Merge "Add concurrent card graying for immune spaces"
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 08a752f..8afc6ba 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -7177,10 +7177,10 @@
instruction, root, /* unpoison_ref_before_marking */ false);
codegen_->AddSlowPath(slow_path);
- // Test the entrypoint (`Thread::Current()->pReadBarrierMarkReg ## root.reg()`).
- const int32_t entry_point_offset =
- CodeGenerator::GetReadBarrierMarkEntryPointsOffset<kX86PointerSize>(root.reg());
- __ fs()->cmpl(Address::Absolute(entry_point_offset), Immediate(0));
+ // Test if the GC is marking. Note that X86 and X86_64 don't switch the entrypoints when the
+ // GC is marking.
+ const int32_t is_marking_offset = Thread::IsGcMarkingOffset<kX86PointerSize>().Int32Value();
+ __ fs()->cmpl(Address::Absolute(is_marking_offset), Immediate(0));
// The entrypoint is null when the GC is not marking.
__ j(kNotEqual, slow_path->GetEntryLabel());
__ Bind(slow_path->GetExitLabel());
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index ff6e099..c2b1a31 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -6542,10 +6542,11 @@
instruction, root, /* unpoison_ref_before_marking */ false);
codegen_->AddSlowPath(slow_path);
- // Test the `Thread::Current()->pReadBarrierMarkReg ## root.reg()` entrypoint.
- const int32_t entry_point_offset =
- CodeGenerator::GetReadBarrierMarkEntryPointsOffset<kX86_64PointerSize>(root.reg());
- __ gs()->cmpl(Address::Absolute(entry_point_offset, /* no_rip */ true), Immediate(0));
+ // Test if the GC is marking. Note that X86 and X86_64 don't switch the entrypoints when the
+ // GC is marking.
+ const int32_t is_marking_offset =
+ Thread::IsGcMarkingOffset<kX86_64PointerSize>().Int32Value();
+ __ gs()->cmpl(Address::Absolute(is_marking_offset, /* no_rip */ true), Immediate(0));
// The entrypoint is null when the GC is not marking.
__ j(kNotEqual, slow_path->GetEntryLabel());
__ Bind(slow_path->GetExitLabel());
diff --git a/runtime/base/mutex.h b/runtime/base/mutex.h
index 2414b5f..03ae63a 100644
--- a/runtime/base/mutex.h
+++ b/runtime/base/mutex.h
@@ -373,19 +373,19 @@
bool IsSharedHeld(const Thread* self) const;
// Assert the current thread has shared access to the ReaderWriterMutex.
- void AssertSharedHeld(const Thread* self) ASSERT_SHARED_CAPABILITY(this) {
+ ALWAYS_INLINE void AssertSharedHeld(const Thread* self) ASSERT_SHARED_CAPABILITY(this) {
if (kDebugLocking && (gAborting == 0)) {
// TODO: we can only assert this well when self != null.
CHECK(IsSharedHeld(self) || self == nullptr) << *this;
}
}
- void AssertReaderHeld(const Thread* self) ASSERT_SHARED_CAPABILITY(this) {
+ ALWAYS_INLINE void AssertReaderHeld(const Thread* self) ASSERT_SHARED_CAPABILITY(this) {
AssertSharedHeld(self);
}
// Assert the current thread doesn't hold this ReaderWriterMutex either in shared or exclusive
// mode.
- void AssertNotHeld(const Thread* self) ASSERT_SHARED_CAPABILITY(!this) {
+ ALWAYS_INLINE void AssertNotHeld(const Thread* self) ASSERT_SHARED_CAPABILITY(!this) {
if (kDebugLocking && (gAborting == 0)) {
CHECK(!IsSharedHeld(self)) << *this;
}
diff --git a/runtime/gc/accounting/card_table.h b/runtime/gc/accounting/card_table.h
index 68ef15d..14aa730 100644
--- a/runtime/gc/accounting/card_table.h
+++ b/runtime/gc/accounting/card_table.h
@@ -51,6 +51,7 @@
static constexpr size_t kCardSize = 1 << kCardShift;
static constexpr uint8_t kCardClean = 0x0;
static constexpr uint8_t kCardDirty = 0x70;
+ static constexpr uint8_t kCardAged = kCardDirty - 1;
static CardTable* Create(const uint8_t* heap_begin, size_t heap_capacity);
~CardTable();
diff --git a/runtime/gc/collector/concurrent_copying-inl.h b/runtime/gc/collector/concurrent_copying-inl.h
index dd449f9..1f06f15 100644
--- a/runtime/gc/collector/concurrent_copying-inl.h
+++ b/runtime/gc/collector/concurrent_copying-inl.h
@@ -152,7 +152,8 @@
inline mirror::Object* ConcurrentCopying::MarkFromReadBarrier(mirror::Object* from_ref) {
mirror::Object* ret;
- if (from_ref == nullptr) {
+ // We can get here before marking starts since we gray immune objects before the marking phase.
