Simplified garbage collection idle handler.

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 {
 
 const double GCIdleTimeHandler::kConservativeTimeRatio = 0.9;
 const size_t GCIdleTimeHandler::kMaxMarkCompactTimeInMs = 1000;
 const size_t GCIdleTimeHandler::kMaxFinalIncrementalMarkCompactTimeInMs = 1000;
 const size_t GCIdleTimeHandler::kMinTimeForFinalizeSweeping = 100;
-const int GCIdleTimeHandler::kMaxMarkCompactsInIdleRound = 7;
+const int GCIdleTimeHandler::kMaxMarkCompactsInIdleRound = 2;
 const int GCIdleTimeHandler::kIdleScavengeThreshold = 5;
 const double GCIdleTimeHandler::kHighContextDisposalRate = 100;
 const size_t GCIdleTimeHandler::kMinTimeForOverApproximatingWeakClosureInMs = 1;
 
 
 void GCIdleTimeAction::Print() {
   switch (type) {
     case DONE:
       PrintF("done");
       break;
@@ skipping 190 matching lines @@
   }
 
   if (ShouldDoScavenge(
           static_cast<size_t>(idle_time_in_ms), heap_state.new_space_capacity,
           heap_state.used_new_space_size,
           heap_state.scavenge_speed_in_bytes_per_ms,
           heap_state.new_space_allocation_throughput_in_bytes_per_ms)) {
     return GCIdleTimeAction::Scavenge();
   }
 
   if (IsMarkCompactIdleRoundFinished()) {

[Hannes Payer (out of office), 2015/03/23 10:55:25]

I am still not happy about the idle round concept. This one triggers
aggressively full garbage collections. Maybe it should be *perform garbage
collection if there was no garbage collection for a long time*.

     if (EnoughGarbageSinceLastIdleRound()) {
       StartIdleRound();
     } else {
       return GCIdleTimeAction::Done();
     }
   }
 
   if (heap_state.incremental_marking_stopped) {
     if (ShouldDoMarkCompact(static_cast<size_t>(idle_time_in_ms),
                             heap_state.size_of_objects,
                             heap_state.mark_compact_speed_in_bytes_per_ms)) {
-      // If there are no more than two GCs left in this idle round and we are
-      // allowed to do a full GC, then make those GCs full in order to compact
-      // the code space.
-      // TODO(ulan): Once we enable code compaction for incremental marking, we
-      // can get rid of this special case and always start incremental marking.
-      int remaining_mark_sweeps =
-          kMaxMarkCompactsInIdleRound - mark_compacts_since_idle_round_started_;
-      if (static_cast<size_t>(idle_time_in_ms) > kMaxScheduledIdleTime &&
-          (remaining_mark_sweeps <= 2 ||
-           !heap_state.can_start_incremental_marking)) {
-        return GCIdleTimeAction::FullGC();
-      }
-    }
-    if (!heap_state.can_start_incremental_marking) {
-      return GCIdleTimeAction::Nothing();
+      return GCIdleTimeAction::FullGC();
     }
   }
+
   // TODO(hpayer): Estimate finalize sweeping time.
   if (heap_state.sweeping_in_progress &&
       static_cast<size_t>(idle_time_in_ms) >= kMinTimeForFinalizeSweeping) {
     return GCIdleTimeAction::FinalizeSweeping();
   }
 
   if (heap_state.incremental_marking_stopped &&
       !heap_state.can_start_incremental_marking) {
     return GCIdleTimeAction::Nothing();
   }
   size_t step_size = EstimateMarkingStepSize(
       static_cast<size_t>(kIncrementalMarkingStepTimeInMs),
       heap_state.incremental_marking_speed_in_bytes_per_ms);
   return GCIdleTimeAction::IncrementalMarking(step_size);
 }
 }
 }