Do full GC for small heaps in idle time 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 {
@@ skipping 60 matching lines @@
 GCIdleTimeAction GCIdleTimeHandler::Compute(size_t idle_time_in_ms,
                                             HeapState heap_state) {
   if (IsIdleRoundFinished()) {
     if (EnoughGarbageSinceLastIdleRound() || heap_state.contexts_disposed > 0) {
       StartIdleRound();
     } else {
       return GCIdleTimeAction::Nothing();
     }
   }
   if (heap_state.incremental_marking_stopped) {
+    const size_t kSmallHeap = 2 * kPointerSize * MB;

[Hannes Payer (out of office), 2014/09/11 09:21:59]

please move this constant to the header file.

     if (idle_time_in_ms >= EstimateMarkCompactTime(
                                heap_state.size_of_objects,
-                               heap_state.mark_compact_speed_in_bytes_per_ms)) {
+                               heap_state.mark_compact_speed_in_bytes_per_ms) ||
+        (heap_state.size_of_objects < kSmallHeap &&
+         heap_state.contexts_disposed > 0)) {
       // 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 (heap_state.contexts_disposed > 0 || remaining_mark_sweeps <= 2 ||
           !heap_state.can_start_incremental_marking) {
         return GCIdleTimeAction::FullGC();
       }
     }
     if (!heap_state.can_start_incremental_marking) {
       return GCIdleTimeAction::Nothing();
     }
   }
   // TODO(hpayer): Estimate finalize sweeping time.
   if (heap_state.sweeping_in_progress &&
       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);
 }
 }
 }