Replace reduce-memory mode in idle notification with delayed clean-up GC.

src/heap/heap.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
 #include "src/compilation-cache.h"
 #include "src/conversions.h"
 #include "src/cpu-profiler.h"
 #include "src/debug.h"
 #include "src/deoptimizer.h"
 #include "src/global-handles.h"
 #include "src/heap/gc-idle-time-handler.h"
 #include "src/heap/incremental-marking.h"
 #include "src/heap/mark-compact.h"
+#include "src/heap/memory-reducer.h"
 #include "src/heap/objects-visiting-inl.h"
 #include "src/heap/objects-visiting.h"
 #include "src/heap/store-buffer.h"
 #include "src/heap-profiler.h"
 #include "src/runtime-profiler.h"
 #include "src/scopeinfo.h"
 #include "src/snapshot/natives.h"
 #include "src/snapshot/serialize.h"
 #include "src/snapshot/snapshot.h"
 #include "src/utils.h"
@@ skipping 67 matching lines @@
       raw_allocations_hash_(0),
       dump_allocations_hash_countdown_(FLAG_dump_allocations_digest_at_alloc),
       ms_count_(0),
       gc_count_(0),
       remembered_unmapped_pages_index_(0),
       unflattened_strings_length_(0),
 #ifdef DEBUG
       allocation_timeout_(0),
 #endif  // DEBUG
       old_generation_allocation_limit_(initial_old_generation_size_),
-      idle_old_generation_allocation_limit_(
-          kMinimumOldGenerationAllocationLimit),
       old_gen_exhausted_(false),
       inline_allocation_disabled_(false),
       store_buffer_rebuilder_(store_buffer()),
       hidden_string_(NULL),
       gc_safe_size_of_old_object_(NULL),
       total_regexp_code_generated_(0),
       tracer_(this),
       new_space_high_promotion_mode_active_(false),
       high_survival_rate_period_length_(0),
       promoted_objects_size_(0),
@@ skipping 14 matching lines @@
       max_alive_after_gc_(0),
       min_in_mutator_(kMaxInt),
       marking_time_(0.0),
       sweeping_time_(0.0),
       last_idle_notification_time_(0.0),
       last_gc_time_(0.0),
       mark_compact_collector_(this),
       store_buffer_(this),
       marking_(this),
       incremental_marking_(this),
+      memory_reducer_(this),
       full_codegen_bytes_generated_(0),
       crankshaft_codegen_bytes_generated_(0),
       new_space_allocation_counter_(0),
       old_generation_allocation_counter_(0),
       old_generation_size_at_last_gc_(0),
       gcs_since_last_deopt_(0),
       allocation_sites_scratchpad_length_(0),
       ring_buffer_full_(false),
       ring_buffer_end_(0),
       promotion_queue_(this),
@@ skipping 763 matching lines @@
         !mark_compact_collector_.marking_deque_.IsEmpty() && !FLAG_gc_global) {
       if (FLAG_trace_incremental_marking) {
         PrintF("[IncrementalMarking] Delaying MarkSweep.\n");
       }
       collector = SCAVENGER;
       collector_reason = "incremental marking delaying mark-sweep";
     }
   }
 
   bool next_gc_likely_to_collect_more = false;
+  intptr_t committed_memory_before;
+
+  if (collector == MARK_COMPACTOR) {
+    committed_memory_before = CommittedOldGenerationMemory();
+  }
 
   {
     tracer()->Start(collector, gc_reason, collector_reason);
     DCHECK(AllowHeapAllocation::IsAllowed());
     DisallowHeapAllocation no_allocation_during_gc;
     GarbageCollectionPrologue();
 
     {
       HistogramTimerScope histogram_timer_scope(
           (collector == SCAVENGER) ? isolate_->counters()->gc_scavenger()
                                    : isolate_->counters()->gc_compactor());
       next_gc_likely_to_collect_more =
           PerformGarbageCollection(collector, gc_callback_flags);
     }
 
