Refactor and improve GC root handling
Changed GcRoot to use compressed references. Changed root visiting to
use virtual functions instead of function pointers. Changed root visting
interface to be an array of roots instead of a single root at a time.
Added buffered root marking helper to avoid dispatch overhead.
Root marking seems a bit faster on EvaluateAndApplyChanges due to batch
marking. Pause times unaffected.
Mips64 is untested but might work, maybe.
Before:
MarkConcurrentRoots: Sum: 67.678ms 99% C.I. 2us-664.999us Avg: 161.138us Max: 671us
After:
MarkConcurrentRoots: Sum: 54.806ms 99% C.I. 2us-499.986us Avg: 136.333us Max: 602us
Bug: 19264997
Change-Id: I0a71ebb5928f205b9b3f7945b25db6489d5657ca
diff --git a/runtime/gc/collector/semi_space.cc b/runtime/gc/collector/semi_space.cc
index b3d59f2..dbf01d8 100644
--- a/runtime/gc/collector/semi_space.cc
+++ b/runtime/gc/collector/semi_space.cc
@@ -603,18 +603,29 @@
reinterpret_cast<SemiSpace*>(arg)->DelayReferenceReferent(klass, ref);
}
-void SemiSpace::MarkRootCallback(Object** root, void* arg, const RootInfo& /*root_info*/) {
- auto ref = StackReference<mirror::Object>::FromMirrorPtr(*root);
- reinterpret_cast<SemiSpace*>(arg)->MarkObject(&ref);
- if (*root != ref.AsMirrorPtr()) {
- *root = ref.AsMirrorPtr();
+void SemiSpace::VisitRoots(mirror::Object*** roots, size_t count,
+ const RootInfo& info ATTRIBUTE_UNUSED) {
+ for (size_t i = 0; i < count; ++i) {
+ auto* root = roots[i];
+ auto ref = StackReference<mirror::Object>::FromMirrorPtr(*root);
+ MarkObject(&ref);
+ if (*root != ref.AsMirrorPtr()) {
+ *root = ref.AsMirrorPtr();
+ }
+ }
+}
+
+void SemiSpace::VisitRoots(mirror::CompressedReference<mirror::Object>** roots, size_t count,
+ const RootInfo& info ATTRIBUTE_UNUSED) {
+ for (size_t i = 0; i < count; ++i) {
+ MarkObject(roots[i]);
}
}
// Marks all objects in the root set.
void SemiSpace::MarkRoots() {
TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings());
- Runtime::Current()->VisitRoots(MarkRootCallback, this);
+ Runtime::Current()->VisitRoots(this);
}
bool SemiSpace::HeapReferenceMarkedCallback(mirror::HeapReference<mirror::Object>* object,