ART: add longest consecutive free bytes in region dump
Test: Run art with -XX:DumpRegionInfoAfterGC on some benchmarks
Bug: 119486919
Change-Id: I03284f7eb27b04ca5458b86bbaf527cb1538f64c
diff --git a/runtime/gc/heap.h b/runtime/gc/heap.h
index aa09cbe..6696cc1 100644
--- a/runtime/gc/heap.h
+++ b/runtime/gc/heap.h
@@ -543,6 +543,10 @@
return total_bytes_freed_ever_;
}
+ space::RegionSpace* GetRegionSpace() const {
+ return region_space_;
+ }
+
// Implements java.lang.Runtime.maxMemory, returning the maximum amount of memory a program can
// consume. For a regular VM this would relate to the -Xmx option and would return -1 if no Xmx
// were specified. Android apps start with a growth limit (small heap size) which is
diff --git a/runtime/gc/space/region_space-inl.h b/runtime/gc/space/region_space-inl.h
index 9f5c117..86a0a6e 100644
--- a/runtime/gc/space/region_space-inl.h
+++ b/runtime/gc/space/region_space-inl.h
@@ -249,27 +249,47 @@
} else if (r->IsLargeTail()) {
// Do nothing.
} else {
- // For newly allocated and evacuated regions, live bytes will be -1.
- uint8_t* pos = r->Begin();
- uint8_t* top = r->Top();
- const bool need_bitmap =
- r->LiveBytes() != static_cast<size_t>(-1) &&
- r->LiveBytes() != static_cast<size_t>(top - pos);
- if (need_bitmap) {
- GetLiveBitmap()->VisitMarkedRange(
- reinterpret_cast<uintptr_t>(pos),
- reinterpret_cast<uintptr_t>(top),
- visitor);
+ WalkNonLargeRegion(visitor, r);
+ }
+ }
+}
+
+template<typename Visitor>
+inline void RegionSpace::WalkNonLargeRegion(Visitor&& visitor, const Region* r) {
+ DCHECK(!r->IsLarge() && !r->IsLargeTail());
+ // For newly allocated and evacuated regions, live bytes will be -1.
+ uint8_t* pos = r->Begin();
+ uint8_t* top = r->Top();
+ // We need the region space bitmap to iterate over a region's objects
+ // if
+ // - its live bytes count is invalid (i.e. -1); or
+ // - its live bytes count is lower than the allocated bytes count.
+ //
+ // In both of the previous cases, we do not have the guarantee that
+ // all allocated objects are "alive" (i.e. valid), so we depend on
+ // the region space bitmap to identify which ones to visit.
+ //
+ // On the other hand, when all allocated bytes are known to be alive,
+ // we know that they form a range of consecutive objects (modulo
+ // object alignment constraints) that can be visited iteratively: we
+ // can compute the next object's location by using the current
+ // object's address and size (and object alignment constraints).
