[heap] Remove js call rate heuristic from memory reducer.

This is an experiment to check whether the heuristics is still useful.

BUG=

Review-Url: https://codereview.chromium.org/2482163002
Cr-Commit-Position: refs/heads/master@{#40833}

src/api.cc

@@ -198,7 +198,6 @@ class CallDepthScope {
       : isolate_(isolate), context_(context), escaped_(false) {
     // TODO(dcarney): remove this when blink stops crashing.
     DCHECK(!isolate_->external_caught_exception());
-    isolate_->IncrementJsCallsFromApiCounter();
     isolate_->handle_scope_implementer()->IncrementCallDepth();
     if (!context.IsEmpty()) {
       i::Handle<i::Context> env = Utils::OpenHandle(*context);

src/heap/memory-reducer.cc

@@ -24,19 +24,16 @@ MemoryReducer::TimerTask::TimerTask(MemoryReducer* memory_reducer)
 
 
 void MemoryReducer::TimerTask::RunInternal() {
-  const double kJsCallsPerMsThreshold = 0.5;
   Heap* heap = memory_reducer_->heap();
   Event event;
   double time_ms = heap->MonotonicallyIncreasingTimeInMs();
   heap->tracer()->SampleAllocation(time_ms, heap->NewSpaceAllocationCounter(),
                                    heap->OldGenerationAllocationCounter());
-  double js_call_rate = memory_reducer_->SampleAndGetJsCallsPerMs(time_ms);
   bool low_allocation_rate = heap->HasLowAllocationRate();
-  bool is_idle = js_call_rate < kJsCallsPerMsThreshold && low_allocation_rate;
   bool optimize_for_memory = heap->ShouldOptimizeForMemoryUsage();
   if (FLAG_trace_gc_verbose) {
     heap->isolate()->PrintWithTimestamp(
-        "Memory reducer: call rate %.3lf, %s, %s\n", js_call_rate,
+        "Memory reducer: %s, %s\n",
         low_allocation_rate ? "low alloc" : "high alloc",
         optimize_for_memory ? "background" : "foreground");
   }
@@ -45,7 +42,8 @@ void MemoryReducer::TimerTask::RunInternal() {
   // The memory reducer will start incremental markig if
   // 1) mutator is likely idle: js call rate is low and allocation rate is low.
   // 2) mutator is in background: optimize for memory flag is set.
-  event.should_start_incremental_gc = is_idle || optimize_for_memory;
+  event.should_start_incremental_gc =
+      low_allocation_rate || optimize_for_memory;
   event.can_start_incremental_gc =
       heap->incremental_marking()->IsStopped() &&
       (heap->incremental_marking()->CanBeActivated() || optimize_for_memory);
@@ -53,16 +51,6 @@ void MemoryReducer::TimerTask::RunInternal() {
 }
 
 
-double MemoryReducer::SampleAndGetJsCallsPerMs(double time_ms) {
-  unsigned int counter = heap()->isolate()->js_calls_from_api_counter();
-  unsigned int call_delta = counter - js_calls_counter_;
-  double time_delta_ms = time_ms - js_calls_sample_time_ms_;
-  js_calls_counter_ = counter;
-  js_calls_sample_time_ms_ = time_ms;
-  return time_delta_ms > 0 ? call_delta / time_delta_ms : 0;
-}
-
-
 void MemoryReducer::NotifyTimer(const Event& event) {
   DCHECK_EQ(kTimer, event.type);
   DCHECK_EQ(kWait, state_.action);
@@ -196,8 +184,6 @@ MemoryReducer::State MemoryReducer::Step(const State& state,
 
 void MemoryReducer::ScheduleTimer(double time_ms, double delay_ms) {
   DCHECK(delay_ms > 0);
-  // Record the time and the js call counter.
-  SampleAndGetJsCallsPerMs(time_ms);
   // Leave some room for precision error in task scheduler.
   const double kSlackMs = 100;
   v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(heap()->isolate());

src/heap/memory-reducer.h

@@ -149,9 +149,6 @@ class V8_EXPORT_PRIVATE MemoryReducer {
 
   static bool WatchdogGC(const State& state, const Event& event);
 
-  // Returns the rate of JS calls initiated from the API.
-  double SampleAndGetJsCallsPerMs(double time_ms);
-
   Heap* heap_;
   State state_;
   unsigned int js_calls_counter_;

src/isolate.cc

@@ -2120,7 +2120,6 @@ Isolate::Isolate(bool enable_serializer)
       optimizing_compile_dispatcher_(NULL),
       stress_deopt_count_(0),
       next_optimization_id_(0),
-      js_calls_from_api_counter_(0),
 #if TRACE_MAPS
       next_unique_sfi_id_(0),
 #endif

src/isolate.h

@@ -1073,12 +1073,6 @@ class Isolate {
     return id;
   }
 
-  void IncrementJsCallsFromApiCounter() { ++js_calls_from_api_counter_; }
-
-  unsigned int js_calls_from_api_counter() {
-    return js_calls_from_api_counter_;
-  }
-
   // Get (and lazily initialize) the registry for per-isolate symbols.
   Handle<JSObject> GetSymbolRegistry();
 
@@ -1416,9 +1410,6 @@ class Isolate {
 
   int next_optimization_id_;
 
-  // Counts javascript calls from the API. Wraps around on overflow.
-  unsigned int js_calls_from_api_counter_;
-
 #if TRACE_MAPS
   int next_unique_sfi_id_;
 #endif

test/cctest/heap/test-heap.cc

@@ -6408,30 +6408,6 @@ TEST(Regress519319) {
 }
 
 
-HEAP_TEST(TestMemoryReducerSampleJsCalls) {
-  CcTest::InitializeVM();
-  v8::HandleScope scope(CcTest::isolate());
-  Heap* heap = CcTest::heap();
-  Isolate* isolate = CcTest::i_isolate();
-  MemoryReducer* memory_reducer = heap->memory_reducer_;
-  memory_reducer->SampleAndGetJsCallsPerMs(0);
-  isolate->IncrementJsCallsFromApiCounter();
-  isolate->IncrementJsCallsFromApiCounter();
-  isolate->IncrementJsCallsFromApiCounter();
-  double calls_per_ms = memory_reducer->SampleAndGetJsCallsPerMs(1);
-  CheckDoubleEquals(3, calls_per_ms);
-
-  calls_per_ms = memory_reducer->SampleAndGetJsCallsPerMs(2);
-  CheckDoubleEquals(0, calls_per_ms);
-
-  isolate->IncrementJsCallsFromApiCounter();
-  isolate->IncrementJsCallsFromApiCounter();
-  isolate->IncrementJsCallsFromApiCounter();
-  isolate->IncrementJsCallsFromApiCounter();
-  calls_per_ms = memory_reducer->SampleAndGetJsCallsPerMs(4);
-  CheckDoubleEquals(2, calls_per_ms);
-}
-
 HEAP_TEST(Regress587004) {
   FLAG_concurrent_sweeping = false;
 #ifdef VERIFY_HEAP