7097002: G1: remove a lot of unused / redundant code from the G1CollectorPolicy class

Summary: Major cleanup of the G1CollectorPolicy class. It removes a lot of unused fields and methods and also consolidates replicated information (mainly various ways of counting the number of CSet regions) into one copy.
Reviewed-by: johnc, brutisso

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -176,8 +176,7 @@ void YoungList::push_region(HeapRegion *hr) {
   hr->set_next_young_region(_head);
   _head = hr;
 
-  hr->set_young();
-  double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
+  _g1h->g1_policy()->set_region_eden(hr, (int) _length);
   ++_length;
 }
 
@@ -190,7 +189,6 @@ void YoungList::add_survivor_region(HeapRegion* hr) {
     _survivor_tail = hr;
   }
   _survivor_head = hr;
-
   ++_survivor_length;
 }
 
@@ -315,16 +313,20 @@ YoungList::reset_auxilary_lists() {
   _g1h->g1_policy()->note_start_adding_survivor_regions();
   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 
+  int young_index_in_cset = 0;
   for (HeapRegion* curr = _survivor_head;
        curr != NULL;
        curr = curr->get_next_young_region()) {
-    _g1h->g1_policy()->set_region_survivors(curr);
+    _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 
     // The region is a non-empty survivor so let's add it to
     // the incremental collection set for the next evacuation
     // pause.
     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
+    young_index_in_cset += 1;
   }
+  assert((size_t) young_index_in_cset == _survivor_length,
+         "post-condition");
   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 
   _head   = _survivor_head;
@@ -3210,8 +3212,6 @@ G1CollectedHeap::doConcurrentMark() {
   }
 }
 
-// <NEW PREDICTION>
-
 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
                                                        bool young) {
   return _g1_policy->predict_region_elapsed_time_ms(hr, young);
@@ -3251,7 +3251,7 @@ size_t G1CollectedHeap::cards_scanned() {
 void
 G1CollectedHeap::setup_surviving_young_words() {
   guarantee( _surviving_young_words == NULL, "pre-condition" );
-  size_t array_length = g1_policy()->young_cset_length();
+  size_t array_length = g1_policy()->young_cset_region_length();
   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
   if (_surviving_young_words == NULL) {
     vm_exit_out_of_memory(sizeof(size_t) * array_length,
@@ -3268,7 +3268,7 @@ G1CollectedHeap::setup_surviving_young_words() {
 void
 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
-  size_t array_length = g1_policy()->young_cset_length();
+  size_t array_length = g1_policy()->young_cset_region_length();
   for (size_t i = 0; i < array_length; ++i)
     _surviving_young_words[i] += surv_young_words[i];
 }
@@ -3280,8 +3280,6 @@ G1CollectedHeap::cleanup_surviving_young_words() {
   _surviving_young_words = NULL;
 }
 
-// </NEW PREDICTION>
-
 #ifdef ASSERT
 class VerifyCSetClosure: public HeapRegionClosure {
 public:
@@ -4158,7 +4156,7 @@ G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
   // non-young regions (where the age is -1)
   // We also add a few elements at the beginning and at the end in
   // an attempt to eliminate cache contention
-  size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
+  size_t real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
   size_t array_length = PADDING_ELEM_NUM +
                         real_length +
                         PADDING_ELEM_NUM;
@@ -5595,8 +5593,8 @@ void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
 
     if (cur->is_young()) {
       int index = cur->young_index_in_cset();
-      guarantee( index != -1, "invariant" );
-      guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
+      assert(index != -1, "invariant");
+      assert((size_t) index < policy->young_cset_region_length(), "invariant");
       size_t words_survived = _surviving_young_words[index];
       cur->record_surv_words_in_group(words_survived);
 
@@ -5607,7 +5605,7 @@ void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
       cur->set_next_young_region(NULL);
     } else {
       int index = cur->young_index_in_cset();
-      guarantee( index == -1, "invariant" );
+      assert(index == -1, "invariant");
     }
 
