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experiment with 2 level pagemap

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daanx 2024-12-22 14:07:57 -08:00
parent 8d16303aa6
commit 3c7d7e1f11
3 changed files with 222 additions and 1 deletions
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18
include/mimalloc/bits.h
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@ -107,6 +107,24 @@ typedef int32_t mi_ssize_t;
// Define big endian if needed
// #define MI_BIG_ENDIAN 1
#if MI_DEFAULT_VIRTUAL_ADDRESS_BITS > 0
#define MI_MAX_VABITS MI_DEFAULT_VIRTUAL_ADDRESS_BITS
#elif MI_ARCH_X64
#define MI_MAX_VABITS (47)
#elif MI_INTPTR_SIZE > 4
#define MI_MAX_VABITS (48)
#else
#define MI_MAX_VABITS (32)
#endif
#ifndef MI_PAGE_MAP_FLAT
#if MI_MAX_VABITS <= 40
#define MI_PAGE_MAP_FLAT 1
#else
#define MI_PAGE_MAP_FLAT 0
#endif
#endif
/* --------------------------------------------------------------------------------
Builtin's

43
include/mimalloc/internal.h
View file

@ -442,6 +442,8 @@ static inline mi_page_t* _mi_heap_get_free_small_page(mi_heap_t* heap, size_t si
Pages
----------------------------------------------------------- */
#if MI_PAGE_MAP_FLAT
// flat page-map committed on demand
extern uint8_t* _mi_page_map;
@ -466,10 +468,49 @@ static inline mi_page_t* _mi_unchecked_ptr_page(const void* p) {
return _mi_ptr_page_ex(p, NULL);
}
#else
// 2-level page map
// one sub page-map = 64 KiB => covers 2^13 * 2^16 = 2^32 = 512 MiB address space
// the page-map needs 48-16-13 = 19 bits => 2^19 sub map pointers = 4 MiB size.
// we commit the page-map and the sub maps on-demand.
#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_page_t*** _mi_page_map;
static inline size_t _mi_page_map_index(const void* p, size_t* sub_idx) {
const uintptr_t u = (uintptr_t)p / MI_ARENA_SLICE_SIZE;
if (sub_idx != NULL) { *sub_idx = (uint32_t)u % MI_PAGE_MAP_SUB_COUNT; }
return (size_t)(u / MI_PAGE_MAP_SUB_COUNT);
}
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];
}
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];
if mi_unlikely(sub == NULL) return NULL;
return sub[sub_idx];
}
#endif
static inline mi_page_t* _mi_ptr_page(const void* p) {
mi_assert_internal(p==NULL || mi_is_in_heap_region(p));
#if MI_DEBUG || defined(__APPLE__)
return _mi_checked_ptr_page(p);
return _mi_checked_ptr_page(p);
#else
return _mi_unchecked_ptr_page(p);
#endif