archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-09-20 19:14:38 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

6720309: G1: don't synchronously update RSet during evacuation pauses

Browse source 
6720334: G1: don't update RSets of collection set regions during an evacuation pause

Introduced a deferred update mechanism for delaying the rset updates during the collection pause

Reviewed-by: apetrusenko, tonyp
This commit is contained in:
Igor Veresov 2009-03-06 13:50:14 -08:00
parent 72bfacbd95
commit 416d70bf91
13 changed files with 380 additions and 102 deletions
Download patch file Download diff file Expand all files Collapse all files

52
hotspot/src/share/vm/memory/cardTableModRefBS.cpp
View file

@ -356,18 +356,62 @@ void CardTableModRefBS::write_ref_field_work(void* field, oop newVal) {
inline_write_ref_field(field, newVal);
}
/*
Claimed and deferred bits are used together in G1 during the evacuation
pause. These bits can have the following state transitions:
1. The claimed bit can be put over any other card state. Except that
the "dirty -> dirty and claimed" transition is checked for in
G1 code and is not used.
2. Deferred bit can be set only if the previous state of the card
was either clean or claimed. mark_card_deferred() is wait-free.
We do not care if the operation is be successful because if
it does not it will only result in duplicate entry in the update
buffer because of the "cache-miss". So it's not worth spinning.
*/
bool CardTableModRefBS::claim_card(size_t card_index) {
jbyte val = _byte_map[card_index];
if (val != claimed_card_val()) {
jbyte res = Atomic::cmpxchg((jbyte) claimed_card_val(), &_byte_map[card_index], val);
if (res == val)
assert(val != dirty_card_val(), "Shouldn't claim a dirty card");
while (val == clean_card_val() ||
(val & (clean_card_mask_val() | claimed_card_val())) != claimed_card_val()) {
jbyte new_val = val;
if (val == clean_card_val()) {
new_val = (jbyte)claimed_card_val();
} else {
new_val = val | (jbyte)claimed_card_val();
}
jbyte res = Atomic::cmpxchg(new_val, &_byte_map[card_index], val);
if (res == val) {
return true;
else return false;
}
val = res;
}
return false;
}
bool CardTableModRefBS::mark_card_deferred(size_t card_index) {
jbyte val = _byte_map[card_index];
// It's already processed
if ((val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val()) {
return false;
}
// Cached bit can be installed either on a clean card or on a claimed card.
jbyte new_val = val;
if (val == clean_card_val()) {
new_val = (jbyte)deferred_card_val();
} else {
if (val & claimed_card_val()) {
new_val = val | (jbyte)deferred_card_val();
}
}
if (new_val != val) {
Atomic::cmpxchg(new_val, &_byte_map[card_index], val);
}
return true;
}
void CardTableModRefBS::non_clean_card_iterate(Space* sp,
MemRegion mr,
DirtyCardToOopClosure* dcto_cl,