8367731: G1: Make G1CollectionSet manage the young gen cset group

Reviewed-by: iwalulya, ayang

Author: Thomas Schatzl

src/hotspot/share/gc/g1/g1CollectedHeap.cpp

@@ -2517,13 +2517,7 @@ void G1CollectedHeap::update_perf_counter_cpu_time() {
 }
 
 void G1CollectedHeap::start_new_collection_set() {
-  // Clear current young cset group to allow adding.
-  // It is fine to clear it this late - evacuation does not add any remembered sets
-  // by itself, but only marks cards.
-  // The regions had their association to this group already removed earlier.
-  young_regions_cset_group()->clear();
-
-  collection_set()->start_incremental_building();
+  collection_set()->start();
 
   clear_region_attr();
 
@@ -2879,12 +2873,7 @@ void G1CollectedHeap::abandon_collection_set() {
   G1AbandonCollectionSetClosure cl;
   collection_set_iterate_all(&cl);
 
-  collection_set()->clear();
-  collection_set()->stop_incremental_building();
-
-  collection_set()->abandon_all_candidates();
-
-  young_regions_cset_group()->clear(true /* uninstall_group_cardset */);
+  collection_set()->abandon();
 }
 
 bool G1CollectedHeap::is_old_gc_alloc_region(G1HeapRegion* hr) {
@@ -3247,9 +3236,3 @@ void G1CollectedHeap::finish_codecache_marking_cycle() {
   CodeCache::on_gc_marking_cycle_finish();
   CodeCache::arm_all_nmethods();
 }
-
-void G1CollectedHeap::prepare_group_cardsets_for_scan() {
-  young_regions_cardset()->reset_table_scanner_for_groups();
-
-  collection_set()->prepare_for_scan();
-}

src/hotspot/share/gc/g1/g1CollectedHeap.hpp

@@ -805,11 +805,6 @@ class G1CollectedHeap : public CollectedHeap {
   G1CardSetConfiguration* card_set_config() { return &_card_set_config; }
 
   G1CSetCandidateGroup* young_regions_cset_group() { return &_young_regions_cset_group; }
-  G1CardSet* young_regions_cardset() { return _young_regions_cset_group.card_set(); };
-
-  G1MonotonicArenaMemoryStats young_regions_card_set_memory_stats() { return _young_regions_cset_group.card_set_memory_stats(); }
-
-  void prepare_group_cardsets_for_scan();
 
   // After a collection pause, reset eden and the collection set.
   void clear_eden();

src/hotspot/share/gc/g1/g1CollectionSet.cpp

@@ -99,12 +99,21 @@ void G1CollectionSet::initialize(uint max_region_length) {
   _candidates.initialize(max_region_length);
 }
 
+void G1CollectionSet::abandon() {
+  _g1h->young_regions_cset_group()->clear(true /* uninstall_cset_group */);
+  clear();
+  abandon_all_candidates();
+
+  stop_incremental_building();
+}
+
 void G1CollectionSet::abandon_all_candidates() {
   _candidates.clear();
   _initial_old_region_length = 0;
 }
 
 void G1CollectionSet::prepare_for_scan () {
+  _g1h->young_regions_cset_group()->card_set()->reset_table_scanner_for_groups();
   _groups.prepare_for_scan();
 }
 
@@ -127,12 +136,15 @@ void G1CollectionSet::add_old_region(G1HeapRegion* hr) {
   _g1h->old_set_remove(hr);
 }
 
-void G1CollectionSet::start_incremental_building() {
+void G1CollectionSet::start() {
   assert(_regions_cur_length == 0, "Collection set must be empty before starting a new collection set.");
   assert(groups_cur_length() == 0, "Collection set groups must be empty before starting a new collection set.");
   assert(_optional_groups.length() == 0, "Collection set optional gorups must be empty before starting a new collection set.");
 
   continue_incremental_building();
+
+  G1CSetCandidateGroup* young_group = _g1h->young_regions_cset_group();
+  young_group->clear();
 }
 
 void G1CollectionSet::continue_incremental_building() {

src/hotspot/share/gc/g1/g1CollectionSet.hpp

@@ -227,13 +227,16 @@ class G1CollectionSet {
                           uint& num_optional_regions,
                           double& predicted_optional_time_ms,
                           double predicted_time_ms);
+
 public:
   G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy);
   ~G1CollectionSet();
 
   // Initializes the collection set giving the maximum possible length of the collection set.
   void initialize(uint max_region_length);
 
+  // Drop the collection set and collection set candidates.
+  void abandon();
   // Drop all collection set candidates (only the candidates).
   void abandon_all_candidates();
 