     GarbageCollectionEpilogue();
     if (collector == MARK_COMPACTOR && FLAG_track_detached_contexts) {
       isolate()->CheckDetachedContextsAfterGC();
     }
 
     if (collector == MARK_COMPACTOR) {
-      gc_idle_time_handler_.NotifyMarkCompact(next_gc_likely_to_collect_more);
+      intptr_t committed_memory_after = CommittedOldGenerationMemory();
+      intptr_t used_memory_after = PromotedSpaceSizeOfObjects();
+      MemoryReducer::Event event;
+      event.type = MemoryReducer::kMarkCompact;
+      event.time_ms = MonotonicallyIncreasingTimeInMs();
+      // Trigger one more GC if
+      // - this GC decreased committed memory,
+      // - there is high fragmentation,
+      // - there are live detached contexts.
+      event.next_gc_likely_to_collect_more =
+          (committed_memory_before - committed_memory_after) > MB ||
+          HasHighFragmentation(used_memory_after, committed_memory_after) ||
+          (detached_contexts()->length() > 0);
+      memory_reducer_.NotifyMarkCompact(event);
     } else {
-      gc_idle_time_handler_.NotifyScavenge();
+      MemoryReducer::Event event;
+      event.type = MemoryReducer::kScavenge;
+      event.time_ms = MonotonicallyIncreasingTimeInMs();
+      memory_reducer_.NotifyScavenge(event);
     }
 
     tracer()->Stop(collector);
   }
 
   if (collector == MARK_COMPACTOR &&
       (gc_callback_flags & kGCCallbackFlagForced) != 0) {
     isolate()->CountUsage(v8::Isolate::kForcedGC);
   }
 
@@ skipping 14 matching lines @@
     tracer()->ResetSurvivalEvents();
     old_generation_size_configured_ = false;
   }
   if (isolate()->concurrent_recompilation_enabled()) {
     // Flush the queued recompilation tasks.
     isolate()->optimizing_compile_dispatcher()->Flush();
   }
   AgeInlineCaches();
   set_retained_maps(ArrayList::cast(empty_fixed_array()));
   tracer()->AddContextDisposalTime(base::OS::TimeCurrentMillis());
+  MemoryReducer::Event event;
+  event.type = MemoryReducer::kContextDisposed;
+  event.time_ms = MonotonicallyIncreasingTimeInMs();
+  memory_reducer_.NotifyContextDisposed(event);
   return ++contexts_disposed_;
 }
 
 
+void Heap::StartIdleIncrementalMarking() {
+  gc_idle_time_handler_.ResetNoProgressCounter();
+  incremental_marking()->Start(kReduceMemoryFootprintMask);
+}
+
+
 void Heap::MoveElements(FixedArray* array, int dst_index, int src_index,
                         int len) {
   if (len == 0) return;
 
   DCHECK(array->map() != fixed_cow_array_map());
   Object** dst_objects = array->data_start() + dst_index;
   MemMove(dst_objects, array->data_start() + src_index, len * kPointerSize);
   if (!InNewSpace(array)) {
     for (int i = 0; i < len; i++) {
       // TODO(hpayer): check store buffer for entries
@@ skipping 3738 matching lines @@
   return mutator_utilization > high_mutator_utilization;
 }
 
 
 bool Heap::HasLowAllocationRate() {
   return HasLowYoungGenerationAllocationRate() &&
          HasLowOldGenerationAllocationRate();
 }
 
 
+bool Heap::HasHighFragmentation() {
+  intptr_t used = PromotedSpaceSizeOfObjects();
+  intptr_t committed = CommittedOldGenerationMemory();
+  return HasHighFragmentation(used, committed);
+}
+
+
+bool Heap::HasHighFragmentation(intptr_t used, intptr_t committed) {
+  const intptr_t kSlack = 16 * MB;
+  // Fragmentation is high if committed > 2 * used + kSlack.
+  // Rewrite the exression to avoid overflow.
+  return committed - used > used + kSlack;
+}
+
+
 void Heap::ReduceNewSpaceSize() {
   if (!FLAG_predictable && HasLowAllocationRate()) {
     new_space_.Shrink();
     UncommitFromSpace();
   }
 }
 
