// Copyright 2012 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following // disclaimer in the documentation and/or other materials provided // with the distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #include "v8.h" #include "incremental-marking.h" #include "code-stubs.h" #include "compilation-cache.h" #include "objects-visiting.h" #include "objects-visiting-inl.h" #include "v8conversions.h" namespace v8 { namespace internal { IncrementalMarking::IncrementalMarking(Heap* heap) : heap_(heap), state_(STOPPED), marking_deque_memory_(NULL), marking_deque_memory_committed_(false), steps_count_(0), steps_took_(0), longest_step_(0.0), old_generation_space_available_at_start_of_incremental_(0), old_generation_space_used_at_start_of_incremental_(0), steps_count_since_last_gc_(0), steps_took_since_last_gc_(0), should_hurry_(false), marking_speed_(0), allocated_(0), no_marking_scope_depth_(0), unscanned_bytes_of_large_object_(0) { } void IncrementalMarking::TearDown() { delete marking_deque_memory_; } void IncrementalMarking::RecordWriteSlow(HeapObject* obj, Object** slot, Object* value) { if (BaseRecordWrite(obj, slot, value) && slot != NULL) { MarkBit obj_bit = Marking::MarkBitFrom(obj); if (Marking::IsBlack(obj_bit)) { // Object is not going to be rescanned we need to record the slot. heap_->mark_compact_collector()->RecordSlot( HeapObject::RawField(obj, 0), slot, value); } } } void IncrementalMarking::RecordWriteFromCode(HeapObject* obj, Object** slot, Isolate* isolate) { ASSERT(obj->IsHeapObject()); IncrementalMarking* marking = isolate->heap()->incremental_marking(); ASSERT(!marking->is_compacting_); MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address()); int counter = chunk->write_barrier_counter(); if (counter < (MemoryChunk::kWriteBarrierCounterGranularity / 2)) { marking->write_barriers_invoked_since_last_step_ += MemoryChunk::kWriteBarrierCounterGranularity - chunk->write_barrier_counter(); chunk->set_write_barrier_counter( MemoryChunk::kWriteBarrierCounterGranularity); } marking->RecordWrite(obj, slot, *slot); } void IncrementalMarking::RecordWriteForEvacuationFromCode(HeapObject* obj, Object** slot, Isolate* isolate) { ASSERT(obj->IsHeapObject()); IncrementalMarking* marking = isolate->heap()->incremental_marking(); ASSERT(marking->is_compacting_); MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address()); int counter = chunk->write_barrier_counter(); if (counter < (MemoryChunk::kWriteBarrierCounterGranularity / 2)) { marking->write_barriers_invoked_since_last_step_ += MemoryChunk::kWriteBarrierCounterGranularity - chunk->write_barrier_counter(); chunk->set_write_barrier_counter( MemoryChunk::kWriteBarrierCounterGranularity); } marking->RecordWrite(obj, slot, *slot); } void IncrementalMarking::RecordCodeTargetPatch(Code* host, Address pc, HeapObject* value) { if (IsMarking()) { RelocInfo rinfo(pc, RelocInfo::CODE_TARGET, 0, host); RecordWriteIntoCode(host, &rinfo, value); } } void IncrementalMarking::RecordCodeTargetPatch(Address pc, HeapObject* value) { if (IsMarking()) { Code* host = heap_->isolate()->inner_pointer_to_code_cache()-> GcSafeFindCodeForInnerPointer(pc); RelocInfo rinfo(pc, RelocInfo::CODE_TARGET, 0, host); RecordWriteIntoCode(host, &rinfo, value); } } void IncrementalMarking::RecordWriteOfCodeEntrySlow(JSFunction* host, Object** slot, Code* value) { if (BaseRecordWrite(host, slot, value)) { ASSERT(slot != NULL); heap_->mark_compact_collector()-> RecordCodeEntrySlot(reinterpret_cast<Address>(slot), value); } } void IncrementalMarking::RecordWriteIntoCodeSlow(HeapObject* obj, RelocInfo* rinfo, Object* value) { MarkBit value_bit = Marking::MarkBitFrom(HeapObject::cast(value)); if (Marking::IsWhite(value_bit)) { MarkBit obj_bit = Marking::MarkBitFrom(obj); if (Marking::IsBlack(obj_bit)) { BlackToGreyAndUnshift(obj, obj_bit); RestartIfNotMarking(); } // Object is either grey or white. It will be scanned if survives. return; } if (is_compacting_) { MarkBit obj_bit = Marking::MarkBitFrom(obj); if (Marking::IsBlack(obj_bit)) { // Object is not going to be rescanned. We need to record the slot. heap_->mark_compact_collector()->RecordRelocSlot(rinfo, Code::cast(value)); } } } static void MarkObjectGreyDoNotEnqueue(Object* obj) { if (obj->IsHeapObject()) { HeapObject* heap_obj = HeapObject::cast(obj); MarkBit mark_bit = Marking::MarkBitFrom(HeapObject::cast(obj)); if (Marking::IsBlack(mark_bit)) { MemoryChunk::IncrementLiveBytesFromGC(heap_obj->address(), -heap_obj->Size()); } Marking::AnyToGrey(mark_bit); } } static inline void MarkBlackOrKeepGrey(HeapObject* heap_object, MarkBit mark_bit, int size) { ASSERT(!Marking::IsImpossible(mark_bit)); if (mark_bit.Get()) return; mark_bit.Set(); MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(), size); ASSERT(Marking::IsBlack(mark_bit)); } static inline void MarkBlackOrKeepBlack(HeapObject* heap_object, MarkBit mark_bit, int size) { ASSERT(!Marking::IsImpossible(mark_bit)); if (Marking::IsBlack(mark_bit)) return; Marking::MarkBlack(mark_bit); MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(), size); ASSERT(Marking::IsBlack(mark_bit)); } class IncrementalMarkingMarkingVisitor : public StaticMarkingVisitor<IncrementalMarkingMarkingVisitor> { public: static void Initialize() { StaticMarkingVisitor<IncrementalMarkingMarkingVisitor>::Initialize(); table_.Register(kVisitFixedArray, &VisitFixedArrayIncremental); table_.Register(kVisitNativeContext, &VisitNativeContextIncremental); table_.Register(kVisitJSRegExp, &VisitJSRegExp); } static const int kProgressBarScanningChunk = 32 * 1024; static void VisitFixedArrayIncremental(Map* map, HeapObject* object) { MemoryChunk* chunk = MemoryChunk::FromAddress(object->address()); // TODO(mstarzinger): Move setting of the flag to the allocation site of // the array. The visitor should just check the flag. if (FLAG_use_marking_progress_bar && chunk->owner()->identity() == LO_SPACE) { chunk->SetFlag(MemoryChunk::HAS_PROGRESS_BAR); } if (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR)) { Heap* heap = map->GetHeap(); // When using a progress bar for large fixed arrays, scan only a chunk of // the array and try to push it onto the marking deque again until it is // fully scanned. Fall back to scanning it through to the end in case this // fails because of a full deque. int object_size = FixedArray::BodyDescriptor::SizeOf(map, object); int start_offset = Max(FixedArray::BodyDescriptor::kStartOffset, chunk->progress_bar()); int end_offset = Min(object_size, start_offset + kProgressBarScanningChunk); int already_scanned_offset = start_offset; bool scan_until_end = false; do { VisitPointersWithAnchor(heap, HeapObject::RawField(object, 0), HeapObject::RawField(object, start_offset), HeapObject::RawField(object, end_offset)); start_offset = end_offset; end_offset = Min(object_size, end_offset + kProgressBarScanningChunk); scan_until_end = heap->incremental_marking()->marking_deque()->IsFull(); } while (scan_until_end && start_offset < object_size); chunk->set_progress_bar(start_offset); if (start_offset < object_size) { heap->incremental_marking()->marking_deque()->UnshiftGrey(object); heap->incremental_marking()->NotifyIncompleteScanOfObject( object_size - (start_offset - already_scanned_offset)); } } else { FixedArrayVisitor::Visit(map, object); } } static void VisitNativeContextIncremental(Map* map, HeapObject* object) { Context* context = Context::cast(object); // We will mark cache black with a separate pass // when we finish