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This commit is contained in:
Erik Trimble 2010-05-13 17:10:32 -07:00
commit 10da52364f
13 changed files with 598 additions and 477 deletions
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6
hotspot/src/cpu/sparc/vm/vm_version_sparc.cpp
View File

@ -104,6 +104,12 @@ void VM_Version::initialize() {
if (FLAG_IS_DEFAULT(OptoLoopAlignment)) {
FLAG_SET_DEFAULT(OptoLoopAlignment, 4);
}
// When using CMS, we cannot use memset() in BOT updates because
// the sun4v/CMT version in libc_psr uses BIS which exposes
// "phantom zeros" to concurrent readers. See 6948537.
if (FLAG_IS_DEFAULT(UseMemSetInBOT) && UseConcMarkSweepGC) {
FLAG_SET_DEFAULT(UseMemSetInBOT, false);
}
}
// Use hardware population count instruction if available.

6
hotspot/src/os_cpu/linux_zero/vm/os_linux_zero.cpp
View File

@ -288,7 +288,7 @@ static void current_stack_region(address *bottom, size_t *size) {
vm_exit_out_of_memory(0, "pthread_getattr_np");
}
else {
fatal1("pthread_getattr_np failed with errno = %d", res);
fatal(err_msg("pthread_getattr_np failed with errno = %d", res));
}
}
@ -296,7 +296,7 @@ static void current_stack_region(address *bottom, size_t *size) {
size_t stack_bytes;
res = pthread_attr_getstack(&attr, (void **) &stack_bottom, &stack_bytes);
if (res != 0) {
fatal1("pthread_attr_getstack failed with errno = %d", res);
fatal(err_msg("pthread_attr_getstack failed with errno = %d", res));
}
address stack_top = stack_bottom + stack_bytes;
@ -308,7 +308,7 @@ static void current_stack_region(address *bottom, size_t *size) {
size_t guard_bytes;
res = pthread_attr_getguardsize(&attr, &guard_bytes);
if (res != 0) {
fatal1("pthread_attr_getguardsize failed with errno = %d", res);
fatal(err_msg("pthread_attr_getguardsize failed with errno = %d", res));
}
int guard_pages = align_size_up(guard_bytes, page_bytes) / page_bytes;
assert(guard_bytes == guard_pages * page_bytes, "unaligned guard");

