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

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 27c24f34b15fd5a9bedd121cad06463456da8f6b..d962167e17090098bf84765780dab11b882653dd 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -20,6 +20,7 @@
 #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"
@@ -107,8 +108,6 @@ Heap::Heap()
       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()),
@@ -143,6 +142,7 @@ Heap::Heap()
       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),
@@ -926,6 +926,11 @@ bool Heap::CollectGarbage(GarbageCollector collector, const char* gc_reason,
   }
 
   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);
@@ -947,9 +952,20 @@ bool Heap::CollectGarbage(GarbageCollector collector, const char* gc_reason,
     }
 
     if (collector == MARK_COMPACTOR) {
-      gc_idle_time_handler_.NotifyMarkCompact(next_gc_likely_to_collect_more);
-    } else {
-      gc_idle_time_handler_.NotifyScavenge();
+      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);
     }
 
     tracer()->Stop(collector);
@@ -984,10 +1000,20 @@ int Heap::NotifyContextDisposed(bool dependant_context) {
   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;
@@ -4746,6 +4772,21 @@ bool Heap::HasLowAllocationRate() {
 }
 
 
+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();
@@ -4772,7 +4813,6 @@ bool Heap::TryFinalizeIdleIncrementalMarking(
                   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;
@@ -4803,15 +4843,6 @@ GCIdleTimeHandler::HeapState Heap::ComputeHeapState() {
   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;
 }
 
@@ -4825,10 +4856,7 @@ bool Heap::PerformIdleTimeAction(GCIdleTimeAction action,
       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(
@@ -4849,17 +4877,9 @@ bool Heap::PerformIdleTimeAction(GCIdleTimeAction action,
       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:
@@ -5594,23 +5614,14 @@ void Heap::SetOldGenerationAllocationLimit(intptr_t old_gen_size,
     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);
   }
 }