+ const bool need_bitmap =
+ r->LiveBytes() != static_cast<size_t>(-1) &&
+ r->LiveBytes() != static_cast<size_t>(top - pos);
+ if (need_bitmap) {
+ GetLiveBitmap()->VisitMarkedRange(
+ reinterpret_cast<uintptr_t>(pos),
+ reinterpret_cast<uintptr_t>(top),
+ visitor);
+ } else {
+ while (pos < top) {
+ mirror::Object* obj = reinterpret_cast<mirror::Object*>(pos);
+ if (obj->GetClass<kDefaultVerifyFlags, kWithoutReadBarrier>() != nullptr) {
+ visitor(obj);
+ pos = reinterpret_cast<uint8_t*>(GetNextObject(obj));
} else {
- while (pos < top) {
- mirror::Object* obj = reinterpret_cast<mirror::Object*>(pos);
- if (obj->GetClass<kDefaultVerifyFlags, kWithoutReadBarrier>() != nullptr) {
- visitor(obj);
- pos = reinterpret_cast<uint8_t*>(GetNextObject(obj));
- } else {
- break;
- }
- }
+ break;
}
}
}
diff --git a/runtime/gc/space/region_space.cc b/runtime/gc/space/region_space.cc
index 07783ba..79b370c 100644
--- a/runtime/gc/space/region_space.cc
+++ b/runtime/gc/space/region_space.cc
@@ -840,6 +840,9 @@
if (live_bytes_ != static_cast<size_t>(-1)) {
os << " ratio over allocated bytes="
<< (static_cast<float>(live_bytes_) / RoundUp(BytesAllocated(), kRegionSize));
+ uint64_t longest_consecutive_free_bytes = GetLongestConsecutiveFreeBytes();
+ os << " longest_consecutive_free_bytes=" << longest_consecutive_free_bytes
+ << " (" << PrettySize(longest_consecutive_free_bytes) << ")";
}
os << " is_newly_allocated=" << std::boolalpha << is_newly_allocated_ << std::noboolalpha
@@ -847,6 +850,30 @@
<< " thread=" << thread_ << '\n';
}
+uint64_t RegionSpace::Region::GetLongestConsecutiveFreeBytes() const {
+ if (IsFree()) {
+ return kRegionSize;
+ }
+ if (IsLarge() || IsLargeTail()) {
+ return 0u;
+ }
+ uintptr_t max_gap = 0u;
+ uintptr_t prev_object_end = reinterpret_cast<uintptr_t>(Begin());
+ // Iterate through all live objects and find the largest free gap.
+ auto visitor = [&max_gap, &prev_object_end](mirror::Object* obj)
+ REQUIRES_SHARED(Locks::mutator_lock_) {
+ uintptr_t current = reinterpret_cast<uintptr_t>(obj);
+ uintptr_t diff = current - prev_object_end;
+ max_gap = std::max(diff, max_gap);
+ uintptr_t object_end = reinterpret_cast<uintptr_t>(obj) + obj->SizeOf();
+ prev_object_end = RoundUp(object_end, kAlignment);
+ };
+ space::RegionSpace* region_space = art::Runtime::Current()->GetHeap()->GetRegionSpace();
+ region_space->WalkNonLargeRegion(visitor, this);
+ return static_cast<uint64_t>(max_gap);
+}
+
+
size_t RegionSpace::AllocationSizeNonvirtual(mirror::Object* obj, size_t* usable_size) {
size_t num_bytes = obj->SizeOf();
if (usable_size != nullptr) {
diff --git a/runtime/gc/space/region_space.h b/runtime/gc/space/region_space.h
index 75c99ec..8a7dd4d 100644
--- a/runtime/gc/space/region_space.h
+++ b/runtime/gc/space/region_space.h
@@ -370,9 +370,6 @@
private:
RegionSpace(const std::string& name, MemMap&& mem_map);
- template<bool kToSpaceOnly, typename Visitor>
- ALWAYS_INLINE void WalkInternal(Visitor&& visitor) NO_THREAD_SAFETY_ANALYSIS;
-
class Region {
public:
Region()
@@ -616,6 +613,8 @@
DCHECK_LE(Top(), end_);
}
+ uint64_t GetLongestConsecutiveFreeBytes() const;
+
private:
size_t idx_; // The region's index in the region space.
size_t live_bytes_; // The live bytes. Used to compute the live percent.
@@ -640,6 +639,14 @@
friend class RegionSpace;
};
+ template<bool kToSpaceOnly, typename Visitor>
+ ALWAYS_INLINE void WalkInternal(Visitor&& visitor) NO_THREAD_SAFETY_ANALYSIS;
+
+ // Visitor will be iterating on objects in increasing address order.
+ template<typename Visitor>
+ ALWAYS_INLINE void WalkNonLargeRegion(Visitor&& visitor, const Region* r)
+ NO_THREAD_SAFETY_ANALYSIS;
+
Region* RefToRegion(mirror::Object* ref) REQUIRES(!region_lock_) {
MutexLock mu(Thread::Current(), region_lock_);
return RefToRegionLocked(ref);