     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
@@ -5620,8 +5618,9 @@ void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
       free_region(cur, &pre_used, &local_free_list, false /* par */);
     } else {
       cur->uninstall_surv_rate_group();
-      if (cur->is_young())
+      if (cur->is_young()) {
         cur->set_young_index_in_cset(-1);
+      }
       cur->set_not_young();
       cur->set_evacuation_failed(false);
       // The region is now considered to be old.
@@ -5722,7 +5721,6 @@ void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
   assert(heap_lock_held_for_gc(),
               "the heap lock should already be held by or for this thread");
   _young_list->push_region(hr);
-  g1_policy()->set_region_short_lived(hr);
 }
 
 class NoYoungRegionsClosure: public HeapRegionClosure {
@@ -5880,7 +5878,6 @@ HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
     HeapRegion* new_alloc_region = new_region(word_size,
                                               false /* do_expand */);
     if (new_alloc_region != NULL) {
-      g1_policy()->update_region_num(true /* next_is_young */);
       set_region_short_lived_locked(new_alloc_region);
       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
       return new_alloc_region;

src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp

@@ -1610,16 +1610,12 @@ public:
 public:
   void stop_conc_gc_threads();
 
-  // <NEW PREDICTION>
-
   double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
   void check_if_region_is_too_expensive(double predicted_time_ms);
   size_t pending_card_num();
   size_t max_pending_card_num();
   size_t cards_scanned();
 
-  // </NEW PREDICTION>
-
 protected:
   size_t _max_heap_capacity;
 };

src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp

@@ -85,9 +85,6 @@ public:
 
 class G1CollectorPolicy: public CollectorPolicy {
 private:
-  // The number of pauses during the execution.
-  long _n_pauses;
-
   // either equal to the number of parallel threads, if ParallelGCThreads
   // has been set, or 1 otherwise
   int _parallel_gc_threads;
@@ -127,18 +124,9 @@ private:
   jlong  _num_cc_clears;                // number of times the card count cache has been cleared
 #endif
 
-  // Statistics for recent GC pauses.  See below for how indexed.
-  TruncatedSeq* _recent_rs_scan_times_ms;
-
   // These exclude marking times.
-  TruncatedSeq* _recent_pause_times_ms;
   TruncatedSeq* _recent_gc_times_ms;
 
-  TruncatedSeq* _recent_CS_bytes_used_before;
-  TruncatedSeq* _recent_CS_bytes_surviving;
-
-  TruncatedSeq* _recent_rs_sizes;
-
   TruncatedSeq* _concurrent_mark_remark_times_ms;
   TruncatedSeq* _concurrent_mark_cleanup_times_ms;
 
@@ -150,13 +138,6 @@ private:
   NumberSeq* _all_stop_world_times_ms;
   NumberSeq* _all_yield_times_ms;
 
-  size_t     _region_num_young;
-  size_t     _region_num_tenured;
-  size_t     _prev_region_num_young;
-  size_t     _prev_region_num_tenured;
-
-  NumberSeq* _all_mod_union_times_ms;
-
   int        _aux_num;
   NumberSeq* _all_aux_times_ms;
   double*    _cur_aux_start_times_ms;
@@ -194,7 +175,6 @@ private:
   // locker is active. This should be >= _young_list_target_length;
   size_t _young_list_max_length;
 
-  size_t _young_cset_length;
   bool   _last_young_gc_full;
 
   unsigned              _full_young_pause_num;
@@ -217,8 +197,6 @@ private:
     return _during_marking;
   }
 
-  // <NEW PREDICTION>
-
 private:
   enum PredictionConstants {
     TruncatedSeqLength = 10
@@ -240,47 +218,32 @@ private:
   TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
 
   TruncatedSeq* _pending_cards_seq;
-  TruncatedSeq* _scanned_cards_seq;
   TruncatedSeq* _rs_lengths_seq;
 
   TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
 
   TruncatedSeq* _young_gc_eff_seq;
 
-  TruncatedSeq* _max_conc_overhead_seq;
-
   bool   _using_new_ratio_calculations;
   size_t _min_desired_young_length; // as set on the command line or default calculations
   size_t _max_desired_young_length; // as set on the command line or default calculations
 
