[heap] Internalize kExternalAllocationLimit

Base the fast-path in AdjustAmountOfExternalMemory on a value + limit. To
preserve the behavior the limit is just set using kExternalAllocationLimit.

Redo naming of related members.

R=jochen@chromium.org
BUG=chromium:621829
LOG=N

Review-Url: https://codereview.chromium.org/2085893002
Cr-Commit-Position: refs/heads/master@{#37131}

include/v8.h

@@ -7493,13 +7493,12 @@ class Internals {
   static const int kExternalOneByteRepresentationTag = 0x06;
 
   static const int kIsolateEmbedderDataOffset = 0 * kApiPointerSize;
-  static const int kAmountOfExternalAllocatedMemoryOffset =
-      4 * kApiPointerSize;
-  static const int kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset =
-      kAmountOfExternalAllocatedMemoryOffset + kApiInt64Size;
-  static const int kIsolateRootsOffset =
-      kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset + kApiInt64Size +
-      kApiPointerSize + kApiPointerSize;
+  static const int kExternalMemoryOffset = 4 * kApiPointerSize;
+  static const int kExternalMemoryLimitOffset =
+      kExternalMemoryOffset + kApiInt64Size;
+  static const int kIsolateRootsOffset = kExternalMemoryLimitOffset +
+                                         kApiInt64Size + kApiInt64Size +
+                                         kApiPointerSize + kApiPointerSize;
   static const int kUndefinedValueRootIndex = 4;
   static const int kTheHoleValueRootIndex = 5;
   static const int kNullValueRootIndex = 6;
@@ -7507,10 +7506,6 @@ class Internals {
   static const int kFalseValueRootIndex = 8;
   static const int kEmptyStringRootIndex = 9;
 
-  // The external allocation limit should be below 256 MB on all architectures
-  // to avoid that resource-constrained embedders run low on memory.
-  static const int kExternalAllocationLimit = 192 * 1024 * 1024;
-
   static const int kNodeClassIdOffset = 1 * kApiPointerSize;
   static const int kNodeFlagsOffset = 1 * kApiPointerSize + 3;
   static const int kNodeStateMask = 0x7;
@@ -8705,21 +8700,16 @@ uint32_t Isolate::GetNumberOfDataSlots() {
 int64_t Isolate::AdjustAmountOfExternalAllocatedMemory(
     int64_t change_in_bytes) {
   typedef internal::Internals I;
-  int64_t* amount_of_external_allocated_memory =
-      reinterpret_cast<int64_t*>(reinterpret_cast<uint8_t*>(this) +
-                                 I::kAmountOfExternalAllocatedMemoryOffset);
-  int64_t* amount_of_external_allocated_memory_at_last_global_gc =
-      reinterpret_cast<int64_t*>(
-          reinterpret_cast<uint8_t*>(this) +
-          I::kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset);
-  int64_t amount = *amount_of_external_allocated_memory + change_in_bytes;
-  if (change_in_bytes > 0 &&
-      amount - *amount_of_external_allocated_memory_at_last_global_gc >
-          I::kExternalAllocationLimit) {
+  int64_t* external_memory = reinterpret_cast<int64_t*>(
+      reinterpret_cast<uint8_t*>(this) + I::kExternalMemoryOffset);
+  const int64_t external_memory_limit = *reinterpret_cast<int64_t*>(
+      reinterpret_cast<uint8_t*>(this) + I::kExternalMemoryLimitOffset);
+  const int64_t amount = *external_memory + change_in_bytes;
+  *external_memory = amount;
+  if (change_in_bytes > 0 && amount > external_memory_limit) {
     ReportExternalAllocationLimitReached();
   }
-  *amount_of_external_allocated_memory = amount;
-  return *amount_of_external_allocated_memory;
+  return *external_memory;
 }
 
 

src/extensions/statistics-extension.cc

@@ -135,8 +135,7 @@ void StatisticsExtension::GetCounters(
     AddNumber(args.GetIsolate(), result, numbers[i].number, numbers[i].name);
   }
 
-  AddNumber64(args.GetIsolate(), result,
-              heap->amount_of_external_allocated_memory(),
+  AddNumber64(args.GetIsolate(), result, heap->external_memory(),
               "amount_of_external_allocated_memory");
   args.GetReturnValue().Set(result);
 }

src/globals.h

@@ -182,6 +182,10 @@ const size_t kCodeRangeAreaAlignment = 4 * KB;  // OS page.
 #endif
 #endif
 
