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refactor regions; add commit tracking on a segment basis

This commit is contained in:
Daan Leijen 2019-11-09 19:30:53 -08:00
parent 7b72a4cd50
commit 9f08ddd0d0
4 changed files with 181 additions and 226 deletions
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7
src/arena.c
View File

@ -123,7 +123,7 @@ static void* mi_arena_alloc_from(mi_arena_t* arena, size_t arena_index, size_t n
mi_bitmap_index_t bitmap_index;
if (mi_arena_alloc(arena, needed_bcount, &bitmap_index)) {
// claimed it! set the dirty bits (todo: no need for an atomic op here?)
*is_zero = mi_bitmap_claim(arena->blocks_dirty, arena->field_count, needed_bcount, bitmap_index);
*is_zero = mi_bitmap_claim(arena->blocks_dirty, arena->field_count, needed_bcount, bitmap_index, NULL);
*memid = mi_memid_create(arena_index, bitmap_index);
*commit = true; // TODO: support commit on demand?
*large = arena->is_large;
@ -182,6 +182,9 @@ void* _mi_arena_alloc_aligned(size_t size, size_t alignment,
// finally, fall back to the OS
*is_zero = true;
*memid = MI_MEMID_OS;
if (*large) {
*large = mi_option_is_enabled(mi_option_large_os_pages); // try large OS pages only if enabled and allowed
}
return _mi_os_alloc_aligned(size, alignment, *commit, large, tld);
}
@ -288,7 +291,7 @@ int mi_reserve_huge_os_pages_at(size_t pages, int numa_node, size_t timeout_msec
if (post > 0) {
// don't use leftover bits at the end
mi_bitmap_index_t postidx = mi_bitmap_index_create(fields - 1, MI_BITMAP_FIELD_BITS - post);
mi_bitmap_claim(arena->blocks_map, fields, post, postidx);
mi_bitmap_claim(arena->blocks_map, fields, post, postidx, NULL);
}
mi_arena_add(arena);

14
src/bitmap.inc.c
View File

@ -61,6 +61,7 @@ static inline size_t mi_bitmap_index_bit(mi_bitmap_index_t bitmap_idx) {
// The bit mask for a given number of blocks at a specified bit index.
static uintptr_t mi_bitmap_mask_(size_t count, size_t bitidx) {
mi_assert_internal(count + bitidx <= MI_BITMAP_FIELD_BITS);
if (count == MI_BITMAP_FIELD_BITS) return MI_BITMAP_FIELD_FULL;
return ((((uintptr_t)1 << count) - 1) << bitidx);
}
@ -183,14 +184,25 @@ static inline bool mi_bitmap_unclaim(mi_bitmap_t bitmap, size_t bitmap_fields, s
// Set `count` bits at `bitmap_idx` to 1 atomically
// Returns `true` if all `count` bits were 0 previously
static inline bool mi_bitmap_claim(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx) {
static inline bool mi_bitmap_claim(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx, bool* any_zero) {
const size_t idx = mi_bitmap_index_field(bitmap_idx);
const size_t bitidx = mi_bitmap_index_bit_in_field(bitmap_idx);
const uintptr_t mask = mi_bitmap_mask_(count, bitidx);
mi_assert_internal(bitmap_fields > idx); UNUSED(bitmap_fields);
// mi_assert_internal((bitmap[idx] & mask) == 0);
uintptr_t prev = mi_atomic_or(&bitmap[idx], mask);
if (any_zero != NULL) *any_zero = ((prev & mask) != mask);
return ((prev & mask) == 0);
}
// Returns `true` if all `count` bits were 1
static inline bool mi_bitmap_is_claimed(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx) {
const size_t idx = mi_bitmap_index_field(bitmap_idx);
const size_t bitidx = mi_bitmap_index_bit_in_field(bitmap_idx);
const uintptr_t mask = mi_bitmap_mask_(count, bitidx);
mi_assert_internal(bitmap_fields > idx); UNUSED(bitmap_fields);
// mi_assert_internal((bitmap[idx] & mask) == 0);
return ((mi_atomic_read(&bitmap[idx]) & mask) == mask);
}
#endif

350
src/memory.c
View File

@ -65,10 +65,11 @@ void* _mi_arena_alloc_aligned(size_t size, size_t alignment, bool* commit, boo
#define MI_SEGMENT_ALIGN MI_SEGMENT_SIZE
#define MI_REGION_MAX_BLOCKS MI_BITMAP_FIELD_BITS
#define MI_REGION_SIZE (MI_SEGMENT_SIZE * MI_BITMAP_FIELD_BITS) // 256MiB (64MiB on 32 bits)
#define MI_REGION_MAX_ALLOC_SIZE (MI_REGION_SIZE/4) // 64MiB
#define MI_REGION_MAX (MI_HEAP_REGION_MAX_SIZE / MI_REGION_SIZE) // 1024 (48 on 32 bits)
#define MI_REGION_MAX_OBJ_BLOCKS (MI_REGION_MAX_BLOCKS/4) // 64MiB
#define MI_REGION_MAX_OBJ_SIZE (MI_REGION_MAX_OBJ_BLOCKS*MI_SEGMENT_SIZE)
// Region info is a pointer to the memory region and two bits for
// its flags: is_large, and is_committed.
