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refactor segment cache and map in a separate source file

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daan 2020-09-08 13:27:34 -07:00
parent 161f9a7751
commit 037285ac09
16 changed files with 378 additions and 365 deletions
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152
src/segment.c
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@ -13,8 +13,6 @@ terms of the MIT license. A copy of the license can be found in the file
#define MI_PAGE_HUGE_ALIGN (256*1024)
static void mi_segment_map_allocated_at(const mi_segment_t* segment);
static void mi_segment_map_freed_at(const mi_segment_t* segment);
static void mi_segment_delayed_decommit(mi_segment_t* segment, bool force, mi_stats_t* stats);
/* --------------------------------------------------------------------------------
@ -183,11 +181,6 @@ static bool mi_segment_is_valid(mi_segment_t* segment, mi_segments_tld_t* tld) {
Segment size calculations
----------------------------------------------------------- */
static size_t mi_segment_size(mi_segment_t* segment) {
return segment->segment_slices * MI_SEGMENT_SLICE_SIZE;
}
static size_t mi_segment_info_size(mi_segment_t* segment) {
return segment->segment_info_slices * MI_SEGMENT_SLICE_SIZE;
}
@ -249,7 +242,7 @@ static void mi_segments_track_size(long segment_size, mi_segments_tld_t* tld) {
static void mi_segment_os_free(mi_segment_t* segment, mi_segments_tld_t* tld) {
segment->thread_id = 0;
mi_segment_map_freed_at(segment);
_mi_segment_map_freed_at(segment);
mi_segments_track_size(-((long)mi_segment_size(segment)),tld);
if (MI_SECURE>0) {
// _mi_os_unprotect(segment, mi_segment_size(segment)); // ensure no more guard pages are set
@ -264,7 +257,13 @@ static void mi_segment_os_free(mi_segment_t* segment, mi_segments_tld_t* tld) {
// mi_segment_delayed_decommit(segment,true,tld->stats);
// _mi_os_free(segment, mi_segment_size(segment), /*segment->memid,*/ tld->stats);
_mi_arena_free(segment, mi_segment_size(segment), segment->memid, segment->commit_mask, segment->mem_is_fixed, tld->os);
const size_t size = mi_segment_size(segment);
if (size != MI_SEGMENT_SIZE || !_mi_segment_cache_push(segment, size, segment->memid, segment->commit_mask, segment->mem_is_fixed, tld->os)) {
const size_t csize = mi_commit_mask_committed_size(segment->commit_mask, size);
if (csize > 0 && !segment->mem_is_fixed) _mi_stat_decrease(&_mi_stats_main.committed, csize);
_mi_abandoned_await_readers(); // wait until safe to free
_mi_arena_free(segment, mi_segment_size(segment), segment->memid, segment->mem_is_fixed /* pretend not committed to not double count decommits */, tld->os);
}
}
@ -647,7 +646,7 @@ static mi_segment_t* mi_segment_init(mi_segment_t* segment, size_t required, mi_
// Commit eagerly only if not the first N lazy segments (to reduce impact of many threads that allocate just a little)
const bool eager_delay = (tld->count < (size_t)mi_option_get(mi_option_eager_commit_delay));
const bool eager = !eager_delay && mi_option_is_enabled(mi_option_eager_commit);
const bool commit = eager || (required > 0);
bool commit = eager || (required > 0);
// Try to get from our cache first
bool is_zero = false;
@ -657,8 +656,12 @@ static mi_segment_t* mi_segment_init(mi_segment_t* segment, size_t required, mi_
// Allocate the segment from the OS
bool mem_large = (!eager_delay && (MI_SECURE==0)); // only allow large OS pages once we are no longer lazy
size_t memid = 0;
segment = (mi_segment_t*)_mi_arena_alloc_aligned(segment_size, MI_SEGMENT_SIZE, commit, &commit_mask, &mem_large, &is_zero, &memid, os_tld);
if (segment == NULL) return NULL; // failed to allocate
segment = (mi_segment_t*)_mi_segment_cache_pop(segment_size, &commit_mask, &mem_large, &is_zero, &memid, os_tld);
if (segment==NULL) {
segment = (mi_segment_t*)_mi_arena_alloc_aligned(segment_size, MI_SEGMENT_SIZE, &commit, &mem_large, &is_zero, &memid, os_tld);
if (segment == NULL) return NULL; // failed to allocate
commit_mask = (commit ? mi_commit_mask_full() : mi_commit_mask_empty());
}
mi_assert_internal(segment != NULL && (uintptr_t)segment % MI_SEGMENT_SIZE == 0);
const size_t commit_needed = _mi_divide_up(info_slices*MI_SEGMENT_SLICE_SIZE, MI_COMMIT_SIZE);
@ -674,7 +677,7 @@ static mi_segment_t* mi_segment_init(mi_segment_t* segment, size_t required, mi_
segment->mem_is_fixed = mem_large;
segment->mem_is_committed = mi_commit_mask_is_full(commit_mask);
mi_segments_track_size((long)(segment_size), tld);
mi_segment_map_allocated_at(segment);
_mi_segment_map_allocated_at(segment);
}
// zero the segment info? -- not always needed as it is zero initialized from the OS
@ -1368,126 +1371,3 @@ mi_page_t* _mi_segment_page_alloc(mi_heap_t* heap, size_t block_size, mi_segment
}
/* -----------------------------------------------------------
The following functions are to reliably find the segment or
block that encompasses any pointer p (or NULL if it is not
in any of our segments).
We maintain a bitmap of all memory with 1 bit per MI_SEGMENT_SIZE (64MiB)
set to 1 if it contains the segment meta data.
