changeset 55920:bf8e76d86d05

8228503: Rename "rs_lengths" to "rs_length" in ergo code Reviewed-by: pliden, kbarrett
author tschatzl
date Wed, 07 Aug 2019 10:29:07 +0200
parents f81dbe27a7b1
children 1d2ea8db7083
files src/hotspot/share/gc/g1/g1Analytics.cpp src/hotspot/share/gc/g1/g1Analytics.hpp src/hotspot/share/gc/g1/g1CollectedHeap.cpp src/hotspot/share/gc/g1/g1CollectionSet.cpp src/hotspot/share/gc/g1/g1CollectionSet.hpp src/hotspot/share/gc/g1/g1ConcurrentMark.cpp src/hotspot/share/gc/g1/g1ConcurrentMark.hpp src/hotspot/share/gc/g1/g1Policy.cpp src/hotspot/share/gc/g1/g1Policy.hpp src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.hpp
diffstat 11 files changed, 114 insertions(+), 114 deletions(-) [+]
line wrap: on
line diff
--- a/src/hotspot/share/gc/g1/g1Analytics.cpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1Analytics.cpp	Wed Aug 07 10:29:07 2019 +0200
@@ -88,7 +88,7 @@
     _young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
     _non_young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
     _pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
-    _rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
+    _rs_length_seq(new TruncatedSeq(TruncatedSeqLength)),
     _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
     _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
     _recent_avg_pause_time_ratio(0.0),
@@ -210,8 +210,8 @@
   _pending_cards_seq->add(pending_cards);
 }
 
-void G1Analytics::report_rs_lengths(double rs_lengths) {
-  _rs_lengths_seq->add(rs_lengths);
+void G1Analytics::report_rs_length(double rs_length) {
+  _rs_length_seq->add(rs_length);
 }
 
 size_t G1Analytics::predict_rs_length_diff() const {
@@ -310,8 +310,8 @@
   return get_new_prediction(_concurrent_mark_cleanup_times_ms);
 }
 
-size_t G1Analytics::predict_rs_lengths() const {
-  return get_new_size_prediction(_rs_lengths_seq);
+size_t G1Analytics::predict_rs_length() const {
+  return get_new_size_prediction(_rs_length_seq);
 }
 
 size_t G1Analytics::predict_pending_cards() const {
--- a/src/hotspot/share/gc/g1/g1Analytics.hpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1Analytics.hpp	Wed Aug 07 10:29:07 2019 +0200
@@ -58,7 +58,7 @@
   TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
 
   TruncatedSeq* _pending_cards_seq;
-  TruncatedSeq* _rs_lengths_seq;
+  TruncatedSeq* _rs_length_seq;
 
   TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
 
@@ -109,7 +109,7 @@
   void report_non_young_other_cost_per_region_ms(double other_cost_per_region_ms);
   void report_constant_other_time_ms(double constant_other_time_ms);
   void report_pending_cards(double pending_cards);
-  void report_rs_lengths(double rs_lengths);
+  void report_rs_length(double rs_length);
 
   size_t predict_rs_length_diff() const;
 
@@ -146,7 +146,7 @@
 
   double predict_cleanup_time_ms() const;
 
-  size_t predict_rs_lengths() const;
+  size_t predict_rs_length() const;
   size_t predict_pending_cards() const;
 
   double predict_cost_per_byte_ms() const;
--- a/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	Wed Aug 07 10:29:07 2019 +0200
@@ -4058,7 +4058,7 @@
   G1SerialFreeCollectionSetClosure _cl;
   const size_t* _surviving_young_words;
 
-  size_t _rs_lengths;
+  size_t _rs_length;
 
   volatile jint _serial_work_claim;
 
@@ -4090,7 +4090,7 @@
     HeapRegion* r = g1h->region_at(region_idx);
     assert(!g1h->is_on_master_free_list(r), "sanity");
 
-    Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
+    Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
 
     if (!is_young) {
       g1h->_hot_card_cache->reset_card_counts(r);
@@ -4123,7 +4123,7 @@
     _cl.complete_work();
 