@ -90,18 +91,14 @@ static inline void* mi_region_info_read(mi_region_info_t info, bool* is_large, b
typedef struct mem_region_s {
volatile _Atomic(mi_region_info_t) info; // start of the memory area (and flags)
volatile _Atomic(uintptr_t) numa_node; // associated numa node + 1 (so 0 is no association)
mi_bitmap_field_t in_use;
mi_bitmap_field_t dirty;
size_t arena_memid; // if allocated from a (huge page) arena
} mem_region_t;
// The region map
static mem_region_t regions[MI_REGION_MAX];
// A bit mask per region for its claimed MI_SEGMENT_SIZE blocks.
static mi_bitmap_field_t regions_map[MI_REGION_MAX];
// A bit mask per region to track which blocks are dirty (= potentially written to)
static mi_bitmap_field_t regions_dirty[MI_REGION_MAX];
// Allocated regions
static volatile _Atomic(uintptr_t) regions_count; // = 0;
@ -112,8 +109,7 @@ Utility functions
// Blocks (of 4MiB) needed for the given size.
static size_t mi_region_block_count(size_t size) {
mi_assert_internal(size <= MI_REGION_MAX_ALLOC_SIZE);
return (size + MI_SEGMENT_SIZE - 1) / MI_SEGMENT_SIZE;
return _mi_divide_up(size, MI_SEGMENT_SIZE);
}
// Return a rounded commit/reset size such that we don't fragment large OS pages into small ones.
@ -134,8 +130,11 @@ bool mi_is_in_heap_region(const void* p) mi_attr_noexcept {
}
static size_t mi_memid_create(mi_bitmap_index_t bitmap_idx) {
return bitmap_idx<<1;
static size_t mi_memid_create(mem_region_t* region, mi_bitmap_index_t bit_idx) {
mi_assert_internal(bit_idx < MI_BITMAP_FIELD_BITS);
size_t idx = region - regions;
mi_assert_internal(&regions[idx] == region);
return (idx*MI_BITMAP_FIELD_BITS + bit_idx)<<1;
}
static size_t mi_memid_create_from_arena(size_t arena_memid) {
@ -146,177 +145,149 @@ static bool mi_memid_is_arena(size_t id) {
return ((id&1)==1);
}
static bool mi_memid_indices(size_t id, mi_bitmap_index_t* bitmap_idx, size_t* arena_memid) {
static bool mi_memid_indices(size_t id, mem_region_t** region, mi_bitmap_index_t* bit_idx, size_t* arena_memid) {
if (mi_memid_is_arena(id)) {
*arena_memid = (id>>1);
return true;
}
else {
*bitmap_idx = (mi_bitmap_index_t)(id>>1);
size_t idx = (id >> 1) / MI_BITMAP_FIELD_BITS;
*bit_idx = (mi_bitmap_index_t)(id>>1) % MI_BITMAP_FIELD_BITS;
*region = &regions[idx];
return false;
}
}
/* ----------------------------------------------------------------------------
Ensure a region is allocated from the OS (or an arena)
Allocate a region is allocated from the OS (or an arena)
-----------------------------------------------------------------------------*/
static bool mi_region_ensure_allocated(size_t idx, bool allow_large, mi_region_info_t* pinfo, mi_os_tld_t* tld)
static bool mi_region_try_alloc_os(size_t blocks, bool commit, bool allow_large, mem_region_t** region, mi_bitmap_index_t* bit_idx, mi_os_tld_t* tld)
{
// ensure the region is reserved
mi_region_info_t info = mi_atomic_read(&regions[idx].info);
if (mi_unlikely(info == 0))
{
bool region_commit = mi_option_is_enabled(mi_option_eager_region_commit);
bool region_large = allow_large;
// not out of regions yet?