marking. MarkObjectGreyDoNotEnqueue(context->normalized_map_cache()); VisitNativeContext(map, context); } static void VisitWeakCollection(Map* map, HeapObject* object) { Heap* heap = map->GetHeap(); VisitPointers(heap, HeapObject::RawField(object, JSWeakCollection::kPropertiesOffset), HeapObject::RawField(object, JSWeakCollection::kSize)); } static void BeforeVisitingSharedFunctionInfo(HeapObject* object) {} INLINE(static void VisitPointer(Heap* heap, Object** p)) { Object* obj = *p; if (obj->NonFailureIsHeapObject()) { heap->mark_compact_collector()->RecordSlot(p, p, obj); MarkObject(heap, obj); } } INLINE(static void VisitPointers(Heap* heap, Object** start, Object** end)) { for (Object** p = start; p < end; p++) { Object* obj = *p; if (obj->NonFailureIsHeapObject()) { heap->mark_compact_collector()->RecordSlot(start, p, obj); MarkObject(heap, obj); } } } INLINE(static void VisitPointersWithAnchor(Heap* heap, Object** anchor, Object** start, Object** end)) { for (Object** p = start; p < end; p++) { Object* obj = *p; if (obj->NonFailureIsHeapObject()) { heap->mark_compact_collector()->RecordSlot(anchor, p, obj); MarkObject(heap, obj); } } } // Marks the object grey and pushes it on the marking stack. INLINE(static void MarkObject(Heap* heap, Object* obj)) { HeapObject* heap_object = HeapObject::cast(obj); MarkBit mark_bit = Marking::MarkBitFrom(heap_object); if (mark_bit.data_only()) { MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size()); } else if (Marking::IsWhite(mark_bit)) { heap->incremental_marking()->WhiteToGreyAndPush(heap_object, mark_bit); } } // Marks the object black without pushing it on the marking stack. // Returns true if object needed marking and false otherwise. INLINE(static bool MarkObjectWithoutPush(Heap* heap, Object* obj)) { HeapObject* heap_object = HeapObject::cast(obj); MarkBit mark_bit = Marking::MarkBitFrom(heap_object); if (Marking::IsWhite(mark_bit)) { mark_bit.Set(); MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(), heap_object->Size()); return true; } return false; } }; class IncrementalMarkingRootMarkingVisitor : public ObjectVisitor { public: explicit IncrementalMarkingRootMarkingVisitor( IncrementalMarking* incremental_marking) : incremental_marking_(incremental_marking) { } void VisitPointer(Object** p) { MarkObjectByPointer(p); } void VisitPointers(Object** start, Object** end) { for (Object** p = start; p < end; p++) MarkObjectByPointer(p); } private: void MarkObjectByPointer(Object** p) { Object* obj = *p; if (!obj->IsHeapObject()) return; HeapObject* heap_object = HeapObject::cast(obj); MarkBit mark_bit = Marking::MarkBitFrom(heap_object); if (mark_bit.data_only()) { MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size()); } else { if (Marking::IsWhite(mark_bit)) { incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit); } } } IncrementalMarking* incremental_marking_; }; void IncrementalMarking::Initialize() { IncrementalMarkingMarkingVisitor::Initialize(); } void IncrementalMarking::SetOldSpacePageFlags(MemoryChunk* chunk, bool is_marking, bool is_compacting) { if (is_marking) { chunk->SetFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING); chunk->SetFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING); // It's difficult to filter out slots recorded for large objects. if (chunk->owner()->identity() == LO_SPACE && chunk->size() > static_cast<size_t>(Page::kPageSize) && is_compacting) { chunk->SetFlag(MemoryChunk::RESCAN_ON_EVACUATION); } } else if (chunk->owner()->identity() == CELL_SPACE || chunk->owner()->identity() == PROPERTY_CELL_SPACE || chunk->scan_on_scavenge()) { chunk->ClearFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING); chunk->ClearFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING); } else { chunk->ClearFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING); chunk->SetFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING); } } void IncrementalMarking::SetNewSpacePageFlags(NewSpacePage* chunk, bool is_marking) { chunk->SetFlag(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING); if (is_marking) { chunk->SetFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING); } else { chunk->ClearFlag(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING); } chunk->SetFlag(MemoryChunk::SCAN_ON_SCAVENGE); } void IncrementalMarking::DeactivateIncrementalWriteBarrierForSpace( PagedSpace* space) { PageIterator it(space); while (it.has_next()) { Page* p = it.next(); SetOldSpacePageFlags(p, false, false); } } void IncrementalMarking::DeactivateIncrementalWriteBarrierForSpace( NewSpace* space) { NewSpacePageIterator it(space); while (it.has_next()) { NewSpacePage* p = it.next(); SetNewSpacePageFlags(p, false); } } void IncrementalMarking::DeactivateIncrementalWriteBarrier() { DeactivateIncrementalWriteBarrierForSpace(heap_->old_pointer_space()); DeactivateIncrementalWriteBarrierForSpace(heap_->old_data_space()); DeactivateIncrementalWriteBarrierForSpace(heap_->cell_space()); DeactivateIncrementalWriteBarrierForSpace(heap_->property_cell_space()); DeactivateIncrementalWriteBarrierForSpace(heap_->map_space()); DeactivateIncrementalWriteBarrierForSpace(heap_->code_space()); DeactivateIncrementalWriteBarrierForSpace(heap_->new_space()); LargePage* lop = heap_->lo_space()->first_page(); while (lop->is_valid()) { SetOldSpacePageFlags(lop, false, false); lop = lop->next_page(); } } void IncrementalMarking::ActivateIncrementalWriteBarrier(PagedSpace* space) { PageIterator it(space); while (it.has_next()) { Page* p = it.next(); SetOldSpacePageFlags(p, true, is_compacting_); } } void IncrementalMarking::ActivateIncrementalWriteBarrier(NewSpace* space) { NewSpacePageIterator it(space->ToSpaceStart(), space->ToSpaceEnd()); while (it.has_next()) { NewSpacePage* p = it.next(); SetNewSpacePageFlags(p, true); } } void IncrementalMarking::ActivateIncrementalWriteBarrier() { ActivateIncrementalWriteBarrier(heap_->old_pointer_space()); ActivateIncrementalWriteBarrier(heap_->old_data_space()); ActivateIncrementalWriteBarrier(heap_->cell_space()); ActivateIncrementalWriteBarrier(heap_->property_cell_space()); ActivateIncrementalWriteBarrier(heap_->map_space()); ActivateIncrementalWriteBarrier(heap_->code_space()); ActivateIncrementalWriteBarrier(heap_->new_space()); LargePage* lop = heap_->lo_space()->first_page(); while (lop->is_valid()) { SetOldSpacePageFlags(lop, true, is_compacting_); lop = lop->next_page(); } } bool IncrementalMarking::WorthActivating() { #ifndef DEBUG static const intptr_t kActivationThreshold = 8 * MB; #else // TODO(gc) consider setting this to some low level so that some // debug tests run with incremental marking and some without. static const intptr_t kActivationThreshold = 0; #endif // Only start incremental marking in a safe state: 1) when expose GC is // deactivated, 2) when incremental marking is turned on, 3) when we are // currently not in a GC, and 4) when we are currently not serializing // or deserializing the heap. return !FLAG_expose_gc && FLAG_incremental_marking && FLAG_incremental_marking_steps && heap_->gc_state() == Heap::NOT_IN_GC && !Serializer::enabled() && heap_->isolate()->IsInitialized() && heap_->PromotedSpaceSizeOfObjects() > kActivationThreshold; } void IncrementalMarking::ActivateGeneratedStub(Code* stub) { ASSERT(RecordWriteStub::GetMode(stub) == RecordWriteStub::STORE_BUFFER_ONLY); if (!IsMarking()) { // Initially stub is generated in STORE_BUFFER_ONLY mode thus // we don't need to do anything if incremental marking is // not active. } else if (IsCompacting()) { RecordWriteStub::Patch(stub, RecordWriteStub::INCREMENTAL_COMPACTION); } else { RecordWriteStub::Patch(stub, RecordWriteStub::INCREMENTAL); } } static void PatchIncrementalMarkingRecordWriteStubs( Heap* heap, RecordWriteStub::Mode mode) { UnseededNumberDictionary* stubs = heap->code_stubs(); int capacity = stubs->Capacity(); for (int i = 0; i < capacity; i++) { Object* k = stubs->KeyAt(i); if (stubs->IsKey(k)) { uint32_t key = NumberToUint32(k); if (CodeStub::MajorKeyFromKey(key) == CodeStub::RecordWrite) { Object* e = stubs->ValueAt(i); if (e->IsCode()) { RecordWriteStub::Patch(Code::cast(e), mode); } } } } } void IncrementalMarking::EnsureMarkingDequeIsCommitted() { if (marking_deque_memory_ == NULL) { marking_deque_memory_ = new VirtualMemory(4 * MB); } if (!marking_deque_memory_committed_) { bool success = marking_deque_memory_->Commit( reinterpret_cast<Address>(marking_deque_memory_->address()), marking_deque_memory_->size(), false); // Not executable. CHECK(success); marking_deque_memory_committed_ = true; } } void IncrementalMarking::UncommitMarkingDeque() { if (state_ == STOPPED && marking_deque_memory_committed_) { bool success = marking_deque_memory_->Uncommit( reinterpret_cast<Address>(marking_deque_memory_->address()), marking_deque_memory_->size()); CHECK(success); marking_deque_memory_committed_ = false; } } void IncrementalMarking::Start(CompactionFlag flag) { if (FLAG_trace_incremental_marking) { PrintF("[IncrementalMarking] Start\n"); } ASSERT(FLAG_incremental_marking); ASSERT(FLAG_incremental_marking_steps); ASSERT(state_ == STOPPED); ASSERT(heap_->gc_state() == Heap::NOT_IN_GC); ASSERT(!Serializer::enabled()); ASSERT(heap_->isolate()->IsInitialized()); ResetStepCounters(); if (heap_->IsSweepingComplete()) { StartMarking(flag); } else { if (FLAG_trace_incremental_marking) { PrintF("[IncrementalMarking] Start sweeping.\n"); } state_ = SWEEPING; } heap_->new_space()->LowerInlineAllocationLimit(kAllocatedThreshold); } void IncrementalMarking::StartMarking(CompactionFlag flag) { if (FLAG_trace_incremental_marking) { PrintF("[IncrementalMarking] Start marking\n"); } is_compacting_ = !FLAG_never_compact && (flag == ALLOW_COMPACTION) && heap_->mark_compact_collector()->StartCompaction( MarkCompactCollector::INCREMENTAL_COMPACTION); state_ = MARKING; RecordWriteStub::Mode mode = is_compacting_ ? RecordWriteStub::INCREMENTAL_COMPACTION : RecordWriteStub::INCREMENTAL; PatchIncrementalMarkingRecordWriteStubs(heap_, mode); EnsureMarkingDequeIsCommitted(); // Initialize marking stack. Address addr = static_cast<Address>(marking_deque_memory_->address()); size_t size = marking_deque_memory_->size(); if (FLAG_force_marking_deque_overflows) size = 64 * kPointerSize; marking_deque_.Initialize(addr, addr + size); ActivateIncrementalWriteBarrier(); // Marking bits are cleared by the sweeper. #ifdef VERIFY_HEAP if (FLAG_verify_heap) { heap_->mark_compact_collector()->VerifyMarkbitsAreClean(); } #endif heap_->CompletelyClearInstanceofCache(); heap_->isolate()->compilation_cache()->MarkCompactPrologue(); if (FLAG_cleanup_code_caches_at_gc) { // We will mark cache black with a separate pass // when we finish marking. MarkObjectGreyDoNotEnqueue(heap_->polymorphic_code_cache()); } // Mark strong roots grey. IncrementalMarkingRootMarkingVisitor visitor(this); heap_->IterateStrongRoots(&visitor, VISIT_ONLY_STRONG); heap_->mark_compact_collector()->MarkWeakObjectToCodeTable(); // Ready to start incremental marking. if (FLAG_trace_incremental_marking) { PrintF("[IncrementalMarking] Running\n"); } } void IncrementalMarking::PrepareForScavenge() { if (!IsMarking()) return; NewSpacePageIterator it(heap_->new_space()->FromSpaceStart(), heap_->new_space()->FromSpaceEnd()); while (it.has_next()) { Bitmap::Clear(it.next()); } } void IncrementalMarking::UpdateMarkingDequeAfterScavenge() { if (!IsMarking()) return; int current = marking_deque_.bottom(); int mask = marking_deque_.mask(); int limit = marking_deque_.top(); HeapObject** array = marking_deque_.array(); int new_top = current; Map* filler_map = heap_->one_pointer_filler_map(); while (current != limit) { HeapObject* obj = array[current]; ASSERT(obj->IsHeapObject()); current = ((current + 1) & mask); if (heap_->InNewSpace(obj)) { MapWord map_word = obj->map_word(); if (map_word.IsForwardingAddress()) { HeapObject* dest = map_word.ToForwardingAddress(); array[new_top] = dest; new_top = ((new_top + 1) & mask); ASSERT(new_top != marking_deque_.bottom()); #ifdef DEBUG MarkBit mark_bit = Marking::MarkBitFrom(obj); ASSERT(Marking::IsGrey(mark_bit) || (obj->IsFiller() && Marking::IsWhite(mark_bit))); #endif } } else if (obj->map() != filler_map) { // Skip one word filler objects that appear on the // stack when we perform in place array shift. array[new_top] = obj; new_top = ((new_top + 1) & mask); ASSERT(new_top != marking_deque_.bottom()); #ifdef DEBUG MarkBit mark_bit = Marking::MarkBitFrom(obj); MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address()); ASSERT(Marking::IsGrey(mark_bit) || (obj->IsFiller() && Marking::IsWhite(mark_bit)) || (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR) && Marking::IsBlack(mark_bit))); #endif } } marking_deque_.set_top(new_top); steps_took_since_last_gc_ = 0; steps_count_since_last_gc_ = 0; longest_step_ = 0.0; } void IncrementalMarking::VisitObject(Map* map, HeapObject* obj, int size) { MarkBit map_mark_bit = Marking::MarkBitFrom(map); if (Marking::IsWhite(map_mark_bit)) { WhiteToGreyAndPush(map, map_mark_bit); } IncrementalMarkingMarkingVisitor::IterateBody(map, obj); MarkBit mark_bit = Marking::MarkBitFrom(obj); #ifdef DEBUG MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address()); SLOW_ASSERT(Marking::IsGrey(mark_bit) || (obj->IsFiller() && Marking::IsWhite(mark_bit)) || (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR) && Marking::IsBlack(mark_bit))); #endif MarkBlackOrKeepBlack(obj, mark_bit, size); } void IncrementalMarking::ProcessMarkingDeque(intptr_t bytes_to_process) { Map* filler_map = heap_->one_pointer_filler_map(); while (!marking_deque_.IsEmpty() && bytes_to_process > 0) { HeapObject* obj = marking_deque_.Pop(); // Explicitly skip one word fillers. Incremental markbit patterns are // correct only for objects that occupy at least two words. Map* map = obj->map(); if (map == filler_map) continue; int size = obj->SizeFromMap(map); unscanned_bytes_of_large_object_ = 0; VisitObject(map, obj, size); bytes_to_process -= (size - unscanned_bytes_of_large_object_); } } void IncrementalMarking::ProcessMarkingDeque() { Map* filler_map = heap_->one_pointer_filler_map(); while (!marking_deque_.IsEmpty()) { HeapObject* obj = marking_deque_.Pop(); // Explicitly skip one word fillers. Incremental markbit patterns are // correct only for objects that occupy at least two words. Map* map = obj->map(); if (map == filler_map) continue; VisitObject(map, obj, obj->SizeFromMap(map)); } } void IncrementalMarking::Hurry() { if (state() == MARKING) { double start = 0.0; if (FLAG_trace_incremental_marking || FLAG_print_cumulative_gc_stat) { start = OS::TimeCurrentMillis(); if (FLAG_trace_incremental_marking) { PrintF("[IncrementalMarking] Hurry\n"); } } // TODO(gc) hurry can mark objects it encounters black as mutator // was stopped. ProcessMarkingDeque(); state_ = COMPLETE; if (FLAG_trace_incremental_marking || FLAG_print_cumulative_gc_stat) { double end = OS::TimeCurrentMillis(); double delta = end - start; heap_->AddMarkingTime(delta); if (FLAG_trace_incremental_marking) { PrintF("[IncrementalMarking] Complete (hurry), spent %d ms.