328
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp
View File

@ -1926,59 +1926,6 @@ oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DEFN)
//////////////////////////////////////////////////////////////////////////////
// We go over the list of promoted objects, removing each from the list,
// and applying the closure (this may, in turn, add more elements to
// the tail of the promoted list, and these newly added objects will
// also be processed) until the list is empty.
// To aid verification and debugging, in the non-product builds
// we actually forward _promoHead each time we process a promoted oop.
// Note that this is not necessary in general (i.e. when we don't need to
// call PromotionInfo::verify()) because oop_iterate can only add to the
// end of _promoTail, and never needs to look at _promoHead.
#define PROMOTED_OOPS_ITERATE_DEFN(OopClosureType, nv_suffix) \
\
void PromotionInfo::promoted_oops_iterate##nv_suffix(OopClosureType* cl) { \
NOT_PRODUCT(verify()); \
PromotedObject *curObj, *nextObj; \
for (curObj = _promoHead; curObj != NULL; curObj = nextObj) { \
if ((nextObj = curObj->next()) == NULL) { \
/* protect ourselves against additions due to closure application \
below by resetting the list. */ \
assert(_promoTail == curObj, "Should have been the tail"); \
_promoHead = _promoTail = NULL; \
} \
if (curObj->hasDisplacedMark()) { \
/* restore displaced header */ \
oop(curObj)->set_mark(nextDisplacedHeader()); \
} else { \
/* restore prototypical header */ \
oop(curObj)->init_mark(); \
} \
/* The "promoted_mark" should now not be set */ \
assert(!curObj->hasPromotedMark(), \
"Should have been cleared by restoring displaced mark-word"); \
NOT_PRODUCT(_promoHead = nextObj); \
if (cl != NULL) oop(curObj)->oop_iterate(cl); \
if (nextObj == NULL) { /* start at head of list reset above */ \
nextObj = _promoHead; \
} \
} \
assert(noPromotions(), "post-condition violation"); \
assert(_promoHead == NULL && _promoTail == NULL, "emptied promoted list");\
assert(_spoolHead == _spoolTail, "emptied spooling buffers"); \
assert(_firstIndex == _nextIndex, "empty buffer"); \
}
// This should have been ALL_SINCE_...() just like the others,
// but, because the body of the method above is somehwat longer,
// the MSVC compiler cannot cope; as a workaround, we split the
// macro into its 3 constituent parts below (see original macro
// definition in specializedOopClosures.hpp).
SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(PROMOTED_OOPS_ITERATE_DEFN)
PROMOTED_OOPS_ITERATE_DEFN(OopsInGenClosure,_v)
void CompactibleFreeListSpace::object_iterate_since_last_GC(ObjectClosure* cl) {
// ugghh... how would one do this efficiently for a non-contiguous space?
@ -2506,281 +2453,6 @@ void CompactibleFreeListSpace::printFLCensus(size_t sweep_count) const {
_dictionary->printDictCensus();
}
// Return the next displaced header, incrementing the pointer and
// recycling spool area as necessary.
markOop PromotionInfo::nextDisplacedHeader() {
assert(_spoolHead != NULL, "promotionInfo inconsistency");
assert(_spoolHead != _spoolTail || _firstIndex < _nextIndex,
"Empty spool space: no displaced header can be fetched");
assert(_spoolHead->bufferSize > _firstIndex, "Off by one error at head?");
markOop hdr = _spoolHead->displacedHdr[_firstIndex];
// Spool forward
if (++_firstIndex == _spoolHead->bufferSize) { // last location in this block
// forward to next block, recycling this block into spare spool buffer
SpoolBlock* tmp = _spoolHead->nextSpoolBlock;
assert(_spoolHead != _spoolTail, "Spooling storage mix-up");
_spoolHead->nextSpoolBlock = _spareSpool;
_spareSpool = _spoolHead;
_spoolHead = tmp;
_firstIndex = 1;
NOT_PRODUCT(
if (_spoolHead == NULL) { // all buffers fully consumed
assert(_spoolTail == NULL && _nextIndex == 1,
"spool buffers processing inconsistency");
}
)
}
return hdr;
}
void PromotionInfo::track(PromotedObject* trackOop) {
track(trackOop, oop(trackOop)->klass());
}
void PromotionInfo::track(PromotedObject* trackOop, klassOop klassOfOop) {
// make a copy of header as it may need to be spooled
markOop mark = oop(trackOop)->mark();
trackOop->clearNext();
if (mark->must_be_preserved_for_cms_scavenge(klassOfOop)) {
// save non-prototypical header, and mark oop
saveDisplacedHeader(mark);
trackOop->setDisplacedMark();
} else {
// we'd like to assert something like the following:
// assert(mark == markOopDesc::prototype(), "consistency check");
// ... but the above won't work because the age bits have not (yet) been
// cleared. The remainder of the check would be identical to the
// condition checked in must_be_preserved() above, so we don't really
// have anything useful to check here!
}
if (_promoTail != NULL) {
assert(_promoHead != NULL, "List consistency");
_promoTail->setNext(trackOop);
_promoTail = trackOop;
} else {
assert(_promoHead == NULL, "List consistency");
_promoHead = _promoTail = trackOop;
}
// Mask as newly promoted, so we can skip over such objects
// when scanning dirty cards
assert(!trackOop->hasPromotedMark(), "Should not have been marked");
trackOop->setPromotedMark();
}
// Save the given displaced header, incrementing the pointer and
// obtaining more spool area as necessary.
void PromotionInfo::saveDisplacedHeader(markOop hdr) {
assert(_spoolHead != NULL && _spoolTail != NULL,
"promotionInfo inconsistency");
assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?");
_spoolTail->displacedHdr[_nextIndex] = hdr;
// Spool forward
if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block
// get a new spooling block
assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list");
_splice_point = _spoolTail; // save for splicing
_spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail
_spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ...
// ... but will attempt filling before next promotion attempt
_nextIndex = 1;
}
}
// Ensure that spooling space exists. Return false if spooling space
// could not be obtained.
bool PromotionInfo::ensure_spooling_space_work() {
assert(!has_spooling_space(), "Only call when there is no spooling space");
// Try and obtain more spooling space
SpoolBlock* newSpool = getSpoolBlock();
assert(newSpool == NULL ||
(newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL),
"getSpoolBlock() sanity check");
if (newSpool == NULL) {
return false;
}
_nextIndex = 1;
if (_spoolTail == NULL) {
_spoolTail = newSpool;
if (_spoolHead == NULL) {
_spoolHead = newSpool;
_firstIndex = 1;
} else {
assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL,
"Splice point invariant");
// Extra check that _splice_point is connected to list
#ifdef ASSERT
{
SpoolBlock* blk = _spoolHead;
for (; blk->nextSpoolBlock != NULL;
blk = blk->nextSpoolBlock);
assert(blk != NULL && blk == _splice_point,
"Splice point incorrect");
}
#endif // ASSERT
_splice_point->nextSpoolBlock = newSpool;
}
} else {
assert(_spoolHead != NULL, "spool list consistency");
_spoolTail->nextSpoolBlock = newSpool;
_spoolTail = newSpool;
}
return true;
}
// Get a free spool buffer from the free pool, getting a new block
// from the heap if necessary.
SpoolBlock* PromotionInfo::getSpoolBlock() {
SpoolBlock* res;
if ((res = _spareSpool) != NULL) {
_spareSpool = _spareSpool->nextSpoolBlock;
res->nextSpoolBlock = NULL;
} else { // spare spool exhausted, get some from heap
res = (SpoolBlock*)(space()->allocateScratch(refillSize()));
if (res != NULL) {
res->init();
}
}
assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition");
return res;
}
void PromotionInfo::startTrackingPromotions() {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"spooling inconsistency?");
_firstIndex = _nextIndex = 1;
_tracking = true;
}
#define CMSPrintPromoBlockInfo 1
void PromotionInfo::stopTrackingPromotions(uint worker_id) {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"spooling inconsistency?");
_firstIndex = _nextIndex = 1;
_tracking = false;
if (CMSPrintPromoBlockInfo > 1) {
print_statistics(worker_id);
}
}
void PromotionInfo::print_statistics(uint worker_id) const {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"Else will undercount");
assert(CMSPrintPromoBlockInfo > 0, "Else unnecessary call");
// Count the number of blocks and slots in the free pool
size_t slots = 0;
size_t blocks = 0;
for (SpoolBlock* cur_spool = _spareSpool;
cur_spool != NULL;
cur_spool = cur_spool->nextSpoolBlock) {
// the first entry is just a self-pointer; indices 1 through
// bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
guarantee((void*)cur_spool->displacedHdr == (void*)&cur_spool->displacedHdr,
"first entry of displacedHdr should be self-referential");
slots += cur_spool->bufferSize - 1;
blocks++;
}
if (_spoolHead != NULL) {
slots += _spoolHead->bufferSize - 1;
blocks++;
}
gclog_or_tty->print_cr(" [worker %d] promo_blocks = %d, promo_slots = %d ",
worker_id, blocks, slots);
}
// When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex>
// points to the next slot available for filling.
// The set of slots holding displaced headers are then all those in the
// right-open interval denoted by:
//
// [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> )
//
// When _spoolTail is NULL, then the set of slots with displaced headers
// is all those starting at the slot <_spoolHead, _firstIndex> and
// going up to the last slot of last block in the linked list.
// In this lartter case, _splice_point points to the tail block of
// this linked list of blocks holding displaced headers.
void PromotionInfo::verify() const {
// Verify the following:
// 1. the number of displaced headers matches the number of promoted
// objects that have displaced headers
// 2. each promoted object lies in this space
debug_only(
PromotedObject* junk = NULL;
assert(junk->next_addr() == (void*)(oop(junk)->mark_addr()),
"Offset of PromotedObject::_next is expected to align with "
" the OopDesc::_mark within OopDesc");
)
// FIXME: guarantee????
guarantee(_spoolHead == NULL || _spoolTail != NULL ||
_splice_point != NULL, "list consistency");
guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency");
// count the number of objects with displaced headers
size_t numObjsWithDisplacedHdrs = 0;
for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) {
guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment");
// the last promoted object may fail the mark() != NULL test of is_oop().
guarantee(curObj->next() == NULL || oop(curObj)->is_oop(), "must be an oop");
if (curObj->hasDisplacedMark()) {
numObjsWithDisplacedHdrs++;
}
}
// Count the number of displaced headers
size_t numDisplacedHdrs = 0;
for (SpoolBlock* curSpool = _spoolHead;
curSpool != _spoolTail && curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
// the first entry is just a self-pointer; indices 1 through
// bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr,
"first entry of displacedHdr should be self-referential");
numDisplacedHdrs += curSpool->bufferSize - 1;
}
guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0),
"internal consistency");
guarantee(_spoolTail != NULL || _nextIndex == 1,
"Inconsistency between _spoolTail and _nextIndex");
// We overcounted (_firstIndex-1) worth of slots in block
// _spoolHead and we undercounted (_nextIndex-1) worth of
// slots in block _spoolTail. We make an appropriate
// adjustment by subtracting the first and adding the
// second: - (_firstIndex - 1) + (_nextIndex - 1)
numDisplacedHdrs += (_nextIndex - _firstIndex);
guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count");
}
void PromotionInfo::print_on(outputStream* st) const {
SpoolBlock* curSpool = NULL;
size_t i = 0;
st->print_cr("start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")",
_firstIndex, _nextIndex);
for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" active ");
i++;
}
for (curSpool = _spoolTail; curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" inactive ");
i++;
}
for (curSpool = _spareSpool; curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" free ");
i++;
}
st->print_cr(SIZE_FORMAT " header spooling blocks", i);
}
void SpoolBlock::print_on(outputStream* st) const {
st->print("[" PTR_FORMAT "," PTR_FORMAT "), " SIZE_FORMAT " HeapWords -> " PTR_FORMAT,
this, (HeapWord*)displacedHdr + bufferSize,
bufferSize, nextSpoolBlock);
}
///////////////////////////////////////////////////////////////////////////
// CFLS_LAB
///////////////////////////////////////////////////////////////////////////

