Start incremental marking only if there are enough promoted objects since the last GC.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 672b490ff479ea8e09e0293aef56694d9a3c34c2..b1c805e167676d75f8bde1d2faa8db7e98f57195 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1337,6 +1337,10 @@ class Heap {
     return PromotedSpaceSize() + PromotedExternalMemorySize();
   }
 
+  inline intptr_t PromotedTotalSizeOfObjects() {
+    return PromotedSpaceSizeOfObjects() + PromotedExternalMemorySize();
+  }
+
   // True if we have reached the allocation limit in the old generation that
   // should force the next GC (caused normally) to be a full one.
   inline bool OldGenerationPromotionLimitReached() {
@@ -1440,8 +1444,15 @@ class Heap {
   }
 
   inline bool NextGCIsLikelyToBeFull() {
+    const int kPromotionFraction = 8;
+
     if (FLAG_gc_global) return true;
 
+    intptr_t promoted_at_gc = total_promoted_at_last_old_space_gc_;
+    intptr_t promoted_since_gc = PromotedTotalSizeOfObjects() - promoted_at_gc;
+
+    if (promoted_since_gc < promoted_at_gc / kPromotionFraction) return false;
+
     intptr_t total_promoted = PromotedTotalSize();
 
     intptr_t adjusted_promotion_limit =
@@ -1690,6 +1701,8 @@ class Heap {
   // Used to adjust the limits that control the timing of the next GC.
   intptr_t size_of_old_gen_at_last_old_space_gc_;
 
+  intptr_t total_promoted_at_last_old_space_gc_;
+
   // Limit on the amount of externally allocated memory allowed
   // between global GCs. If reached a global GC is forced.
   intptr_t external_allocation_limit_;