----------------------------------------------------------- */
#if (MI_INTPTR_SIZE==8)
#define MI_MAX_ADDRESS ((size_t)20 << 40) // 20TB
#else
#define MI_MAX_ADDRESS ((size_t)2 << 30) // 2Gb
#endif
#define MI_SEGMENT_MAP_BITS (MI_MAX_ADDRESS / MI_SEGMENT_SIZE)
#define MI_SEGMENT_MAP_SIZE (MI_SEGMENT_MAP_BITS / 8)
#define MI_SEGMENT_MAP_WSIZE (MI_SEGMENT_MAP_SIZE / MI_INTPTR_SIZE)
static _Atomic(uintptr_t) mi_segment_map[MI_SEGMENT_MAP_WSIZE]; // 2KiB per TB with 64MiB segments
static size_t mi_segment_map_index_of(const mi_segment_t* segment, size_t* bitidx) {
mi_assert_internal(_mi_ptr_segment(segment) == segment); // is it aligned on MI_SEGMENT_SIZE?
uintptr_t segindex = ((uintptr_t)segment % MI_MAX_ADDRESS) / MI_SEGMENT_SIZE;
*bitidx = segindex % (8*MI_INTPTR_SIZE);
return (segindex / (8*MI_INTPTR_SIZE));
}
static void mi_segment_map_allocated_at(const mi_segment_t* segment) {
size_t bitidx;
size_t index = mi_segment_map_index_of(segment, &bitidx);
mi_assert_internal(index < MI_SEGMENT_MAP_WSIZE);
if (index==0) return;
uintptr_t mask = mi_atomic_load_relaxed(&mi_segment_map[index]);
uintptr_t newmask;
do {
newmask = (mask | ((uintptr_t)1 << bitidx));
} while (!mi_atomic_cas_weak_release(&mi_segment_map[index], &mask, newmask));
}
static void mi_segment_map_freed_at(const mi_segment_t* segment) {
size_t bitidx;
size_t index = mi_segment_map_index_of(segment, &bitidx);
mi_assert_internal(index < MI_SEGMENT_MAP_WSIZE);
if (index == 0) return;
uintptr_t mask = mi_atomic_load_relaxed(&mi_segment_map[index]);
uintptr_t newmask;
do {
newmask = (mask & ~((uintptr_t)1 << bitidx));
} while (!mi_atomic_cas_weak_release(&mi_segment_map[index], &mask, newmask));
}
// Determine the segment belonging to a pointer or NULL if it is not in a valid segment.
static mi_segment_t* _mi_segment_of(const void* p) {
mi_segment_t* segment = _mi_ptr_segment(p);
size_t bitidx;
size_t index = mi_segment_map_index_of(segment, &bitidx);
// fast path: for any pointer to valid small/medium/large object or first MI_SEGMENT_SIZE in huge
const uintptr_t mask = mi_atomic_load_relaxed(&mi_segment_map[index]);
if (mi_likely((mask & ((uintptr_t)1 << bitidx)) != 0)) {
return segment; // yes, allocated by us
}
if (index==0) return NULL;
// search downwards for the first segment in case it is an interior pointer
// could be slow but searches in MI_INTPTR_SIZE * MI_SEGMENT_SIZE (512MiB) steps trough
// valid huge objects
// note: we could maintain a lowest index to speed up the path for invalid pointers?
size_t lobitidx;
size_t loindex;
uintptr_t lobits = mask & (((uintptr_t)1 << bitidx) - 1);
if (lobits != 0) {
loindex = index;
lobitidx = mi_bsr(lobits); // lobits != 0
}
else {
uintptr_t lomask = mask;
loindex = index - 1;
while (loindex > 0 && (lomask = mi_atomic_load_relaxed(&mi_segment_map[loindex])) == 0) loindex--;
if (loindex==0) return NULL;
lobitidx = mi_bsr(lomask); // lomask != 0
}
// take difference as the addresses could be larger than the MAX_ADDRESS space.
size_t diff = (((index - loindex) * (8*MI_INTPTR_SIZE)) + bitidx - lobitidx) * MI_SEGMENT_SIZE;
segment = (mi_segment_t*)((uint8_t*)segment - diff);
if (segment == NULL) return NULL;
mi_assert_internal((void*)segment < p);
bool cookie_ok = (_mi_ptr_cookie(segment) == segment->cookie);
mi_assert_internal(cookie_ok);
if (mi_unlikely(!cookie_ok)) return NULL;
if (((uint8_t*)segment + mi_segment_size(segment)) <= (uint8_t*)p) return NULL; // outside the range
mi_assert_internal(p >= (void*)segment && (uint8_t*)p < (uint8_t*)segment + mi_segment_size(segment));
return segment;
}
// Is this a valid pointer in our heap?
static bool mi_is_valid_pointer(const void* p) {
return (_mi_segment_of(p) != NULL);
}
bool mi_is_in_heap_region(const void* p) mi_attr_noexcept {
return mi_is_valid_pointer(p);
}
/*
// Return the full segment range belonging to a pointer
static void* mi_segment_range_of(const void* p, size_t* size) {
mi_segment_t* segment = _mi_segment_of(p);
if (segment == NULL) {
if (size != NULL) *size = 0;
return NULL;
}
else {
if (size != NULL) *size = segment->segment_size;
return segment;
}
mi_assert_expensive(page == NULL || mi_segment_is_valid(_mi_page_segment(page),tld));
mi_assert_internal(page == NULL || (mi_segment_page_size(_mi_page_segment(page)) - (MI_SECURE == 0 ? 0 : _mi_os_page_size())) >= block_size);
mi_reset_delayed(tld);
mi_assert_internal(page == NULL || mi_page_not_in_queue(page, tld));
return page;
}
*/