140
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp
View File

@ -33,140 +33,6 @@ class UpwardsObjectClosure;
class ObjectClosureCareful;
class Klass;
class PromotedObject VALUE_OBJ_CLASS_SPEC {
private:
enum {
promoted_mask = right_n_bits(2), // i.e. 0x3
displaced_mark = nth_bit(2), // i.e. 0x4
next_mask = ~(right_n_bits(3)) // i.e. ~(0x7)
};
intptr_t _next;
public:
inline PromotedObject* next() const {
return (PromotedObject*)(_next & next_mask);
}
inline void setNext(PromotedObject* x) {
assert(((intptr_t)x & ~next_mask) == 0,
"Conflict in bit usage, "
" or insufficient alignment of objects");
_next |= (intptr_t)x;
}
inline void setPromotedMark() {
_next |= promoted_mask;
}
inline bool hasPromotedMark() const {
return (_next & promoted_mask) == promoted_mask;
}
inline void setDisplacedMark() {
_next |= displaced_mark;
}
inline bool hasDisplacedMark() const {
return (_next & displaced_mark) != 0;
}
inline void clearNext() { _next = 0; }
debug_only(void *next_addr() { return (void *) &_next; })
};
class SpoolBlock: public FreeChunk {
friend class PromotionInfo;
protected:
SpoolBlock* nextSpoolBlock;
size_t bufferSize; // number of usable words in this block
markOop* displacedHdr; // the displaced headers start here
// Note about bufferSize: it denotes the number of entries available plus 1;
// legal indices range from 1 through BufferSize - 1. See the verification
// code verify() that counts the number of displaced headers spooled.
size_t computeBufferSize() {
return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);
}
public:
void init() {
bufferSize = computeBufferSize();
displacedHdr = (markOop*)&displacedHdr;
nextSpoolBlock = NULL;
}
void print_on(outputStream* st) const;
void print() const { print_on(gclog_or_tty); }
};
class PromotionInfo VALUE_OBJ_CLASS_SPEC {
bool _tracking; // set if tracking
CompactibleFreeListSpace* _space; // the space to which this belongs
PromotedObject* _promoHead; // head of list of promoted objects
PromotedObject* _promoTail; // tail of list of promoted objects
SpoolBlock* _spoolHead; // first spooling block
SpoolBlock* _spoolTail; // last non-full spooling block or null
SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail
SpoolBlock* _spareSpool; // free spool buffer
size_t _firstIndex; // first active index in
// first spooling block (_spoolHead)
size_t _nextIndex; // last active index + 1 in last
// spooling block (_spoolTail)
private:
// ensure that spooling space exists; return true if there is spooling space
bool ensure_spooling_space_work();
public:
PromotionInfo() :
_tracking(0), _space(NULL),
_promoHead(NULL), _promoTail(NULL),
_spoolHead(NULL), _spoolTail(NULL),
_spareSpool(NULL), _firstIndex(1),
_nextIndex(1) {}
bool noPromotions() const {
assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");
return _promoHead == NULL;
}
void startTrackingPromotions();
void stopTrackingPromotions(uint worker_id = 0);
bool tracking() const { return _tracking; }
void track(PromotedObject* trackOop); // keep track of a promoted oop
// The following variant must be used when trackOop is not fully
// initialized and has a NULL klass:
void track(PromotedObject* trackOop, klassOop klassOfOop); // keep track of a promoted oop
void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }
CompactibleFreeListSpace* space() const { return _space; }
markOop nextDisplacedHeader(); // get next header & forward spool pointer
void saveDisplacedHeader(markOop hdr);
// save header and forward spool
inline size_t refillSize() const;
SpoolBlock* getSpoolBlock(); // return a free spooling block
inline bool has_spooling_space() {
return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;
}
// ensure that spooling space exists
bool ensure_spooling_space() {
return has_spooling_space() || ensure_spooling_space_work();
}
#define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \
void promoted_oops_iterate##nv_suffix(OopClosureType* cl);
ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)
#undef PROMOTED_OOPS_ITERATE_DECL
void promoted_oops_iterate(OopsInGenClosure* cl) {
promoted_oops_iterate_v(cl);
}
void verify() const;
void reset() {
_promoHead = NULL;
_promoTail = NULL;
_spoolHead = NULL;
_spoolTail = NULL;
_spareSpool = NULL;
_firstIndex = 0;
_nextIndex = 0;
}
void print_on(outputStream* st) const;
void print_statistics(uint worker_id) const;
};
class LinearAllocBlock VALUE_OBJ_CLASS_SPEC {
public:
LinearAllocBlock() : _ptr(0), _word_size(0), _refillSize(0),
@ -557,6 +423,12 @@ class CompactibleFreeListSpace: public CompactibleSpace {
// promoted since the most recent call to save_marks() on
// this generation and has not subsequently been iterated
// over (using oop_since_save_marks_iterate() above).
// This property holds only for single-threaded collections,
// and is typically used for Cheney scans; for MT scavenges,
// the property holds for all objects promoted during that
// scavenge for the duration of the scavenge and is used
// by card-scanning to avoid scanning objects (being) promoted
// during that scavenge.
bool obj_allocated_since_save_marks(const oop obj) const {
assert(is_in_reserved(obj), "Wrong space?");
return ((PromotedObject*)obj)->hasPromotedMark();

13
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
View File

@ -789,6 +789,14 @@ CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen,
_gc_counters = new CollectorCounters("CMS", 1);
_completed_initialization = true;
_inter_sweep_timer.start(); // start of time
#ifdef SPARC
// Issue a stern warning, but allow use for experimentation and debugging.
if (VM_Version::is_sun4v() && UseMemSetInBOT) {
assert(!FLAG_IS_DEFAULT(UseMemSetInBOT), "Error");
warning("Experimental flag -XX:+UseMemSetInBOT is known to cause instability"
" on sun4v; please understand that you are using at your own risk!");
}
#endif
}
const char* ConcurrentMarkSweepGeneration::name() const {
@ -1356,7 +1364,7 @@ ConcurrentMarkSweepGeneration::par_promote(int thread_num,
obj->set_mark(m);
// Now we can track the promoted object, if necessary. We take care
// To delay the transition from uninitialized to full object
// to delay the transition from uninitialized to full object
// (i.e., insertion of klass pointer) until after, so that it
// atomically becomes a promoted object.
if (promoInfo->tracking()) {
@ -1416,10 +1424,9 @@ bool ConcurrentMarkSweepGeneration::should_collect(bool full,
bool CMSCollector::shouldConcurrentCollect() {
if (_full_gc_requested) {
assert(ExplicitGCInvokesConcurrent, "Unexpected state");
if (Verbose && PrintGCDetails) {
gclog_or_tty->print_cr("CMSCollector: collect because of explicit "
" gc request");
" gc request (or gc_locker)");
}
return true;
}

360
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.cpp Normal file
View File

