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prefer pages that do not expand

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daanx 2024-10-09 11:27:57 -07:00
parent db3d8485d2
commit ffa8bce581
1 changed files with 48 additions and 2 deletions
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50
src/page.c
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@ -715,6 +715,14 @@ static void mi_page_init(mi_heap_t* heap, mi_page_t* page, size_t block_size, mi
Find pages with free blocks
-------------------------------------------------------------*/
#define MI_MAX_CANDIDATE_SEARCH (16)
static inline bool mi_page_is_expandable(const mi_page_t* page) {
mi_assert_internal(page != NULL);
mi_assert_internal(page->capacity <= page->reserved);
return (page->capacity < page->reserved);
}
// Find a page with free blocks of `page->block_size`.
static mi_page_t* mi_page_queue_find_free_ex(mi_heap_t* heap, mi_page_queue_t* pq, bool first_try)
{
@ -722,6 +730,8 @@ static mi_page_t* mi_page_queue_find_free_ex(mi_heap_t* heap, mi_page_queue_t* p
#if MI_STAT
size_t count = 0;
#endif
size_t candidate_count = 0; // we reset this on the first candidate to limit the search
mi_page_t* page_candidate = NULL; // a page with free space
mi_page_t* page = pq->first;
while (page != NULL)
{
@ -729,10 +739,36 @@ static mi_page_t* mi_page_queue_find_free_ex(mi_heap_t* heap, mi_page_queue_t* p
#if MI_STAT
count++;
#endif
candidate_count++;
#if defined(MI_MAX_CANDIDATE_SEARCH)
// 0. collect freed blocks by us and other threads
_mi_page_free_collect(page, false);
_mi_page_free_collect(page, false); // todo: should we free empty pages?
// is the local free list non-empty?
const bool immediate_available = mi_page_immediate_available(page);
// 1. If the page is completely full, move it to the `mi_pages_full`
// queue so we don't visit long-lived pages too often.
if (!immediate_available && !mi_page_is_expandable(page)) {
mi_assert_internal(!mi_page_is_in_full(page) && !mi_page_immediate_available(page));
mi_page_to_full(page, pq);
}
else {
// the page has free space, make it a candidate
// we prefer non-expandable pages with high usage as candidates (to reduce commit, and increase chances of free-ing up pages)
if (page_candidate == NULL) {
page_candidate = page;
candidate_count = 0;
}
else if (!mi_page_is_expandable(page) && page->used > page_candidate->used) {
page_candidate = page;
}
if (immediate_available || candidate_count > MI_MAX_CANDIDATE_SEARCH) {
mi_assert_internal(page_candidate!=NULL);
break;
}
}
#else
// 1. if the page contains free blocks, we are done
if (mi_page_immediate_available(page)) {
break; // pick this one
@ -749,12 +785,22 @@ static mi_page_t* mi_page_queue_find_free_ex(mi_heap_t* heap, mi_page_queue_t* p
// queue so we don't visit long-lived pages too often.
mi_assert_internal(!mi_page_is_in_full(page) && !mi_page_immediate_available(page));
mi_page_to_full(page, pq);
#endif
page = next;
} // for each page
mi_heap_stat_counter_increase(heap, searches, count);
// set the page to the best candidate
if (page_candidate != NULL) {
page = page_candidate;
}
if (page != NULL && !mi_page_immediate_available(page)) {
mi_assert_internal(mi_page_is_expandable(page));
mi_page_extend_free(heap, page, heap->tld);
}
if (page == NULL) {
_mi_heap_collect_retired(heap, false); // perhaps make a page available
page = mi_page_fresh(heap, pq);