if (mi_atomic_read_relaxed(&regions_count) >= MI_REGION_MAX - 1) return false;
// try to allocate a fresh region from the OS
bool region_commit = (commit && mi_option_is_enabled(mi_option_eager_region_commit));
bool region_large = (commit && allow_large);
bool is_zero = false;
size_t arena_memid = 0;
void* const start = _mi_arena_alloc_aligned(MI_REGION_SIZE, MI_SEGMENT_ALIGN, &region_commit, &region_large, &is_zero, &arena_memid, tld);
if (start == NULL) return false;
mi_assert_internal(!(region_large && !allow_large));
if (start == NULL) {
// failure to allocate from the OS! fail
*pinfo = 0;
// claim a fresh slot
const uintptr_t idx = mi_atomic_increment(&regions_count);
if (idx >= MI_REGION_MAX) {
mi_atomic_decrement(&regions_count);
_mi_arena_free(start, MI_REGION_SIZE, arena_memid, tld->stats);
return false;
}
// set the newly allocated region
// try to initialize any region up to 4 beyond the current one in
// care multiple threads are doing this concurrently (common at startup)
info = mi_region_info_create(start, region_large, region_commit);
bool claimed = false;
for (size_t i = 0; i <= 4 && idx + i < MI_REGION_MAX && !claimed; i++) {
if (!is_zero) {
// set dirty bits before CAS; this might race with a zero block but that is ok.
// (but writing before cas prevents a concurrent allocation to assume it is not dirty)
mi_atomic_write(&regions_dirty[idx+i], MI_BITMAP_FIELD_FULL);
// allocated, initialize and claim the initial blocks
mem_region_t* r = &regions[idx];
r->numa_node = _mi_os_numa_node(tld) + 1;
r->arena_memid = arena_memid;
*bit_idx = 0;
mi_bitmap_claim(&r->in_use, 1, blocks, *bit_idx, NULL);
mi_atomic_write(&r->info, mi_region_info_create(start, region_large, region_commit)); // now make it available to others
*region = r;
return true;
}
/* ----------------------------------------------------------------------------
Try to claim blocks in suitable regions
-----------------------------------------------------------------------------*/
static bool mi_region_is_suitable(const mem_region_t* region, int numa_node, bool commit, bool allow_large ) {
// initialized at all?
mi_region_info_t info = mi_atomic_read_relaxed(&region->info);
if (info==0) return false;
// numa correct
if (numa_node >= 0) { // use negative numa node to always succeed
int rnode = ((int)mi_atomic_read_relaxed(&region->numa_node)) - 1;
if (rnode >= 0 && rnode != numa_node) return false;
}
if (mi_atomic_cas_strong(&regions[idx+i].info, info, 0)) {
// claimed!
