Add stats for objects marked

Author: markshannon

Include/cpython/pystats.h

@@ -99,6 +99,7 @@ typedef struct _gc_stats {
     uint64_t collections;
     uint64_t object_visits;
     uint64_t objects_collected;
+    uint64_t objects_marked;
 } GCStats;
 
 typedef struct _uop_stats {

Python/gc.c

@@ -1445,21 +1445,23 @@ gc_mark(PyThreadState *tstate, struct gc_collection_stats *stats)
     gc_list_init(&reachable);
     // Move all reachable objects into visited space.
     PyGC_Head *gc = AS_GC(tstate->interp->sysdict);
+    Py_ssize_t objects_marked = 0;
     if (gc_old_space(gc) != gcstate->visited_space) {
         gc_flip_old_space(gc);
         gc_list_move(gc, &reachable);
+        objects_marked++;
     }
     gc = AS_GC(tstate->interp->builtins);
     if (gc_old_space(gc) != gcstate->visited_space) {
         gc_flip_old_space(gc);
         gc_list_move(gc, &reachable);
+        objects_marked++;
     }
     // Move all objects on stacks to reachable
     _PyRuntimeState *runtime = &_PyRuntime;
     HEAD_LOCK(runtime);
     PyThreadState* ts = PyInterpreterState_ThreadHead(tstate->interp);
     HEAD_UNLOCK(runtime);
-    Py_ssize_t objects_marked = 0;
     while (ts) {
         _PyInterpreterFrame *frame = ts->current_frame;
         while (frame) {
@@ -1503,8 +1505,14 @@ gc_mark(PyThreadState *tstate, struct gc_collection_stats *stats)
                         visit_add_to_container,
                         &arg);
     }
+    objects_marked += arg.size;
     validate_old(gcstate);
     gcstate->work_to_do -= objects_marked;
+#ifdef Py_STATS
+    if (_Py_stats) {
+        GC_STAT_ADD(1, objects_marked, objects_marked);
+    }
+#endif
     gcstate->phase = GC_PHASE_COLLECT;
 }
 

Python/specialize.c

@@ -230,6 +230,7 @@ print_gc_stats(FILE *out, GCStats *stats)
     for (int i = 0; i < NUM_GENERATIONS; i++) {
         fprintf(out, "GC[%d] collections: %" PRIu64 "\n", i, stats[i].collections);
         fprintf(out, "GC[%d] object visits: %" PRIu64 "\n", i, stats[i].object_visits);
+        fprintf(out, "GC[%d] objects marked: %" PRIu64 "\n", i, stats[i].objects_marked);
         fprintf(out, "GC[%d] objects collected: %" PRIu64 "\n", i, stats[i].objects_collected);
     }
 }

Tools/scripts/summarize_stats.py

@@ -1118,6 +1118,7 @@ def calc_gc_stats(stats: Stats) -> Rows:
                 Count(gen["collections"]),
                 Count(gen["objects collected"]),
                 Count(gen["object visits"]),
+                Count(gen["objects marked"]),
             )
             for (i, gen) in enumerate(gc_stats)
         ]
@@ -1127,7 +1128,7 @@ def calc_gc_stats(stats: Stats) -> Rows:
         "GC collections and effectiveness",
         [
             Table(
-                ("Generation:", "Collections:", "Objects collected:", "Object visits:"),
+                ("Generation:", "Collections:", "Objects collected:", "Object visits:", "Objects marked:"),
                 calc_gc_stats,
             )
         ],