     G1Policy* policy = G1CollectedHeap::heap()->policy();
-    policy->record_max_rs_lengths(_rs_lengths);
+    policy->record_max_rs_length(_rs_length);
     policy->cset_regions_freed();
   }
 public:
@@ -4132,7 +4132,7 @@
     _collection_set(collection_set),
     _cl(evacuation_info, surviving_young_words),
     _surviving_young_words(surviving_young_words),
-    _rs_lengths(0),
+    _rs_length(0),
     _serial_work_claim(0),
     _parallel_work_claim(0),
     _num_work_items(collection_set->region_length()),
--- a/src/hotspot/share/gc/g1/g1CollectionSet.cpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1CollectionSet.cpp	Wed Aug 07 10:29:07 2019 +0200
@@ -61,14 +61,14 @@
   _collection_set_max_length(0),
   _num_optional_regions(0),
   _bytes_used_before(0),
-  _recorded_rs_lengths(0),
+  _recorded_rs_length(0),
   _inc_build_state(Inactive),
   _inc_part_start(0),
   _inc_bytes_used_before(0),
-  _inc_recorded_rs_lengths(0),
-  _inc_recorded_rs_lengths_diffs(0),
+  _inc_recorded_rs_length(0),
+  _inc_recorded_rs_length_diff(0),
   _inc_predicted_elapsed_time_ms(0.0),
-  _inc_predicted_elapsed_time_ms_diffs(0.0) {
+  _inc_predicted_elapsed_time_ms_diff(0.0) {
 }
 
 G1CollectionSet::~G1CollectionSet() {
@@ -108,8 +108,8 @@
   _candidates = NULL;
 }
 
-void G1CollectionSet::set_recorded_rs_lengths(size_t rs_lengths) {
-  _recorded_rs_lengths = rs_lengths;
+void G1CollectionSet::set_recorded_rs_length(size_t rs_length) {
+  _recorded_rs_length = rs_length;
 }
 
 // Add the heap region at the head of the non-incremental collection set
@@ -127,7 +127,7 @@
   assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set now larger than maximum size.");
 
   _bytes_used_before += hr->used();
-  _recorded_rs_lengths += hr->rem_set()->occupied();
+  _recorded_rs_length += hr->rem_set()->occupied();
   _old_region_length++;
 
   _g1h->old_set_remove(hr);
@@ -148,10 +148,10 @@
 
   _inc_bytes_used_before = 0;
 
-  _inc_recorded_rs_lengths = 0;
-  _inc_recorded_rs_lengths_diffs = 0;
+  _inc_recorded_rs_length = 0;
+  _inc_recorded_rs_length_diff = 0;
   _inc_predicted_elapsed_time_ms = 0.0;
-  _inc_predicted_elapsed_time_ms_diffs = 0.0;
+  _inc_predicted_elapsed_time_ms_diff = 0.0;
 
   update_incremental_marker();
 }
@@ -160,32 +160,32 @@
   assert(_inc_build_state == Active, "Precondition");
   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
 
-  // The two "main" fields, _inc_recorded_rs_lengths and
+  // The two "main" fields, _inc_recorded_rs_length and
   // _inc_predicted_elapsed_time_ms, are updated by the thread
   // that adds a new region to the CSet. Further updates by the
   // concurrent refinement thread that samples the young RSet lengths
-  // are accumulated in the *_diffs fields. Here we add the diffs to
+  // are accumulated in the *_diff fields. Here we add the diffs to
   // the "main" fields.
 
