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8224115: Shenandoah: Eliminate RWLock that protects recorded nmethod data array

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Reviewed-by: shade
This commit is contained in:
Zhengyu Gu 2019-05-22 21:24:09 -04:00
parent 96c9fcf22f
commit deaba32229
2 changed files with 4 additions and 65 deletions
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13
src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
View File

@ -120,15 +120,14 @@ public:
}
};
ShenandoahCodeRoots::PaddedLock ShenandoahCodeRoots::_recorded_nms_lock;
GrowableArray<ShenandoahNMethod*>* ShenandoahCodeRoots::_recorded_nms;
void ShenandoahCodeRoots::initialize() {
_recorded_nms_lock._lock = 0;
_recorded_nms = new (ResourceObj::C_HEAP, mtGC) GrowableArray<ShenandoahNMethod*>(100, true, mtGC);
}
void ShenandoahCodeRoots::add_nmethod(nmethod* nm) {
assert(CodeCache_lock->owned_by_self(), "Must own CodeCache_lock");
switch (ShenandoahCodeRootsStyle) {
case 0:
case 1:
@ -140,9 +139,6 @@ void ShenandoahCodeRoots::add_nmethod(nmethod* nm) {
if (detector.has_oops()) {
ShenandoahNMethod* nmr = new ShenandoahNMethod(nm, detector.oops());
nmr->assert_alive_and_correct();
ShenandoahCodeRootsLock lock(true);
int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
if (idx != -1) {
ShenandoahNMethod* old = _recorded_nms->at(idx);
@ -160,6 +156,7 @@ void ShenandoahCodeRoots::add_nmethod(nmethod* nm) {
};
void ShenandoahCodeRoots::remove_nmethod(nmethod* nm) {
assert(CodeCache_lock->owned_by_self(), "Must own CodeCache_lock");
switch (ShenandoahCodeRootsStyle) {
case 0:
case 1: {
@ -170,8 +167,6 @@ void ShenandoahCodeRoots::remove_nmethod(nmethod* nm) {
nm->oops_do(&detector, /* allow_zombie = */ true);
if (detector.has_oops()) {
ShenandoahCodeRootsLock lock(true);
int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
assert(idx != -1, "nmethod " PTR_FORMAT " should be registered", p2i(nm));
ShenandoahNMethod* old = _recorded_nms->at(idx);
@ -199,7 +194,7 @@ ShenandoahCodeRootsIterator::ShenandoahCodeRootsIterator() :
break;
}
case 2: {
ShenandoahCodeRoots::acquire_lock(false);
CodeCache_lock->lock();
break;
}
default:
@ -215,7 +210,7 @@ ShenandoahCodeRootsIterator::~ShenandoahCodeRootsIterator() {
break;
}
case 2: {
ShenandoahCodeRoots::release_lock(false);
CodeCache_lock->unlock();
break;
}
default:

56
src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.hpp
View File

@ -31,7 +31,6 @@
class ShenandoahHeap;
class ShenandoahHeapRegion;
class ShenandoahCodeRootsLock;
class ShenandoahParallelCodeHeapIterator {
friend class CodeCache;
@ -124,7 +123,6 @@ public:
class ShenandoahCodeRoots : public CHeapObj<mtGC> {
friend class ShenandoahHeap;
friend class ShenandoahCodeRootsLock;
friend class ShenandoahCodeRootsIterator;
public:
@ -133,61 +131,7 @@ public:
static void remove_nmethod(nmethod* nm);
private:
struct PaddedLock {
DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));
volatile int _lock;
DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
};
static PaddedLock _recorded_nms_lock;
static GrowableArray<ShenandoahNMethod*>* _recorded_nms;
static void acquire_lock(bool write) {
volatile int* loc = &_recorded_nms_lock._lock;
if (write) {
while ((OrderAccess::load_acquire(loc) != 0) ||
Atomic::cmpxchg(-1, loc, 0) != 0) {
SpinPause();
}
assert (*loc == -1, "acquired for write");
} else {
while (true) {
int cur = OrderAccess::load_acquire(loc);
if (cur >= 0) {
if (Atomic::cmpxchg(cur + 1, loc, cur) == cur) {
// Success!
assert (*loc > 0, "acquired for read");
return;
}
}
SpinPause();
}
}
}
static void release_lock(bool write) {
volatile int* loc = &ShenandoahCodeRoots::_recorded_nms_lock._lock;
if (write) {
OrderAccess::release_store_fence(loc, 0);
} else {
Atomic::dec(loc);
}
}
};
// Very simple unranked read-write lock
class ShenandoahCodeRootsLock : public StackObj {
friend class ShenandoahCodeRoots;
private:
const bool _write;
public:
ShenandoahCodeRootsLock(bool write) : _write(write) {
ShenandoahCodeRoots::acquire_lock(write);
}
~ShenandoahCodeRootsLock() {
ShenandoahCodeRoots::release_lock(_write);
}
};
#endif // SHARE_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP