🏄 [heap] Add page evacuation mode for new->old

src/heap/mark-compact.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/heap/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 1648 matching lines @@
   explicit EvacuateNewSpaceVisitor(Heap* heap,
                                    CompactionSpaceCollection* compaction_spaces,
                                    HashMap* local_pretenuring_feedback)
       : EvacuateVisitorBase(heap, compaction_spaces),
         buffer_(LocalAllocationBuffer::InvalidBuffer()),
         space_to_allocate_(NEW_SPACE),
         promoted_size_(0),
         semispace_copied_size_(0),
         local_pretenuring_feedback_(local_pretenuring_feedback) {}
 
-  bool Visit(HeapObject* object) override {
+  inline bool Visit(HeapObject* object) override {
     heap_->UpdateAllocationSite<Heap::kCached>(object,
                                                local_pretenuring_feedback_);
     int size = object->Size();
     HeapObject* target_object = nullptr;
     if (heap_->ShouldBePromoted(object->address(), size) &&
         TryEvacuateObject(compaction_spaces_->Get(OLD_SPACE), object,
                           &target_object)) {
       // If we end up needing more special cases, we should factor this out.
       if (V8_UNLIKELY(target_object->IsJSArrayBuffer())) {
         heap_->array_buffer_tracker()->Promote(
@@ skipping 111 matching lines @@
     return allocation;
   }
 
   LocalAllocationBuffer buffer_;
   AllocationSpace space_to_allocate_;
   intptr_t promoted_size_;
   intptr_t semispace_copied_size_;
   HashMap* local_pretenuring_feedback_;
 };
 
+class MarkCompactCollector::EvacuateNewSpacePageVisitor final
+    : public MarkCompactCollector::HeapObjectVisitor {
+ public:
+  EvacuateNewSpacePageVisitor() : promoted_size_(0) {}
+
+  static void MoveToOldSpace(NewSpacePage* page, PagedSpace* owner) {
+    page->heap()->new_space()->ReplaceWithEmptyPage(page);
+    Page* new_page = Page::Convert(page, owner);
+    new_page->SetFlag(Page::FAST_NEW_OLD_EVACUATION);
+  }
+
+  inline bool Visit(HeapObject* object) {
+    if (V8_UNLIKELY(object->IsJSArrayBuffer())) {
+      object->GetHeap()->array_buffer_tracker()->Promote(
+          JSArrayBuffer::cast(object));
+    }
+    RecordMigratedSlotVisitor visitor;
+    object->IterateBodyFast(&visitor);
+    promoted_size_ += object->Size();
+    return true;
+  }
+
+  intptr_t promoted_size() { return promoted_size_; }
+
+ private:
+  intptr_t promoted_size_;
+};
 
 class MarkCompactCollector::EvacuateOldSpaceVisitor final
     : public MarkCompactCollector::EvacuateVisitorBase {
  public:
   EvacuateOldSpaceVisitor(Heap* heap,
                           CompactionSpaceCollection* compaction_spaces)
       : EvacuateVisitorBase(heap, compaction_spaces) {}
 
-  bool Visit(HeapObject* object) override {
+  inline bool Visit(HeapObject* object) override {
     CompactionSpace* target_space = compaction_spaces_->Get(
         Page::FromAddress(object->address())->owner()->identity());
     HeapObject* target_object = nullptr;
     if (TryEvacuateObject(target_space, object, &target_object)) {
       DCHECK(object->map_word().IsForwardingAddress());
       return true;
     }
     return false;
   }
 };
@@ skipping 1192 matching lines @@
     newspace_evacuation_candidates_.Add(it.next());
   }
   new_space->Flip();
   new_space->ResetAllocationInfo();
 }
 
 void MarkCompactCollector::EvacuateNewSpaceEpilogue() {
   newspace_evacuation_candidates_.Rewind(0);
 }
 
-
 class MarkCompactCollector::Evacuator : public Malloced {
  public:
+  // NewSpacePages with more live bytes than this threshold qualify for fast
+  // evacuation.
+  static int PageEvacuationThreshold() {
+    if (!FLAG_page_evacuation)

[Hannes Payer (out of office), 2016/04/18 12:12:23]

Invert this case:
if (FLAG_page_evacuation)

[Michael Lippautz, 2016/04/18 12:57:38]

Done.

