From b86dbab4c6d520c26dc8722250e83556324e828e Mon Sep 17 00:00:00 2001 From: Liu Dongming Date: Fri, 18 Mar 2022 11:49:06 +0800 Subject: [PATCH 1/2] Re-bin segment when dsa memory is freed. Extract re-bin segment into a separate function called rebin_segment, call it to ajust the segment to appropriate bin when dsa memory is freed. Otherwise, when allocating memory, due to the segment with enough contiguous pages is in a smaller bin, a suitable segment may not be found to allocate memory. --- src/backend/utils/mmgr/dsa.c | 68 ++++++++++++++++++++++++------------ 1 file changed, 46 insertions(+), 22 deletions(-) diff --git a/src/backend/utils/mmgr/dsa.c b/src/backend/utils/mmgr/dsa.c index b6cb8fa13d..ea95527ddc 100644 --- a/src/backend/utils/mmgr/dsa.c +++ b/src/backend/utils/mmgr/dsa.c @@ -406,6 +406,7 @@ static dsa_area *attach_internal(void *place, dsm_segment *segment, dsa_handle handle); static void check_for_freed_segments(dsa_area *area); static void check_for_freed_segments_locked(dsa_area *area); +static void rebin_segment(dsa_area *area, dsa_segment_map *segment_map); /* * Create a new shared area in a new DSM segment. Further DSM segments will @@ -857,7 +858,11 @@ dsa_free(dsa_area *area, dsa_pointer dp) FreePageManagerPut(segment_map->fpm, DSA_EXTRACT_OFFSET(span->start) / FPM_PAGE_SIZE, span->npages); + + /* Try to adjust segment to appropriate bin */ + rebin_segment(area, segment_map); LWLockRelease(DSA_AREA_LOCK(area)); + /* Unlink span. */ LWLockAcquire(DSA_SCLASS_LOCK(area, DSA_SCLASS_SPAN_LARGE), LW_EXCLUSIVE); @@ -1846,6 +1851,10 @@ destroy_superblock(dsa_area *area, dsa_pointer span_pointer) segment_map->mapped_address = NULL; } } + + /* Try to adjust segment to appropriate bin */ + rebin_segment(area, segment_map); + LWLockRelease(DSA_AREA_LOCK(area)); /* @@ -2009,28 +2018,7 @@ get_best_segment(dsa_area *area, size_t npages) /* Re-bin it if it's no longer in the appropriate bin. */ if (contiguous_pages < threshold) { - size_t new_bin; - - new_bin = contiguous_pages_to_segment_bin(contiguous_pages); - - /* Remove it from its current bin. */ - unlink_segment(area, segment_map); - - /* Push it onto the front of its new bin. */ - segment_map->header->prev = DSA_SEGMENT_INDEX_NONE; - segment_map->header->next = - area->control->segment_bins[new_bin]; - segment_map->header->bin = new_bin; - area->control->segment_bins[new_bin] = segment_index; - if (segment_map->header->next != DSA_SEGMENT_INDEX_NONE) - { - dsa_segment_map *next; - - next = get_segment_by_index(area, - segment_map->header->next); - Assert(next->header->bin == new_bin); - next->header->prev = segment_index; - } + rebin_segment(area, segment_map); /* * But fall through to see if it's enough to satisfy this @@ -2285,3 +2273,39 @@ check_for_freed_segments_locked(dsa_area *area) area->freed_segment_counter = freed_segment_counter; } } + +/* + * Re-bin segment if it's no longer in the appropriate bin. + */ +static void +rebin_segment(dsa_area *area, dsa_segment_map *segment_map) +{ + size_t new_bin; + dsa_segment_index segment_index; + + if (segment_map->header == NULL) + return; + + new_bin = contiguous_pages_to_segment_bin(fpm_largest(segment_map->fpm)); + if (segment_map->header->bin == new_bin) + return; + + segment_index = get_segment_index(area, segment_map); + + /* Re-bin it to the appropriate bin. */ + unlink_segment(area, segment_map); + + /* Push it onto the front of its new bin. */ + segment_map->header->prev = DSA_SEGMENT_INDEX_NONE; + segment_map->header->next = area->control->segment_bins[new_bin]; + segment_map->header->bin = new_bin; + area->control->segment_bins[new_bin] = segment_index; + if (segment_map->header->next != DSA_SEGMENT_INDEX_NONE) + { + dsa_segment_map *next; + + next = get_segment_by_index(area, segment_map->header->next); + Assert(next->header->bin == new_bin); + next->header->prev = segment_index; + } +} -- 2.32.0.3.g01195cf9f