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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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17
hotspot/src/share/vm/memory/defNewGeneration.cpp
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@ -684,23 +684,28 @@ void DefNewGeneration::remove_forwarding_pointers() {
_preserved_marks_of_objs.clear(true);
}
void DefNewGeneration::preserve_mark(oop obj, markOop m) {
assert(promotion_failed() && m->must_be_preserved_for_promotion_failure(obj),
"Oversaving!");
_objs_with_preserved_marks.push(obj);
_preserved_marks_of_objs.push(m);
}
void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) {
if (m->must_be_preserved_for_promotion_failure(obj)) {
_objs_with_preserved_marks.push(obj);
_preserved_marks_of_objs.push(m);
preserve_mark(obj, m);
}
}
void DefNewGeneration::handle_promotion_failure(oop old) {
preserve_mark_if_necessary(old, old->mark());
if (!_promotion_failed && PrintPromotionFailure) {
if (PrintPromotionFailure && !_promotion_failed) {
gclog_or_tty->print(" (promotion failure size = " SIZE_FORMAT ") ",
old->size());
}
_promotion_failed = true;
preserve_mark_if_necessary(old, old->mark());
// forward to self
old->forward_to(old);
_promotion_failed = true;
_promo_failure_scan_stack.push(old);