Activate memory reducer for small heaps in background tabs.

BUG=chromium:587574
LOG=NO

Review URL: https://codereview.chromium.org/1705183003

Cr-Commit-Position: refs/heads/master@{#34188}

src/heap/heap.cc

@@ -1063,9 +1063,9 @@ int Heap::NotifyContextDisposed(bool dependant_context) {
     tracer()->ResetSurvivalEvents();
     old_generation_size_configured_ = false;
     MemoryReducer::Event event;
-    event.type = MemoryReducer::kContextDisposed;
+    event.type = MemoryReducer::kPossibleGarbage;
     event.time_ms = MonotonicallyIncreasingTimeInMs();
-    memory_reducer_->NotifyContextDisposed(event);
+    memory_reducer_->NotifyPossibleGarbage(event);
   }
   if (isolate()->concurrent_recompilation_enabled()) {
     // Flush the queued recompilation tasks.
@@ -4113,6 +4113,20 @@ bool Heap::HasHighFragmentation(intptr_t used, intptr_t committed) {
   return committed - used > used + kSlack;
 }
 
+void Heap::SetOptimizeForMemoryUsage() {
+  // Activate memory reducer when switching to background if
+  // - there was no mark compact since the start.
+  // - the committed memory can be potentially reduced.
+  // 2 pages for the old, code, and map space + 1 page for new space.
+  const int kMinCommittedMemory = 7 * Page::kPageSize;
+  if (ms_count_ == 0 && CommittedMemory() > kMinCommittedMemory) {
+    MemoryReducer::Event event;
+    event.type = MemoryReducer::kPossibleGarbage;
+    event.time_ms = MonotonicallyIncreasingTimeInMs();
+    memory_reducer_->NotifyPossibleGarbage(event);
+  }
+  optimize_for_memory_usage_ = true;
+}
 
 void Heap::ReduceNewSpaceSize() {
   // TODO(ulan): Unify this constant with the similar constant in

src/heap/heap.h

@@ -821,7 +821,7 @@ class Heap {
   bool HasHighFragmentation(intptr_t used, intptr_t committed);
 
   void SetOptimizeForLatency() { optimize_for_memory_usage_ = false; }
-  void SetOptimizeForMemoryUsage() { optimize_for_memory_usage_ = true; }
+  void SetOptimizeForMemoryUsage();
   bool ShouldOptimizeForMemoryUsage() { return optimize_for_memory_usage_; }
 
   // ===========================================================================

src/heap/incremental-marking.cc

@@ -444,7 +444,16 @@ void IncrementalMarking::ActivateIncrementalWriteBarrier() {
 
 
 bool IncrementalMarking::ShouldActivateEvenWithoutIdleNotification() {
+#ifndef DEBUG
+  static const intptr_t kActivationThreshold = 8 * MB;
+#else
+  // TODO(gc) consider setting this to some low level so that some
+  // debug tests run with incremental marking and some without.
+  static const intptr_t kActivationThreshold = 0;
+#endif
+  // Don't switch on for very small heaps.
   return CanBeActivated() &&
+         heap_->PromotedSpaceSizeOfObjects() > kActivationThreshold &&
          heap_->HeapIsFullEnoughToStartIncrementalMarking(
              heap_->old_generation_allocation_limit());
 }
@@ -454,21 +463,12 @@ bool IncrementalMarking::WasActivated() { return was_activated_; }
 
 
 bool IncrementalMarking::CanBeActivated() {
-#ifndef DEBUG
-  static const intptr_t kActivationThreshold = 8 * MB;
-#else
-  // TODO(gc) consider setting this to some low level so that some
-  // debug tests run with incremental marking and some without.
-  static const intptr_t kActivationThreshold = 0;
-#endif
   // Only start incremental marking in a safe state: 1) when incremental
   // marking is turned on, 2) when we are currently not in a GC, and
   // 3) when we are currently not serializing or deserializing the heap.
-  // Don't switch on for very small heaps.
   return FLAG_incremental_marking && heap_->gc_state() == Heap::NOT_IN_GC &&
          heap_->deserialization_complete() &&
-         !heap_->isolate()->serializer_enabled() &&
-         heap_->PromotedSpaceSizeOfObjects() > kActivationThreshold;
+         !heap_->isolate()->serializer_enabled();
 }
 
 

src/heap/memory-reducer.cc

@@ -47,7 +47,7 @@ void MemoryReducer::TimerTask::RunInternal() {
   event.should_start_incremental_gc = is_idle || optimize_for_memory;
   event.can_start_incremental_gc =
       heap->incremental_marking()->IsStopped() &&
-      heap->incremental_marking()->CanBeActivated();
+      (heap->incremental_marking()->CanBeActivated() || optimize_for_memory);
   memory_reducer_->NotifyTimer(event);
 }
 
