Fix responsiveness of high promotion mode heuristics.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 6295788f0af9a2f4d1e772143ff684362b568d75..20e37034988236b9e748109a51756149f10a166d 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -688,12 +688,18 @@ void Heap::UpdateSurvivalRateTrend(int start_new_space_size) {
       (static_cast<double>(young_survivors_after_last_gc_) * 100) /
       start_new_space_size;
 
-  if (survival_rate > kYoungSurvivalRateThreshold) {
+  if (survival_rate > kYoungSurvivalRateHighThreshold) {
     high_survival_rate_period_length_++;
   } else {
     high_survival_rate_period_length_ = 0;
   }
 
+  if (survival_rate < kYoungSurvivalRateLowThreshold) {
+    low_survival_rate_period_length_++;
+  } else {
+    low_survival_rate_period_length_ = 0;
+  }
+
   double survival_rate_diff = survival_rate_ - survival_rate;
 
   if (survival_rate_diff > kYoungSurvivalRateAllowedDeviation) {
@@ -753,32 +759,6 @@ bool Heap::PerformGarbageCollection(GarbageCollector collector,
 
     UpdateSurvivalRateTrend(start_new_space_size);
 
-    if (!new_space_high_promotion_mode_active_ &&
-        new_space_.Capacity() == new_space_.MaximumCapacity() &&
-        IsStableOrIncreasingSurvivalTrend() &&
-        IsHighSurvivalRate()) {
-      // Stable high survival rates even though young generation is at
-      // maximum capacity indicates that most objects will be promoted.
-      // To decrease scavenger pauses and final mark-sweep pauses, we
-      // have to limit maximal capacity of the young generation.
-      new_space_high_promotion_mode_active_ = true;
-      if (FLAG_trace_gc) {
-        PrintF("Limited new space size due to high promotion rate: %d MB\n",
-               new_space_.InitialCapacity() / MB);
-      }
-    } else if (new_space_high_promotion_mode_active_ &&
-        IsDecreasingSurvivalTrend() &&
-        !IsHighSurvivalRate()) {
-      // Decreasing low survival rates might indicate that the above high
-      // promotion mode is over and we should allow the young generation
-      // to grow again.
-      new_space_high_promotion_mode_active_ = false;
-      if (FLAG_trace_gc) {
-        PrintF("Unlimited new space size due to low promotion rate: %d MB\n",
-               new_space_.MaximumCapacity() / MB);
-      }
-    }
-
     size_of_old_gen_at_last_old_space_gc_ = PromotedSpaceSize();
 
     if (high_survival_rate_during_scavenges &&
@@ -808,6 +788,32 @@ bool Heap::PerformGarbageCollection(GarbageCollector collector,
     UpdateSurvivalRateTrend(start_new_space_size);
   }
 
+  if (!new_space_high_promotion_mode_active_ &&
+      new_space_.Capacity() == new_space_.MaximumCapacity() &&
+      IsStableOrIncreasingSurvivalTrend() &&
+      IsHighSurvivalRate()) {
+    // Stable high survival rates even though young generation is at
+    // maximum capacity indicates that most objects will be promoted.
+    // To decrease scavenger pauses and final mark-sweep pauses, we
+    // have to limit maximal capacity of the young generation.
+    new_space_high_promotion_mode_active_ = true;
+    if (FLAG_trace_gc) {
+      PrintF("Limited new space size due to high promotion rate: %d MB\n",
+             new_space_.InitialCapacity() / MB);
+    }
+  } else if (new_space_high_promotion_mode_active_ &&
+      IsStableOrDecreasingSurvivalTrend() &&
+      IsLowSurvivalRate()) {
+    // Decreasing low survival rates might indicate that the above high
+    // promotion mode is over and we should allow the young generation
+    // to grow again.
+    new_space_high_promotion_mode_active_ = false;
+    if (FLAG_trace_gc) {
+      PrintF("Unlimited new space size due to low promotion rate: %d MB\n",
+             new_space_.MaximumCapacity() / MB);
+    }
+  }
+
   if (new_space_high_promotion_mode_active_ &&
       new_space_.Capacity() > new_space_.InitialCapacity()) {
     new_space_.Shrink();
@@ -5404,12 +5410,12 @@ void Heap::RecordStats(HeapStats* stats, bool take_snapshot) {
 
 
 intptr_t Heap::PromotedSpaceSize() {

[Vyacheslav Egorov (Chromium), 2012/01/16 12:36:11]

Size->SizeOfObjects for consistency.

[Michael Starzinger, 2012/01/17 11:56:26]

Done. Other NewGC heuristics are tuned for the original version, so I had to
split them anyways.

-  return old_pointer_space_->Size()
-      + old_data_space_->Size()
-      + code_space_->Size()
-      + map_space_->Size()
-      + cell_space_->Size()
-      + lo_space_->Size();
+  return old_pointer_space_->SizeOfObjects()
+      + old_data_space_->SizeOfObjects()
+      + code_space_->SizeOfObjects()
+      + map_space_->SizeOfObjects()
+      + cell_space_->SizeOfObjects()
+      + lo_space_->SizeOfObjects();
 }