Use deadline in IdleNotification.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 97c7d6dac6434437fa50fa647294c34addbc379f..6811eca20a5f5943f681f10413cb0ef36fe7973e 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -4392,10 +4392,13 @@ bool Heap::WorthActivatingIncrementalMarking() {
 
 
 bool Heap::IdleNotification(int idle_time_in_ms) {
-  base::ElapsedTimer timer;
-  timer.Start();
-  isolate()->counters()->gc_idle_time_allotted_in_ms()->AddSample(
-      idle_time_in_ms);
+  return IdleNotification(
+      V8::GetCurrentPlatform()->MonotonicallyIncreasingTime() +
+      static_cast<double>(idle_time_in_ms));
+}
+
+
+bool Heap::IdleNotification(double deadline) {
   HistogramTimerScope idle_notification_scope(
       isolate_->counters()->gc_idle_notification());
 
@@ -4422,11 +4425,14 @@ bool Heap::IdleNotification(int idle_time_in_ms) {
       static_cast<size_t>(
           tracer()->NewSpaceAllocationThroughputInBytesPerMillisecond());
 
+  double idle_time =
+      deadline - V8::GetCurrentPlatform()->MonotonicallyIncreasingTime();

[rmcilroy, 2014/11/25 10:35:41]

Both deadline and MonotonicallyIncreasingTime() return time in seconds, not ms. 
Probably better to rename the arguments to deadline_seconds to avoid this
confusion in the future.  Actually, it might be even better to translate to
base::TimeTicks / base::TimeDelta initially to avoid issues (I would have
returned base::TimeTicks for MonotonicallyIncreasingTime() if it was available
in Blink, but unfortunately it's not).

[Hannes Payer (out of office), 2014/11/25 12:28:59]

I am using now seconds granularity on the api level and internally I convert it
to milliseconds.

   GCIdleTimeAction action =
-      gc_idle_time_handler_.Compute(idle_time_in_ms, heap_state);
+      gc_idle_time_handler_.Compute(idle_time, heap_state);
+  isolate()->counters()->gc_idle_time_allotted_in_ms()->AddSample(
+      static_cast<int>(idle_time));
 
   bool result = false;
-  int actual_time_in_ms = 0;
   switch (action.type) {
     case DONE:
       result = true;
@@ -4439,11 +4445,12 @@ bool Heap::IdleNotification(int idle_time_in_ms) {
                                   IncrementalMarking::NO_GC_VIA_STACK_GUARD,
                                   IncrementalMarking::FORCE_MARKING,
                                   IncrementalMarking::DO_NOT_FORCE_COMPLETION);
-      actual_time_in_ms = static_cast<int>(timer.Elapsed().InMilliseconds());
-      int remaining_idle_time_in_ms = idle_time_in_ms - actual_time_in_ms;
-      if (remaining_idle_time_in_ms > 0) {
+      double remaining_idle_time_in_ms =
+          deadline - V8::GetCurrentPlatform()->MonotonicallyIncreasingTime();
+      if (remaining_idle_time_in_ms > 0.0) {
         TryFinalizeIdleIncrementalMarking(
-            remaining_idle_time_in_ms, heap_state.size_of_objects,
+            static_cast<size_t>(remaining_idle_time_in_ms),
+            heap_state.size_of_objects,
             heap_state.mark_compact_speed_in_bytes_per_ms);
       }
       break;
@@ -4469,20 +4476,24 @@ bool Heap::IdleNotification(int idle_time_in_ms) {
       break;
   }
 
-  actual_time_in_ms = static_cast<int>(timer.Elapsed().InMilliseconds());
-  if (actual_time_in_ms <= idle_time_in_ms) {
+
+  double deadline_difference =
+      deadline - V8::GetCurrentPlatform()->MonotonicallyIncreasingTime();
+  if (deadline_difference >= 0) {
     if (action.type != DONE && action.type != DO_NOTHING) {
       isolate()->counters()->gc_idle_time_limit_undershot()->AddSample(
-          idle_time_in_ms - actual_time_in_ms);
+          static_cast<int>(deadline_difference));
     }
   } else {
     isolate()->counters()->gc_idle_time_limit_overshot()->AddSample(
-        actual_time_in_ms - idle_time_in_ms);
+        static_cast<int>(-deadline_difference));
   }
 
   if (FLAG_trace_idle_notification) {
-    PrintF("Idle notification: requested idle time %d ms, actual time %d ms [",
-           idle_time_in_ms, actual_time_in_ms);
+    PrintF(
+        "Idle notification: requested idle time %.2f ms, deadline difference "
+        "%.2f ms [",
+        idle_time, deadline_difference);
     action.Print();
     PrintF("]");
     if (FLAG_trace_idle_notification_verbose) {