regions[idx+i].arena_memid = arena_memid;
mi_atomic_write(&regions[idx+i].numa_node, _mi_os_numa_node(tld) + 1);
mi_atomic_increment(&regions_count);
claimed = true;
}
}
if (!claimed) {
// free our OS allocation if we didn't succeed to store it in some region
_mi_arena_free(start, MI_REGION_SIZE, arena_memid, tld->stats);
}
// continue with the actual info at our index in case another thread was quicker with the allocation
info = mi_atomic_read(&regions[idx].info);
mi_assert_internal(info != 0);
}
mi_assert_internal(info == mi_atomic_read(&regions[idx].info));
mi_assert_internal(info != 0);
*pinfo = info;
// note: we also skip if commit is false and the region is committed,
// that is a bit strong but prevents allocation of eager-delayed segments in an eagerly committed region
bool is_large;
bool is_committed;
mi_region_info_read(info, &is_large, &is_committed);
if (!commit && is_committed) return false;
if (!allow_large && is_large) return false;
return true;
}
/* ----------------------------------------------------------------------------
Commit blocks
-----------------------------------------------------------------------------*/
static void* mi_region_commit_blocks(mi_bitmap_index_t bitmap_idx, mi_region_info_t info, size_t blocks, size_t size, bool* commit, bool* is_large, bool* is_zero, mi_os_tld_t* tld)
static bool mi_region_try_claim(size_t blocks, bool commit, bool allow_large, mem_region_t** region, mi_bitmap_index_t* bit_idx, mi_os_tld_t* tld)
{
// set dirty bits
*is_zero = mi_bitmap_claim(regions_dirty, MI_REGION_MAX, blocks, bitmap_idx);
// try all regions for a free slot
const int numa_node = (_mi_os_numa_node_count() <= 1 ? -1 : _mi_os_numa_node(tld));
const size_t count = mi_atomic_read(&regions_count);
size_t idx = tld->region_idx; // Or start at 0 to reuse low addresses?
for (size_t visited = 0; visited < count; visited++, idx++) {
if (idx >= count) idx = 0; // wrap around
mem_region_t* r = &regions[idx];
if (mi_region_is_suitable(r, numa_node, commit, allow_large)) {
if (mi_bitmap_try_claim_field(&r->in_use, 0, blocks, bit_idx)) {
tld->region_idx = idx; // remember the last found position
*region = r;
return true;
}
}
}
return false;
}
// Commit the blocks to memory
static void* mi_region_try_alloc(size_t blocks, bool* commit, bool* is_large, bool* is_zero, size_t* memid, mi_os_tld_t* tld)
{
mi_assert_internal(blocks <= MI_BITMAP_FIELD_BITS);
mem_region_t* region;
mi_bitmap_index_t bit_idx;
// first try to claim in existing regions
if (!mi_region_try_claim(blocks, *commit, *is_large, &region, &bit_idx, tld)) {
// otherwise try to allocate a fresh region
if (!mi_region_try_alloc_os(blocks, *commit, *is_large, &region, &bit_idx, tld)) {
// out of regions or memory
return NULL;
}
}
// found a region and claimed `blocks` at `bit_idx`
mi_assert_internal(region != NULL);
mi_assert_internal(mi_bitmap_is_claimed(&region->in_use, 1, blocks, bit_idx));
mi_region_info_t info = mi_atomic_read(&region->info);
bool region_is_committed = false;
bool region_is_large = false;
void* start = mi_region_info_read(info, &region_is_large, &region_is_committed);
mi_assert_internal(!(region_is_large && !*is_large));
mi_assert_internal(start!=NULL);
mi_assert_internal(start != NULL);
void* blocks_start = (uint8_t*)start + (mi_bitmap_index_bit_in_field(bitmap_idx) * MI_SEGMENT_SIZE);
if (*commit && !region_is_committed) {
bool any_zero = false;
*is_zero = mi_bitmap_claim(&region->dirty, 1, blocks, bit_idx, &any_zero);
if (!mi_option_is_enabled(mi_option_eager_commit)) any_zero = true; // if no eager commit, even dirty segments may be partially committed
*is_large = region_is_large;
*memid = mi_memid_create(region, bit_idx);
void* p = (uint8_t*)start + (mi_bitmap_index_bit_in_field(bit_idx) * MI_SEGMENT_SIZE);
if (*commit && !region_is_committed && any_zero) { // want to commit, but not yet fully committed?
