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src/share/vm/gc/g1/g1CollectedHeap.cpp
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@@ -4522,11 +4522,12 @@
create_g1_evac_summary(&_old_evac_stats));
}
void G1CollectedHeap::free_region(HeapRegion* hr,
FreeRegionList* free_list,
- bool par,
+ bool skip_remset,
+ bool skip_hot_card_cache,
bool locked) {
assert(!hr->is_free(), "the region should not be free");
assert(!hr->is_empty(), "the region should not be empty");
assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
assert(free_list != NULL, "pre-condition");
@@ -4537,24 +4538,24 @@
}
// Clear the card counts for this region.
// Note: we only need to do this if the region is not young
// (since we don't refine cards in young regions).
- if (!hr->is_young()) {
+ if (!skip_hot_card_cache && !hr->is_young()) {
_hot_card_cache->reset_card_counts(hr);
}
- hr->hr_clear(par, true /* clear_space */, locked /* locked */);
+ hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
free_list->add_ordered(hr);
}
void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
FreeRegionList* free_list,
- bool par) {
+ bool skip_remset) {
assert(hr->is_humongous(), "this is only for humongous regions");
assert(free_list != NULL, "pre-condition");
hr->clear_humongous();
- free_region(hr, free_list, par);
+ free_region(hr, free_list, skip_remset);
}
void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
const uint humongous_regions_removed) {
if (old_regions_removed > 0 || humongous_regions_removed > 0) {
@@ -4598,80 +4599,79 @@
uint num_workers = workers()->active_workers();
G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), num_workers);
workers()->run_task(&g1_par_scrub_rs_task);
}
-class G1FreeCollectionSetClosure : public HeapRegionClosure {
+class G1FreeCollectionSetTask : public AbstractGangTask {
private:
+
+ // Closure applied to all regions in the collection set to do work that needs to
+ // be done serially in a single thread.
+ class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
+ private:
+ EvacuationInfo* _evacuation_info;
const size_t* _surviving_young_words;
- FreeRegionList _local_free_list;
- size_t _rs_lengths;
// Bytes used in successfully evacuated regions before the evacuation.
size_t _before_used_bytes;
// Bytes used in unsucessfully evacuated regions before the evacuation
size_t _after_used_bytes;
size_t _bytes_allocated_in_old_since_last_gc;
size_t _failure_used_words;
size_t _failure_waste_words;
- double _young_time;
- double _non_young_time;
-public:
- G1FreeCollectionSetClosure(const size_t* surviving_young_words) :
+ FreeRegionList _local_free_list;
+ public:
+ G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
HeapRegionClosure(),
+ _evacuation_info(evacuation_info),
_surviving_young_words(surviving_young_words),
- _local_free_list("Local Region List for CSet Freeing"),
- _rs_lengths(0),
_before_used_bytes(0),
_after_used_bytes(0),
_bytes_allocated_in_old_since_last_gc(0),
_failure_used_words(0),
_failure_waste_words(0),
- _young_time(0.0),
- _non_young_time(0.0) {
+ _local_free_list("Local Region List for CSet Freeing") {
}
virtual bool doHeapRegion(HeapRegion* r) {
- double start_time = os::elapsedTime();
-
- bool is_young = r->is_young();
-
G1CollectedHeap* g1h = G1CollectedHeap::heap();
- assert(!g1h->is_on_master_free_list(r), "sanity");
-
- _rs_lengths += r->rem_set()->occupied_locked();
assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
g1h->clear_in_cset(r);
- if (is_young) {
- int index = r->young_index_in_cset();
- assert(index != -1, "Young index in collection set must not be -1 for region %u", r->hrm_index());
- assert((uint) index < g1h->collection_set()->young_region_length(), "invariant");
- size_t words_survived = _surviving_young_words[index];
+ if (r->is_young()) {
+ assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
+ "Young index %d is wrong for region %u of type %s with %u young regions",
+ r->young_index_in_cset(),
+ r->hrm_index(),
+ r->get_type_str(),
+ g1h->collection_set()->young_region_length());
+ size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
r->record_surv_words_in_group(words_survived);
- } else {
- assert(r->young_index_in_cset() == -1, "Young index for old region %u in collection set must be -1", r->hrm_index());
}
if (!r->evacuation_failed()) {
assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
_before_used_bytes += r->used();
- g1h->free_region(r, &_local_free_list, false /* par */, true /* locked */);
+ g1h->free_region(r,
+ &_local_free_list,
+ true, /* skip_remset */
+ true, /* skip_hot_card_cache */
+ true /* locked */);
} else {
r->uninstall_surv_rate_group();
r->set_young_index_in_cset(-1);
r->set_evacuation_failed(false);
// When moving a young gen region to old gen, we "allocate" that whole region
// there. This is in addition to any already evacuated objects. Notify the
// policy about that.
