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improving level 2 page-map

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daanx 2024-12-22 14:18:33 -08:00
parent 3c7d7e1f11
commit a42a2a926b
2 changed files with 18 additions and 10 deletions
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11
include/mimalloc/internal.h
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@ -470,11 +470,12 @@ static inline mi_page_t* _mi_unchecked_ptr_page(const void* p) {
#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.
// 2-level page map:
// The page-map is usually 4 MiB 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 2^13 * 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.
// (Choosing a MI_PAGE_MAP_SUB_SHIFT of 16 gives slightly better code but will commit the initial sub-map at 512 KiB)
#define MI_PAGE_MAP_SUB_SHIFT (13)
#define MI_PAGE_MAP_SUB_COUNT (MI_ZU(1) << MI_PAGE_MAP_SUB_SHIFT)