[heap] Print more info in incremental marking tracing.

BUG=

Review-Url: https://codereview.chromium.org/2299543010
Cr-Commit-Position: refs/heads/master@{#39077}

src/heap/heap.cc

@@ -964,7 +964,8 @@ bool Heap::CollectGarbage(GarbageCollector collector, const char* gc_reason,
 
   if (collector == SCAVENGER && !incremental_marking()->IsStopped()) {
     if (FLAG_trace_incremental_marking) {
-      PrintF("[IncrementalMarking] Scavenge during marking.\n");
+      isolate()->PrintWithTimestamp(
+          "[IncrementalMarking] Scavenge during marking.\n");
     }
   }
 
@@ -976,7 +977,8 @@ bool Heap::CollectGarbage(GarbageCollector collector, const char* gc_reason,
         !mark_compact_collector()->marking_deque_.IsEmpty() &&
         !FLAG_gc_global) {
       if (FLAG_trace_incremental_marking) {
-        PrintF("[IncrementalMarking] Delaying MarkSweep.\n");
+        isolate()->PrintWithTimestamp(
+            "[IncrementalMarking] Delaying MarkSweep.\n");
       }
       collector = SCAVENGER;
       collector_reason = "incremental marking delaying mark-sweep";

src/heap/incremental-marking.cc

@@ -487,9 +487,16 @@ static void PatchIncrementalMarkingRecordWriteStubs(
 
 void IncrementalMarking::Start(const char* reason) {
   if (FLAG_trace_incremental_marking) {
+    int old_generation_size_mb =
+        static_cast<int>(heap()->PromotedSpaceSizeOfObjects() / MB);
+    int old_generation_limit_mb =
+        static_cast<int>(heap()->old_generation_allocation_limit() / MB);
     heap()->isolate()->PrintWithTimestamp(
-        "[IncrementalMarking] Start (%s)\n",
-        (reason == nullptr) ? "unknown reason" : reason);
+        "[IncrementalMarking] Start (%s): old generation %dMB, limit %dMB, "
+        "slack %dMB\n",
+        (reason == nullptr) ? "unknown reason" : reason, old_generation_size_mb,
+        old_generation_limit_mb,
+        Max(0, old_generation_limit_mb - old_generation_size_mb));
   }
   DCHECK(FLAG_incremental_marking);
   DCHECK(state_ == STOPPED);
@@ -959,7 +966,15 @@ void IncrementalMarking::Hurry() {
 void IncrementalMarking::Stop() {
   if (IsStopped()) return;
   if (FLAG_trace_incremental_marking) {
-    heap()->isolate()->PrintWithTimestamp("[IncrementalMarking] Stopping.\n");
+    int old_generation_size_mb =
+        static_cast<int>(heap()->PromotedSpaceSizeOfObjects() / MB);
+    int old_generation_limit_mb =
+        static_cast<int>(heap()->old_generation_allocation_limit() / MB);
+    heap()->isolate()->PrintWithTimestamp(
+        "[IncrementalMarking] Stopping: old generation %dMB, limit %dMB, "
+        "overshoot %dMB\n",
+        old_generation_size_mb, old_generation_limit_mb,
+        Max(0, old_generation_size_mb - old_generation_limit_mb));
   }
 
   heap_->new_space()->RemoveAllocationObserver(&observer_);