Turn off background sweep page bookkeeping

Author: luke-gruber

gc/default/default.c

@@ -490,7 +490,6 @@ typedef struct rb_heap_struct {
     rb_atomic_t background_sweep_steps; // only incremented/checked by sweep thread
     rb_nativethread_cond_t sweep_page_cond; // associated with global sweep lock
     rb_nativethread_lock_t swept_pages_lock;
-    size_t pre_swept_slots_nodeferred;
     size_t pre_swept_slots_deferred;
     deferred_sweep_data_t deferred_sweep_data;
     bool is_finished_sweeping;
@@ -4690,63 +4689,6 @@ gc_sweep_step_worker(rb_objspace_t *objspace, rb_heap_t *heap)
         int pre_empty_slots = sweep_page->pre_empty_slots;
         int free_slots = pre_freed_slots + pre_empty_slots;
 
-        if (objspace->background_sweep_mode && sweep_page->pre_deferred_free_slots == 0) {
-            if (free_slots == sweep_page->total_slots) {
-                GC_ASSERT(sweep_page->total_slots > 0);
-                psweep_debug(-6, "[sweep] (bg) gc_sweep_step_worker: heap %ld adding to empty_pages:%p (pre_empty:%d, pre_freed:%d)\n",
-                    heap - heaps, sweep_page, sweep_page->pre_empty_slots, sweep_page->pre_freed_slots);
-                // We're guaranteed to stay in background mode during this (starting GC requires taking the
-                // sweep_lock to change sweep background mode to false)
-                GC_ASSERT(sweep_page->pre_final_slots == 0);
-                clear_pre_sweep_fields(sweep_page);
-                gc_post_sweep_page(objspace, heap, sweep_page, true);
-                move_to_empty_pages(objspace, heap, sweep_page);
-                continue;
-            }
-            else if (free_slots > 0) {
-                // These are just for statistics, not used in calculations
-                heap->freed_slots += sweep_page->pre_freed_slots;
-                heap->empty_slots += sweep_page->pre_empty_slots;
-
-                sweep_page->free_slots = free_slots;
-                sweep_page->heap->total_freed_objects += sweep_page->pre_freed_slots;
-                clear_pre_sweep_fields(sweep_page);
-                gc_post_sweep_page(objspace, heap, sweep_page, false);
-                if (sweep_page->deferred_freelist) {
-                    merge_freelists(sweep_page->deferred_freelist, sweep_page->freelist);
-                    sweep_page->freelist = sweep_page->deferred_freelist;
-                }
-                sweep_page->deferred_freelist = NULL;
-                if (heap->pre_swept_slots_nodeferred < GC_INCREMENTAL_SWEEP_POOL_SLOT_COUNT) {
-                    psweep_debug(-6, "[sweep] (bg) gc_sweep_step_worker: heap %ld adding to pooled pages:%p (pre_empty:%d, pre_freed:%d, pre_swept:%lu->%lu)\n",
-                                 heap - heaps, sweep_page, pre_empty_slots, pre_freed_slots, heap->pre_swept_slots_nodeferred,
-                                 heap->pre_swept_slots_nodeferred + free_slots);
-                    heap->pre_swept_slots_nodeferred += free_slots;
-                    heap_add_poolpage(objspace, heap, sweep_page);
-                    continue;
-                }
-                else {
-                    psweep_debug(-6, "[sweep] (bg) gc_sweep_step_worker: heap %ld adding to free pages:%p (pre_empty:%d, pre_freed:%d, pre_swept:%lu->%lu)\n",
-                                 heap - heaps, sweep_page, pre_empty_slots, pre_freed_slots, heap->pre_swept_slots_nodeferred,
-                                 heap->pre_swept_slots_nodeferred + free_slots);
-                    heap_add_freepage(heap, sweep_page, "gc_sweep_step_worker");
-                    heap->pre_swept_slots_nodeferred += free_slots;
-                    if (heap->pre_swept_slots_nodeferred > (GC_INCREMENTAL_SWEEP_SLOT_COUNT + GC_INCREMENTAL_SWEEP_POOL_SLOT_COUNT)) {
-                        heap->pre_swept_slots_nodeferred = 0;
-                        /*break;*/
-                    }
-                    continue;
-                }
-            }
-            else {
-                // Don't even add to `swept_pages`, no further processing needed by ruby thread (no free slots)
-                clear_pre_sweep_fields(sweep_page);
-                gc_post_sweep_page(objspace, heap, sweep_page, false);
-                continue;
-            }
-        }
-
-
 #if PSWEEP_LOCK_STATS > 0
         instrumented_lock_acquire(&heap->swept_pages_lock, &swept_pages_lock_stats);
 #else
@@ -4857,7 +4799,6 @@ gc_sweep_start_heap(rb_objspace_t *objspace, rb_heap_t *heap)
     heap->swept_pages = NULL;
     heap->pooled_pages = NULL;
     heap->latest_swept_page = NULL;
-    heap->pre_swept_slots_nodeferred = 0;
     heap->pre_swept_slots_deferred = 0;
 
     heap->pre_sweeping_page = NULL;
@@ -5180,13 +5121,6 @@ gc_sweep_step(rb_objspace_t *objspace, rb_heap_t *heap)
 {
     size_t swept_slots = 0;
     size_t pooled_slots = 0;
-    if (heap->pre_swept_slots_nodeferred >= GC_INCREMENTAL_SWEEP_POOL_SLOT_COUNT) {
-        swept_slots = heap->pre_swept_slots_nodeferred - GC_INCREMENTAL_SWEEP_POOL_SLOT_COUNT;
-    }
-    else if (heap->pre_swept_slots_nodeferred > 0) {
-        pooled_slots = heap->pre_swept_slots_nodeferred;
-    }
-    heap->pre_swept_slots_nodeferred = 0;
 
 #if VM_CHECK_MODE > 0
     sweep_lock_lock(&objspace->sweep_lock);