Limit rate of full garbage collections triggered by idle notification.

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::kIdleScavengeThreshold = 5;
 const double GCIdleTimeHandler::kHighContextDisposalRate = 100;
 const size_t GCIdleTimeHandler::kMinTimeForOverApproximatingWeakClosureInMs = 1;
+const double GCIdleTimeHandler::kMinMillisecondsInBetweenMarkCompact = 1000;
 
 
 void GCIdleTimeAction::Print() {
   switch (type) {
     case DONE:
       PrintF("done");
       break;
     case DO_NOTHING:
       PrintF("no action");
       break;
@@ skipping 115 matching lines @@
         idle_time_in_ms) {
       return true;
     }
   }
   return false;
 }
 
 
 bool GCIdleTimeHandler::ShouldDoMarkCompact(
     size_t idle_time_in_ms, size_t size_of_objects,
-    size_t mark_compact_speed_in_bytes_per_ms) {
-  return idle_time_in_ms >=
-         EstimateMarkCompactTime(size_of_objects,
-                                 mark_compact_speed_in_bytes_per_ms);
+    size_t mark_compact_speed_in_bytes_per_ms, double last_mark_compact_time,
+    double current_time) {
+  bool mark_compact_rate_high =
+      current_time <
+      last_mark_compact_time + kMinMillisecondsInBetweenMarkCompact;

[jochen (gone - plz use gerrit), 2015/03/20 12:41:52]

you're adding seconds + milliseconds here as far as I can tell

[Hannes Payer (out of office), 2015/03/20 14:20:39]

yeah, found it when I run the experiment. already removed.

+  return !mark_compact_rate_high &&
+         idle_time_in_ms >=
+             EstimateMarkCompactTime(size_of_objects,
+                                     mark_compact_speed_in_bytes_per_ms);
 }
 
 
 bool GCIdleTimeHandler::ShouldDoContextDisposalMarkCompact(
     int contexts_disposed, double contexts_disposal_rate) {
   return contexts_disposed > 0 && contexts_disposal_rate > 0 &&
          contexts_disposal_rate < kHighContextDisposalRate;
 }
 
 
@@ skipping 28 matching lines @@
 // round or if we are not allowed to start incremental marking. Otherwise we
 // do not perform garbage collection to keep system utilization low.
 // (5) If sweeping is in progress and we received a large enough idle time
 // request, we finalize sweeping here.
 // (6) If incremental marking is in progress, we perform a marking step. Note,
 // that this currently may trigger a full garbage collection.
 GCIdleTimeAction GCIdleTimeHandler::Compute(double idle_time_in_ms,
                                             HeapState heap_state) {
   if (static_cast<int>(idle_time_in_ms) <= 0) {
     if (heap_state.contexts_disposed > 0) {
+      printf("start idle round, contexts disposed\n");

[jochen (gone - plz use gerrit), 2015/03/20 12:41:52]

debug code?

[Hannes Payer (out of office), 2015/03/20 14:20:39]

Done.

       StartIdleRound();
     }
     if (heap_state.incremental_marking_stopped) {
       if (ShouldDoContextDisposalMarkCompact(
               heap_state.contexts_disposed,
               heap_state.contexts_disposal_rate)) {
         return GCIdleTimeAction::FullGC();
       }
     }
     return GCIdleTimeAction::Nothing();
   }
 
   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()) {
     if (EnoughGarbageSinceLastIdleRound()) {
+      printf("start idle round, enough garbage\n");
       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 (ShouldDoMarkCompact(
+            static_cast<size_t>(idle_time_in_ms), heap_state.size_of_objects,
+            heap_state.mark_compact_speed_in_bytes_per_ms,
+            heap_state.last_mark_compact_time, heap_state.current_time)) {
       // 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)) {
@@ skipping 14 matching lines @@
       !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);
 }
 }
 }