Replace ObjectSet with LargeObjectBitmap.
Speeds up large object marking since large objects no longer required
a lock. Changed the GCs to use the heap bitmap for marking objects
which aren't in the fast path. This eliminates the need for a
MarkLargeObject function.
Maps before (10 GC iterations):
Mean partial time: 180ms
Mean sticky time: 151ms
Maps after:
Mean partial time: 161ms
Mean sticky time: 101ms
Note: the GC durations are long due to recent ergonomic changes and
because the fast bulk free hasn't yet been enabled. Over 50% of the
GC time is spent in RosAllocSpace::FreeList.
Bug: 13571028
Change-Id: Id8f94718aeaa13052672ccbae1e8edf77d653f62
diff --git a/runtime/gc/collector/semi_space.cc b/runtime/gc/collector/semi_space.cc
index 4a1bf18..b67bbb1 100644
--- a/runtime/gc/collector/semi_space.cc
+++ b/runtime/gc/collector/semi_space.cc
@@ -126,6 +126,11 @@
CHECK(from_space_->CanMoveObjects()) << "Attempting to move from " << *from_space_;
// Set the initial bitmap.
to_space_live_bitmap_ = to_space_->GetLiveBitmap();
+ {
+ // TODO: I don't think we should need heap bitmap lock to get the mark bitmap.
+ ReaderMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
+ mark_bitmap_ = heap_->GetMarkBitmap();
+ }
}
void SemiSpace::ProcessReferences(Thread* self) {
@@ -314,8 +319,8 @@
accounting::ObjectStack* live_stack = heap_->GetLiveStack();
heap_->MarkAllocStackAsLive(live_stack);
live_stack->Reset();
- timings_.EndSplit();
+ timings_.NewSplit("UpdateAndMarkRememberedSets");
for (auto& space : heap_->GetContinuousSpaces()) {
// If the space is immune and has no mod union table (the
// non-moving space when the bump pointer space only collection is
@@ -353,6 +358,7 @@
}
if (is_large_object_space_immune_) {
+ timings_.NewSplit("VisitLargeObjects");
DCHECK(generational_ && !whole_heap_collection_);
// Delay copying the live set to the marked set until here from
// BindBitmaps() as the large objects on the allocation stack may
@@ -364,13 +370,13 @@
// classes (primitive array classes) that could move though they
// don't contain any other references.
space::LargeObjectSpace* large_object_space = GetHeap()->GetLargeObjectsSpace();
- accounting::ObjectSet* large_live_objects = large_object_space->GetLiveObjects();
+ accounting::LargeObjectBitmap* large_live_bitmap = large_object_space->GetLiveBitmap();
SemiSpaceScanObjectVisitor visitor(this);
- for (const Object* obj : large_live_objects->GetObjects()) {
- visitor(const_cast<Object*>(obj));
- }
+ large_live_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(large_object_space->Begin()),
+ reinterpret_cast<uintptr_t>(large_object_space->End()),
+ visitor);
}
-
+ timings_.EndSplit();
// Recursively process the mark stack.
ProcessMarkStack();
}
@@ -452,19 +458,6 @@
mark_stack_->PushBack(obj);
}
-// Rare case, probably not worth inlining since it will increase instruction cache miss rate.
-bool SemiSpace::MarkLargeObject(const Object* obj) {
- // TODO: support >1 discontinuous space.
- space::LargeObjectSpace* large_object_space = GetHeap()->GetLargeObjectsSpace();
- DCHECK(large_object_space->Contains(obj));
- accounting::ObjectSet* large_objects = large_object_space->GetMarkObjects();
- if (UNLIKELY(!large_objects->Test(obj))) {
- large_objects->Set(obj);
- return true;
- }
- return false;
-}
-
static inline size_t CopyAvoidingDirtyingPages(void* dest, const void* src, size_t size) {
if (LIKELY(size <= static_cast<size_t>(kPageSize))) {
// We will dirty the current page and somewhere in the middle of the next page. This means