + + return NULL; +} + /* Do any-best-fit extent selection, i.e. select any extent that best fits. */ static extent_t * extents_best_fit_locked(tsdn_t *tsdn, arena_t *arena, extents_t *extents, @@ -424,12 +461,30 @@ extents_first_fit_locked(tsdn_t *tsdn, arena_t *arena, extents_t *extents, */ static extent_t * extents_fit_locked(tsdn_t *tsdn, arena_t *arena, extents_t *extents, - size_t size) { + size_t esize, size_t alignment) { malloc_mutex_assert_owner(tsdn, &extents->mtx); - return extents->delay_coalesce ? extents_best_fit_locked(tsdn, arena, - extents, size) : extents_first_fit_locked(tsdn, arena, extents, - size); + size_t max_size = esize + PAGE_CEILING(alignment) - PAGE; + /* Beware size_t wrap-around. */ + if (max_size < esize) { + return NULL; + } + + extent_t *extent = extents->delay_coalesce ? + extents_best_fit_locked(tsdn, arena, extents, max_size) : + extents_first_fit_locked(tsdn, arena, extents, max_size); + + if (alignment > PAGE && extent == NULL) { + /* + * max_size guarantees the alignment requirement but is rather + * pessimistic. Next we try to satisfy the aligned allocation + * with sizes in [esize, max_size). + */ + extent = extents_fit_alignment(extents, esize, max_size, + alignment); + } + + return extent; } static bool @@ -821,11 +876,6 @@ extent_recycle_extract(tsdn_t *tsdn, arena_t *arena, } size_t esize = size + pad; - size_t alloc_size = esize + PAGE_CEILING(alignment) - PAGE; - /* Beware size_t wrap-around. */ - if (alloc_size < esize) { - return NULL; - } malloc_mutex_lock(tsdn, &extents->mtx); extent_hooks_assure_initialized(arena, r_extent_hooks); extent_t *extent; @@ -847,7 +897,8 @@ extent_recycle_extract(tsdn_t *tsdn, arena_t *arena, extent_unlock(tsdn, unlock_extent); } } else { - extent = extents_fit_locked(tsdn, arena, extents, alloc_size); + extent = extents_fit_locked(tsdn, arena, extents, esize, + alignment); } if (extent == NULL) { malloc_mutex_unlock(tsdn, &extents->mtx); |