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6865703: G1: Parallelize hot card cache cleanup

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Have the GC worker threads clear the hot card cache in parallel by having each worker thread claim a chunk of the card cache and process the cards in that chunk. The size of the chunks that each thread will claim is determined at VM initialization from the size of the card cache and the number of worker threads.

Reviewed-by: jmasa, tonyp
This commit is contained in:
John Cuthbertson 2009-08-03 12:59:30 -07:00
parent 73392a7312
commit 36917caf5e
3 changed files with 46 additions and 22 deletions
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32
hotspot/src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp
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@ -57,8 +57,8 @@ size_t ConcurrentG1Refine::thread_num() {
}
void ConcurrentG1Refine::init() {
G1CollectedHeap* g1h = G1CollectedHeap::heap();
if (G1ConcRSLogCacheSize > 0 || G1ConcRSCountTraversals) {
G1CollectedHeap* g1h = G1CollectedHeap::heap();
_n_card_counts =
(unsigned) (g1h->g1_reserved_obj_bytes() >> CardTableModRefBS::card_shift);
_card_counts = NEW_C_HEAP_ARRAY(unsigned char, _n_card_counts);
@ -83,6 +83,12 @@ void ConcurrentG1Refine::init() {
_hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size);
_n_hot = 0;
_hot_cache_idx = 0;
// For refining the cards in the hot cache in parallel
int n_workers = (ParallelGCThreads > 0 ?
g1h->workers()->total_workers() : 1);
_hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / n_workers);
_hot_cache_par_claimed_idx = 0;
}
}
@ -161,17 +167,23 @@ jbyte* ConcurrentG1Refine::cache_insert(jbyte* card_ptr) {
void ConcurrentG1Refine::clean_up_cache(int worker_i, G1RemSet* g1rs) {
assert(!use_cache(), "cache should be disabled");
int start_ind = _hot_cache_idx-1;
for (int i = 0; i < _n_hot; i++) {
int ind = start_ind - i;
if (ind < 0) ind = ind + _hot_cache_size;
jbyte* entry = _hot_cache[ind];
if (entry != NULL) {
g1rs->concurrentRefineOneCard(entry, worker_i);
int start_idx;
while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once
int end_idx = start_idx + _hot_cache_par_chunk_size;
if (start_idx ==
Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {
// The current worker has successfully claimed the chunk [start_idx..end_idx)
end_idx = MIN2(end_idx, _n_hot);
for (int i = start_idx; i < end_idx; i++) {
jbyte* entry = _hot_cache[i];
if (entry != NULL) {
g1rs->concurrentRefineOneCard(entry, worker_i);
}
}
}
}
_n_hot = 0;
_hot_cache_idx = 0;
}
void ConcurrentG1Refine::clear_and_record_card_counts() {