@@ -118,9 +118,8 @@ void MemoryReducer::NotifyMarkCompact(const Event& event) {
   }
 }
 
-
-void MemoryReducer::NotifyContextDisposed(const Event& event) {
-  DCHECK_EQ(kContextDisposed, event.type);
+void MemoryReducer::NotifyPossibleGarbage(const Event& event) {
+  DCHECK_EQ(kPossibleGarbage, event.type);
   Action old_action = state_.action;
   state_ = Step(state_, event);
   if (old_action != kWait && state_.action == kWait) {
@@ -147,14 +146,14 @@ MemoryReducer::State MemoryReducer::Step(const State& state,
       if (event.type == kTimer) {
         return state;
       } else {
-        DCHECK(event.type == kContextDisposed || event.type == kMarkCompact);
+        DCHECK(event.type == kPossibleGarbage || event.type == kMarkCompact);
         return State(
             kWait, 0, event.time_ms + kLongDelayMs,
             event.type == kMarkCompact ? event.time_ms : state.last_gc_time_ms);
       }
     case kWait:
       switch (event.type) {
-        case kContextDisposed:
+        case kPossibleGarbage:
           return state;
         case kTimer:
           if (state.started_gcs >= kMaxNumberOfGCs) {

src/heap/memory-reducer.h

@@ -96,7 +96,7 @@ class MemoryReducer {
     double last_gc_time_ms;
   };
 
-  enum EventType { kTimer, kMarkCompact, kContextDisposed };
+  enum EventType { kTimer, kMarkCompact, kPossibleGarbage };
 
   struct Event {
     EventType type;
@@ -113,7 +113,7 @@ class MemoryReducer {
         js_calls_sample_time_ms_(0.0) {}
   // Callbacks.
   void NotifyMarkCompact(const Event& event);
-  void NotifyContextDisposed(const Event& event);
+  void NotifyPossibleGarbage(const Event& event);
   void NotifyBackgroundIdleNotification(const Event& event);
   // The step function that computes the next state from the current state and
   // the incoming event.

test/unittests/heap/memory-reducer-unittest.cc

@@ -74,10 +74,9 @@ MemoryReducer::Event TimerEventPendingGC(double time_ms) {
   return TimerEvent(time_ms, true, false);
 }
 
-
-MemoryReducer::Event ContextDisposedEvent(double time_ms) {
+MemoryReducer::Event PossibleGarbageEvent(double time_ms) {
   MemoryReducer::Event event;
-  event.type = MemoryReducer::kContextDisposed;
+  event.type = MemoryReducer::kPossibleGarbage;
   event.time_ms = time_ms;
   return event;
 }
@@ -114,7 +113,7 @@ TEST(MemoryReducer, FromDoneToWait) {
   EXPECT_EQ(0, state1.started_gcs);
   EXPECT_EQ(2, state1.last_gc_time_ms);
 
-  state1 = MemoryReducer::Step(state0, ContextDisposedEvent(0));
+  state1 = MemoryReducer::Step(state0, PossibleGarbageEvent(0));
   EXPECT_EQ(MemoryReducer::kWait, state1.action);
   EXPECT_EQ(MemoryReducer::kLongDelayMs, state1.next_gc_start_ms);
   EXPECT_EQ(0, state1.started_gcs);
@@ -127,7 +126,7 @@ TEST(MemoryReducer, FromWaitToWait) {
 
   MemoryReducer::State state0(WaitState(2, 1000.0)), state1(DoneState());
 
-  state1 = MemoryReducer::Step(state0, ContextDisposedEvent(2000));
+  state1 = MemoryReducer::Step(state0, PossibleGarbageEvent(2000));
   EXPECT_EQ(MemoryReducer::kWait, state1.action);
   EXPECT_EQ(state0.next_gc_start_ms, state1.next_gc_start_ms);
   EXPECT_EQ(state0.started_gcs, state1.started_gcs);
@@ -250,7 +249,7 @@ TEST(MemoryReducer, FromRunToRun) {
   EXPECT_EQ(state0.started_gcs, state1.started_gcs);
   EXPECT_EQ(state0.last_gc_time_ms, state1.last_gc_time_ms);
 
-  state1 = MemoryReducer::Step(state0, ContextDisposedEvent(2000));
+  state1 = MemoryReducer::Step(state0, PossibleGarbageEvent(2000));
   EXPECT_EQ(MemoryReducer::kRun, state1.action);
   EXPECT_EQ(state0.next_gc_start_ms, state1.next_gc_start_ms);
   EXPECT_EQ(state0.started_gcs, state1.started_gcs);