Thread-local mark stacks for the CC collector.
Thread-local mark stacks are assigned to mutators where they push
references in read barriers to reduce the (CAS) synchronization cost
in a global mark stack/queue.
We step through three mark stack modes (thread-local, shared,
GC-exclusive) and use per-thread flags to disable/enable system weak
accesses (only for the CC collector) instead of the existing global
one to safely perform the marking phase. The reasons are 1)
thread-local mark stacks for mutators need to be revoked using a
checkpoint to avoid races (incorrectly leaving a reference on mark
stacks) when terminating marking, and 2) we can’t use a checkpoint
while system weak accesses are disabled (or a deadlock would
happen). More details are described in the code comments.
Performance improvements in Ritzperf EAAC: a ~2.8% improvement
(13290->12918) in run time and a ~23% improvement (51.6s->39.8s) in
the total GC time on N5.
Bug: 12687968
Change-Id: I5d234d7e48bf115cd773d38bdb62ad24ce9116c7
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index 5067b0d..a2a745e 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -1512,6 +1512,13 @@
java_vm_->EnsureNewWeakGlobalsDisallowed();
}
+void Runtime::BroadcastForNewSystemWeaks() {
+ CHECK(kUseReadBarrier);
+ monitor_list_->BroadcastForNewMonitors();
+ intern_table_->BroadcastForNewInterns();
+ java_vm_->BroadcastForNewWeakGlobals();
+}
+
void Runtime::SetInstructionSet(InstructionSet instruction_set) {
instruction_set_ = instruction_set;
if ((instruction_set_ == kThumb2) || (instruction_set_ == kArm)) {