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use proper atomics for the page_map

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daanx 2025-05-20 21:04:17 -07:00
parent 20a0b1ffde
commit a7411ae9c5
2 changed files with 16 additions and 12 deletions
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14
include/mimalloc/internal.h
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@ -547,16 +547,16 @@ static inline mi_page_t* _mi_unchecked_ptr_page(const void* p) {
// 2-level page map:
// double indirection, but low commit and low virtual reserve.
//
// the page-map is usually 4 MiB (for 48 bits virtual addresses) and points to sub maps of 64 KiB.
// the page-map is usually 4 MiB (for 48 bit virtual addresses) and points to sub maps of 64 KiB.
// the page-map is committed on-demand (in 64 KiB parts) (and sub-maps are committed on-demand as well)
// one sub page-map = 64 KiB => covers 2^(16-3) * 2^16 = 2^29 = 512 MiB address space
// the page-map needs 48-(16+13) = 19 bits => 2^19 sub map pointers = 4 MiB size.
// the page-map needs 48-(16+13) = 19 bits => 2^19 sub map pointers = 2^22 bytes = 4 MiB reserved size.
#define MI_PAGE_MAP_SUB_SHIFT (13)
#define MI_PAGE_MAP_SUB_COUNT (MI_ZU(1) << MI_PAGE_MAP_SUB_SHIFT)
#define MI_PAGE_MAP_SHIFT (MI_MAX_VABITS - MI_PAGE_MAP_SUB_SHIFT - MI_ARENA_SLICE_SHIFT)
#define MI_PAGE_MAP_COUNT (MI_ZU(1) << MI_PAGE_MAP_SHIFT)
extern mi_decl_hidden mi_page_t*** _mi_page_map;
extern mi_decl_hidden _Atomic(mi_page_t**)* _mi_page_map;
static inline size_t _mi_page_map_index(const void* p, size_t* sub_idx) {
const size_t u = (size_t)((uintptr_t)p / MI_ARENA_SLICE_SIZE);
@ -564,16 +564,20 @@ static inline size_t _mi_page_map_index(const void* p, size_t* sub_idx) {
return (u / MI_PAGE_MAP_SUB_COUNT);
}
static inline mi_page_t** _mi_page_map_at(size_t idx) {
return mi_atomic_load_ptr_relaxed(mi_page_t*, &_mi_page_map[idx]);
}
static inline mi_page_t* _mi_unchecked_ptr_page(const void* p) {
size_t sub_idx;
const size_t idx = _mi_page_map_index(p, &sub_idx);
return _mi_page_map[idx][sub_idx]; // NULL if p==NULL
return (_mi_page_map_at(idx))[sub_idx]; // NULL if p==NULL
}
static inline mi_page_t* _mi_checked_ptr_page(const void* p) {
size_t sub_idx;
const size_t idx = _mi_page_map_index(p, &sub_idx);
mi_page_t** const sub = _mi_page_map[idx];
mi_page_t** const sub = _mi_page_map_at(idx);
if mi_unlikely(sub == NULL) return NULL;
return sub[sub_idx];
}