\n", static_cast<int>(delta)); } } } if (FLAG_cleanup_code_caches_at_gc) { PolymorphicCodeCache* poly_cache = heap_->polymorphic_code_cache(); Marking::GreyToBlack(Marking::MarkBitFrom(poly_cache)); MemoryChunk::IncrementLiveBytesFromGC(poly_cache->address(), PolymorphicCodeCache::kSize); } Object* context = heap_->native_contexts_list(); while (!context->IsUndefined()) { // GC can happen when the context is not fully initialized, // so the cache can be undefined. HeapObject* cache = HeapObject::cast( Context::cast(context)->get(Context::NORMALIZED_MAP_CACHE_INDEX)); if (!cache->IsUndefined()) { MarkBit mark_bit = Marking::MarkBitFrom(cache); if (Marking::IsGrey(mark_bit)) { Marking::GreyToBlack(mark_bit); MemoryChunk::IncrementLiveBytesFromGC(cache->address(), cache->Size()); } } context = Context::cast(context)->get(Context::NEXT_CONTEXT_LINK); } } void IncrementalMarking::Abort() { if (IsStopped()) return; if (FLAG_trace_incremental_marking) { PrintF("[IncrementalMarking] Aborting.\n"); } heap_->new_space()->LowerInlineAllocationLimit(0); IncrementalMarking::set_should_hurry(false); ResetStepCounters(); if (IsMarking()) { PatchIncrementalMarkingRecordWriteStubs(heap_, RecordWriteStub::STORE_BUFFER_ONLY); DeactivateIncrementalWriteBarrier(); if (is_compacting_) { LargeObjectIterator it(heap_->lo_space()); for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) { Page* p = Page::FromAddress(obj->address()); if (p->IsFlagSet(Page::RESCAN_ON_EVACUATION)) { p->ClearFlag(Page::RESCAN_ON_EVACUATION); } } } } heap_->isolate()->stack_guard()->Continue(GC_REQUEST); state_ = STOPPED; is_compacting_ = false; } void IncrementalMarking::Finalize() { Hurry(); state_ = STOPPED; is_compacting_ = false; heap_->new_space()->LowerInlineAllocationLimit(0); IncrementalMarking::set_should_hurry(false); ResetStepCounters(); PatchIncrementalMarkingRecordWriteStubs(heap_, RecordWriteStub::STORE_BUFFER_ONLY); DeactivateIncrementalWriteBarrier(); ASSERT(marking_deque_.IsEmpty()); heap_->isolate()->stack_guard()->Continue(GC_REQUEST); } void IncrementalMarking::MarkingComplete(CompletionAction action) { state_ = COMPLETE; // We will set the stack guard to request a GC now. This will mean the rest // of the GC gets performed as soon as possible (we can't do a GC here in a // record-write context). If a few things get allocated between now and then // that shouldn't make us do a scavenge and keep being incremental, so we set // the should-hurry flag to indicate that there can't be much work left to do. set_should_hurry(true); if (FLAG_trace_incremental_marking) { PrintF("[IncrementalMarking] Complete (normal).\n"); } if (action == GC_VIA_STACK_GUARD) { heap_->isolate()->stack_guard()->RequestGC(); } } void IncrementalMarking::OldSpaceStep(intptr_t allocated) { if (IsStopped() && WorthActivating() && heap_->NextGCIsLikelyToBeFull()) { // TODO(hpayer): Let's play safe for now, but compaction should be // in principle possible. Start(PREVENT_COMPACTION); } else { Step(allocated * kFastMarking / kInitialMarkingSpeed, GC_VIA_STACK_GUARD); } } void IncrementalMarking::Step(intptr_t allocated_bytes, CompletionAction action) { if (heap_->gc_state() != Heap::NOT_IN_GC || !FLAG_incremental_marking || !FLAG_incremental_marking_steps || (state_ != SWEEPING && state_ != MARKING)) { return; } allocated_ += allocated_bytes; if (allocated_ < kAllocatedThreshold && write_barriers_invoked_since_last_step_ < kWriteBarriersInvokedThreshold) { return; } if (state_ == MARKING && no_marking_scope_depth_ > 0) return; // The marking speed is driven either by the allocation rate or by the rate // at which we are having to check the