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8304820: Statically allocate ObjectSynchronizer mutexes

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Reviewed-by: dcubed, dholmes
(cherry picked from commit fe42312f9b)
This commit is contained in:
Justin King
2023-03-31 14:28:22 +00:00
committed by Vitaly Provodin
parent e8e90325bd
commit 094dc9a38f
1 changed files with 17 additions and 9 deletions
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26
src/hotspot/share/runtime/synchronizer.cpp
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@@ -245,12 +245,20 @@ int dtrace_waited_probe(ObjectMonitor* monitor, Handle obj, JavaThread* thr) {
return 0;
}
static const int NINFLATIONLOCKS = 256;
static PlatformMutex* gInflationLocks[NINFLATIONLOCKS];
static constexpr size_t inflation_lock_count() {
return 256;
}
// Static storage for an array of PlatformMutex.
alignas(PlatformMutex) static uint8_t _inflation_locks[inflation_lock_count()][sizeof(PlatformMutex)];
static inline PlatformMutex* inflation_lock(size_t index) {
return reinterpret_cast<PlatformMutex*>(_inflation_locks[index]);
}
void ObjectSynchronizer::initialize() {
for (int i = 0; i < NINFLATIONLOCKS; i++) {
gInflationLocks[i] = new PlatformMutex();
for (size_t i = 0; i < inflation_lock_count(); i++) {
::new(static_cast<void*>(inflation_lock(i))) PlatformMutex();
}
// Start the ceiling with the estimate for one thread.
set_in_use_list_ceiling(AvgMonitorsPerThreadEstimate);
@@ -740,11 +748,11 @@ static markWord read_stable_mark(oop obj) {
// then for each thread on the list, set the flag and unpark() the thread.
// Index into the lock array based on the current object address.
static_assert(is_power_of_2(NINFLATIONLOCKS), "must be");
int ix = (cast_from_oop<intptr_t>(obj) >> 5) & (NINFLATIONLOCKS-1);
static_assert(is_power_of_2(inflation_lock_count()), "must be");
size_t ix = (cast_from_oop<intptr_t>(obj) >> 5) & (inflation_lock_count() - 1);
int YieldThenBlock = 0;
assert(ix >= 0 && ix < NINFLATIONLOCKS, "invariant");
gInflationLocks[ix]->lock();
assert(ix < inflation_lock_count(), "invariant");
inflation_lock(ix)->lock();
while (obj->mark_acquire() == markWord::INFLATING()) {
// Beware: naked_yield() is advisory and has almost no effect on some platforms
// so we periodically call current->_ParkEvent->park(1).
@@ -755,7 +763,7 @@ static markWord read_stable_mark(oop obj) {
os::naked_yield();
}
}
gInflationLocks[ix]->unlock();
inflation_lock(ix)->unlock();
}
} else {
SpinPause(); // SMP-polite spinning