8206003: SafepointSynchronize with TLH: StoreStore barriers should be moved out of the loop
Reviewed-by: eosterlund, rehn, dholmes
--- a/src/hotspot/share/runtime/handshake.cpp Mon Jul 02 09:38:20 2018 +0200
+++ b/src/hotspot/share/runtime/handshake.cpp Mon Jul 02 11:46:15 2018 +0200
@@ -297,12 +297,12 @@
void HandshakeState::set_operation(JavaThread* target, HandshakeOperation* op) {
_operation = op;
- SafepointMechanism::arm_local_poll(target);
+ SafepointMechanism::arm_local_poll_release(target);
}
void HandshakeState::clear_handshake(JavaThread* target) {
_operation = NULL;
- SafepointMechanism::disarm_local_poll(target);
+ SafepointMechanism::disarm_local_poll_release(target);
}
void HandshakeState::process_self_inner(JavaThread* thread) {
--- a/src/hotspot/share/runtime/safepoint.cpp Mon Jul 02 09:38:20 2018 +0200
+++ b/src/hotspot/share/runtime/safepoint.cpp Mon Jul 02 11:46:15 2018 +0200
@@ -243,9 +243,10 @@
if (SafepointMechanism::uses_thread_local_poll()) {
// Arming the per thread poll while having _state != _not_synchronized means safepointing
log_trace(safepoint)("Setting thread local yield flag for threads");
+ OrderAccess::storestore(); // storestore, global state -> local state
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *cur = jtiwh.next(); ) {
// Make sure the threads start polling, it is time to yield.
- SafepointMechanism::arm_local_poll(cur); // release store, global state -> local state
+ SafepointMechanism::arm_local_poll(cur);
}
}
OrderAccess::fence(); // storestore|storeload, global state -> local state
@@ -546,7 +547,7 @@
for (; JavaThread *current = jtiwh.next(); ) {
ThreadSafepointState* cur_state = current->safepoint_state();
cur_state->restart(); // TSS _running
- SafepointMechanism::disarm_local_poll(current); // release store, local state -> polling page
+ SafepointMechanism::disarm_local_poll(current);
}
log_info(safepoint)("Leaving safepoint region");
} else {
--- a/src/hotspot/share/runtime/safepointMechanism.hpp Mon Jul 02 09:38:20 2018 +0200
+++ b/src/hotspot/share/runtime/safepointMechanism.hpp Mon Jul 02 11:46:15 2018 +0200
@@ -79,9 +79,13 @@
// Blocks a thread until safepoint is completed
static inline void block_if_requested(JavaThread* thread);
+ // Caller is responsible for using a memory barrier if needed.
static inline void arm_local_poll(JavaThread* thread);
static inline void disarm_local_poll(JavaThread* thread);
+ static inline void arm_local_poll_release(JavaThread* thread);
+ static inline void disarm_local_poll_release(JavaThread* thread);
+
// Setup the selected safepoint mechanism
static void initialize();
static void initialize_header(JavaThread* thread);
--- a/src/hotspot/share/runtime/safepointMechanism.inline.hpp Mon Jul 02 09:38:20 2018 +0200
+++ b/src/hotspot/share/runtime/safepointMechanism.inline.hpp Mon Jul 02 11:46:15 2018 +0200
@@ -87,4 +87,12 @@
thread->set_polling_page(poll_disarmed_value());
}
+void SafepointMechanism::arm_local_poll_release(JavaThread* thread) {
+ thread->set_polling_page_release(poll_armed_value());
+}
+
+void SafepointMechanism::disarm_local_poll_release(JavaThread* thread) {
+ thread->set_polling_page_release(poll_disarmed_value());
+}
+
#endif // SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_INLINE_HPP
--- a/src/hotspot/share/runtime/thread.hpp Mon Jul 02 09:38:20 2018 +0200
+++ b/src/hotspot/share/runtime/thread.hpp Mon Jul 02 11:46:15 2018 +0200
@@ -1207,6 +1207,7 @@
bool do_not_unlock_if_synchronized() { return _do_not_unlock_if_synchronized; }
void set_do_not_unlock_if_synchronized(bool val) { _do_not_unlock_if_synchronized = val; }
+ inline void set_polling_page_release(void* poll_value);
inline void set_polling_page(void* poll_value);
inline volatile void* get_polling_page();
--- a/src/hotspot/share/runtime/thread.inline.hpp Mon Jul 02 09:38:20 2018 +0200
+++ b/src/hotspot/share/runtime/thread.inline.hpp Mon Jul 02 11:46:15 2018 +0200
@@ -170,8 +170,13 @@
// The release make sure this store is done after storing the handshake
// operation or global state
+inline void JavaThread::set_polling_page_release(void* poll_value) {
+ OrderAccess::release_store(polling_page_addr(), poll_value);
+}
+
+// Caller is responsible for using a memory barrier if needed.
inline void JavaThread::set_polling_page(void* poll_value) {
- OrderAccess::release_store(polling_page_addr(), poll_value);
+ *polling_page_addr() = poll_value;
}
// The aqcquire make sure reading of polling page is done before