@ -0,0 +1,360 @@
/*
* Copyright 2001-2009 Sun Microsystems, Inc. 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
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
# include "incls/_precompiled.incl"
# include "incls/_promotionInfo.cpp.incl"
/////////////////////////////////////////////////////////////////////////
//// PromotionInfo
/////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////
// We go over the list of promoted objects, removing each from the list,
// and applying the closure (this may, in turn, add more elements to
// the tail of the promoted list, and these newly added objects will
// also be processed) until the list is empty.
// To aid verification and debugging, in the non-product builds
// we actually forward _promoHead each time we process a promoted oop.
// Note that this is not necessary in general (i.e. when we don't need to
// call PromotionInfo::verify()) because oop_iterate can only add to the
// end of _promoTail, and never needs to look at _promoHead.
#define PROMOTED_OOPS_ITERATE_DEFN(OopClosureType, nv_suffix) \
\
void PromotionInfo::promoted_oops_iterate##nv_suffix(OopClosureType* cl) { \
NOT_PRODUCT(verify()); \
PromotedObject *curObj, *nextObj; \
for (curObj = _promoHead; curObj != NULL; curObj = nextObj) { \
if ((nextObj = curObj->next()) == NULL) { \
/* protect ourselves against additions due to closure application \
below by resetting the list. */ \
assert(_promoTail == curObj, "Should have been the tail"); \
_promoHead = _promoTail = NULL; \
} \
if (curObj->hasDisplacedMark()) { \
/* restore displaced header */ \
oop(curObj)->set_mark(nextDisplacedHeader()); \
} else { \
/* restore prototypical header */ \
oop(curObj)->init_mark(); \
} \
/* The "promoted_mark" should now not be set */ \
assert(!curObj->hasPromotedMark(), \
"Should have been cleared by restoring displaced mark-word"); \
NOT_PRODUCT(_promoHead = nextObj); \
if (cl != NULL) oop(curObj)->oop_iterate(cl); \
if (nextObj == NULL) { /* start at head of list reset above */ \
nextObj = _promoHead; \
} \
} \
assert(noPromotions(), "post-condition violation"); \
assert(_promoHead == NULL && _promoTail == NULL, "emptied promoted list");\
assert(_spoolHead == _spoolTail, "emptied spooling buffers"); \
assert(_firstIndex == _nextIndex, "empty buffer"); \
}
// This should have been ALL_SINCE_...() just like the others,
// but, because the body of the method above is somehwat longer,
// the MSVC compiler cannot cope; as a workaround, we split the
// macro into its 3 constituent parts below (see original macro
// definition in specializedOopClosures.hpp).
SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(PROMOTED_OOPS_ITERATE_DEFN)
PROMOTED_OOPS_ITERATE_DEFN(OopsInGenClosure,_v)
// Return the next displaced header, incrementing the pointer and
// recycling spool area as necessary.
markOop PromotionInfo::nextDisplacedHeader() {
assert(_spoolHead != NULL, "promotionInfo inconsistency");
assert(_spoolHead != _spoolTail || _firstIndex < _nextIndex,
"Empty spool space: no displaced header can be fetched");
assert(_spoolHead->bufferSize > _firstIndex, "Off by one error at head?");
markOop hdr = _spoolHead->displacedHdr[_firstIndex];
// Spool forward
if (++_firstIndex == _spoolHead->bufferSize) { // last location in this block
// forward to next block, recycling this block into spare spool buffer
SpoolBlock* tmp = _spoolHead->nextSpoolBlock;
assert(_spoolHead != _spoolTail, "Spooling storage mix-up");
_spoolHead->nextSpoolBlock = _spareSpool;
_spareSpool = _spoolHead;
_spoolHead = tmp;
_firstIndex = 1;
NOT_PRODUCT(
if (_spoolHead == NULL) { // all buffers fully consumed
assert(_spoolTail == NULL && _nextIndex == 1,
"spool buffers processing inconsistency");
}
)
}
return hdr;
}
void PromotionInfo::track(PromotedObject* trackOop) {
track(trackOop, oop(trackOop)->klass());
}
void PromotionInfo::track(PromotedObject* trackOop, klassOop klassOfOop) {
// make a copy of header as it may need to be spooled
markOop mark = oop(trackOop)->mark();
trackOop->clearNext();
if (mark->must_be_preserved_for_cms_scavenge(klassOfOop)) {
// save non-prototypical header, and mark oop
saveDisplacedHeader(mark);
trackOop->setDisplacedMark();
} else {
// we'd like to assert something like the following:
// assert(mark == markOopDesc::prototype(), "consistency check");
// ... but the above won't work because the age bits have not (yet) been
// cleared. The remainder of the check would be identical to the
// condition checked in must_be_preserved() above, so we don't really
// have anything useful to check here!
}
if (_promoTail != NULL) {
assert(_promoHead != NULL, "List consistency");
_promoTail->setNext(trackOop);
_promoTail = trackOop;
} else {
assert(_promoHead == NULL, "List consistency");
_promoHead = _promoTail = trackOop;
}
// Mask as newly promoted, so we can skip over such objects
// when scanning dirty cards
assert(!trackOop->hasPromotedMark(), "Should not have been marked");
trackOop->setPromotedMark();
}
// Save the given displaced header, incrementing the pointer and
// obtaining more spool area as necessary.
void PromotionInfo::saveDisplacedHeader(markOop hdr) {
assert(_spoolHead != NULL && _spoolTail != NULL,
"promotionInfo inconsistency");
assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?");
_spoolTail->displacedHdr[_nextIndex] = hdr;
// Spool forward
if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block
// get a new spooling block
assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list");
_splice_point = _spoolTail; // save for splicing
_spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail
_spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ...
// ... but will attempt filling before next promotion attempt
_nextIndex = 1;
}
}
// Ensure that spooling space exists. Return false if spooling space
// could not be obtained.
bool PromotionInfo::ensure_spooling_space_work() {
assert(!has_spooling_space(), "Only call when there is no spooling space");
// Try and obtain more spooling space
SpoolBlock* newSpool = getSpoolBlock();
assert(newSpool == NULL ||
(newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL),
"getSpoolBlock() sanity check");
if (newSpool == NULL) {
return false;
}
_nextIndex = 1;
if (_spoolTail == NULL) {
_spoolTail = newSpool;
if (_spoolHead == NULL) {
_spoolHead = newSpool;
_firstIndex = 1;
} else {
assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL,
"Splice point invariant");
// Extra check that _splice_point is connected to list
#ifdef ASSERT
{
SpoolBlock* blk = _spoolHead;
for (; blk->nextSpoolBlock != NULL;
blk = blk->nextSpoolBlock);
assert(blk != NULL && blk == _splice_point,
"Splice point incorrect");
}
#endif // ASSERT
_splice_point->nextSpoolBlock = newSpool;
}
} else {
assert(_spoolHead != NULL, "spool list consistency");
_spoolTail->nextSpoolBlock = newSpool;
_spoolTail = newSpool;
}
return true;
}
// Get a free spool buffer from the free pool, getting a new block
// from the heap if necessary.
SpoolBlock* PromotionInfo::getSpoolBlock() {
SpoolBlock* res;
if ((res = _spareSpool) != NULL) {
_spareSpool = _spareSpool->nextSpoolBlock;
res->nextSpoolBlock = NULL;
} else { // spare spool exhausted, get some from heap
res = (SpoolBlock*)(space()->allocateScratch(refillSize()));
if (res != NULL) {
res->init();
}
}
assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition");
return res;
}
void PromotionInfo::startTrackingPromotions() {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"spooling inconsistency?");
_firstIndex = _nextIndex = 1;
_tracking = true;
}
#define CMSPrintPromoBlockInfo 1
void PromotionInfo::stopTrackingPromotions(uint worker_id) {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"spooling inconsistency?");
_firstIndex = _nextIndex = 1;
_tracking = false;
if (CMSPrintPromoBlockInfo > 1) {
print_statistics(worker_id);
}
}
void PromotionInfo::print_statistics(uint worker_id) const {
assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
"Else will undercount");
assert(CMSPrintPromoBlockInfo > 0, "Else unnecessary call");
// Count the number of blocks and slots in the free pool
size_t slots = 0;
size_t blocks = 0;
for (SpoolBlock* cur_spool = _spareSpool;
cur_spool != NULL;
cur_spool = cur_spool->nextSpoolBlock) {
// the first entry is just a self-pointer; indices 1 through
// bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
guarantee((void*)cur_spool->displacedHdr == (void*)&cur_spool->displacedHdr,
"first entry of displacedHdr should be self-referential");
slots += cur_spool->bufferSize - 1;
blocks++;
}
if (_spoolHead != NULL) {
slots += _spoolHead->bufferSize - 1;
blocks++;
}
gclog_or_tty->print_cr(" [worker %d] promo_blocks = %d, promo_slots = %d ",
worker_id, blocks, slots);
}
// When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex>
// points to the next slot available for filling.
// The set of slots holding displaced headers are then all those in the
// right-open interval denoted by:
//
// [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> )
//
// When _spoolTail is NULL, then the set of slots with displaced headers
// is all those starting at the slot <_spoolHead, _firstIndex> and
// going up to the last slot of last block in the linked list.
// In this lartter case, _splice_point points to the tail block of
// this linked list of blocks holding displaced headers.
void PromotionInfo::verify() const {
// Verify the following:
// 1. the number of displaced headers matches the number of promoted
// objects that have displaced headers
// 2. each promoted object lies in this space
debug_only(
PromotedObject* junk = NULL;
assert(junk->next_addr() == (void*)(oop(junk)->mark_addr()),
"Offset of PromotedObject::_next is expected to align with "
" the OopDesc::_mark within OopDesc");
)
// FIXME: guarantee????
guarantee(_spoolHead == NULL || _spoolTail != NULL ||
_splice_point != NULL, "list consistency");
guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency");
// count the number of objects with displaced headers
size_t numObjsWithDisplacedHdrs = 0;
for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) {
guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment");
// the last promoted object may fail the mark() != NULL test of is_oop().
guarantee(curObj->next() == NULL || oop(curObj)->is_oop(), "must be an oop");
if (curObj->hasDisplacedMark()) {
numObjsWithDisplacedHdrs++;
}
}
// Count the number of displaced headers
size_t numDisplacedHdrs = 0;
for (SpoolBlock* curSpool = _spoolHead;
curSpool != _spoolTail && curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
// the first entry is just a self-pointer; indices 1 through
// bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr,
"first entry of displacedHdr should be self-referential");
numDisplacedHdrs += curSpool->bufferSize - 1;
}
guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0),
"internal consistency");
guarantee(_spoolTail != NULL || _nextIndex == 1,
"Inconsistency between _spoolTail and _nextIndex");
// We overcounted (_firstIndex-1) worth of slots in block
// _spoolHead and we undercounted (_nextIndex-1) worth of
// slots in block _spoolTail. We make an appropriate
// adjustment by subtracting the first and adding the
// second: - (_firstIndex - 1) + (_nextIndex - 1)
numDisplacedHdrs += (_nextIndex - _firstIndex);
guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count");
}
void PromotionInfo::print_on(outputStream* st) const {
SpoolBlock* curSpool = NULL;
size_t i = 0;
st->print_cr("start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")",
_firstIndex, _nextIndex);
for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" active ");
i++;
}
for (curSpool = _spoolTail; curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" inactive ");
i++;
}
for (curSpool = _spareSpool; curSpool != NULL;
curSpool = curSpool->nextSpoolBlock) {
curSpool->print_on(st);
st->print_cr(" free ");
i++;
}
st->print_cr(SIZE_FORMAT " header spooling blocks", i);
}
void SpoolBlock::print_on(outputStream* st) const {
st->print("[" PTR_FORMAT "," PTR_FORMAT "), " SIZE_FORMAT " HeapWords -> " PTR_FORMAT,
this, (HeapWord*)displacedHdr + bufferSize,
bufferSize, nextSpoolBlock);
}

