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6807801: CMS: could save/restore fewer header words during scavenge

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Age bits need not enter the mark-word preservation calculus; also affected, in addition to CMS, per CR synopsis above, were ParNew (but not DefNew), ParallelScavenge and G1, albeit to a lesser degree than CMS.

Reviewed-by: tonyp, johnc
This commit is contained in:
Y. Srinivas Ramakrishna 2010-12-17 23:41:31 -08:00
parent b2fa4708ad
commit 41bf31bff4
6 changed files with 37 additions and 21 deletions
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7
hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
View file

@ -3958,8 +3958,6 @@ void G1CollectedHeap::remove_self_forwarding_pointers() {
// Now restore saved marks, if any.
if (_objs_with_preserved_marks != NULL) {
assert(_preserved_marks_of_objs != NULL, "Both or none.");
assert(_objs_with_preserved_marks->length() ==
_preserved_marks_of_objs->length(), "Both or none.");
guarantee(_objs_with_preserved_marks->length() ==
_preserved_marks_of_objs->length(), "Both or none.");
for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
@ -4054,7 +4052,10 @@ void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
}
void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
if (m != markOopDesc::prototype()) {
assert(evacuation_failed(), "Oversaving!");
// We want to call the "for_promotion_failure" version only in the
// case of a promotion failure.
if (m->must_be_preserved_for_promotion_failure(obj)) {
if (_objs_with_preserved_marks == NULL) {
assert(_preserved_marks_of_objs == NULL, "Both or none.");
_objs_with_preserved_marks =

7
hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp
View file

@ -1058,10 +1058,11 @@ bool ParNewGeneration::is_legal_forward_ptr(oop p) {
#endif
void ParNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) {
if ((m != markOopDesc::prototype()) &&
(!UseBiasedLocking || (m != markOopDesc::biased_locking_prototype()))) {
if (m->must_be_preserved_for_promotion_failure(obj)) {
// We should really have separate per-worker stacks, rather
// than use locking of a common pair of stacks.
MutexLocker ml(ParGCRareEvent_lock);
DefNewGeneration::preserve_mark_if_necessary(obj, m);
preserve_mark(obj, m);
}
}

2
hotspot/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp
View file

@ -694,6 +694,8 @@ void PSScavenge::clean_up_failed_promotion() {
void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
_promotion_failed = true;
if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
// Should use per-worker private stakcs hetre rather than
// locking a common pair of stacks.
ThreadCritical tc;
_preserved_oop_stack.push(obj);
_preserved_mark_stack.push(obj_mark);