// Old gen regions do not cause an additional allocation: both the objects
// still in the region and the ones already moved are accounted for elsewhere.
- if (is_young) {
+ if (r->is_young()) {
_bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
}
// The region is now considered to be old.
r->set_old();
// Do some allocation statistics accounting. Regions that failed evacuation
@@ -4683,56 +4683,200 @@
_failure_waste_words += HeapRegion::GrainWords - used_words;
g1h->old_set_add(r);
_after_used_bytes += r->used();
}
+ return false;
+ }
- if (is_young) {
- _young_time += os::elapsedTime() - start_time;
- } else {
- _non_young_time += os::elapsedTime() - start_time;
+ void complete_work() {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ _evacuation_info->set_regions_freed(_local_free_list.length());
+ _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
+
+ g1h->prepend_to_freelist(&_local_free_list);
+ g1h->decrement_summary_bytes(_before_used_bytes);
+
+ G1Policy* policy = g1h->g1_policy();
+ policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
+
+ g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
}
- return false;
+ };
+
+ G1CollectionSet* _collection_set;
+ G1SerialFreeCollectionSetClosure _cl;
+ const size_t* _surviving_young_words;
+
+ size_t _rs_lengths;
+
+ volatile jint _serial_work_claim;
+
+ struct WorkItem {
+ uint region_idx;
+ bool is_young;
+ bool evacuation_failed;
+
+ WorkItem(HeapRegion* r) {
+ region_idx = r->hrm_index();
+ is_young = r->is_young();
+ evacuation_failed = r->evacuation_failed();
+ }
+ };
+
+ volatile size_t _parallel_work_claim;
+ size_t _num_work_items;
+ WorkItem* _work_items;
+
+ void do_serial_work() {
+ // Need to grab the lock to be allowed to modify the old region list.
+ MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
+ _collection_set->iterate(&_cl);
}
- FreeRegionList* local_free_list() { return &_local_free_list; }
- size_t rs_lengths() const { return _rs_lengths; }
- size_t before_used_bytes() const { return _before_used_bytes; }
- size_t after_used_bytes() const { return _after_used_bytes; }
+ void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
- size_t bytes_allocated_in_old_since_last_gc() const { return _bytes_allocated_in_old_since_last_gc; }
+ HeapRegion* r = g1h->region_at(region_idx);
+ assert(!g1h->is_on_master_free_list(r), "sanity");
- size_t failure_used_words() const { return _failure_used_words; }
- size_t failure_waste_words() const { return _failure_waste_words; }
+ Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
- double young_time() const { return _young_time; }
- double non_young_time() const { return _non_young_time; }
-};
+ if (!is_young) {
+ g1h->_hot_card_cache->reset_card_counts(r);
+ }
-void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
- _eden.clear();
+ if (!evacuation_failed) {
+ r->rem_set()->clear_locked();
+ }
+ }
- G1FreeCollectionSetClosure cl(surviving_young_words);
- collection_set_iterate(&cl);
+ class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
+ private:
+ size_t _cur_idx;
+ WorkItem* _work_items;
+ public:
+ G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
+
+ virtual bool doHeapRegion(HeapRegion* r) {
+ _work_items[_cur_idx++] = WorkItem(r);
+ return false;
+ }
+ };
- evacuation_info.set_regions_freed(cl.local_free_list()->length());
- evacuation_info.increment_collectionset_used_after(cl.after_used_bytes());
+ void prepare_work() {
+ G1PrepareFreeCollectionSetClosure cl(_work_items);
+ _collection_set->iterate(&cl);
+ }
- G1Policy* policy = g1_policy();
+ void complete_work() {
+ _cl.complete_work();
- policy->record_max_rs_lengths(cl.rs_lengths());
+ G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