[Michael Lippautz, 2016/04/18 12:57:38]

Done.

+      return NewSpacePage::kAllocatableMemory + kPointerSize;
+    return FLAG_page_evacuation_threshold * NewSpacePage::kAllocatableMemory /
+           100;
+  }
+
   explicit Evacuator(MarkCompactCollector* collector)
       : collector_(collector),
         compaction_spaces_(collector->heap()),
         local_pretenuring_feedback_(HashMap::PointersMatch,
                                     kInitialLocalPretenuringFeedbackCapacity),
         new_space_visitor_(collector->heap(), &compaction_spaces_,
                            &local_pretenuring_feedback_),
+        new_space_page_visitor(),
         old_space_visitor_(collector->heap(), &compaction_spaces_),
         duration_(0.0),
         bytes_compacted_(0) {}
 
   inline bool EvacuatePage(MemoryChunk* chunk);
 
   // Merge back locally cached info sequentially. Note that this method needs
   // to be called from the main thread.
   inline void Finalize();
 
   CompactionSpaceCollection* compaction_spaces() { return &compaction_spaces_; }
 
  private:
+  enum EvacuationMode {
+    kObjectsNewToOld,
+    kPageNewToOld,
+    kObjectsOldToOld,
+  };
+
   static const int kInitialLocalPretenuringFeedbackCapacity = 256;
 
-  Heap* heap() { return collector_->heap(); }
+  inline Heap* heap() { return collector_->heap(); }
+
+  inline EvacuationMode ComputeEvacuationMode(MemoryChunk* chunk) {
+    // Note: The order of checks is important in this function.
+    if (chunk->InNewSpace()) return kObjectsNewToOld;
+    if (chunk->IsFlagSet(MemoryChunk::FAST_NEW_OLD_EVACUATION))
+      return kPageNewToOld;
+    DCHECK(chunk->IsEvacuationCandidate());
+    return kObjectsOldToOld;
+  }
 
   void ReportCompactionProgress(double duration, intptr_t bytes_compacted) {
     duration_ += duration;
     bytes_compacted_ += bytes_compacted;
   }
 
-  template <IterationMode mode>
-  inline bool EvacuateSinglePage(MemoryChunk* p, HeapObjectVisitor* visitor);
+  template <IterationMode mode, class Visitor>
+  inline bool EvacuateSinglePage(MemoryChunk* p, Visitor* visitor);
 
   MarkCompactCollector* collector_;
 
   // Locally cached collector data.
   CompactionSpaceCollection compaction_spaces_;
   HashMap local_pretenuring_feedback_;
 
   // Visitors for the corresponding spaces.
   EvacuateNewSpaceVisitor new_space_visitor_;
+  EvacuateNewSpacePageVisitor new_space_page_visitor;
   EvacuateOldSpaceVisitor old_space_visitor_;
 
   // Book keeping info.
   double duration_;
   intptr_t bytes_compacted_;
 };
 