+ if (from_ref == nullptr || !Thread::Current()->GetIsGcMarking()) {
return from_ref;
}
// TODO: Consider removing this check when we are done investigating slow paths. b/30162165
diff --git a/runtime/gc/collector/concurrent_copying.cc b/runtime/gc/collector/concurrent_copying.cc
index 4192f34..9c3ce0b 100644
--- a/runtime/gc/collector/concurrent_copying.cc
+++ b/runtime/gc/collector/concurrent_copying.cc
@@ -163,6 +163,12 @@
ReaderMutexLock mu(self, *Locks::mutator_lock_);
InitializePhase();
}
+ if (kUseBakerReadBarrier && kGrayDirtyImmuneObjects) {
+ // Gray dirty immune objects concurrently to reduce GC pause times. We re-process gray cards in
+ // the pause.
+ ReaderMutexLock mu(self, *Locks::mutator_lock_);
+ GrayAllDirtyImmuneObjects();
+ }
FlipThreadRoots();
{
ReaderMutexLock mu(self, *Locks::mutator_lock_);
@@ -352,9 +358,12 @@
if (kVerifyNoMissingCardMarks) {
cc->VerifyNoMissingCardMarks();
}
- CHECK(thread == self);
+ CHECK_EQ(thread, self);
Locks::mutator_lock_->AssertExclusiveHeld(self);
- cc->region_space_->SetFromSpace(cc->rb_table_, cc->force_evacuate_all_);
+ {
+ TimingLogger::ScopedTiming split2("(Paused)SetFromSpace", cc->GetTimings());
+ cc->region_space_->SetFromSpace(cc->rb_table_, cc->force_evacuate_all_);
+ }
cc->SwapStacks();
if (ConcurrentCopying::kEnableFromSpaceAccountingCheck) {
cc->RecordLiveStackFreezeSize(self);
@@ -368,11 +377,11 @@
}
if (UNLIKELY(Runtime::Current()->IsActiveTransaction())) {
CHECK(Runtime::Current()->IsAotCompiler());
- TimingLogger::ScopedTiming split2("(Paused)VisitTransactionRoots", cc->GetTimings());
+ TimingLogger::ScopedTiming split3("(Paused)VisitTransactionRoots", cc->GetTimings());
Runtime::Current()->VisitTransactionRoots(cc);
}
if (kUseBakerReadBarrier && kGrayDirtyImmuneObjects) {
- cc->GrayAllDirtyImmuneObjects();
+ cc->GrayAllNewlyDirtyImmuneObjects();
if (kIsDebugBuild) {
// Check that all non-gray immune objects only refernce immune objects.
cc->VerifyGrayImmuneObjects();
@@ -519,8 +528,8 @@
void ConcurrentCopying::VerifyNoMissingCardMarkCallback(mirror::Object* obj, void* arg) {
auto* collector = reinterpret_cast<ConcurrentCopying*>(arg);
- // Objects not on dirty cards should never have references to newly allocated regions.
- if (!collector->heap_->GetCardTable()->IsDirty(obj)) {
+ // Objects not on dirty or aged cards should never have references to newly allocated regions.
+ if (collector->heap_->GetCardTable()->GetCard(obj) == gc::accounting::CardTable::kCardClean) {
VerifyNoMissingCardMarkVisitor visitor(collector, /*holder*/ obj);
obj->VisitReferences</*kVisitNativeRoots*/true, kVerifyNone, kWithoutReadBarrier>(
visitor,
@@ -583,53 +592,100 @@
}
}
+template <bool kConcurrent>
class ConcurrentCopying::GrayImmuneObjectVisitor {
public:
- explicit GrayImmuneObjectVisitor() {}
+ explicit GrayImmuneObjectVisitor(Thread* self) : self_(self) {}
ALWAYS_INLINE void operator()(mirror::Object* obj) const REQUIRES_SHARED(Locks::mutator_lock_) {
- if (kUseBakerReadBarrier) {
- if (kIsDebugBuild) {
- Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
+ if (kUseBakerReadBarrier && obj->GetReadBarrierState() == ReadBarrier::WhiteState()) {
+ if (kConcurrent) {
+ Locks::mutator_lock_->AssertSharedHeld(self_);
+ obj->AtomicSetReadBarrierState(ReadBarrier::WhiteState(), ReadBarrier::GrayState());
+ // Mod union table VisitObjects may visit the same object multiple times so we can't check
+ // the result of the atomic set.
+ } else {
+ Locks::mutator_lock_->AssertExclusiveHeld(self_);
+ obj->SetReadBarrierState(ReadBarrier::GrayState());
}
- obj->SetReadBarrierState(ReadBarrier::GrayState());
}
}
static void Callback(mirror::Object* obj, void* arg) REQUIRES_SHARED(Locks::mutator_lock_) {
- reinterpret_cast<GrayImmuneObjectVisitor*>(arg)->operator()(obj);
+ reinterpret_cast<GrayImmuneObjectVisitor<kConcurrent>*>(arg)->operator()(obj);
}
+
+ private:
+ Thread* const self_;
};
void ConcurrentCopying::GrayAllDirtyImmuneObjects() {
- TimingLogger::ScopedTiming split(__FUNCTION__, GetTimings());
- gc::Heap* const heap = Runtime::Current()->GetHeap();
- accounting::CardTable* const card_table = heap->GetCardTable();
- WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
+ TimingLogger::ScopedTiming split("GrayAllDirtyImmuneObjects", GetTimings());
+ accounting::CardTable* const card_table = heap_->GetCardTable();
+ Thread* const self = Thread::Current();
+ using VisitorType = GrayImmuneObjectVisitor</* kIsConcurrent */ true>;
+ VisitorType visitor(self);
+ WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
for (space::ContinuousSpace* space : immune_spaces_.GetSpaces()) {
DCHECK(space->IsImageSpace() || space->IsZygoteSpace());
- GrayImmuneObjectVisitor visitor;
- accounting::ModUnionTable* table = heap->FindModUnionTableFromSpace(space);
+ accounting::ModUnionTable* table = heap_->FindModUnionTableFromSpace(space);
// Mark all the objects on dirty cards since these may point to objects in other space.
// Once these are marked, the GC will eventually clear them later.
// Table is non null for boot image and zygote spaces. It is only null for application image
// spaces.
if (table != nullptr) {
- // TODO: Consider adding precleaning outside the pause.
table->ProcessCards();
- table->VisitObjects(GrayImmuneObjectVisitor::Callback, &visitor);
- // Since the cards are recorded in the mod-union table and this is paused, we can clear
- // the cards for the space (to madvise).
+ table->VisitObjects(&VisitorType::Callback, &visitor);
+ // Don't clear cards here since we need to rescan in the pause. If we cleared the cards here,
+ // there would be races with the mutator marking new cards.
+ } else {
+ // Keep cards aged if we don't have a mod-union table since we may need to scan them in future
+ // GCs. This case is for app images.
+ card_table->ModifyCardsAtomic(
+ space->Begin(),
+ space->End(),
+ [](uint8_t card) {
+ return (card != gc::accounting::CardTable::kCardClean)
+ ? gc::accounting::CardTable::kCardAged
+ : card;
+ },
+ /* card modified visitor */ VoidFunctor());
+ card_table->Scan</* kClearCard */ false>(space->GetMarkBitmap(),
+ space->Begin(),
+ space->End(),
+ visitor,
+ gc::accounting::CardTable::kCardAged);
+ }
+ }
+}
+
+void ConcurrentCopying::GrayAllNewlyDirtyImmuneObjects() {
+ TimingLogger::ScopedTiming split("(Paused)GrayAllNewlyDirtyImmuneObjects", GetTimings());
+ accounting::CardTable* const card_table = heap_->GetCardTable();
+ using VisitorType = GrayImmuneObjectVisitor</* kIsConcurrent */ false>;
+ Thread* const self = Thread::Current();
+ VisitorType visitor(self);
+ WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
+ for (space::ContinuousSpace* space : immune_spaces_.GetSpaces()) {
+ DCHECK(space->IsImageSpace() || space->IsZygoteSpace());
+ accounting::ModUnionTable* table = heap_->FindModUnionTableFromSpace(space);
+
+ // Don't need to scan aged cards since we did these before the pause. Note that scanning cards
+ // also handles the mod-union table cards.
+ card_table->Scan</* kClearCard */ false>(space->GetMarkBitmap(),
+ space->Begin(),
+ space->End(),
+ visitor,
+ gc::accounting::CardTable::kCardDirty);
+ if (table != nullptr) {
+ // Add the cards to the mod-union table so that we can clear cards to save RAM.
