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8202615: Remove NativeMonitorSpinLimit, NativeMonitorFlags and NativeMonitorTimeout experimental flags

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Removed NativeMonitorSpinLimit, NativeMonitorFlags and NativeMonitorTimeout experimental flags from globals.hpp and mutex.cpp and marked them as obsolete.

Reviewed-by: kbarrett, dholmes
This commit is contained in:
Patricio Chilano Mateo 2018-06-25 13:47:27 -04:00 • committed by Coleen Phillimore
parent 0a0a8a5791
commit 46f2f92658
3 changed files with 7 additions and 32 deletions
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3
src/hotspot/share/runtime/arguments.cpp
View file

@ -570,6 +570,9 @@ static SpecialFlag const special_jvm_flags[] = {
{ "InlineNotify", JDK_Version::undefined(), JDK_Version::jdk(11), JDK_Version::jdk(12) },
{ "EnableTracing", JDK_Version::undefined(), JDK_Version::jdk(11), JDK_Version::jdk(12) },
{ "UseLockedTracing", JDK_Version::undefined(), JDK_Version::jdk(11), JDK_Version::jdk(12) },
{ "NativeMonitorTimeout", JDK_Version::undefined(), JDK_Version::jdk(11), JDK_Version::jdk(12) },
{ "NativeMonitorSpinLimit", JDK_Version::undefined(), JDK_Version::jdk(11), JDK_Version::jdk(12) },
{ "NativeMonitorFlags", JDK_Version::undefined(), JDK_Version::jdk(11), JDK_Version::jdk(12) },
#ifdef TEST_VERIFY_SPECIAL_JVM_FLAGS
{ "dep > obs", JDK_Version::jdk(9), JDK_Version::jdk(8), JDK_Version::undefined() },

6
src/hotspot/share/runtime/globals.hpp
View file

@ -854,12 +854,6 @@ define_pd_global(uint64_t,MaxRAM, 1ULL*G);
"When true prevents OS-level spurious, or premature, wakeups " \
"from Object.wait (Ignored for Windows)") \
\
experimental(intx, NativeMonitorTimeout, -1, "(Unstable)") \
\
experimental(intx, NativeMonitorFlags, 0, "(Unstable)") \
\
experimental(intx, NativeMonitorSpinLimit, 20, "(Unstable)") \
\
develop(bool, UsePthreads, false, \
"Use pthread-based instead of libthread-based synchronization " \
"(SPARC only)") \

28
src/hotspot/share/runtime/mutex.cpp
View file

@ -348,9 +348,7 @@ int Monitor::TrySpin(Thread * const Self) {
int Probes = 0;
int Delay = 0;
int Steps = 0;
int SpinMax = NativeMonitorSpinLimit;
int flgs = NativeMonitorFlags;
int SpinMax = 20;
for (;;) {
intptr_t v = _LockWord.FullWord;
if ((v & _LBIT) == 0) {
@ -360,9 +358,7 @@ int Monitor::TrySpin(Thread * const Self) {
continue;
}
if ((flgs & 8) == 0) {
SpinPause();
}
// Periodically increase Delay -- variable Delay form
// conceptually: delay *= 1 + 1/Exponent
@ -374,8 +370,6 @@ int Monitor::TrySpin(Thread * const Self) {
// CONSIDER: Delay += 1 + (Delay/4); Delay &= 0x7FF ;
}
if (flgs & 2) continue;
// Consider checking _owner's schedctl state, if OFFPROC abort spin.
// If the owner is OFFPROC then it's unlike that the lock will be dropped
// in a timely fashion, which suggests that spinning would not be fruitful
@ -390,12 +384,11 @@ int Monitor::TrySpin(Thread * const Self) {
// spin loop. N1 and brethren write-around the L1$ over the xbar into the L2$.
// Furthermore, they don't have a W$ like traditional SPARC processors.
// We currently use a Marsaglia Shift-Xor RNG loop.
Steps += Delay;
if (Self != NULL) {
jint rv = Self->rng[0];
for (int k = Delay; --k >= 0;) {
rv = MarsagliaXORV(rv);
if ((flgs & 4) == 0 && SafepointMechanism::poll(Self)) return 0;
if (SafepointMechanism::poll(Self)) return 0;
}
Self->rng[0] = rv;
} else {
@ -406,10 +399,6 @@ int Monitor::TrySpin(Thread * const Self) {
static int ParkCommon(ParkEvent * ev, jlong timo) {
// Diagnostic support - periodically unwedge blocked threads
intx nmt = NativeMonitorTimeout;
if (nmt > 0 && (nmt < timo || timo <= 0)) {
timo = nmt;
}
int err = OS_OK;
if (0 == timo) {
ev->park();
@ -466,11 +455,6 @@ void Monitor::ILock(Thread * Self) {
ESelf->reset();
OrderAccess::fence();
// Optional optimization ... try barging on the inner lock
if ((NativeMonitorFlags & 32) && Atomic::replace_if_null(ESelf, &_OnDeck)) {
goto OnDeck_LOOP;
}
if (AcquireOrPush(ESelf)) goto Exeunt;
// At any given time there is at most one ondeck thread.
@ -484,7 +468,6 @@ void Monitor::ILock(Thread * Self) {
// Self is now in the OnDeck position and will remain so until it
// manages to acquire the lock.
OnDeck_LOOP:
for (;;) {
assert(_OnDeck == ESelf, "invariant");
if (TrySpin(Self)) break;
@ -706,11 +689,6 @@ bool Monitor::notify() {
nfy->Notified = 1;
}
Thread::muxRelease(_WaitLock);
if (nfy != NULL && (NativeMonitorFlags & 16)) {
// Experimental code ... light up the wakee in the hope that this thread (the owner)
// will drop the lock just about the time the wakee comes ONPROC.
nfy->unpark();
}
assert(ILocked(), "invariant");
return true;
}
@ -794,7 +772,7 @@ int Monitor::IWait(Thread * Self, jlong timo) {
for (;;) {
if (ESelf->Notified) break;
int err = ParkCommon(ESelf, timo);
if (err == OS_TIMEOUT || (NativeMonitorFlags & 1)) break;
if (err == OS_TIMEOUT) break;
}
// Prepare for reentry - if necessary, remove ESelf from WaitSet