color of objects in the write barrier. // It is possible for a tight non-allocating loop to run a lot of write // barriers before we get here and check them (marking can only take place on // allocation), so to reduce the lumpiness we don't use the write barriers // invoked since last step directly to determine the amount of work to do. intptr_t bytes_to_process = marking_speed_ * Max(allocated_, write_barriers_invoked_since_last_step_); allocated_ = 0; write_barriers_invoked_since_last_step_ = 0; bytes_scanned_ += bytes_to_process; double start = 0; if (FLAG_trace_incremental_marking || FLAG_trace_gc || FLAG_print_cumulative_gc_stat) { start = OS::TimeCurrentMillis(); } if (state_ == SWEEPING) { if (heap_->EnsureSweepersProgressed(static_cast<int>(bytes_to_process))) { bytes_scanned_ = 0; StartMarking(PREVENT_COMPACTION); } } else if (state_ == MARKING) { ProcessMarkingDeque(bytes_to_process); if (marking_deque_.IsEmpty()) MarkingComplete(action); } steps_count_++; steps_count_since_last_gc_++; bool speed_up = false; if ((steps_count_ % kMarkingSpeedAccellerationInterval) == 0) { if (FLAG_trace_gc) { PrintPID("Speed up marking after %d steps\n", static_cast<int>(kMarkingSpeedAccellerationInterval)); } speed_up = true; } bool space_left_is_very_small = (old_generation_space_available_at_start_of_incremental_ < 10 * MB); bool only_1_nth_of_space_that_was_available_still_left = (SpaceLeftInOldSpace() * (marking_speed_ + 1) < old_generation_space_available_at_start_of_incremental_); if (space_left_is_very_small || only_1_nth_of_space_that_was_available_still_left) { if (FLAG_trace_gc) PrintPID("Speed up marking because of low space left\n"); speed_up = true; } bool size_of_old_space_multiplied_by_n_during_marking = (heap_->PromotedTotalSize() > (marking_speed_ + 1) * old_generation_space_used_at_start_of_incremental_); if (size_of_old_space_multiplied_by_n_during_marking) { speed_up = true; if (FLAG_trace_gc) { PrintPID("Speed up marking because of heap size increase\n"); } } int64_t promoted_during_marking = heap_->PromotedTotalSize() - old_generation_space_used_at_start_of_incremental_; intptr_t delay = marking_speed_ * MB; intptr_t scavenge_slack = heap_->MaxSemiSpaceSize(); // We try to scan at at least twice the speed that we are allocating. if (promoted_during_marking > bytes_scanned_ / 2 + scavenge_slack + delay) { if (FLAG_trace_gc) { PrintPID("Speed up marking because marker was not keeping up\n"); } speed_up = true; } if (speed_up) { if (state_ != MARKING) { if (FLAG_trace_gc) { PrintPID("Postponing speeding up marking until marking starts\n"); } } else { marking_speed_ += kMarkingSpeedAccelleration; marking_speed_ = static_cast<int>( Min(kMaxMarkingSpeed, static_cast<intptr_t>(marking_speed_ * 1.3))); if (FLAG_trace_gc) { PrintPID("Marking speed increased to %d\n", marking_speed_); } } } if (FLAG_trace_incremental_marking || FLAG_trace_gc || FLAG_print_cumulative_gc_stat) { double end = OS::TimeCurrentMillis(); double delta = (end - start); longest_step_ = Max(longest_step_, delta); steps_took_ += delta; steps_took_since_last_gc_ += delta; heap_->AddMarkingTime(delta); } } void IncrementalMarking::ResetStepCounters() { steps_count_ = 0; steps_took_ = 0; longest_step_ = 0.0; old_generation_space_available_at_start_of_incremental_ = SpaceLeftInOldSpace(); old_generation_space_used_at_start_of_incremental_ = heap_->PromotedTotalSize(); steps_count_since_last_gc_ = 0; steps_took_since_last_gc_ = 0; bytes_rescanned_ = 0; marking_speed_ = kInitialMarkingSpeed; bytes_scanned_ = 0; write_barriers_invoked_since_last_step_ = 0; } int64_t IncrementalMarking::SpaceLeftInOldSpace() { return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSizeOfObjects(); } } } // namespace v8::internal