commit 8256da35feac0ba7589fcd4b692a4b9a936679a4
author Hiroshi Yamauchi <yamauchi@google.com> Wed Jul 27 14:08:19 2016 -0700
committer Hiroshi Yamauchi <yamauchi@google.com> Wed Jul 27 14:45:53 2016 -0700
tree 3b7b51dc3dbe824c5d62f984ece78f96654c1b59
parent 9755c262df1be7f5d5b98d038c8fd3734e974f9d

Scan immune spaces using mod union tables.

It's faster to scan the immune spaces using the mod union tables (gray
objects on dirty pages) than the live bitmaps (gray objects).

The immune space scan time goes from ~13ms down to ~10ms in the
testWidgetsContainerFling test on angler at 1 GHz.

Change-Id: I0914d7bdb50cbf8a49c859070a3501b48eb79f3e
Test: N9 boot, art tests, Ritz EAAC.
Bug: 29516968
Bug: 29517059
Bug: 12687968

runtime/gc/collector/concurrent_copying.cc

diff --git a/runtime/gc/collector/concurrent_copying.cc b/runtime/gc/collector/concurrent_copying.cc
index d413a50..4a80089 100644
--- a/runtime/gc/collector/concurrent_copying.cc
+++ b/runtime/gc/collector/concurrent_copying.cc
@@ -520,7 +520,7 @@
   explicit ImmuneSpaceScanObjVisitor(ConcurrentCopying* cc)
       : collector_(cc) {}
 
-  void operator()(mirror::Object* obj) const SHARED_REQUIRES(Locks::mutator_lock_) {
+  ALWAYS_INLINE void operator()(mirror::Object* obj) const SHARED_REQUIRES(Locks::mutator_lock_) {
     if (kUseBakerReadBarrier && kGrayDirtyImmuneObjects) {
       if (obj->GetReadBarrierPointer() == ReadBarrier::GrayPtr()) {
         collector_->ScanImmuneObject(obj);
@@ -534,6 +534,10 @@
     }
   }
 
+  static void Callback(mirror::Object* obj, void* arg) SHARED_REQUIRES(Locks::mutator_lock_) {
+    reinterpret_cast<ImmuneSpaceScanObjVisitor*>(arg)->operator()(obj);
+  }
+
  private:
   ConcurrentCopying* const collector_;
 };
@@ -558,10 +562,15 @@
     for (auto& space : immune_spaces_.GetSpaces()) {
       DCHECK(space->IsImageSpace() || space->IsZygoteSpace());
       accounting::ContinuousSpaceBitmap* live_bitmap = space->GetLiveBitmap();
+      accounting::ModUnionTable* table = heap_->FindModUnionTableFromSpace(space);
       ImmuneSpaceScanObjVisitor visitor(this);
-      live_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(space->Begin()),
-                                    reinterpret_cast<uintptr_t>(space->Limit()),
-                                    visitor);
+      if (table != nullptr) {
+        table->VisitObjects(ImmuneSpaceScanObjVisitor::Callback, &visitor);
+      } else {
+        live_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(space->Begin()),
+                                      reinterpret_cast<uintptr_t>(space->Limit()),
+                                      visitor);
+      }
     }
   }
   if (kUseBakerReadBarrier) {