--- a/src/hotspot/share/runtime/safepoint.cpp Sat Nov 11 01:21:09 2017 +0100
+++ b/src/hotspot/share/runtime/safepoint.cpp Thu Aug 31 10:00:28 2017 +0200
@@ -52,6 +52,7 @@
#include "runtime/orderAccess.inline.hpp"
#include "runtime/osThread.hpp"
#include "runtime/safepoint.hpp"
+#include "runtime/safepointMechanism.inline.hpp"
#include "runtime/signature.hpp"
#include "runtime/stubCodeGenerator.hpp"
#include "runtime/stubRoutines.hpp"
@@ -169,21 +170,32 @@
int initial_running = 0;
_state = _synchronizing;
- OrderAccess::fence();
+
+ 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");
+ for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
+ // Make sure the threads start polling, it is time to yield.
+ SafepointMechanism::arm_local_poll(cur); // release store, global state -> local state
+ }
+ }
+ OrderAccess::fence(); // storestore|storeload, global state -> local state
// Flush all thread states to memory
if (!UseMembar) {
os::serialize_thread_states();
}
- // Make interpreter safepoint aware
- Interpreter::notice_safepoints();
+ if (SafepointMechanism::uses_global_page_poll()) {
+ // Make interpreter safepoint aware
+ Interpreter::notice_safepoints();
- if (DeferPollingPageLoopCount < 0) {
- // Make polling safepoint aware
- guarantee (PageArmed == 0, "invariant") ;
- PageArmed = 1 ;
- os::make_polling_page_unreadable();
+ if (DeferPollingPageLoopCount < 0) {
+ // Make polling safepoint aware
+ guarantee (PageArmed == 0, "invariant") ;
+ PageArmed = 1 ;
+ os::make_polling_page_unreadable();
+ }
}
// Consider using active_processor_count() ... but that call is expensive.
@@ -293,7 +305,7 @@
// 9. On windows consider using the return value from SwitchThreadTo()
// to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
- if (int(iterations) == DeferPollingPageLoopCount) {
+ if (SafepointMechanism::uses_global_page_poll() && int(iterations) == DeferPollingPageLoopCount) {
guarantee (PageArmed == 0, "invariant") ;
PageArmed = 1 ;
os::make_polling_page_unreadable();
@@ -444,7 +456,7 @@
// A pending_exception cannot be installed during a safepoint. The threads
// may install an async exception after they come back from a safepoint into
// pending_exception after they unblock. But that should happen later.
- for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
+ for (JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
assert (!(cur->has_pending_exception() &&
cur->safepoint_state()->is_at_poll_safepoint()),
"safepoint installed a pending exception");
@@ -452,46 +464,60 @@
#endif // ASSERT
if (PageArmed) {
+ assert(SafepointMechanism::uses_global_page_poll(), "sanity");
// Make polling safepoint aware
os::make_polling_page_readable();
PageArmed = 0 ;
}
- // Remove safepoint check from interpreter
- Interpreter::ignore_safepoints();
+ if (SafepointMechanism::uses_global_page_poll()) {
+ // Remove safepoint check from interpreter
+ Interpreter::ignore_safepoints();
+ }
{
MutexLocker mu(Safepoint_lock);
assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
- // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
- // when they get restarted.
- _state = _not_synchronized;
- OrderAccess::fence();
+ if (SafepointMechanism::uses_thread_local_poll()) {
+ _state = _not_synchronized;
+ OrderAccess::storestore(); // global state -> local state
+ for (JavaThread *current = Threads::first(); current; current = current->next()) {
+ ThreadSafepointState* cur_state = current->safepoint_state();
+ cur_state->restart(); // TSS _running
+ SafepointMechanism::disarm_local_poll(current); // release store, local state -> polling page
+ }
+ log_debug(safepoint)("Leaving safepoint region");
+ } else {
+ // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
+ // when they get restarted.