-  size_t _recorded_young_regions;
-  size_t _recorded_non_young_regions;
-  size_t _recorded_region_num;
+  size_t _eden_cset_region_length;
+  size_t _survivor_cset_region_length;
+  size_t _old_cset_region_length;
+
+  void init_cset_region_lengths(size_t eden_cset_region_length,
+                                size_t survivor_cset_region_length);
+
+  size_t eden_cset_region_length()     { return _eden_cset_region_length;     }
+  size_t survivor_cset_region_length() { return _survivor_cset_region_length; }
+  size_t old_cset_region_length()      { return _old_cset_region_length;      }
 
   size_t _free_regions_at_end_of_collection;
 
   size_t _recorded_rs_lengths;
   size_t _max_rs_lengths;
 
-  size_t _recorded_marked_bytes;
-  size_t _recorded_young_bytes;
-
-  size_t _predicted_pending_cards;
-  size_t _predicted_cards_scanned;
-  size_t _predicted_rs_lengths;
-  size_t _predicted_bytes_to_copy;
-
-  double _predicted_survival_ratio;
-  double _predicted_rs_update_time_ms;
-  double _predicted_rs_scan_time_ms;
-  double _predicted_object_copy_time_ms;
-  double _predicted_constant_other_time_ms;
-  double _predicted_young_other_time_ms;
-  double _predicted_non_young_other_time_ms;
-  double _predicted_pause_time_ms;
-
-  double _vtime_diff_ms;
-
   double _recorded_young_free_cset_time_ms;
   double _recorded_non_young_free_cset_time_ms;
 
@@ -320,18 +283,21 @@ private:
   double _pause_time_target_ms;
   double _recorded_young_cset_choice_time_ms;
   double _recorded_non_young_cset_choice_time_ms;
-  bool   _within_target;
   size_t _pending_cards;
   size_t _max_pending_cards;
 
 public:
 
-  void set_region_short_lived(HeapRegion* hr) {
+  void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
+    hr->set_young();
     hr->install_surv_rate_group(_short_lived_surv_rate_group);
+    hr->set_young_index_in_cset(young_index_in_cset);
   }
 
-  void set_region_survivors(HeapRegion* hr) {
+  void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
+    assert(hr->is_young() && hr->is_survivor(), "pre-condition");
     hr->install_surv_rate_group(_survivor_surv_rate_group);
+    hr->set_young_index_in_cset(young_index_in_cset);
   }
 
 #ifndef PRODUCT
@@ -343,10 +309,6 @@ public:
                 seq->davg() * confidence_factor(seq->num()));
   }
 
-  size_t young_cset_length() {
-    return _young_cset_length;
-  }
-
   void record_max_rs_lengths(size_t rs_lengths) {
     _max_rs_lengths = rs_lengths;
   }
@@ -465,20 +427,12 @@ public:
   size_t predict_bytes_to_copy(HeapRegion* hr);
   double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
 
-  void start_recording_regions();
-  void record_cset_region_info(HeapRegion* hr, bool young);
-  void record_non_young_cset_region(HeapRegion* hr);
-
-  void set_recorded_young_regions(size_t n_regions);
-  void set_recorded_young_bytes(size_t bytes);
   void set_recorded_rs_lengths(size_t rs_lengths);
-  void set_predicted_bytes_to_copy(size_t bytes);
-
-  void end_recording_regions();
 
-  void record_vtime_diff_ms(double vtime_diff_ms) {
-    _vtime_diff_ms = vtime_diff_ms;
-  }
+  size_t cset_region_length()       { return young_cset_region_length() +
+                                             old_cset_region_length(); }
+  size_t young_cset_region_length() { return eden_cset_region_length() +
+                                             survivor_cset_region_length(); }
 
   void record_young_free_cset_time_ms(double time_ms) {
     _recorded_young_free_cset_time_ms = time_ms;
@@ -494,8 +448,6 @@ public:
 
   double predict_survivor_regions_evac_time();
 
-  // </NEW PREDICTION>
-
   void cset_regions_freed() {
     bool propagate = _last_young_gc_full && !_in_marking_window;
     _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
@@ -576,7 +528,6 @@ private:
   double max_sum (double* data1, double* data2);
 
   int _last_satb_drain_processed_buffers;
-  int _last_update_rs_processed_buffers;
   double _last_pause_time_ms;
 
   size_t _bytes_in_collection_set_before_gc;
@@ -596,10 +547,6 @@ private:
   // set at the start of the pause.
   HeapRegion* _collection_set;
 