-template <MarkCompactCollector::IterationMode mode>
-bool MarkCompactCollector::Evacuator::EvacuateSinglePage(
-    MemoryChunk* p, HeapObjectVisitor* visitor) {
+template <MarkCompactCollector::IterationMode mode, class Visitor>
+bool MarkCompactCollector::Evacuator::EvacuateSinglePage(MemoryChunk* p,
+                                                         Visitor* visitor) {
   bool success = false;
-  DCHECK(p->IsEvacuationCandidate() || p->InNewSpace());
+  DCHECK(p->IsEvacuationCandidate() || p->InNewSpace() ||
+         p->IsFlagSet(Page::FAST_NEW_OLD_EVACUATION));
   int saved_live_bytes = p->LiveBytes();
   double evacuation_time;
   {
     AlwaysAllocateScope always_allocate(heap()->isolate());
     TimedScope timed_scope(&evacuation_time);
-    success = collector_->VisitLiveObjects(p, visitor, mode);
+    success = collector_->VisitLiveObjects<Visitor>(p, visitor, mode);
   }
   if (FLAG_trace_evacuation) {
     const char age_mark_tag =
         !p->InNewSpace()
             ? 'x'
             : !p->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK)
                   ? '>'
                   : !p->ContainsLimit(heap()->new_space()->age_mark()) ? '<'
                                                                        : '#';
     PrintIsolate(heap()->isolate(),
                  "evacuation[%p]: page=%p new_space=%d age_mark_tag=%c "
-                 "executable=%d live_bytes=%d time=%f\n",
+                 "page_evacuation=%d executable=%d live_bytes=%d time=%f\n",
                  this, p, p->InNewSpace(), age_mark_tag,
+                 p->IsFlagSet(MemoryChunk::FAST_NEW_OLD_EVACUATION),
                  p->IsFlagSet(MemoryChunk::IS_EXECUTABLE), saved_live_bytes,
                  evacuation_time);
   }
   if (success) {
     ReportCompactionProgress(evacuation_time, saved_live_bytes);
   }
   return success;
 }
 
 bool MarkCompactCollector::Evacuator::EvacuatePage(MemoryChunk* chunk) {
-  bool success = false;
-  if (chunk->InNewSpace()) {
-    DCHECK_EQ(chunk->concurrent_sweeping_state().Value(),
-              NewSpacePage::kSweepingDone);
-    success = EvacuateSinglePage<kClearMarkbits>(chunk, &new_space_visitor_);
-    DCHECK(success);
-    USE(success);
-  } else {
-    DCHECK(chunk->IsEvacuationCandidate());
-    DCHECK_EQ(chunk->concurrent_sweeping_state().Value(), Page::kSweepingDone);
-    success = EvacuateSinglePage<kClearMarkbits>(chunk, &old_space_visitor_);
-    if (!success) {
-      // Aborted compaction page. We can record slots here to have them
-      // processed in parallel later on.
-      EvacuateRecordOnlyVisitor record_visitor(chunk->owner()->identity());
-      success = EvacuateSinglePage<kKeepMarking>(chunk, &record_visitor);
-      DCHECK(success);
-      USE(success);
-      // We need to return failure here to indicate that we want this page added
-      // to the sweeper.
-      return false;
-    }
+  bool result = false;
+  DCHECK_EQ(chunk->concurrent_sweeping_state().Value(),
+            NewSpacePage::kSweepingDone);
+  switch (ComputeEvacuationMode(chunk)) {
+    case kObjectsNewToOld:
+      result = EvacuateSinglePage<kClearMarkbits>(chunk, &new_space_visitor_);
+      DCHECK(result);
+      USE(result);
+      break;
+    case kPageNewToOld:
+      result = EvacuateSinglePage<kKeepMarking>(chunk, &new_space_page_visitor);
+      DCHECK(result);
+      USE(result);
+      break;
+    case kObjectsOldToOld:
+      result = EvacuateSinglePage<kClearMarkbits>(chunk, &old_space_visitor_);
+      if (!result) {
+        // Aborted compaction page. We can record slots here to have them
+        // processed in parallel later on.
+        EvacuateRecordOnlyVisitor record_visitor(chunk->owner()->identity());
+        result = EvacuateSinglePage<kKeepMarking>(chunk, &record_visitor);
+        DCHECK(result);
+        USE(result);
+        // We need to return failure here to indicate that we want this page
+        // added to the sweeper.
+        return false;
+      }
+      break;
+    default:
+      UNREACHABLE();
   }
-  return success;
+  return result;
 }
 
