Allow IdleNotification to trigger Scavenges.

src/heap/gc-idle-time-handler.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/gc-idle-time-handler.h"
 #include "src/heap/gc-tracer.h"
 #include "src/utils.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 50 matching lines @@
 size_t GCIdleTimeHandler::EstimateMarkCompactTime(
     size_t size_of_objects, size_t mark_compact_speed_in_bytes_per_ms) {
   if (mark_compact_speed_in_bytes_per_ms == 0) {
     mark_compact_speed_in_bytes_per_ms = kInitialConservativeMarkCompactSpeed;
   }
   size_t result = size_of_objects / mark_compact_speed_in_bytes_per_ms;
   return Min(result, kMaxMarkCompactTimeInMs);
 }
 
 
+size_t GCIdleTimeHandler::EstimateScavengeTime(
+    size_t new_space_size, size_t scavenge_speed_in_bytes_per_ms) {
+  if (scavenge_speed_in_bytes_per_ms == 0) {
+    scavenge_speed_in_bytes_per_ms = kInitialConservativeScavengeSpeed;
+  }
+  return new_space_size / scavenge_speed_in_bytes_per_ms;
+}
+
+
+// The following logic is implemented by the controller:
+// (1) If the new space is almost full and we can effort a Scavenge, then a
+// Scavenge is performed.
+// (2) If there is currently no MarkCompact idle round going on, we start a
+// new idle round if enough garbage was created or we received a context
+// disposal event. Otherwise we do not perform garbage collection to keep
+// system utilization low.
+// (3) If incremental marking is done, we perform a full garbage collection
+// if context was disposed or if we are allowed to still do full garbage
+// collections during this idle round or if we are not allowed to start
+// incremental marking. Otherwise we do not perform garbage collection to
+// keep system utilization low.
+// (4) If sweeping is in progress and we received a large enough idle time
+// request, we finalize sweeping here.
+// (5) If incremental marking is in progress, we perform a marking step. Note,
+// that this currently may trigger a full garbage collection.
 GCIdleTimeAction GCIdleTimeHandler::Compute(size_t idle_time_in_ms,
                                             HeapState heap_state) {
-  if (IsIdleRoundFinished()) {
+  if (heap_state.available_new_space_memory < kNewSpaceAlmostFullTreshold &&
+      idle_time_in_ms >=
+          EstimateScavengeTime(heap_state.new_space_capacity,
+                               heap_state.scavenge_speed_in_bytes_per_ms)) {
+    return GCIdleTimeAction::Scavenge();
+  }
+  if (IsMarkCompactIdleRoundFinished()) {
     if (EnoughGarbageSinceLastIdleRound() || heap_state.contexts_disposed > 0) {
       StartIdleRound();
     } else {
       return GCIdleTimeAction::Nothing();
     }
   }
   if (heap_state.incremental_marking_stopped) {
     if (idle_time_in_ms >= EstimateMarkCompactTime(
                                heap_state.size_of_objects,
                                heap_state.mark_compact_speed_in_bytes_per_ms)) {
@@ skipping 18 matching lines @@
       idle_time_in_ms >= kMinTimeForFinalizeSweeping) {
     return GCIdleTimeAction::FinalizeSweeping();
   }
 
   size_t step_size = EstimateMarkingStepSize(
       idle_time_in_ms, heap_state.incremental_marking_speed_in_bytes_per_ms);
   return GCIdleTimeAction::IncrementalMarking(step_size);
 }
 }
 }