-  // The number of regions in the collection set. Set from the incrementally
-  // built collection set at the start of an evacuation pause.
-  size_t _collection_set_size;
-
   // The number of bytes in the collection set before the pause. Set from
   // the incrementally built collection set at the start of an evacuation
   // pause.
@@ -622,16 +569,6 @@ private:
   // The tail of the incrementally built collection set.
   HeapRegion* _inc_cset_tail;
 
-  // The number of regions in the incrementally built collection set.
-  // Used to set _collection_set_size at the start of an evacuation
-  // pause.
-  size_t _inc_cset_size;
-
-  // Used as the index in the surving young words structure
-  // which tracks the amount of space, for each young region,
-  // that survives the pause.
-  size_t _inc_cset_young_index;
-
   // The number of bytes in the incrementally built collection set.
   // Used to set _collection_set_bytes_used_before at the start of
   // an evacuation pause.
@@ -640,11 +577,6 @@ private:
   // Used to record the highest end of heap region in collection set
   HeapWord* _inc_cset_max_finger;
 
-  // The number of recorded used bytes in the young regions
-  // of the collection set. This is the sum of the used() bytes
-  // of retired young regions in the collection set.
-  size_t _inc_cset_recorded_young_bytes;
-
   // The RSet lengths recorded for regions in the collection set
   // (updated by the periodic sampling of the regions in the
   // young list/collection set).
@@ -655,68 +587,9 @@ private:
   // regions in the young list/collection set).
   double _inc_cset_predicted_elapsed_time_ms;
 
-  // The predicted bytes to copy for the regions in the collection
-  // set (updated by the periodic sampling of the regions in the
-  // young list/collection set).
-  size_t _inc_cset_predicted_bytes_to_copy;
-
   // Stash a pointer to the g1 heap.
   G1CollectedHeap* _g1;
 
-  // The average time in ms per collection pause, averaged over recent pauses.
-  double recent_avg_time_for_pauses_ms();
-
-  // The average time in ms for RS scanning, per pause, averaged
-  // over recent pauses. (Note the RS scanning time for a pause
-  // is itself an average of the RS scanning time for each worker
-  // thread.)
-  double recent_avg_time_for_rs_scan_ms();
-
-  // The number of "recent" GCs recorded in the number sequences
-  int number_of_recent_gcs();
-
-  // The average survival ratio, computed by the total number of bytes
-  // suriviving / total number of bytes before collection over the last
-  // several recent pauses.
-  double recent_avg_survival_fraction();
-  // The survival fraction of the most recent pause; if there have been no
-  // pauses, returns 1.0.
-  double last_survival_fraction();
-
-  // Returns a "conservative" estimate of the recent survival rate, i.e.,
-  // one that may be higher than "recent_avg_survival_fraction".
-  // This is conservative in several ways:
-  //   If there have been few pauses, it will assume a potential high
-  //     variance, and err on the side of caution.
-  //   It puts a lower bound (currently 0.1) on the value it will return.
-  //   To try to detect phase changes, if the most recent pause ("latest") has a
-  //     higher-than average ("avg") survival rate, it returns that rate.
-  // "work" version is a utility function; young is restricted to young regions.
-  double conservative_avg_survival_fraction_work(double avg,
-                                                 double latest);
-
-  // The arguments are the two sequences that keep track of the number of bytes
-  //   surviving and the total number of bytes before collection, resp.,
-  //   over the last evereal recent pauses
-  // Returns the survival rate for the category in the most recent pause.
-  // If there have been no pauses, returns 1.0.
-  double last_survival_fraction_work(TruncatedSeq* surviving,
-                                     TruncatedSeq* before);
-
-  // The arguments are the two sequences that keep track of the number of bytes
-  //   surviving and the total number of bytes before collection, resp.,
-  //   over the last several recent pauses
-  // Returns the average survival ration over the last several recent pauses
-  // If there have been no pauses, return 1.0
-  double recent_avg_survival_fraction_work(TruncatedSeq* surviving,
-                                           TruncatedSeq* before);
-
-  double conservative_avg_survival_fraction() {
-    double avg = recent_avg_survival_fraction();
-    double latest = last_survival_fraction();
-    return conservative_avg_survival_fraction_work(avg, latest);
-  }
-
   // The ratio of gc time to elapsed time, computed over recent pauses.
   double _recent_avg_pause_time_ratio;
 
