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8194085: Obsolete the deprecated SafepointSynchronize flags and remove related code

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Obsolete SafepointSpinBeforeYield, DeferThrSuspendLoopCount, and DeferPollingPageLoopCount and remove associated code.

Reviewed-by: dcubed, coleenp, dholmes
This commit is contained in:
Harold Seigel 2018-02-26 11:28:05 -05:00
parent e447371492
commit 114e61d126
4 changed files with 26 additions and 56 deletions
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49
src/hotspot/share/runtime/safepoint.cpp
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@ -78,6 +78,8 @@ volatile int SafepointSynchronize::_waiting_to_block = 0;
volatile int SafepointSynchronize::_safepoint_counter = 0;
int SafepointSynchronize::_current_jni_active_count = 0;
long SafepointSynchronize::_end_of_last_safepoint = 0;
int SafepointSynchronize::_defer_thr_suspend_loop_count = 4000;
static const int safepoint_spin_before_yield = 2000;
static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
static bool timeout_error_printed = false;
@ -191,12 +193,10 @@ void SafepointSynchronize::begin() {
// 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();
}
// 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.
@ -309,19 +309,21 @@ void SafepointSynchronize::begin() {
// 9. On windows consider using the return value from SwitchThreadTo()
// to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
if (SafepointMechanism::uses_global_page_poll() && int(iterations) == DeferPollingPageLoopCount) {
guarantee (PageArmed == 0, "invariant") ;
PageArmed = 1 ;
os::make_polling_page_unreadable();
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 == 0, "invariant");
}
// Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
// ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
++steps ;
if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
if (ncpus > 1 && steps < safepoint_spin_before_yield) {
SpinPause() ; // MP-Polite spin
} else
if (steps < DeferThrSuspendLoopCount) {
if (steps < _defer_thr_suspend_loop_count) {
os::naked_yield() ;
} else {
os::naked_short_sleep(1);
@ -1190,7 +1192,6 @@ jlong SafepointSynchronize::_max_vmop_time = 0;
float SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
static jlong cleanup_end_time = 0;
static bool need_to_track_page_armed_status = false;
static bool init_done = false;
// Helper method to print the header.
@ -1202,11 +1203,6 @@ static void print_header() {
"[ threads: total initially_running wait_to_block ]"
"[ time: spin block sync cleanup vmop ] ");
// no page armed status printed out if it is always armed.
if (need_to_track_page_armed_status) {
tty->print("page_armed ");
}
tty->print_cr("page_trap_count");
}
@ -1229,9 +1225,6 @@ void SafepointSynchronize::deferred_initialize_stat() {
guarantee(_safepoint_stats != NULL,
"not enough memory for safepoint instrumentation data");
if (DeferPollingPageLoopCount >= 0) {
need_to_track_page_armed_status = true;
}
init_done = true;
}
@ -1271,10 +1264,6 @@ void SafepointSynchronize::update_statistics_on_spin_end() {
spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
}
if (need_to_track_page_armed_status) {
spstat->_page_armed = (PageArmed == 1);
}
// Records the start time of waiting for to block. Updated when block is done.
if (_waiting_to_block != 0) {
spstat->_time_to_wait_to_block = cur_time;
@ -1363,9 +1352,6 @@ void SafepointSynchronize::print_statistics() {
(int64_t)(sstats->_time_to_do_cleanups / MICROUNITS),
(int64_t)(sstats->_time_to_exec_vmop / MICROUNITS));
if (need_to_track_page_armed_status) {
tty->print(INT32_FORMAT_W(10) " ", sstats->_page_armed);
}
tty->print_cr(INT32_FORMAT_W(15) " ", sstats->_nof_threads_hit_page_trap);
}
}
@ -1392,12 +1378,7 @@ void SafepointSynchronize::print_stat_on_exit() {
tty->cr();
// Print out polling page sampling status.
if (!need_to_track_page_armed_status) {
tty->print_cr("Polling page always armed");
} else {
tty->print_cr("Defer polling page loop count = " INTX_FORMAT "\n",
DeferPollingPageLoopCount);
}
tty->print_cr("Polling page always armed");
for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
if (_safepoint_reasons[index] != 0) {