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search N pages for a best fit

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daanx 2024-10-09 14:21:50 -07:00
parent ffa8bce581
commit a05b5ab0a1
1 changed files with 16 additions and 15 deletions
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31
src/page.c
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@ -715,14 +715,17 @@ static void mi_page_init(mi_heap_t* heap, mi_page_t* page, size_t block_size, mi
Find pages with free blocks
-------------------------------------------------------------*/
// search for a best next page to use for at most N pages (often cut short if immediate blocks are available)
#define MI_MAX_CANDIDATE_SEARCH (16)
static inline bool mi_page_is_expandable(const mi_page_t* page) {
// is the page not yet used up to its reserved space?
static 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)
{
@ -740,14 +743,17 @@ static mi_page_t* mi_page_queue_find_free_ex(mi_heap_t* heap, mi_page_queue_t* p
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); // todo: should we free empty pages?
// collect freed blocks by us and other threads
_mi_page_free_collect(page, false);
#if defined(MI_MAX_CANDIDATE_SEARCH)
// search up to N pages for a best candidate
// 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`
// 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));
@ -763,25 +769,20 @@ static mi_page_t* mi_page_queue_find_free_ex(mi_heap_t* heap, mi_page_queue_t* p
else if (!mi_page_is_expandable(page) && page->used > page_candidate->used) {
page_candidate = page;
}
// if we find a non-expandable candidate, or searched for N pages, return with the best candidate
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)) {
// first-fit algorithm
// If the page contains free blocks, we are done
if (mi_page_immediate_available(page) || mi_page_is_expandable(page)) {
break; // pick this one
}
// 2. Try to extend
if (page->capacity < page->reserved) {
mi_page_extend_free(heap, page, heap->tld);
mi_assert_internal(mi_page_immediate_available(page));
break;
}
// 3. If the page is completely full, move it to the `mi_pages_full`
// If the page is completely full, move it to the `mi_pages_full`
// 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);