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Do not discard segments for large object allocations

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Sergiy Kuryata 2024-11-30 18:44:35 -08:00
parent 0be44b2b0f
commit 8dd6460d5e
2 changed files with 46 additions and 5 deletions
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2
src/heap.c
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@ -743,7 +743,7 @@ void mi_heap_drop_segment_if_required(mi_heap_t* heap, size_t alloc_block_size)
{
size_t targetSegmentCount = mi_option_get_size(mi_option_max_segments_per_heap);
if ((targetSegmentCount > 0) &&
(alloc_block_size <= MI_LARGE_OBJ_SIZE_MAX) &&
(alloc_block_size <= MI_MEDIUM_OBJ_SIZE_MAX) &&
(heap->tld->segments.count >= targetSegmentCount)) {
mi_heap_drop_segment(heap, targetSegmentCount);

47
src/segment.c
View file

@ -1222,6 +1222,7 @@ static bool mi_segment_check_free(mi_segment_t* segment, size_t slices_needed, s
if (slice->slice_count >= slices_needed) {
has_page = true;
}
free_space_mask |= mi_free_space_mask_from_slicecount(slice->slice_count);
}
slice = slice + slice->slice_count;
}
@ -1344,6 +1345,9 @@ static mi_segment_t* mi_segment_try_reclaim(mi_heap_t* heap, size_t needed_slice
if (max_tries <= 0) return NULL;
mi_segment_t* segment;
mi_segment_t* best_candidate_segment = NULL;
size_t best_free_space_mask = MI_FREE_SPACE_MASK_ANY;
int candidates_to_check = 5;
size_t free_space_mask = mi_free_space_mask_from_blocksize(block_size);
mi_arena_field_cursor_t current; _mi_arena_field_cursor_init2(heap, &current, free_space_mask);
while ((max_tries-- > 0) && ((segment = _mi_arena_segment_clear_abandoned_next(&current)) != NULL))
@ -1366,10 +1370,42 @@ static mi_segment_t* mi_segment_try_reclaim(mi_heap_t* heap, size_t needed_slice
// found a large enough free span, or a page of the right block_size with free space
// we return the result of reclaim (which is usually `segment`) as it might free
// the segment due to concurrent frees (in which case `NULL` is returned).
mi_segment_t* segmentToReturn = mi_segment_reclaim(segment, heap, block_size, reclaimed, tld);
if (segmentToReturn != NULL) {
mi_segment_t* candidate_segment = segment;
size_t candidates_free_space_mask = segment->free_space_mask & MI_FREE_SPACE_MASK_ANY; // clear the abandoned bit
// If the requested block size is the largest available in the segment then use this segment
if (free_space_mask > ((~free_space_mask) & candidates_free_space_mask)) {
candidate_segment = mi_segment_reclaim(candidate_segment, heap, block_size, reclaimed, tld);
if (candidate_segment != NULL) {
// Found a better candidate; return the current best candidate to the abandoned list.
if (best_candidate_segment != NULL) {
_mi_arena_segment_mark_abandoned(best_candidate_segment);
}
best_candidate_segment = candidate_segment;
// found a good candidate segment; break the serch loop.
mi_segment_increment_reclaimed_stats();
return segmentToReturn;
return best_candidate_segment;
}
// The current segment was freed. Look for another one.
} else if (candidates_free_space_mask < best_free_space_mask || best_candidate_segment == NULL) {
//candidate_segment = mi_segment_reclaim(segment, heap, block_size, reclaimed, tld);
if (candidate_segment != NULL) {
// Found a better candidate; return the current best candidate to the abandoned list.
if (best_candidate_segment != NULL) {
_mi_arena_segment_mark_abandoned(best_candidate_segment);
}
best_candidate_segment = candidate_segment;
best_free_space_mask = candidates_free_space_mask;
candidate_segment = NULL;
}
}
if (candidate_segment != NULL) {
_mi_arena_segment_mark_abandoned(candidate_segment);
}
candidates_to_check--;
if (candidates_to_check == 0) {
break;
}
}
else if (segment->abandoned_visits > 3 && is_suitable && mi_option_get_size(mi_option_max_segments_per_heap) == 0) {
@ -1383,6 +1419,11 @@ static mi_segment_t* mi_segment_try_reclaim(mi_heap_t* heap, size_t needed_slice
}
}
if (best_candidate_segment != NULL) {
mi_segment_increment_reclaimed_stats();
return mi_segment_reclaim(best_candidate_segment, heap, block_size, reclaimed, tld);
}
mi_segment_increment_reclaim_failed_stats();
return NULL;
}