+ policy->record_max_rs_lengths(_rs_lengths);
policy->cset_regions_freed();
+ }
+public:
+ G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
+ AbstractGangTask("G1 Free Collection Set"),
+ _cl(evacuation_info, surviving_young_words),
+ _collection_set(collection_set),
+ _surviving_young_words(surviving_young_words),
+ _serial_work_claim(0),
+ _rs_lengths(0),
+ _parallel_work_claim(0),
+ _num_work_items(collection_set->region_length()),
+ _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
+ prepare_work();
+ }
+
+ ~G1FreeCollectionSetTask() {
+ complete_work();
+ FREE_C_HEAP_ARRAY(WorkItem, _work_items);
+ }
+
+ // Chunk size for work distribution. The chosen value has been determined experimentally
+ // to be a good tradeoff between overhead and achievable parallelism.
+ static uint chunk_size() { return 32; }
+
+ virtual void work(uint worker_id) {
+ G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
+
+ // Claim serial work.
+ if (_serial_work_claim == 0) {
+ jint value = Atomic::add(1, &_serial_work_claim) - 1;
+ if (value == 0) {
+ double serial_time = os::elapsedTime();
+ do_serial_work();
+ timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
+ }
+ }
+
+ // Start parallel work.
+ double young_time = 0.0;
+ bool has_young_time = false;
+ double non_young_time = 0.0;
+ bool has_non_young_time = false;
+
+ while (true) {
+ size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
+ size_t cur = end - chunk_size();
+
+ if (cur >= _num_work_items) {
+ break;
+ }
+
+ double start_time = os::elapsedTime();
- prepend_to_freelist(cl.local_free_list());
- decrement_summary_bytes(cl.before_used_bytes());
+ end = MIN2(end, _num_work_items);
- policy->add_bytes_allocated_in_old_since_last_gc(cl.bytes_allocated_in_old_since_last_gc());
+ for (; cur < end; cur++) {
+ bool is_young = _work_items[cur].is_young;
- _old_evac_stats.add_failure_used_and_waste(cl.failure_used_words(), cl.failure_waste_words());
+ do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
- policy->phase_times()->record_young_free_cset_time_ms(cl.young_time() * 1000.0);
- policy->phase_times()->record_non_young_free_cset_time_ms(cl.non_young_time() * 1000.0);
+ double end_time = os::elapsedTime();
+ double time_taken = end_time - start_time;
+ if (is_young) {
+ young_time += time_taken;
+ has_young_time = true;
+ } else {
+ non_young_time += time_taken;
+ has_non_young_time = true;
+ }
+ start_time = end_time;
+ }
+ }
+
+ if (has_young_time) {
+ timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
+ }
+ if (has_non_young_time) {
+ timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, young_time);
+ }
+ }
+};
+
+void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
+ _eden.clear();
+
+ double free_cset_start_time = os::elapsedTime();
+
+ {
+ uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
+ uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
+
+ G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
+
+ log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
+ cl.name(),
+ num_workers,
+ _collection_set.region_length());
+ workers()->run_task(&cl, num_workers);
+ }
+ g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
collection_set->clear();
}
class G1FreeHumongousRegionClosure : public HeapRegionClosure {
@@ -4823,11 +4967,11 @@
do {
HeapRegion* next = g1h->next_region_in_humongous(r);
_freed_bytes += r->used();
r->set_containing_set(NULL);
_humongous_regions_removed++;
- g1h->free_humongous_region(r, _free_region_list, false);
+ g1h->free_humongous_region(r, _free_region_list, false /* skip_remset */ );
r = next;
} while (r != NULL);
return false;
}
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