// ensure commit
bool commit_zero = false;
_mi_os_commit(blocks_start, mi_good_commit_size(size), &commit_zero, tld->stats); // only commit needed size (unless using large OS pages)
if (commit_zero) *is_zero = true;
_mi_os_commit(p, blocks * MI_SEGMENT_SIZE, is_zero, tld->stats);
}
else if (!*commit && region_is_committed) {
// but even when no commit is requested, we might have committed anyway (in a huge OS page for example)
*commit = true;
else {
*commit = region_is_committed || !any_zero;
}
// and return the allocation
mi_assert_internal(blocks_start != NULL);
*is_large = region_is_large;
return blocks_start;
mi_assert_internal(p != NULL);
return p;
}
/* ----------------------------------------------------------------------------
Claim and allocate blocks in a region
-----------------------------------------------------------------------------*/
static bool mi_region_alloc_blocks(
size_t idx, size_t blocks, size_t size,
bool* commit, bool* allow_large, bool* is_zero,
void** p, size_t* id, mi_os_tld_t* tld)
{
mi_bitmap_index_t bitmap_idx;
if (!mi_bitmap_try_claim_field(regions_map, idx, blocks, &bitmap_idx)) {
return true; // no error, but also no success
}
mi_region_info_t info;
if (!mi_region_ensure_allocated(idx,*allow_large,&info,tld)) {
// failed to allocate region memory, unclaim the bits and fail
mi_bitmap_unclaim(regions_map, MI_REGION_MAX, blocks, bitmap_idx);
return false;
}
*p = mi_region_commit_blocks(bitmap_idx,info,blocks,size,commit,allow_large,is_zero,tld);
*id = mi_memid_create(bitmap_idx);
return true;
}
/* ----------------------------------------------------------------------------
Try to allocate blocks in suitable regions
-----------------------------------------------------------------------------*/
static bool mi_region_is_suitable(int numa_node, size_t idx, bool commit, bool allow_large ) {
uintptr_t m = mi_atomic_read_relaxed(&regions_map[idx]);
if (m == MI_BITMAP_FIELD_FULL) return false;
if (numa_node >= 0) { // use negative numa node to always succeed
int rnode = ((int)mi_atomic_read_relaxed(&regions[idx].numa_node)) - 1;
if (rnode >= 0 && rnode != numa_node) return false;
}
if (commit && allow_large) return true; // always ok
// otherwise skip incompatible regions if possible.
// this is not guaranteed due to multiple threads allocating at the same time but
// that's ok. In secure mode, large is never allowed for any thread, so that works out;
// otherwise we might just not be able to reset/decommit individual pages sometimes.
mi_region_info_t info = mi_atomic_read_relaxed(&regions[idx].info);
bool is_large;
bool is_committed;
void* start = mi_region_info_read(info, &is_large, &is_committed);
// note: we also skip if commit is false and the region is committed,
// that is a bit strong but prevents allocation of eager delayed segments in
// committed memory
bool ok = (start == NULL || (commit || !is_committed) || (allow_large || !is_large)); // Todo: test with one bitmap operation?
return ok;
}
// Try to allocate `blocks` in a `region` at `idx` of a given `size`. Does a quick check before trying to claim.
// Returns `false` on an error (OOM); `true` otherwise. `p` and `id` are only written
// if the blocks were successfully claimed so ensure they are initialized to NULL/0 before the call.
// (not being able to claim is not considered an error so check for `p != NULL` afterwards).
static bool mi_region_try_alloc_blocks(
int numa_node, size_t idx, size_t blocks, size_t size,
bool* commit, bool* allow_large, bool* is_zero,
void** p, size_t* id, mi_os_tld_t* tld)
{
// check if there are available blocks in the region..
mi_assert_internal(idx < MI_REGION_MAX);
if (mi_region_is_suitable(numa_node, idx, *commit, *allow_large)) {
return mi_region_alloc_blocks(idx, blocks, size, commit, allow_large, is_zero, p, id, tld);
}
return true; // no error, but no success either
}
/* ----------------------------------------------------------------------------
Allocation
@ -324,63 +295,35 @@ static bool mi_region_try_alloc_blocks(
// Allocate `size` memory aligned at `alignment`. Return non NULL on success, with a given memory `id`.