+ table->ProcessCards();
TimingLogger::ScopedTiming split2("(Paused)ClearCards", GetTimings());
card_table->ClearCardRange(space->Begin(),
AlignDown(space->End(), accounting::CardTable::kCardSize));
- } else {
- // TODO: Consider having a mark bitmap for app image spaces and avoid scanning during the
- // pause because app image spaces are all dirty pages anyways.
- card_table->Scan<false>(space->GetMarkBitmap(), space->Begin(), space->End(), visitor);
}
}
- // Since all of the objects that may point to other spaces are marked, we can avoid all the read
+ // Since all of the objects that may point to other spaces are gray, we can avoid all the read
// barriers in the immune spaces.
updated_all_immune_objects_.StoreRelaxed(true);
}
@@ -658,6 +714,7 @@
ALWAYS_INLINE void operator()(mirror::Object* obj) const REQUIRES_SHARED(Locks::mutator_lock_) {
if (kUseBakerReadBarrier && kGrayDirtyImmuneObjects) {
+ // Only need to scan gray objects.
if (obj->GetReadBarrierState() == ReadBarrier::GrayState()) {
collector_->ScanImmuneObject(obj);
// Done scanning the object, go back to white.
@@ -707,6 +764,7 @@
if (kUseBakerReadBarrier && kGrayDirtyImmuneObjects && table != nullptr) {
table->VisitObjects(ImmuneSpaceScanObjVisitor::Callback, &visitor);
} else {
+ // TODO: Scan only the aged cards.
live_bitmap->VisitMarkedRange(reinterpret_cast<uintptr_t>(space->Begin()),
reinterpret_cast<uintptr_t>(space->Limit()),
visitor);
diff --git a/runtime/gc/collector/concurrent_copying.h b/runtime/gc/collector/concurrent_copying.h
index f877314..d8dc9f6 100644
--- a/runtime/gc/collector/concurrent_copying.h
+++ b/runtime/gc/collector/concurrent_copying.h
@@ -162,6 +162,9 @@
void GrayAllDirtyImmuneObjects()
REQUIRES(Locks::mutator_lock_)
REQUIRES(!mark_stack_lock_);
+ void GrayAllNewlyDirtyImmuneObjects()
+ REQUIRES(Locks::mutator_lock_)
+ REQUIRES(!mark_stack_lock_);
void VerifyGrayImmuneObjects()
REQUIRES(Locks::mutator_lock_)
REQUIRES(!mark_stack_lock_);
@@ -336,7 +339,7 @@
class DisableMarkingCheckpoint;
class DisableWeakRefAccessCallback;
class FlipCallback;
- class GrayImmuneObjectVisitor;
+ template <bool kConcurrent> class GrayImmuneObjectVisitor;
class ImmuneSpaceScanObjVisitor;
class LostCopyVisitor;
class RefFieldsVisitor;
diff --git a/runtime/oat.h b/runtime/oat.h
index 05706252..84ca2a6 100644
--- a/runtime/oat.h
+++ b/runtime/oat.h
@@ -32,7 +32,8 @@
class PACKED(4) OatHeader {
public:
static constexpr uint8_t kOatMagic[] = { 'o', 'a', 't', '\n' };
- static constexpr uint8_t kOatVersion[] = { '1', '1', '9', '\0' }; // Add thread_local_limit.
+ // Go back to checking is_marking for x86 and x86_64.
+ static constexpr uint8_t kOatVersion[] = { '1', '2', '0', '\0' };
static constexpr const char* kImageLocationKey = "image-location";
static constexpr const char* kDex2OatCmdLineKey = "dex2oat-cmdline";
diff --git a/runtime/thread.cc b/runtime/thread.cc
index 62a616b..0a81bfd 100644
--- a/runtime/thread.cc
+++ b/runtime/thread.cc
@@ -134,6 +134,13 @@
void Thread::SetIsGcMarkingAndUpdateEntrypoints(bool is_marking) {
CHECK(kUseReadBarrier);
tls32_.is_gc_marking = is_marking;
+ if (kUseReadBarrier && (kRuntimeISA == kX86_64 || kRuntimeISA == kX86)) {
+ // Disable entrypoint switching for X86 since we don't always check is_marking with the gray
+ // bit. This causes a race between GrayAllDirtyImmuneObjects and FlipThreadRoots where
+ // we may try to go slow path with a null entrypoint. The fix is to never do entrypoint
+ // switching for x86.
+ is_marking = true;
+ }
UpdateReadBarrierEntrypoints(&tlsPtr_.quick_entrypoints, is_marking);
ResetQuickAllocEntryPointsForThread(is_marking);
}