Use smaller heap growing factor in idle notification to start incremental marking when there is idl…

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 4f624a3ab4b538d0b0eb128fc094516d6e03883c..88b0868b681f87fa66e02a700051c780ee724f63 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -1225,13 +1225,13 @@ class Heap {
     survived_since_last_expansion_ += survived;
   }
 
-  inline bool NextGCIsLikelyToBeFull() {
+  inline bool NextGCIsLikelyToBeFull(intptr_t limit = 0) {

[ulan, 2015/04/16 14:17:22]

Always pass the limit (either the old_generation_allocation_limit_ or the
idle_limit) and get rid of the conditional below?

[Hannes Payer (out of office), 2015/04/16 14:46:45]

Done.

     if (FLAG_gc_global) return true;
 
     if (FLAG_stress_compaction && (gc_count_ & 1) != 0) return true;
 
-    intptr_t adjusted_allocation_limit =
-        old_generation_allocation_limit_ - new_space_.Capacity();
+    if (limit == 0) limit = old_generation_allocation_limit_;
+    intptr_t adjusted_allocation_limit = limit - new_space_.Capacity();
 
     if (PromotedTotalSize() >= adjusted_allocation_limit) return true;
 
@@ -1633,6 +1633,19 @@ class Heap {
   // generation and on every allocation in large object space.
   intptr_t old_generation_allocation_limit_;
 
+  // The minimum factor used to grow the old generation.

[ulan, 2015/04/16 14:17:22]

Each additional state variable complicates GC scheduling. Let's minimize the
number of state variables.

One state variable is unavoidable: either current_old_generation_growing_factor_
or better idle_limit_.

Everything else should be a (local) constant I think.

[Hannes Payer (out of office), 2015/04/16 14:46:45]

Done.

+  double min_old_generation_growing_factor_;

[Erik Corry Chromium.org, 2015/04/16 14:16:44]

This never changes.

[Hannes Payer (out of office), 2015/04/16 14:46:45]

Done.

+
+  // The maximum factor used to grow the old generation.
+  double max_old_generation_growing_factor_;
+
+  // The factor used in the idle notification to grow the old generation.
+  double idle_old_generation_growing_factor_;

[Erik Corry Chromium.org, 2015/04/16 14:16:44]

This never changes.

I think it keeps things simpler to have these as genuine constants.

[Hannes Payer (out of office), 2015/04/16 14:46:45]

Done.

+
+  // The currently used old generation growing factor determined by the heap
+  // growing strategy (not by the idle notification).
+  double current_old_generation_growing_factor_;
+
   // Indicates that an allocation has failed in the old generation since the
   // last GC.
   bool old_gen_exhausted_;