 void MarkCompactCollector::Evacuator::Finalize() {
   heap()->old_space()->MergeCompactionSpace(compaction_spaces_.Get(OLD_SPACE));
   heap()->code_space()->MergeCompactionSpace(
       compaction_spaces_.Get(CODE_SPACE));
   heap()->tracer()->AddCompactionEvent(duration_, bytes_compacted_);
-  heap()->IncrementPromotedObjectsSize(new_space_visitor_.promoted_size());
+  heap()->IncrementPromotedObjectsSize(new_space_visitor_.promoted_size() +
+                                       new_space_page_visitor.promoted_size());
   heap()->IncrementSemiSpaceCopiedObjectSize(
       new_space_visitor_.semispace_copied_size());
   heap()->IncrementYoungSurvivorsCounter(
       new_space_visitor_.promoted_size() +
-      new_space_visitor_.semispace_copied_size());
+      new_space_visitor_.semispace_copied_size() +
+      new_space_page_visitor.promoted_size());
   heap()->MergeAllocationSitePretenuringFeedback(local_pretenuring_feedback_);
 }
 
 int MarkCompactCollector::NumberOfParallelCompactionTasks(int pages,
                                                           intptr_t live_bytes) {
   if (!FLAG_parallel_compaction) return 1;
   // Compute the number of needed tasks based on a target compaction time, the
   // profiled compaction speed and marked live memory.
   //
   // The number of parallel compaction tasks is limited by:
@@ skipping 29 matching lines @@
 
   static bool ProcessPageInParallel(Heap* heap, PerTaskData evacuator,
                                     MemoryChunk* chunk, PerPageData) {
     return evacuator->EvacuatePage(chunk);
   }
 
   static void FinalizePageSequentially(Heap* heap, MemoryChunk* chunk,
                                        bool success, PerPageData data) {
     if (chunk->InNewSpace()) {
       DCHECK(success);
+    } else if (chunk->IsFlagSet(Page::FAST_NEW_OLD_EVACUATION)) {
+      DCHECK(success);
+      Page* p = static_cast<Page*>(chunk);
+      p->ClearFlag(Page::FAST_NEW_OLD_EVACUATION);
+      p->ForAllFreeListCategories(
+          [](FreeListCategory* category) { DCHECK(!category->is_linked()); });
+      heap->mark_compact_collector()->sweeper().AddLatePage(
+          p->owner()->identity(), p);
     } else {
       Page* p = static_cast<Page*>(chunk);
       if (success) {
         DCHECK(p->IsEvacuationCandidate());
         DCHECK(p->SweepingDone());
         p->Unlink();
       } else {
         // We have partially compacted the page, i.e., some objects may have
         // moved, others are still in place.
         p->SetFlag(Page::COMPACTION_WAS_ABORTED);
         p->ClearEvacuationCandidate();
         // Slots have already been recorded so we just need to add it to the
         // sweeper.
         *data += 1;
       }
     }
   }
 };
 
 void MarkCompactCollector::EvacuatePagesInParallel() {
   PageParallelJob<EvacuationJobTraits> job(
       heap_, heap_->isolate()->cancelable_task_manager());
 
+  bool evacuated_pages = false;
   int abandoned_pages = 0;
   intptr_t live_bytes = 0;
   for (Page* page : evacuation_candidates_) {
     live_bytes += page->LiveBytes();
     job.AddPage(page, &abandoned_pages);
   }
+  const Address age_mark = heap()->new_space()->age_mark();
   for (NewSpacePage* page : newspace_evacuation_candidates_) {
     live_bytes += page->LiveBytes();
+    if (!page->NeverEvacuate() &&
+        (page->LiveBytes() > Evacuator::PageEvacuationThreshold()) &&
+        page->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK) &&
+        !page->Contains(age_mark)) {
+      evacuated_pages = true;
+      EvacuateNewSpacePageVisitor::MoveToOldSpace(page, heap()->old_space());
+    }
     job.AddPage(page, &abandoned_pages);
   }
   DCHECK_GE(job.NumberOfPages(), 1);
 
   // Used for trace summary.
   double compaction_speed = 0;
   if (FLAG_trace_evacuation) {
     compaction_speed = heap()->tracer()->CompactionSpeedInBytesPerMillisecond();
   }
 
   const int wanted_num_tasks =
       NumberOfParallelCompactionTasks(job.NumberOfPages(), live_bytes);
   Evacuator** evacuators = new Evacuator*[wanted_num_tasks];
   for (int i = 0; i < wanted_num_tasks; i++) {
     evacuators[i] = new Evacuator(this);
   }
   job.Run(wanted_num_tasks, [evacuators](int i) { return evacuators[i]; });
   for (int i = 0; i < wanted_num_tasks; i++) {
     evacuators[i]->Finalize();
     delete evacuators[i];
   }
   delete[] evacuators;
 
