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8220051: Remove global safepoint code

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Reviewed-by: mdoerr, dcubed, eosterlund, bulasevich, coleenp
This commit is contained in:
Robbin Ehn 2020-04-01 14:54:44 +02:00
parent 8d84cf5a3b
commit bf41f548e1
86 changed files with 263 additions and 927 deletions
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55
src/hotspot/share/runtime/safepoint.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -140,7 +140,6 @@ int SafepointSynchronize::_current_jni_active_count = 0;
WaitBarrier* SafepointSynchronize::_wait_barrier;
static volatile bool PageArmed = false; // safepoint polling page is RO|RW vs PROT_NONE
static bool timeout_error_printed = false;
// Statistic related
@ -250,13 +249,6 @@ int SafepointSynchronize::synchronize_threads(jlong safepoint_limit_time, int no
if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
print_safepoint_timeout();
}
if (int(iterations) == -1) { // overflow - something is wrong.
// We can only overflow here when we are using global
// polling pages. We keep this guarantee in its original
// form so that searches of the bug database for this
// failure mode find the right bugs.
guarantee (!PageArmed, "invariant");
}
p_prev = &tss_head;
ThreadSafepointState *cur_tss = tss_head;
@ -297,9 +289,6 @@ void SafepointSynchronize::arm_safepoint() {
// 1. Running interpreted
// When executing branching/returning byte codes interpreter
// checks if the poll is armed, if so blocks in SS::block().
// When using global polling the interpreter dispatch table
// is changed to force it to check for a safepoint condition
// between bytecodes.
// 2. Running in native code
// When returning from the native code, a Java thread must check
// the safepoint _state to see if we must block. If the
@ -334,26 +323,15 @@ void SafepointSynchronize::arm_safepoint() {
OrderAccess::storestore(); // Ordered with _safepoint_counter
_state = _synchronizing;
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);
}
// 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);
}
OrderAccess::fence(); // storestore|storeload, global state -> local state
if (SafepointMechanism::uses_global_page_poll()) {
// Make interpreter safepoint aware
Interpreter::notice_safepoints();
// Make polling safepoint aware
guarantee (!PageArmed, "invariant") ;
PageArmed = true;
os::make_polling_page_unreadable();
}
}
// Roll all threads forward to a safepoint and suspend them all
@ -464,15 +442,6 @@ void SafepointSynchronize::disarm_safepoint() {
}
#endif // ASSERT
if (SafepointMechanism::uses_global_page_poll()) {
guarantee (PageArmed, "invariant");
// Make polling safepoint aware
os::make_polling_page_readable();
PageArmed = false;
// Remove safepoint check from interpreter
Interpreter::ignore_safepoints();
}
OrderAccess::fence(); // keep read and write of _state from floating up
assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
@ -878,9 +847,6 @@ void SafepointSynchronize::block(JavaThread *thread) {
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");
if (!SafepointMechanism::uses_thread_local_poll()) {
assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
}
if (log_is_enabled(Info, safepoint, stats)) {
Atomic::inc(&_nof_threads_hit_polling_page);
@ -1049,11 +1015,6 @@ void ThreadSafepointState::print_on(outputStream *st) const {
// Block the thread at poll or poll return for safepoint/handshake.
void ThreadSafepointState::handle_polling_page_exception() {
// If we're using a global poll, then the thread should not be
// marked as safepoint safe yet.
assert(!SafepointMechanism::uses_global_page_poll() || !_safepoint_safe,
"polling page exception on thread safepoint safe");
// Step 1: Find the nmethod from the return address
address real_return_addr = thread()->saved_exception_pc();