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wip: further progress on removing segments

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daanx 2024-11-29 10:40:18 -08:00
parent 71cfa45e76
commit 441d4fed9f
21 changed files with 2396 additions and 2492 deletions
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55
src/os.c
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@ -59,6 +59,10 @@ size_t _mi_os_large_page_size(void) {
return (mi_os_mem_config.large_page_size != 0 ? mi_os_mem_config.large_page_size : _mi_os_page_size());
}
size_t _mi_os_virtual_address_bits(void) {
return mi_os_mem_config.virtual_address_bits;
}
bool _mi_os_use_large_page(size_t size, size_t alignment) {
// if we have access, check the size and alignment requirements
if (mi_os_mem_config.large_page_size == 0 || !mi_option_is_enabled(mi_option_allow_large_os_pages)) return false;
@ -103,58 +107,10 @@ static void* mi_align_down_ptr(void* p, size_t alignment) {
return (void*)_mi_align_down((uintptr_t)p, alignment);
}
/* -----------------------------------------------------------
aligned hinting
-------------------------------------------------------------- */
// On systems with enough virtual address bits, we can do efficient aligned allocation by using
// the 2TiB to 30TiB area to allocate those. If we have at least 46 bits of virtual address
// space (64TiB) we use this technique. (but see issue #939)
#if (MI_INTPTR_SIZE >= 8) && !defined(MI_NO_ALIGNED_HINT)
static mi_decl_cache_align _Atomic(uintptr_t)aligned_base;
// Return a MI_SEGMENT_SIZE aligned address that is probably available.
// If this returns NULL, the OS will determine the address but on some OS's that may not be
// properly aligned which can be more costly as it needs to be adjusted afterwards.
// For a size > 1GiB this always returns NULL in order to guarantee good ASLR randomization;
// (otherwise an initial large allocation of say 2TiB has a 50% chance to include (known) addresses
// in the middle of the 2TiB - 6TiB address range (see issue #372))
#define MI_HINT_BASE ((uintptr_t)2 << 40) // 2TiB start
#define MI_HINT_AREA ((uintptr_t)4 << 40) // upto 6TiB (since before win8 there is "only" 8TiB available to processes)
#define MI_HINT_MAX ((uintptr_t)30 << 40) // wrap after 30TiB (area after 32TiB is used for huge OS pages)
void* _mi_os_get_aligned_hint(size_t try_alignment, size_t size)
{
if (try_alignment <= 1 || try_alignment > MI_SEGMENT_SIZE) return NULL;
if (mi_os_mem_config.virtual_address_bits < 46) return NULL; // < 64TiB virtual address space
size = _mi_align_up(size, MI_SEGMENT_SIZE);
if (size > 1*MI_GiB) return NULL; // guarantee the chance of fixed valid address is at most 1/(MI_HINT_AREA / 1<<30) = 1/4096.
#if (MI_SECURE>0)
size += MI_SEGMENT_SIZE; // put in `MI_SEGMENT_SIZE` virtual gaps between hinted blocks; this splits VLA's but increases guarded areas.
#endif
uintptr_t hint = mi_atomic_add_acq_rel(&aligned_base, size);
if (hint == 0 || hint > MI_HINT_MAX) { // wrap or initialize
uintptr_t init = MI_HINT_BASE;
#if (MI_SECURE>0 || MI_DEBUG==0) // security: randomize start of aligned allocations unless in debug mode
uintptr_t r = _mi_heap_random_next(mi_prim_get_default_heap());
init = init + ((MI_SEGMENT_SIZE * ((r>>17) & 0xFFFFF)) % MI_HINT_AREA); // (randomly 20 bits)*4MiB == 0 to 4TiB
#endif
uintptr_t expected = hint + size;
mi_atomic_cas_strong_acq_rel(&aligned_base, &expected, init);
hint = mi_atomic_add_acq_rel(&aligned_base, size); // this may still give 0 or > MI_HINT_MAX but that is ok, it is a hint after all
}
if (hint%try_alignment != 0) return NULL;
return (void*)hint;
}
#else
void* _mi_os_get_aligned_hint(size_t try_alignment, size_t size) {
MI_UNUSED(try_alignment); MI_UNUSED(size);
return NULL;
}
#endif
/* -----------------------------------------------------------
@ -380,12 +336,10 @@ void* _mi_os_zalloc(size_t size, mi_memid_t* memid, mi_stats_t* stats) {
----------------------------------------------------------- */
void* _mi_os_alloc_aligned_at_offset(size_t size, size_t alignment, size_t offset, bool commit, bool allow_large, mi_memid_t* memid, mi_stats_t* stats) {
mi_assert(offset <= MI_SEGMENT_SIZE);
mi_assert(offset <= size);
mi_assert((alignment % _mi_os_page_size()) == 0);
*memid = _mi_memid_none();
if (stats == NULL) stats = &_mi_stats_main;
if (offset > MI_SEGMENT_SIZE) return NULL;
if (offset == 0) {
// regular aligned allocation
return _mi_os_alloc_aligned(size, alignment, commit, allow_large, memid, stats);
@ -605,7 +559,6 @@ static uint8_t* mi_os_claim_huge_pages(size_t pages, size_t* total_size) {
#endif
}
end = start + size;
mi_assert_internal(end % MI_SEGMENT_SIZE == 0);
} while (!mi_atomic_cas_strong_acq_rel(&mi_huge_start, &huge_start, end));
if (total_size != NULL) *total_size = size;