+// The external allocation limit should be below 256 MB on all architectures
+// to avoid that resource-constrained embedders run low on memory.
+const int kExternalAllocationLimit = 192 * 1024 * 1024;
+
 STATIC_ASSERT(kPointerSize == (1 << kPointerSizeLog2));
 
 const int kBitsPerByte = 8;

src/heap/array-buffer-tracker-inl.h

@@ -44,8 +44,7 @@ void ArrayBufferTracker::Unregister(Heap* heap, JSArrayBuffer* buffer) {
     DCHECK_NOT_NULL(tracker);
     length = tracker->Remove(buffer).second;
   }
-  heap->update_amount_of_external_allocated_memory(
-      -static_cast<intptr_t>(length));
+  heap->update_external_memory(-static_cast<intptr_t>(length));
 }
 
 void LocalArrayBufferTracker::Add(Key key, const Value& value) {

src/heap/array-buffer-tracker.cc

@@ -29,7 +29,7 @@ void LocalArrayBufferTracker::Free() {
     }
   }
   if (freed_memory > 0) {
-    heap_->update_amount_of_external_allocated_freed_memory(
+    heap_->update_external_memory_concurrently_freed(
         static_cast<intptr_t>(freed_memory));
   }
 }
@@ -68,7 +68,7 @@ void LocalArrayBufferTracker::Process(Callback callback) {
     }
   }
   if (freed_memory > 0) {
-    heap_->update_amount_of_external_allocated_freed_memory(
+    heap_->update_external_memory_concurrently_freed(
         static_cast<intptr_t>(freed_memory));
   }
 }
@@ -82,7 +82,7 @@ void ArrayBufferTracker::FreeDeadInNewSpace(Heap* heap) {
     bool empty = ProcessBuffers(page, kUpdateForwardedRemoveOthers);
     CHECK(empty);
   }
-  heap->account_amount_of_external_allocated_freed_memory();
+  heap->account_external_memory_concurrently_freed();
 }
 
 void ArrayBufferTracker::FreeDead(Page* page) {

src/heap/heap.cc

@@ -68,8 +68,9 @@ class IdleScavengeObserver : public AllocationObserver {
 };
 
 Heap::Heap()
-    : amount_of_external_allocated_memory_(0),
-      amount_of_external_allocated_memory_at_last_global_gc_(0),
+    : external_memory_(0),
+      external_memory_limit_(kExternalAllocationLimit),
+      external_memory_at_last_mark_compact_(0),
       isolate_(nullptr),
       code_range_size_(0),
       // semispace_size_ should be a power of 2 and old_generation_size_ should
@@ -383,9 +384,8 @@ void Heap::PrintShortHeapStatistics() {
                          ", committed: %6" V8PRIdPTR " KB\n",
                this->SizeOfObjects() / KB, this->Available() / KB,
                this->CommittedMemory() / KB);
-  PrintIsolate(
-      isolate_, "External memory reported: %6" V8PRIdPTR " KB\n",
-      static_cast<intptr_t>(amount_of_external_allocated_memory_ / KB));
+  PrintIsolate(isolate_, "External memory reported: %6" V8PRIdPTR " KB\n",
+               static_cast<intptr_t>(external_memory_ / KB));
   PrintIsolate(isolate_, "Total time spent in GC  : %.1f ms\n",
                total_gc_time_ms_);
 }
@@ -1339,8 +1339,8 @@ bool Heap::PerformGarbageCollection(
   intptr_t old_gen_size = PromotedSpaceSizeOfObjects();
   if (collector == MARK_COMPACTOR) {
     // Register the amount of external allocated memory.
-    amount_of_external_allocated_memory_at_last_global_gc_ =
-        amount_of_external_allocated_memory_;
+    external_memory_at_last_mark_compact_ = external_memory_;
+    external_memory_limit_ = external_memory_ + kExternalAllocationLimit;
     SetOldGenerationAllocationLimit(old_gen_size, gc_speed, mutator_speed);
   } else if (HasLowYoungGenerationAllocationRate() &&
              old_generation_size_configured_) {
@@ -4425,8 +4425,8 @@ void Heap::CollectGarbageOnMemoryPressure(const char* source) {
   double end = MonotonicallyIncreasingTimeInMs();
 
   // Estimate how much memory we can free.
-  int64_t potential_garbage = (CommittedMemory() - SizeOfObjects()) +
-                              amount_of_external_allocated_memory_;
+  int64_t potential_garbage =
+      (CommittedMemory() - SizeOfObjects()) + external_memory_;
   // If we can potentially free large amount of memory, then start GC right
   // away instead of waiting for memory reducer.
   if (potential_garbage >= kGarbageThresholdInBytes &&
@@ -5048,11 +5048,8 @@ intptr_t Heap::PromotedSpaceSizeOfObjects() {
 
 
 int64_t Heap::PromotedExternalMemorySize() {
-  if (amount_of_external_allocated_memory_ <=
-      amount_of_external_allocated_memory_at_last_global_gc_)
-    return 0;
-  return amount_of_external_allocated_memory_ -
-         amount_of_external_allocated_memory_at_last_global_gc_;
+  if (external_memory_ <= external_memory_at_last_mark_compact_) return 0;
+  return external_memory_ - external_memory_at_last_mark_compact_;
 }
 
 

src/heap/heap.h

@@ -821,22 +821,16 @@ class Heap {
     global_ic_age_ = (global_ic_age_ + 1) & SharedFunctionInfo::ICAgeBits::kMax;
   }
 
-  int64_t amount_of_external_allocated_memory() {
-    return amount_of_external_allocated_memory_;
+  int64_t external_memory() { return external_memory_; }
+  void update_external_memory(int64_t delta) { external_memory_ += delta; }
+
+  void update_external_memory_concurrently_freed(intptr_t freed) {
+    external_memory_concurrently_freed_.Increment(freed);
   }
 
