truffle: src/share/vm/memory/cardTableModRefBS.cpp comparison

comparison src/share/vm/memory/cardTableModRefBS.cpp @ 628:7bb995fbd3c0

Merge

author	trims
date	Thu, 12 Mar 2009 18:16:36 -0700
parents	0fbdb4381b99 4f360ec815ba
children	ff004bcd2596

comparison

equal deleted inserted replaced

-:ce2272390558
+:7bb995fbd3c0
 jbyte* const new_end = byte_after(new_region.last());
 HeapWord* new_end_aligned =
 (HeapWord*) align_size_up((uintptr_t)new_end, _page_size);
 assert(new_end_aligned >= (HeapWord*) new_end,
 "align up, but less");
+// Check the other regions (excludes "ind") to ensure that
+// the new_end_aligned does not intrude onto the committed
+// space of another region.
 int ri = 0;
 for (ri = 0; ri < _cur_covered_regions; ri++) {
 if (ri != ind) {
 if (_committed[ri].contains(new_end_aligned)) {
-assert((new_end_aligned >= _committed[ri].start()) &&
+// The prior check included in the assert
-(_committed[ri].start() > _committed[ind].start()),
+// (new_end_aligned >= _committed[ri].start())
+// is redundant with the "contains" test.
+// Any region containing the new end
+// should start at or beyond the region found (ind)
+// for the new end (committed regions are not expected to
+// be proper subsets of other committed regions).
+assert(_committed[ri].start() >= _committed[ind].start(),
 "New end of committed region is inconsistent");
 new_end_aligned = _committed[ri].start();
-assert(new_end_aligned > _committed[ind].start(),
+// new_end_aligned can be equal to the start of its
+// committed region (i.e., of "ind") if a second
+// region following "ind" also start at the same location
+// as "ind".
+assert(new_end_aligned >= _committed[ind].start(),
 "New end of committed region is before start");
 debug_only(collided = true;)
 // Should only collide with 1 region
 break;
 }
 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()) {
+assert(val != dirty_card_val(), "Shouldn't claim a dirty card");
-jbyte res = Atomic::cmpxchg((jbyte) claimed_card_val(), &_byte_map[card_index], val);
+while (val == clean_card_val() ||
-if (res == 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,
 MemRegionClosure* cl,

Mercurial > hg > truffle

comparison src/share/vm/memory/cardTableModRefBS.cpp @ 628:7bb995fbd3c0