161
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.hpp Normal file
View File

@ -0,0 +1,161 @@
/*
* Copyright 2001-2009 Sun Microsystems, Inc. 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
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
// Forward declarations
class CompactibleFreeListSpace;
class PromotedObject VALUE_OBJ_CLASS_SPEC {
private:
enum {
promoted_mask = right_n_bits(2), // i.e. 0x3
displaced_mark = nth_bit(2), // i.e. 0x4
next_mask = ~(right_n_bits(3)) // i.e. ~(0x7)
};
intptr_t _next;
public:
inline PromotedObject* next() const {
return (PromotedObject*)(_next & next_mask);
}
inline void setNext(PromotedObject* x) {
assert(((intptr_t)x & ~next_mask) == 0,
"Conflict in bit usage, "
" or insufficient alignment of objects");
_next |= (intptr_t)x;
}
inline void setPromotedMark() {
_next |= promoted_mask;
}
inline bool hasPromotedMark() const {
return (_next & promoted_mask) == promoted_mask;
}
inline void setDisplacedMark() {
_next |= displaced_mark;
}
inline bool hasDisplacedMark() const {
return (_next & displaced_mark) != 0;
}
inline void clearNext() { _next = 0; }
debug_only(void *next_addr() { return (void *) &_next; })
};
class SpoolBlock: public FreeChunk {
friend class PromotionInfo;
protected:
SpoolBlock* nextSpoolBlock;
size_t bufferSize; // number of usable words in this block
markOop* displacedHdr; // the displaced headers start here
// Note about bufferSize: it denotes the number of entries available plus 1;
// legal indices range from 1 through BufferSize - 1. See the verification
// code verify() that counts the number of displaced headers spooled.
size_t computeBufferSize() {
return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);
}
public:
void init() {
bufferSize = computeBufferSize();
displacedHdr = (markOop*)&displacedHdr;
nextSpoolBlock = NULL;
}
void print_on(outputStream* st) const;
void print() const { print_on(gclog_or_tty); }
};
class PromotionInfo VALUE_OBJ_CLASS_SPEC {
bool _tracking; // set if tracking
CompactibleFreeListSpace* _space; // the space to which this belongs
PromotedObject* _promoHead; // head of list of promoted objects
PromotedObject* _promoTail; // tail of list of promoted objects
SpoolBlock* _spoolHead; // first spooling block
SpoolBlock* _spoolTail; // last non-full spooling block or null
SpoolBlock* _splice_point; // when _spoolTail is null, holds list tail
SpoolBlock* _spareSpool; // free spool buffer
size_t _firstIndex; // first active index in
// first spooling block (_spoolHead)
size_t _nextIndex; // last active index + 1 in last
// spooling block (_spoolTail)
private:
// ensure that spooling space exists; return true if there is spooling space
bool ensure_spooling_space_work();
public:
PromotionInfo() :
_tracking(0), _space(NULL),
_promoHead(NULL), _promoTail(NULL),
_spoolHead(NULL), _spoolTail(NULL),
_spareSpool(NULL), _firstIndex(1),
_nextIndex(1) {}
bool noPromotions() const {
assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");
return _promoHead == NULL;
}
void startTrackingPromotions();
void stopTrackingPromotions(uint worker_id = 0);
bool tracking() const { return _tracking; }
void track(PromotedObject* trackOop); // keep track of a promoted oop
// The following variant must be used when trackOop is not fully
// initialized and has a NULL klass:
void track(PromotedObject* trackOop, klassOop klassOfOop); // keep track of a promoted oop
void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }
CompactibleFreeListSpace* space() const { return _space; }
markOop nextDisplacedHeader(); // get next header & forward spool pointer
void saveDisplacedHeader(markOop hdr);
// save header and forward spool
inline size_t refillSize() const;
SpoolBlock* getSpoolBlock(); // return a free spooling block
inline bool has_spooling_space() {
return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;
}
// ensure that spooling space exists
bool ensure_spooling_space() {
return has_spooling_space() || ensure_spooling_space_work();
}
#define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix) \
void promoted_oops_iterate##nv_suffix(OopClosureType* cl);
ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)
#undef PROMOTED_OOPS_ITERATE_DECL
void promoted_oops_iterate(OopsInGenClosure* cl) {
promoted_oops_iterate_v(cl);
}
void verify() const;
void reset() {
_promoHead = NULL;
_promoTail = NULL;
_spoolHead = NULL;
_spoolTail = NULL;
_spareSpool = NULL;
_firstIndex = 0;
_nextIndex = 0;
}
void print_on(outputStream* st) const;
void print_statistics(uint worker_id) const;
};

7
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp
View File

@ -163,6 +163,7 @@ void VM_CMS_Final_Remark::doit() {
// GenCollectedHeap heap.
void VM_GenCollectFullConcurrent::doit() {
assert(Thread::current()->is_VM_thread(), "Should be VM thread");
assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected");
GenCollectedHeap* gch = GenCollectedHeap::heap();
if (_gc_count_before == gch->total_collections()) {
@ -190,7 +191,7 @@ void VM_GenCollectFullConcurrent::doit() {
CMSCollector::disable_icms();
// In case CMS thread was in icms_wait(), wake it up.
CMSCollector::start_icms();
// Nudge the CMS thread to start a concurrent collection
// Nudge the CMS thread to start a concurrent collection.
CMSCollector::request_full_gc(_full_gc_count_before);
} else {
FullGCCount_lock->notify_all(); // Inform the Java thread its work is done
@ -231,7 +232,9 @@ void VM_GenCollectFullConcurrent::doit_epilogue() {
// e.g. at the rate of 1 full gc per ms, this could
// overflow in about 1000 years.
GenCollectedHeap* gch = GenCollectedHeap::heap();
if (gch->total_full_collections_completed() <= _full_gc_count_before) {
if (_gc_cause != GCCause::_gc_locker &&
gch->total_full_collections_completed() <= _full_gc_count_before) {
assert(ExplicitGCInvokesConcurrent, "Error");
// Now, wait for witnessing concurrent gc cycle to complete,
// but do so in native mode, because we want to lock the
// FullGCEvent_lock, which may be needed by the VM thread

