src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp
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rev 5920 : 8035406: Improve data structure for Code Cache remembered sets
Summary: Change the code cache remembered sets data structure from a GrowableArray to a chunked list of nmethods. This makes the data structure more amenable to parallelization, and decreases freeing time.
Reviewed-by:
rev 5921 : 8027295: Free CSet takes ~50% of young pause time
Summary: Improve fast card cache iteration and avoid taking locks when freeing the collection set.
Reviewed-by:
@@ -360,21 +360,32 @@
int** OtherRegionsTable::_from_card_cache = NULL;
size_t OtherRegionsTable::_from_card_cache_max_regions = 0;
size_t OtherRegionsTable::_from_card_cache_mem_size = 0;
void OtherRegionsTable::init_from_card_cache(size_t max_regions) {
- _from_card_cache_max_regions = max_regions;
+ guarantee(_from_card_cache == NULL, "Should not call this multiple times");
+ // Pad rows to cache line sizes.
+ static const int ints_per_cache_line = DEFAULT_CACHE_LINE_SIZE / sizeof(int);
int n_par_rs = HeapRegionRemSet::num_par_rem_sets();
+ _from_card_cache_max_regions = align_size_up(max_regions, ints_per_cache_line);
+
+ // Need to make sure that the arrays are aligned too. Allocate a suitably
+ // large array to be able to align its base address later. We do not store
+ // the old pointer as we never free that memory.
+ size_t num_ints_to_alloc = n_par_rs * _from_card_cache_max_regions + ints_per_cache_line - 1;
+ int* data = NEW_C_HEAP_ARRAY(int, num_ints_to_alloc, mtGC);
+ data = (int*) (align_size_up_((uintptr_t)data, DEFAULT_CACHE_LINE_SIZE));
+
_from_card_cache = NEW_C_HEAP_ARRAY(int*, n_par_rs, mtGC);
for (int i = 0; i < n_par_rs; i++) {
- _from_card_cache[i] = NEW_C_HEAP_ARRAY(int, max_regions, mtGC);
- for (size_t j = 0; j < max_regions; j++) {
+ _from_card_cache[i] = data + i * _from_card_cache_max_regions;
+ for (size_t j = 0; j < _from_card_cache_max_regions; j++) {
_from_card_cache[i][j] = -1; // An invalid value.
}
}
- _from_card_cache_mem_size = n_par_rs * max_regions * sizeof(int);
+ _from_card_cache_mem_size = num_ints_to_alloc * sizeof(int);
}
void OtherRegionsTable::shrink_from_card_cache(size_t new_n_regs) {
for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
assert(new_n_regs <= _from_card_cache_max_regions, "Must be within max.");
@@ -726,11 +737,12 @@
return PerRegionTable::fl_mem_size();
}
void OtherRegionsTable::clear_fcc() {
size_t hrs_idx = hr()->hrs_index();
- for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
+ uint num_par_remsets = HeapRegionRemSet::num_par_rem_sets();
+ for (uint i = 0; i < num_par_remsets; i++) {
_from_card_cache[i][hrs_idx] = -1;
}
}
void OtherRegionsTable::clear() {