growth diag

Author: luke-gruber

gc/default/default.c

@@ -139,6 +139,18 @@
 #define major_gc_diag(...) (void)0
 #endif
 
+/* Logs the heap-growth gate decisions (gc_marks_finish + gc_sweep_finish_heap)
+ * so a serial vs. parallel-sweep run can be diffed. Compile with
+ * -DGROWTH_DIAG=1 to enable. */
+#ifndef GROWTH_DIAG
+#define GROWTH_DIAG 0
+#endif
+#if GROWTH_DIAG
+#define growth_diag(...) fprintf(stderr, __VA_ARGS__)
+#else
+#define growth_diag(...) (void)0
+#endif
+
 #ifndef PSWEEP_LOCK_STATS
 #define PSWEEP_LOCK_STATS 0
 #endif
@@ -5482,6 +5494,13 @@ gc_sweep_finish_heap(rb_objspace_t *objspace, rb_heap_t *heap)
     }
 #endif
 
+#if GROWTH_DIAG
+    const char *gd_decision = "no_growth_gate";
+    size_t gd_swept_initial = swept_slots;
+    size_t gd_alloc_before = objspace->heap_pages.allocatable_bytes;
+    size_t gd_resurrected = 0;
+#endif
+
     if (swept_slots < min_free_slots &&
             /* The heap is a growth heap if it freed more slots than had empty slots. */
             ((heap->empty_slots == 0 && total_slots > 0) || heap->freed_slots > heap->empty_slots)) {
@@ -5496,6 +5515,10 @@ gc_sweep_finish_heap(rb_objspace_t *objspace, rb_heap_t *heap)
             heap_add_freepage(heap, resurrected_page, "gc_sweep_finish_heap");
 
             swept_slots += resurrected_page->free_slots;
+#if GROWTH_DIAG
+            gd_resurrected++;
+            gd_decision = "resurrect";
+#endif
         }
 
         if (swept_slots < min_free_slots) {
@@ -5505,15 +5528,32 @@ gc_sweep_finish_heap(rb_objspace_t *objspace, rb_heap_t *heap)
                     objspace->profile.count - objspace->rgengc.last_major_gc < RVALUE_OLD_AGE) {
                 if (objspace->heap_pages.allocatable_bytes < min_free_slots * heap->slot_size) {
                     heap_allocatable_bytes_expand(objspace, heap, swept_slots, heap->total_slots, heap->slot_size);
+#if GROWTH_DIAG
+                    gd_decision = "expand";
+#endif
                 }
             }
             else if (swept_slots < min_free_slots * 7 / 8 &&
                      objspace->heap_pages.allocatable_bytes < (min_free_slots * 7 / 8 - swept_slots) * heap->slot_size) {
                 gc_needs_major_flags |= GPR_FLAG_MAJOR_BY_NOFREE;
                 heap->force_major_gc_count++;
+#if GROWTH_DIAG
+                gd_decision = "force_major_nofree";
+#endif
             }
         }
     }
+
+    growth_diag("[growth_diag] site=sweep_finish_heap psweep=%d heap=%d reason=0x%x count=%zu "
+                "since_major=%zd full_mark=%d total_slots=%zu swept=%zu(freed=%zu+empty=%zu) "
+                "min_free=%zu alloc_bytes=%zu->%zu resurrected=%zu decision=%s\n",
+                USE_PARALLEL_SWEEP, (int)(heap - heaps), objspace->profile.latest_gc_info,
+                objspace->profile.count,
+                (ssize_t)(objspace->profile.count - objspace->rgengc.last_major_gc),
+                is_full_marking(objspace), total_slots, gd_swept_initial,
+                heap->freed_slots, heap->empty_slots, min_free_slots,
+                gd_alloc_before, objspace->heap_pages.allocatable_bytes,
+                gd_resurrected, gd_decision);
 }
 
 static void
@@ -7542,14 +7582,35 @@ gc_marks_finish(rb_objspace_t *objspace)
             heap_pages_freeable_pages = 0;
         }
 
+#if GROWTH_DIAG
+        const char *gd_decision;
+        int gd_full_entry = full_marking;
+        size_t gd_alloc_before = objspace->heap_pages.allocatable_bytes;
+        if (objspace->heap_pages.allocatable_bytes != 0) {
+            gd_decision = "closed:alloc_bytes_nonzero";
+        }
+        else if (sweep_slots >= min_free_slots) {
+            gd_decision = "closed:enough_free";
+        }
+        else {
+            gd_decision = "open:noop";
+        }
+#endif
+
         if (objspace->heap_pages.allocatable_bytes == 0 && sweep_slots < min_free_slots) {
             if (!full_marking && sweep_slots < min_free_slots * 7 / 8) {
                 if (objspace->profile.count - objspace->rgengc.last_major_gc < RVALUE_OLD_AGE) {
                     full_marking = TRUE;
+#if GROWTH_DIAG
+                    gd_decision = "promote_to_full";
+#endif
                 }
                 else {
                     gc_report(1, objspace, "gc_marks_finish: next is full GC!!)\n");
                     gc_needs_major_flags |= GPR_FLAG_MAJOR_BY_NOFREE;
+#if GROWTH_DIAG
+                    gd_decision = "force_major_nofree";
+#endif
                 }
             }
 
@@ -7562,9 +7623,21 @@ gc_marks_finish(rb_objspace_t *objspace)
                 /*size_t avg_slot_size = total_slots > 0 ? total_heap_bytes / total_slots : (size_t)heaps[0].slot_size;*/
                 /*heap_allocatable_bytes_expand(objspace, NULL, sweep_slots, total_slots, avg_slot_size);*/
                 heap_allocatable_bytes_expand(objspace, NULL, sweep_slots, total_slots, heaps[0].slot_size);
+#if GROWTH_DIAG
+                if (gd_full_entry) gd_decision = "expand";
+#endif
             }
         }
 
+        growth_diag("[growth_diag] site=marks_finish psweep=%d reason=0x%x count=%zu since_major=%zd "
+                    "full_mark=%d total_slots=%zu sweep_slots=%zu min_free=%zu max_free=%zu "
+                    "freeable_pages=%zu alloc_bytes=%zu->%zu decision=%s\n",
+                    USE_PARALLEL_SWEEP, objspace->profile.latest_gc_info, objspace->profile.count,
+                    (ssize_t)(objspace->profile.count - objspace->rgengc.last_major_gc),
+                    gd_full_entry, total_slots, sweep_slots, min_free_slots, max_free_slots,
+                    heap_pages_freeable_pages, gd_alloc_before, objspace->heap_pages.allocatable_bytes,
+                    gd_decision);
+
         if (full_marking) {
             /* See the comment about RUBY_GC_HEAP_OLDOBJECT_LIMIT_FACTOR */
             const double r = gc_params.oldobject_limit_factor;