3
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp
View File

@ -126,8 +126,7 @@ class VM_GenCollectFullConcurrent: public VM_GC_Operation {
GCCause::Cause gc_cause)
: VM_GC_Operation(gc_count_before, full_gc_count_before, true /* full */) {
_gc_cause = gc_cause;
assert(FullGCCount_lock != NULL && UseConcMarkSweepGC &&
ExplicitGCInvokesConcurrent, "Otherwise shouldn't be here");
assert(FullGCCount_lock != NULL, "Error");
assert(UseAsyncConcMarkSweepGC, "Else will hang caller");
}
~VM_GenCollectFullConcurrent() {}

9
hotspot/src/share/vm/gc_implementation/includeDB_gc_concurrentMarkSweep
View File

@ -122,6 +122,7 @@ compactibleFreeListSpace.cpp vmThread.hpp
compactibleFreeListSpace.hpp binaryTreeDictionary.hpp
compactibleFreeListSpace.hpp freeList.hpp
compactibleFreeListSpace.hpp promotionInfo.hpp
compactibleFreeListSpace.hpp space.hpp
compactingPermGenGen.cpp concurrentMarkSweepGeneration.inline.hpp
@ -225,6 +226,14 @@ freeList.cpp vmThread.hpp
freeList.hpp allocationStats.hpp
promotionInfo.cpp compactibleFreeListSpace.hpp
promotionInfo.cpp markOop.inline.hpp
promotionInfo.cpp oop.inline.hpp
promotionInfo.cpp promotionInfo.hpp
promotionInfo.hpp allocation.hpp
promotionInfo.hpp freeChunk.hpp
vmCMSOperations.cpp concurrentMarkSweepGeneration.inline.hpp
vmCMSOperations.cpp concurrentMarkSweepThread.hpp
vmCMSOperations.cpp dtrace.hpp

28
hotspot/src/share/vm/memory/blockOffsetTable.hpp
View File

@ -140,14 +140,38 @@ class BlockOffsetSharedArray: public CHeapObj {
"right address out of range");
assert(left < right, "Heap addresses out of order");
size_t num_cards = pointer_delta(right, left) >> LogN_words;
memset(&_offset_array[index_for(left)], offset, num_cards);
// Below, we may use an explicit loop instead of memset()
// because on certain platforms memset() can give concurrent
// readers "out-of-thin-air," phantom zeros; see 6948537.
if (UseMemSetInBOT) {
memset(&_offset_array[index_for(left)], offset, num_cards);
} else {
size_t i = index_for(left);
const size_t end = i + num_cards;
for (; i < end; i++) {
_offset_array[i] = offset;
}
}
}
void set_offset_array(size_t left, size_t right, u_char offset) {
assert(right < _vs.committed_size(), "right address out of range");
assert(left <= right, "indexes out of order");
size_t num_cards = right - left + 1;
memset(&_offset_array[left], offset, num_cards);
// Below, we may use an explicit loop instead of memset
// because on certain platforms memset() can give concurrent
// readers "out-of-thin-air," phantom zeros; see 6948537.
if (UseMemSetInBOT) {
memset(&_offset_array[left], offset, num_cards);
} else {
size_t i = left;
const size_t end = i + num_cards;
for (; i < end; i++) {
_offset_array[i] = offset;
}
}
}
void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const {

6
hotspot/src/share/vm/memory/genCollectedHeap.cpp
View File

@ -410,9 +410,9 @@ bool GenCollectedHeap::must_clear_all_soft_refs() {
}
bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
return (cause == GCCause::_java_lang_system_gc ||
cause == GCCause::_gc_locker) &&
UseConcMarkSweepGC && ExplicitGCInvokesConcurrent;
return UseConcMarkSweepGC &&
((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
(cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
}
void GenCollectedHeap::do_collection(bool full,

8
hotspot/src/share/vm/runtime/globals.hpp
View File

@ -327,6 +327,10 @@ class CommandLineFlags {
product(bool, UseMembar, false, \
"(Unstable) Issues membars on thread state transitions") \
\
/* Temporary: See 6948537 */ \
experimental(bool, UseMemSetInBOT, true, \
"(Unstable) uses memset in BOT updates in GC code") \
\
diagnostic(bool, UnlockDiagnosticVMOptions, trueInDebug, \
"Enable normal processing of flags relating to field diagnostics")\
\
@ -1299,6 +1303,10 @@ class CommandLineFlags {
"also unloads classes during such a concurrent gc cycle " \
"(effective only when UseConcMarkSweepGC)") \
\
product(bool, GCLockerInvokesConcurrent, false, \
"The exit of a JNI CS necessitating a scavenge also" \
" kicks off a bkgrd concurrent collection") \
\
develop(bool, UseCMSAdaptiveFreeLists, true, \
"Use Adaptive Free Lists in the CMS generation") \
\