@@ -724,9 +597,6 @@ private:
     return _recent_avg_pause_time_ratio;
   }
 
-  // Number of pauses between concurrent marking.
-  size_t _pauses_btwn_concurrent_mark;
-
   // At the end of a pause we check the heap occupancy and we decide
   // whether we will start a marking cycle during the next pause. If
   // we decide that we want to do that, we will set this parameter to
@@ -849,9 +719,6 @@ public:
 
   GenRemSet::Name  rem_set_name()     { return GenRemSet::CardTable; }
 
-  // The number of collection pauses so far.
-  long n_pauses() const { return _n_pauses; }
-
   // Update the heuristic info to record a collection pause of the given
   // start time, where the given number of bytes were used at the start.
   // This may involve changing the desired size of a collection set.
@@ -905,10 +772,6 @@ public:
     _last_satb_drain_processed_buffers = processed_buffers;
   }
 
-  void record_mod_union_time(double ms) {
-    _all_mod_union_times_ms->add(ms);
-  }
-
   void record_update_rs_time(int thread, double ms) {
     _par_last_update_rs_times_ms[thread] = ms;
   }
@@ -1009,11 +872,8 @@ public:
 
   void clear_collection_set() { _collection_set = NULL; }
 
-  // The number of elements in the current collection set.
-  size_t collection_set_size() { return _collection_set_size; }
-
-  // Add "hr" to the CS.
-  void add_to_collection_set(HeapRegion* hr);
+  // Add old region "hr" to the CSet.
+  void add_old_region_to_cset(HeapRegion* hr);
 
   // Incremental CSet Support
 
@@ -1023,9 +883,6 @@ public:
   // The tail of the incrementally built collection set.
   HeapRegion* inc_set_tail() { return _inc_cset_tail; }
 
-  // The number of elements in the incrementally built collection set.
-  size_t inc_cset_size() { return _inc_cset_size; }
-
   // Initialize incremental collection set info.
   void start_incremental_cset_building();
 
@@ -1125,8 +982,6 @@ public:
     return _young_list_max_length;
   }
 
-  void update_region_num(bool young);
-
   bool full_young_gcs() {
     return _full_young_gcs;
   }

src/share/vm/gc_implementation/g1/g1RemSet.cpp

@@ -219,7 +219,7 @@ public:
 HeapRegion* G1RemSet::calculateStartRegion(int worker_i) {
   HeapRegion* result = _g1p->collection_set();
   if (ParallelGCThreads > 0) {
-    size_t cs_size = _g1p->collection_set_size();
+    size_t cs_size = _g1p->cset_region_length();
     int n_workers = _g1->workers()->total_workers();
     size_t cs_spans = cs_size / n_workers;
     size_t ind      = cs_spans * worker_i;

src/share/vm/gc_implementation/g1/g1_globals.hpp

@@ -39,10 +39,6 @@
   develop(intx, G1MarkingOverheadPercent, 0,                                \
           "Overhead of concurrent marking")                                 \
                                                                             \
-                                                                            \
-  develop(intx, G1PolicyVerbose, 0,                                         \
-          "The verbosity level on G1 policy decisions")                     \
-                                                                            \
   develop(intx, G1MarkingVerboseLevel, 0,                                   \
           "Level (0-4) of verboseness of the marking code")                 \
                                                                             \
@@ -58,9 +54,6 @@
   develop(bool, G1TraceMarkStackOverflow, false,                            \
           "If true, extra debugging code for CM restart for ovflw.")        \
                                                                             \
-  develop(intx, G1PausesBtwnConcMark, -1,                                   \
-          "If positive, fixed number of pauses between conc markings")      \
-                                                                            \
   diagnostic(bool, G1SummarizeConcMark, false,                              \
           "Summarize concurrent mark info")                                 \
                                                                             \