-  if (_inc_recorded_rs_lengths_diffs >= 0) {
-    _inc_recorded_rs_lengths += _inc_recorded_rs_lengths_diffs;
+  if (_inc_recorded_rs_length_diff >= 0) {
+    _inc_recorded_rs_length += _inc_recorded_rs_length_diff;
   } else {
     // This is defensive. The diff should in theory be always positive
     // as RSets can only grow between GCs. However, given that we
     // sample their size concurrently with other threads updating them
     // it's possible that we might get the wrong size back, which
     // could make the calculations somewhat inaccurate.
-    size_t diffs = (size_t) (-_inc_recorded_rs_lengths_diffs);
-    if (_inc_recorded_rs_lengths >= diffs) {
-      _inc_recorded_rs_lengths -= diffs;
+    size_t diffs = (size_t) (-_inc_recorded_rs_length_diff);
+    if (_inc_recorded_rs_length >= diffs) {
+      _inc_recorded_rs_length -= diffs;
     } else {
-      _inc_recorded_rs_lengths = 0;
+      _inc_recorded_rs_length = 0;
     }
   }
-  _inc_predicted_elapsed_time_ms += _inc_predicted_elapsed_time_ms_diffs;
+  _inc_predicted_elapsed_time_ms += _inc_predicted_elapsed_time_ms_diff;
 
-  _inc_recorded_rs_lengths_diffs = 0;
-  _inc_predicted_elapsed_time_ms_diffs = 0.0;
+  _inc_recorded_rs_length_diff = 0;
+  _inc_predicted_elapsed_time_ms_diff = 0.0;
 }
 
 void G1CollectionSet::clear() {
@@ -252,23 +252,23 @@
   assert(hr->is_young(), "Precondition");
   assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint");
 
-  // We could have updated _inc_recorded_rs_lengths and
+  // We could have updated _inc_recorded_rs_length and
   // _inc_predicted_elapsed_time_ms directly but we'd need to do
   // that atomically, as this code is executed by a concurrent
   // refinement thread, potentially concurrently with a mutator thread
   // allocating a new region and also updating the same fields. To
   // avoid the atomic operations we accumulate these updates on two
-  // separate fields (*_diffs) and we'll just add them to the "main"
+  // separate fields (*_diff) and we'll just add them to the "main"
   // fields at the start of a GC.
 
   ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
-  ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
-  _inc_recorded_rs_lengths_diffs += rs_lengths_diff;
+  ssize_t rs_length_diff = (ssize_t) new_rs_length - old_rs_length;
+  _inc_recorded_rs_length_diff += rs_length_diff;
 
   double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
   double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr);
   double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
-  _inc_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
+  _inc_predicted_elapsed_time_ms_diff += elapsed_ms_diff;
 
   hr->set_recorded_rs_length(new_rs_length);
   hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
@@ -316,7 +316,7 @@
     hr->set_recorded_rs_length(rs_length);
     hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
 
-    _inc_recorded_rs_lengths += rs_length;
+    _inc_recorded_rs_length += rs_length;
     _inc_predicted_elapsed_time_ms += region_elapsed_time_ms;
     _inc_bytes_used_before += hr->used();
   }
@@ -437,7 +437,7 @@
 
   // The number of recorded young regions is the incremental
   // collection set's current size
-  set_recorded_rs_lengths(_inc_recorded_rs_lengths);
+  set_recorded_rs_length(_inc_recorded_rs_length);
 
   double young_end_time_sec = os::elapsedTime();
   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
--- a/src/hotspot/share/gc/g1/g1CollectionSet.hpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1CollectionSet.hpp	Wed Aug 07 10:29:07 2019 +0200
@@ -164,7 +164,7 @@
   // The number of cards in the remembered set in the collection set. Set from
   // the incrementally built collection set at the start of an evacuation
   // pause, and updated as more regions are added to the collection set.
-  size_t _recorded_rs_lengths;
+  size_t _recorded_rs_length;
 
   enum CSetBuildType {
     Active,             // We are actively building the collection set
@@ -188,25 +188,25 @@
   // only one thread can be allocating a new CSet region (currently,
   // it does so after taking the Heap_lock) hence no need to
   // synchronize updates to this field.
-  size_t _inc_recorded_rs_lengths;
+  size_t _inc_recorded_rs_length;
 