// (`id` is abstract, but `id = idx*MI_REGION_MAP_BITS + bitidx`)
void* _mi_mem_alloc_aligned(size_t size, size_t alignment, bool* commit, bool* large, bool* is_zero,
size_t* id, mi_os_tld_t* tld)
void* _mi_mem_alloc_aligned(size_t size, size_t alignment, bool* commit, bool* large, bool* is_zero, size_t* memid, mi_os_tld_t* tld)
{
mi_assert_internal(id != NULL && tld != NULL);
mi_assert_internal(memid != NULL && tld != NULL);
mi_assert_internal(size > 0);
*id = 0;
*memid = 0;
*is_zero = false;
bool default_large = false;
if (large==NULL) large = &default_large; // ensure `large != NULL`
// use direct OS allocation for huge blocks or alignment
if (size > MI_REGION_MAX_ALLOC_SIZE || alignment > MI_SEGMENT_ALIGN) {
size_t arena_memid = 0;
void* p = _mi_arena_alloc_aligned(mi_good_commit_size(size), alignment, commit, large, is_zero, &arena_memid, tld); // round up size
*id = mi_memid_create_from_arena(arena_memid);
return p;
}
// always round size to OS page size multiple (so commit/decommit go over the entire range)
// TODO: use large OS page size here?
if (size == 0) return NULL;
size = _mi_align_up(size, _mi_os_page_size());
// calculate the number of needed blocks
// allocate from regions if possible
size_t arena_memid;
const size_t blocks = mi_region_block_count(size);
mi_assert_internal(blocks > 0 && blocks <= 8*MI_INTPTR_SIZE);
// find a range of free blocks
const int numa_node = (_mi_os_numa_node_count() <= 1 ? -1 : _mi_os_numa_node(tld));
void* p = NULL;
const size_t count = mi_atomic_read(&regions_count);
size_t idx = tld->region_idx; // Or start at 0 to reuse low addresses?
for (size_t visited = 0; visited < count; visited++, idx++) {
if (idx >= count) idx = 0; // wrap around
if (!mi_region_try_alloc_blocks(numa_node, idx, blocks, size, commit, large, is_zero, &p, id, tld)) return NULL; // error
if (p != NULL) break;
if (blocks <= MI_REGION_MAX_OBJ_BLOCKS && alignment <= MI_SEGMENT_ALIGN) {
void* p = mi_region_try_alloc(blocks, commit, large, is_zero, memid, tld);
mi_assert_internal(p == NULL || (uintptr_t)p % alignment == 0);
if (p != NULL) {
if (*commit) { ((uint8_t*)p)[0] = 0; }
return p;
}
if (p == NULL) {
// no free range in existing regions -- try to extend beyond the count.. but at most 8 regions
for (idx = count; idx < mi_atomic_read_relaxed(&regions_count) + 8 && idx < MI_REGION_MAX; idx++) {
if (!mi_region_try_alloc_blocks(numa_node, idx, blocks, size, commit, large, is_zero, &p, id, tld)) return NULL; // error
if (p != NULL) break;
}
}
if (p == NULL) {
// we could not find a place to allocate, fall back to the os directly
_mi_warning_message("unable to allocate from region: size %zu\n", size);
size_t arena_memid = 0;
p = _mi_arena_alloc_aligned(size, alignment, commit, large, is_zero, &arena_memid, tld);
*id = mi_memid_create_from_arena(arena_memid);
}
else {
tld->region_idx = idx; // next start of search
}
// and otherwise fall back to the OS
void* p = _mi_arena_alloc_aligned(size, alignment, commit, large, is_zero, &arena_memid, tld);
*memid = mi_memid_create_from_arena(arena_memid);
mi_assert_internal( p == NULL || (uintptr_t)p % alignment == 0);
if (p != NULL && *commit) { ((uint8_t*)p)[0] = 0; }
return p;
}
@ -396,31 +339,28 @@ void _mi_mem_free(void* p, size_t size, size_t id, mi_stats_t* stats) {
if (p==NULL) return;
if (size==0) return;
size_t arena_memid = 0;
mi_bitmap_index_t bitmap_idx;
if (mi_memid_indices(id,&bitmap_idx,&arena_memid)) {
mi_bitmap_index_t bit_idx;
mem_region_t* region;
if (mi_memid_indices(id,&region,&bit_idx,&arena_memid)) {
// was a direct arena allocation, pass through
_mi_arena_free(p, size, arena_memid, stats);
}
else {
// allocated in a region
mi_assert_internal(size <= MI_REGION_MAX_ALLOC_SIZE); if (size > MI_REGION_MAX_ALLOC_SIZE) return;
mi_assert_internal(size <= MI_REGION_MAX_OBJ_SIZE); if (size > MI_REGION_MAX_OBJ_SIZE) return;
// we can align the size up to page size (as we allocate that way too)
// this ensures we fully commit/decommit/reset
size = _mi_align_up(size, _mi_os_page_size());
const size_t blocks = mi_region_block_count(size);
const size_t idx = mi_bitmap_index_field(bitmap_idx);
const size_t bitidx = mi_bitmap_index_bit_in_field(bitmap_idx);
mi_assert_internal(idx < MI_REGION_MAX); if (idx >= MI_REGION_MAX) return; // or `abort`?