 
 bool Heap::TryFinalizeIdleIncrementalMarking(
     double idle_time_in_ms, size_t size_of_objects,
     size_t final_incremental_mark_compact_speed_in_bytes_per_ms) {
   if (FLAG_overapproximate_weak_closure &&
       (incremental_marking()->IsReadyToOverApproximateWeakClosure() ||
        (!incremental_marking()->weak_closure_was_overapproximated() &&
         mark_compact_collector_.marking_deque()->IsEmpty() &&
         gc_idle_time_handler_.ShouldDoOverApproximateWeakClosure(
             static_cast<size_t>(idle_time_in_ms))))) {
     OverApproximateWeakClosure(
         "Idle notification: overapproximate weak closure");
     return true;
   } else if (incremental_marking()->IsComplete() ||
              (mark_compact_collector_.marking_deque()->IsEmpty() &&
               gc_idle_time_handler_.ShouldDoFinalIncrementalMarkCompact(
                   static_cast<size_t>(idle_time_in_ms), size_of_objects,
                   final_incremental_mark_compact_speed_in_bytes_per_ms))) {
     CollectAllGarbage(kNoGCFlags, "idle notification: finalize incremental");
-    gc_idle_time_handler_.NotifyIdleMarkCompact();
     return true;
   }
   return false;
 }
 
 
 GCIdleTimeHandler::HeapState Heap::ComputeHeapState() {
   GCIdleTimeHandler::HeapState heap_state;
   heap_state.contexts_disposed = contexts_disposed_;
   heap_state.contexts_disposal_rate =
@@ skipping 10 matching lines @@
       tracer()->IncrementalMarkingSpeedInBytesPerMillisecond());
   heap_state.final_incremental_mark_compact_speed_in_bytes_per_ms =
       static_cast<size_t>(
           tracer()->FinalIncrementalMarkCompactSpeedInBytesPerMillisecond());
   heap_state.scavenge_speed_in_bytes_per_ms =
       static_cast<size_t>(tracer()->ScavengeSpeedInBytesPerMillisecond());
   heap_state.used_new_space_size = new_space_.Size();
   heap_state.new_space_capacity = new_space_.Capacity();
   heap_state.new_space_allocation_throughput_in_bytes_per_ms =
       tracer()->NewSpaceAllocationThroughputInBytesPerMillisecond();
-  heap_state.has_low_allocation_rate = HasLowAllocationRate();
-  intptr_t limit = old_generation_allocation_limit_;
-  if (heap_state.has_low_allocation_rate) {
-    limit = idle_old_generation_allocation_limit_;
-  }
-  heap_state.can_start_incremental_marking =
-      incremental_marking()->CanBeActivated() &&
-      HeapIsFullEnoughToStartIncrementalMarking(limit) &&
-      !mark_compact_collector()->sweeping_in_progress();
   return heap_state;
 }
 