@@ -261,13 +264,15 @@ class G1CollectionSet {
   template <class CardOrRangeVisitor>
   inline void merge_cardsets_for_collection_groups(CardOrRangeVisitor& cl, uint worker_id, uint num_workers);
 
+  uint groups_increment_length() const;
+
   // Reset the contents of the collection set.
   void clear();
 
   // Incremental collection set support
 
-  // Initialize incremental collection set info.
-  void start_incremental_building();
+  // Start a new collection set for the next mutator phase.
+  void start();
   // Start a new collection set increment, continuing the incremental building.
   void continue_incremental_building();
   // Stop adding regions to the current collection set increment.
@@ -282,8 +287,6 @@ class G1CollectionSet {
   // Returns the length of the whole current collection set in number of regions
   size_t cur_length() const { return _regions_cur_length; }
 
-  uint groups_increment_length() const;
-
   // Iterate over the entire collection set (all increments calculated so far), applying
   // the given G1HeapRegionClosure on all of the regions.
   void iterate(G1HeapRegionClosure* cl) const;

src/hotspot/share/gc/g1/g1CollectionSet.inline.hpp

@@ -31,20 +31,24 @@
 
 template <class CardOrRangeVisitor>
 inline void G1CollectionSet::merge_cardsets_for_collection_groups(CardOrRangeVisitor& cl, uint worker_id, uint num_workers) {
-  uint length = groups_increment_length();
   uint offset =  _groups_inc_part_start;
-  if (length == 0) {
+  if (offset == 0) {
+    G1HeapRegionRemSet::iterate_for_merge(_g1h->young_regions_cset_group()->card_set(), cl);
+  }
+
+  uint next_increment_length = groups_increment_length();
+  if (next_increment_length == 0) {
     return;
   }
 
-  uint start_pos = (worker_id * length) / num_workers;
+  uint start_pos = (worker_id * next_increment_length) / num_workers;
   uint cur_pos = start_pos;
   uint count = 0;
   do {
     G1HeapRegionRemSet::iterate_for_merge(_groups.at(offset + cur_pos)->card_set(), cl);
     cur_pos++;
     count++;
-    if (cur_pos == length) {
+    if (cur_pos == next_increment_length) {
       cur_pos = 0;
     }
   } while (cur_pos != start_pos);

src/hotspot/share/gc/g1/g1CollectionSetCandidates.hpp

@@ -122,6 +122,10 @@ class G1CSetCandidateGroup : public CHeapObj<mtGCCardSet>{
     return _card_set_mm.memory_stats();
   }
 
+  size_t cards_occupied() const {
+    return _card_set.occupied();
+  }
+
   void clear(bool uninstall_group_cardset = false);
 
   G1CSetCandidateGroupIterator begin() const {

src/hotspot/share/gc/g1/g1RemSet.cpp

@@ -1166,10 +1166,6 @@ class G1MergeHeapRootsTask : public WorkerTask {
         // 2. collection set
         G1MergeCardSetClosure merge(_scan_state);
 
-        if (_initial_evacuation) {
-          G1HeapRegionRemSet::iterate_for_merge(g1h->young_regions_cardset(), merge);
-        }
-
         g1h->collection_set()->merge_cardsets_for_collection_groups(merge, worker_id, _num_workers);
 
         G1MergeCardSetStats stats = merge.stats();

src/hotspot/share/gc/g1/g1YoungCollector.cpp

@@ -506,7 +506,7 @@ void G1YoungCollector::pre_evacuate_collection_set(G1EvacInfo* evacuation_info)
     Ticks start = Ticks::now();
     rem_set()->prepare_for_scan_heap_roots();
 
-    _g1h->prepare_group_cardsets_for_scan();
+    _g1h->collection_set()->prepare_for_scan();
 
     phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
   }
@@ -516,7 +516,7 @@ void G1YoungCollector::pre_evacuate_collection_set(G1EvacInfo* evacuation_info)
     Tickspan task_time = run_task_timed(&g1_prep_task);
 
     G1MonotonicArenaMemoryStats sampled_card_set_stats = g1_prep_task.all_card_set_stats();
-    sampled_card_set_stats.add(_g1h->young_regions_card_set_memory_stats());
+    sampled_card_set_stats.add(_g1h->young_regions_cset_group()->card_set_memory_stats());
     _g1h->set_young_gen_card_set_stats(sampled_card_set_stats);
     _g1h->set_humongous_stats(g1_prep_task.humongous_total(), g1_prep_task.humongous_candidates());