mem_region_t* region = &regions[idx];
mi_region_info_t info = mi_atomic_read(&region->info);
bool is_large;
bool is_eager_committed;
void* start = mi_region_info_read(info,&is_large,&is_eager_committed);
mi_assert_internal(start != NULL);
void* blocks_start = (uint8_t*)start + (bitidx * MI_SEGMENT_SIZE);
void* blocks_start = (uint8_t*)start + (bit_idx * MI_SEGMENT_SIZE);
mi_assert_internal(blocks_start == p); // not a pointer in our area?
mi_assert_internal(bitidx + blocks <= MI_BITMAP_FIELD_BITS);
if (blocks_start != p || bitidx + blocks > MI_BITMAP_FIELD_BITS) return; // or `abort`?
mi_assert_internal(bit_idx + blocks <= MI_BITMAP_FIELD_BITS);
if (blocks_start != p || bit_idx + blocks > MI_BITMAP_FIELD_BITS) return; // or `abort`?
// decommit (or reset) the blocks to reduce the working set.
// TODO: implement delayed decommit/reset as these calls are too expensive
@ -446,7 +386,7 @@ void _mi_mem_free(void* p, size_t size, size_t id, mi_stats_t* stats) {
// this frees up virtual address space which might be useful on 32-bit systems?
// and unclaim
mi_bitmap_unclaim(regions_map, MI_REGION_MAX, blocks, bitmap_idx);
mi_bitmap_unclaim(&region->in_use, 1, blocks, bit_idx);
}
}
@ -456,13 +396,15 @@ void _mi_mem_free(void* p, size_t size, size_t id, mi_stats_t* stats) {
-----------------------------------------------------------------------------*/
void _mi_mem_collect(mi_stats_t* stats) {
// free every region that has no segments in use.
for (size_t i = 0; i < regions_count; i++) {
if (mi_atomic_read_relaxed(&regions_map[i]) == 0) {
uintptr_t rcount = mi_atomic_read_relaxed(&regions_count);
for (size_t i = 0; i < rcount; i++) {
mem_region_t* region = &regions[i];
if (mi_atomic_read_relaxed(&region->info) != 0) {
// if no segments used, try to claim the whole region
uintptr_t m;
do {
m = mi_atomic_read_relaxed(&regions_map[i]);
} while(m == 0 && !mi_atomic_cas_weak(&regions_map[i], MI_BITMAP_FIELD_FULL, 0 ));
m = mi_atomic_read_relaxed(&region->in_use);
} while(m == 0 && !mi_atomic_cas_weak(&region->in_use, MI_BITMAP_FIELD_FULL, 0 ));
if (m == 0) {
// on success, free the whole region
bool is_eager_committed;
@ -471,9 +413,7 @@ void _mi_mem_collect(mi_stats_t* stats) {
_mi_arena_free(start, MI_REGION_SIZE, regions[i].arena_memid, stats);
}
// and release
mi_atomic_write(&regions[i].info,0);
mi_atomic_write(&regions_dirty[i],0);
mi_atomic_write(&regions_map[i],0);
mi_atomic_write(&region->info,0);
}
}
}