 
 bool Heap::PerformIdleTimeAction(GCIdleTimeAction action,
                                  GCIdleTimeHandler::HeapState heap_state,
                                  double deadline_in_ms) {
   bool result = false;
   switch (action.type) {
     case DONE:
       result = true;
       break;
     case DO_INCREMENTAL_MARKING: {
-      if (incremental_marking()->IsStopped()) {
-        incremental_marking()->Start(
-            action.reduce_memory ? kReduceMemoryFootprintMask : kNoGCFlags);
-      }
+      DCHECK(!incremental_marking()->IsStopped());
       double remaining_idle_time_in_ms = 0.0;
       do {
         incremental_marking()->Step(
             action.parameter, IncrementalMarking::NO_GC_VIA_STACK_GUARD,
             IncrementalMarking::FORCE_MARKING,
             IncrementalMarking::DO_NOT_FORCE_COMPLETION);
         remaining_idle_time_in_ms =
             deadline_in_ms - MonotonicallyIncreasingTimeInMs();
       } while (remaining_idle_time_in_ms >=
                    2.0 * GCIdleTimeHandler::kIncrementalMarkingStepTimeInMs &&
                !incremental_marking()->IsComplete() &&
                !mark_compact_collector_.marking_deque()->IsEmpty());
       if (remaining_idle_time_in_ms > 0.0) {
         action.additional_work = TryFinalizeIdleIncrementalMarking(
             remaining_idle_time_in_ms, heap_state.size_of_objects,
             heap_state.final_incremental_mark_compact_speed_in_bytes_per_ms);
       }
       break;
     }
     case DO_FULL_GC: {
-      if (action.reduce_memory) {
-        isolate_->compilation_cache()->Clear();
-      }
-      if (contexts_disposed_) {
-        HistogramTimerScope scope(isolate_->counters()->gc_context());
-        CollectAllGarbage(kNoGCFlags, "idle notification: contexts disposed");
-      } else {
-        CollectAllGarbage(kReduceMemoryFootprintMask,
-                          "idle notification: finalize idle round");
-      }
-      gc_idle_time_handler_.NotifyIdleMarkCompact();
+      DCHECK(contexts_disposed_ > 0);
+      HistogramTimerScope scope(isolate_->counters()->gc_context());
+      CollectAllGarbage(kNoGCFlags, "idle notification: contexts disposed");
       break;
     }
     case DO_SCAVENGE:
       CollectGarbage(NEW_SPACE, "idle notification: scavenge");
       break;
     case DO_FINALIZE_SWEEPING:
       mark_compact_collector()->EnsureSweepingCompleted();
       break;
     case DO_NOTHING:
       break;
@@ skipping 714 matching lines @@
   // memory-constrained devices.
   if (max_old_generation_size_ <= kMaxOldSpaceSizeMediumMemoryDevice) {
     factor = Min(factor, kMaxHeapGrowingFactorMemoryConstrained);
   }
 
   if (FLAG_stress_compaction ||
       mark_compact_collector()->reduce_memory_footprint_) {
     factor = kMinHeapGrowingFactor;
   }
 
-  // TODO(hpayer): Investigate if idle_old_generation_allocation_limit_ is still
-  // needed after taking the allocation rate for the old generation limit into
-  // account.
-  double idle_factor = Min(factor, kMaxHeapGrowingFactorIdle);
-
   old_generation_allocation_limit_ =
       CalculateOldGenerationAllocationLimit(factor, old_gen_size);
-  idle_old_generation_allocation_limit_ =
-      CalculateOldGenerationAllocationLimit(idle_factor, old_gen_size);
 
   if (FLAG_trace_gc_verbose) {
-    PrintIsolate(
-        isolate_,
-        "Grow: old size: %" V8_PTR_PREFIX "d KB, new limit: %" V8_PTR_PREFIX
-        "d KB (%.1f), new idle limit: %" V8_PTR_PREFIX "d KB (%.1f)\n",
-        old_gen_size / KB, old_generation_allocation_limit_ / KB, factor,
-        idle_old_generation_allocation_limit_ / KB, idle_factor);
+    PrintIsolate(isolate_, "Grow: old size: %" V8_PTR_PREFIX
+                           "d KB, new limit: %" V8_PTR_PREFIX "d KB (%.1f)\n",
+                 old_gen_size / KB, old_generation_allocation_limit_ / KB,
+                 factor);
   }
 }
 
 
 void Heap::DampenOldGenerationAllocationLimit(intptr_t old_gen_size,
                                               double gc_speed,
                                               double mutator_speed) {
   double factor = HeapGrowingFactor(gc_speed, mutator_speed);
   intptr_t limit = CalculateOldGenerationAllocationLimit(factor, old_gen_size);
   if (limit < old_generation_allocation_limit_) {
@@ skipping 1222 matching lines @@
     *object_type = "CODE_TYPE";                                                \
     *object_sub_type = "CODE_AGE/" #name;                                      \
     return true;
     CODE_AGE_LIST_COMPLETE(COMPARE_AND_RETURN_NAME)
 #undef COMPARE_AND_RETURN_NAME
   }
   return false;
 }
 }  // namespace internal
 }  // namespace v8