+  if (evacuated_pages) {

[Hannes Payer (out of office), 2016/04/18 12:12:23]

This should be part of UpdatePointersAfterEvacuation. And there we already
process the string table. Have a look how to integrate into that cleanup logic.

[Michael Lippautz, 2016/04/18 12:57:38]

Removed. As you said, this should fall out from regular pointers evacuation.

+    heap()
+        ->external_string_table_
+        .CleanUp<Heap::ExternalStringTable::CleanupMode::kPromoteOnly>();
+  }
+
   if (FLAG_trace_evacuation) {
     PrintIsolate(isolate(),
                  "%8.0f ms: evacuation-summary: parallel=%s pages=%d "
                  "aborted=%d wanted_tasks=%d tasks=%d cores=%" PRIuS
                  " live_bytes=%" V8PRIdPTR " compaction_speed=%.f\n",
                  isolate()->time_millis_since_init(),
                  FLAG_parallel_compaction ? "yes" : "no", job.NumberOfPages(),
                  abandoned_pages, wanted_num_tasks, job.NumberOfTasks(),
                  V8::GetCurrentPlatform()->NumberOfAvailableBackgroundThreads(),
                  live_bytes, compaction_speed);
@@ skipping 116 matching lines @@
 #ifdef VERIFY_HEAP
 static void VerifyAllBlackObjects(MemoryChunk* page) {
   LiveObjectIterator<kAllLiveObjects> it(page);
   HeapObject* object = NULL;
   while ((object = it.Next()) != NULL) {
     CHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
   }
 }
 #endif  // VERIFY_HEAP
 
-
-bool MarkCompactCollector::VisitLiveObjects(MemoryChunk* page,
-                                            HeapObjectVisitor* visitor,
+template <class Visitor>
+bool MarkCompactCollector::VisitLiveObjects(MemoryChunk* page, Visitor* visitor,
                                             IterationMode mode) {
 #ifdef VERIFY_HEAP
   VerifyAllBlackObjects(page);
 #endif  // VERIFY_HEAP
 
   LiveObjectIterator<kBlackObjects> it(page);
   HeapObject* object = nullptr;
   while ((object = it.Next()) != nullptr) {
     DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
     if (!visitor->Visit(object)) {
@@ skipping 140 matching lines @@
       RememberedSet<OLD_TO_OLD>::IterateTyped(
           chunk, [isolate, visitor](SlotType type, Address slot) {
             UpdateTypedSlot(isolate, visitor, type, slot);
             return REMOVE_SLOT;
           });
     }
   }
 
   static void UpdateOldToNewSlot(HeapObject** address, HeapObject* object) {
     MapWord map_word = object->map_word();
-    // Since we only filter invalid slots in old space, the store buffer can
-    // still contain stale pointers in large object and in map spaces. Ignore
-    // these pointers here.
-    DCHECK(map_word.IsForwardingAddress() ||
-           !object->GetHeap()->old_space()->Contains(
-               reinterpret_cast<Address>(address)));
+    // There could still be stale pointers in large object space, map space,
+    // and old space for pages that have been promoted.
     if (map_word.IsForwardingAddress()) {
       // Update the corresponding slot.
       *address = map_word.ToForwardingAddress();
     }
   }
 };
 
 int NumberOfPointerUpdateTasks(int pages) {
   if (!FLAG_parallel_pointer_update) return 1;
   const int kMaxTasks = 4;
@@ skipping 315 matching lines @@
     MarkBit mark_bit = Marking::MarkBitFrom(host);
     if (Marking::IsBlack(mark_bit)) {
       RelocInfo rinfo(isolate(), pc, RelocInfo::CODE_TARGET, 0, host);
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8