-  void update_amount_of_external_allocated_memory(int64_t delta) {
-    amount_of_external_allocated_memory_ += delta;
-  }
-
-  void update_amount_of_external_allocated_freed_memory(intptr_t freed) {
-    amount_of_external_allocated_memory_freed_.Increment(freed);
-  }
-
-  void account_amount_of_external_allocated_freed_memory() {
-    amount_of_external_allocated_memory_ -=
-        amount_of_external_allocated_memory_freed_.Value();
-    amount_of_external_allocated_memory_freed_.SetValue(0);
+  void account_external_memory_concurrently_freed() {
+    external_memory_ -= external_memory_concurrently_freed_.Value();
+    external_memory_concurrently_freed_.SetValue(0);
   }
 
   void DeoptMarkedAllocationSites();
@@ -1997,14 +1991,17 @@ class Heap {
 
   void set_force_oom(bool value) { force_oom_ = value; }
 
-  // The amount of external memory registered through the API kept alive
-  // by global handles
-  int64_t amount_of_external_allocated_memory_;
+  // The amount of external memory registered through the API.
+  int64_t external_memory_;
 
-  // Caches the amount of external memory registered at the last global gc.
-  int64_t amount_of_external_allocated_memory_at_last_global_gc_;
+  // The limit when to trigger memory pressure from the API.
+  int64_t external_memory_limit_;
 
-  base::AtomicNumber<intptr_t> amount_of_external_allocated_memory_freed_;
+  // Caches the amount of external memory registered at the last MC.
+  int64_t external_memory_at_last_mark_compact_;
+
+  // The amount of memory that has been freed concurrently.
+  base::AtomicNumber<intptr_t> external_memory_concurrently_freed_;
 
   // This can be calculated directly from a pointer to the heap; however, it is
   // more expedient to get at the isolate directly from within Heap methods.

src/heap/mark-compact.cc

@@ -898,7 +898,7 @@ void MarkCompactCollector::Prepare() {
        space = spaces.next()) {
     space->PrepareForMarkCompact();
   }
-  heap()->account_amount_of_external_allocated_freed_memory();
+  heap()->account_external_memory_concurrently_freed();
 
 #ifdef VERIFY_HEAP
   if (!was_marked_incrementally_ && FLAG_verify_heap) {

src/isolate.cc

@@ -2312,13 +2312,10 @@ bool Isolate::Init(Deserializer* des) {
            Internals::kIsolateEmbedderDataOffset);
   CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, heap_.roots_)),
            Internals::kIsolateRootsOffset);
-  CHECK_EQ(static_cast<int>(
-               OFFSET_OF(Isolate, heap_.amount_of_external_allocated_memory_)),
-           Internals::kAmountOfExternalAllocatedMemoryOffset);
-  CHECK_EQ(static_cast<int>(OFFSET_OF(
-               Isolate,
-               heap_.amount_of_external_allocated_memory_at_last_global_gc_)),
-           Internals::kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset);
+  CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, heap_.external_memory_)),
+           Internals::kExternalMemoryOffset);
+  CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, heap_.external_memory_limit_)),
+           Internals::kExternalMemoryLimitOffset);
 
   time_millis_at_init_ = heap_.MonotonicallyIncreasingTimeInMs();
 

test/cctest/heap/test-heap.cc

@@ -6717,7 +6717,7 @@ TEST(Regress618958) {
   v8::HandleScope scope(CcTest::isolate());
   Heap* heap = CcTest::heap();
   bool isolate_is_locked = true;
-  heap->update_amount_of_external_allocated_memory(100 * MB);
+  heap->update_external_memory(100 * MB);
   int mark_sweep_count_before = heap->ms_count();
   heap->MemoryPressureNotification(MemoryPressureLevel::kCritical,
                                    isolate_is_locked);

test/cctest/test-api.cc

@@ -14853,8 +14853,7 @@ THREADED_TEST(ExternalAllocatedMemory) {
            isolate->AdjustAmountOfExternalAllocatedMemory(kSize));
   CHECK_EQ(baseline,
            isolate->AdjustAmountOfExternalAllocatedMemory(-kSize));
-  const int64_t kTriggerGCSize =
-      v8::internal::Internals::kExternalAllocationLimit + 1;
+  const int64_t kTriggerGCSize = i::kExternalAllocationLimit + 1;
   CHECK_EQ(baseline + kTriggerGCSize,
            isolate->AdjustAmountOfExternalAllocatedMemory(kTriggerGCSize));
   CHECK_EQ(baseline,
@@ -14866,8 +14865,7 @@ TEST(Regress51719) {
   i::FLAG_incremental_marking = false;
   CcTest::InitializeVM();
 
-  const int64_t kTriggerGCSize =
-      v8::internal::Internals::kExternalAllocationLimit + 1;
+  const int64_t kTriggerGCSize = i::kExternalAllocationLimit + 1;
   v8::Isolate* isolate = CcTest::isolate();
   isolate->AdjustAmountOfExternalAllocatedMemory(kTriggerGCSize);
 }