+ _state = _not_synchronized;
+ OrderAccess::fence();
- log_debug(safepoint)("Leaving safepoint region");
+ log_debug(safepoint)("Leaving safepoint region");
- // Start suspended threads
- for(JavaThread *current = Threads::first(); current; current = current->next()) {
- // A problem occurring on Solaris is when attempting to restart threads
- // the first #cpus - 1 go well, but then the VMThread is preempted when we get
- // to the next one (since it has been running the longest). We then have
- // to wait for a cpu to become available before we can continue restarting
- // threads.
- // FIXME: This causes the performance of the VM to degrade when active and with
- // large numbers of threads. Apparently this is due to the synchronous nature
- // of suspending threads.
- //
- // TODO-FIXME: the comments above are vestigial and no longer apply.
- // Furthermore, using solaris' schedctl in this particular context confers no benefit
- if (VMThreadHintNoPreempt) {
- os::hint_no_preempt();
+ // Start suspended threads
+ for (JavaThread *current = Threads::first(); current; current = current->next()) {
+ // A problem occurring on Solaris is when attempting to restart threads
+ // the first #cpus - 1 go well, but then the VMThread is preempted when we get
+ // to the next one (since it has been running the longest). We then have
+ // to wait for a cpu to become available before we can continue restarting
+ // threads.
+ // FIXME: This causes the performance of the VM to degrade when active and with
+ // large numbers of threads. Apparently this is due to the synchronous nature
+ // of suspending threads.
+ //
+ // TODO-FIXME: the comments above are vestigial and no longer apply.
+ // Furthermore, using solaris' schedctl in this particular context confers no benefit
+ if (VMThreadHintNoPreempt) {
+ os::hint_no_preempt();
+ }
+ ThreadSafepointState* cur_state = current->safepoint_state();
+ assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
+ cur_state->restart();
+ assert(cur_state->is_running(), "safepoint state has not been reset");
}
- ThreadSafepointState* cur_state = current->safepoint_state();
- assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
- cur_state->restart();
- assert(cur_state->is_running(), "safepoint state has not been reset");
}
RuntimeService::record_safepoint_end();
@@ -855,7 +881,9 @@
void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
- assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
+ if (!ThreadLocalHandshakes) {
+ assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
+ }
if (ShowSafepointMsgs) {
tty->print("handle_polling_page_exception: ");
@@ -887,7 +915,7 @@
tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
ThreadSafepointState *cur_state;
ResourceMark rm;
- for(JavaThread *cur_thread = Threads::first(); cur_thread;
+ for (JavaThread *cur_thread = Threads::first(); cur_thread;
cur_thread = cur_thread->next()) {
cur_state = cur_thread->safepoint_state();
@@ -1053,13 +1081,14 @@
// ---------------------------------------------------------------------------------------------------------------------
-// Block the thread at the safepoint poll or poll return.
+// Block the thread at poll or poll return for safepoint/handshake.
void ThreadSafepointState::handle_polling_page_exception() {
// Check state. block() will set thread state to thread_in_vm which will
// cause the safepoint state _type to become _call_back.
- assert(type() == ThreadSafepointState::_running,
- "polling page exception on thread not running state");
+ suspend_type t = type();
+ assert(!SafepointMechanism::uses_global_page_poll() || t == ThreadSafepointState::_running,
+ "polling page exception on thread not running state: %u", uint(t));
// Step 1: Find the nmethod from the return address
if (ShowSafepointMsgs && Verbose) {
@@ -1101,7 +1130,7 @@
}
// Block the thread
- SafepointSynchronize::block(thread());
+ SafepointMechanism::block_if_requested(thread());
// restore oop result, if any
if (return_oop) {
@@ -1117,7 +1146,7 @@
assert(real_return_addr == caller_fr.pc(), "must match");
// Block the thread
- SafepointSynchronize::block(thread());
+ SafepointMechanism::block_if_requested(thread());
set_at_poll_safepoint(false);
// If we have a pending async exception deoptimize the frame
@@ -1398,7 +1427,7 @@
tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
"synchronized");
- for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
+ for (JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
cur->safepoint_state()->print();
}
}