   // A concurrent refinement thread periodically samples the young
-  // region RSets and needs to update _inc_recorded_rs_lengths as
+  // region RSets and needs to update _inc_recorded_rs_length as
   // the RSets grow. Instead of having to synchronize updates to that
   // field we accumulate them in this field and add it to
-  // _inc_recorded_rs_lengths_diffs at the start of a GC.
-  ssize_t _inc_recorded_rs_lengths_diffs;
+  // _inc_recorded_rs_length_diff at the start of a GC.
+  ssize_t _inc_recorded_rs_length_diff;
 
   // The predicted elapsed time it will take to collect the regions in
   // the CSet. This is updated by the thread that adds a new region to
-  // the CSet. See the comment for _inc_recorded_rs_lengths about
+  // the CSet. See the comment for _inc_recorded_rs_length about
   // MT-safety assumptions.
   double _inc_predicted_elapsed_time_ms;
 
-  // See the comment for _inc_recorded_rs_lengths_diffs.
-  double _inc_predicted_elapsed_time_ms_diffs;
+  // See the comment for _inc_recorded_rs_length_diff.
+  double _inc_predicted_elapsed_time_ms_diff;
 
-  void set_recorded_rs_lengths(size_t rs_lengths);
+  void set_recorded_rs_length(size_t rs_length);
 
   G1CollectorState* collector_state();
   G1GCPhaseTimes* phase_times();
@@ -293,7 +293,7 @@
 
   void iterate_optional(HeapRegionClosure* cl) const;
 
-  size_t recorded_rs_lengths() { return _recorded_rs_lengths; }
+  size_t recorded_rs_length() { return _recorded_rs_length; }
 
   size_t bytes_used_before() const {
     return _bytes_used_before;
--- a/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	Wed Aug 07 10:29:07 2019 +0200
@@ -2587,7 +2587,7 @@
   // and do_marking_step() is not being called serially.
   bool do_stealing = do_termination && !is_serial;
 
-  double diff_prediction_ms = _g1h->policy()->predictor().get_new_prediction(&_marking_step_diffs_ms);
+  double diff_prediction_ms = _g1h->policy()->predictor().get_new_prediction(&_marking_step_diff_ms);
   _time_target_ms = time_target_ms - diff_prediction_ms;
 
   // set up the variables that are used in the work-based scheme to
@@ -2829,7 +2829,7 @@
       // Keep statistics of how well we did with respect to hitting
       // our target only if we actually timed out (if we aborted for
       // other reasons, then the results might get skewed).
-      _marking_step_diffs_ms.add(diff_ms);
+      _marking_step_diff_ms.add(diff_ms);
     }
 
     if (_cm->has_overflown()) {
@@ -2912,11 +2912,11 @@
   _elapsed_time_ms(0.0),
   _termination_time_ms(0.0),
   _termination_start_time_ms(0.0),
-  _marking_step_diffs_ms()
+  _marking_step_diff_ms()
 {
   guarantee(task_queue != NULL, "invariant");
 
-  _marking_step_diffs_ms.add(0.5);
+  _marking_step_diff_ms.add(0.5);
 }
 
 // These are formatting macros that are used below to ensure
--- a/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp	Wed Aug 07 10:29:07 2019 +0200
@@ -700,7 +700,7 @@
   // When this task got into the termination protocol
   double                      _termination_start_time_ms;
 
-  TruncatedSeq                _marking_step_diffs_ms;
+  TruncatedSeq                _marking_step_diff_ms;
 
   // Updates the local fields after this task has claimed
   // a new region to scan
--- a/src/hotspot/share/gc/g1/g1Policy.cpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1Policy.cpp	Wed Aug 07 10:29:07 2019 +0200
@@ -68,8 +68,8 @@
   _reserve_regions(0),
   _young_gen_sizer(G1YoungGenSizer::create_gen_sizer()),
   _free_regions_at_end_of_collection(0),
-  _max_rs_lengths(0),
-  _rs_lengths_prediction(0),
+  _max_rs_length(0),
+  _rs_length_prediction(0),
   _pending_cards(0),
   _bytes_allocated_in_old_since_last_gc(0),
   _initial_mark_to_mixed(),
@@ -219,23 +219,23 @@
 }
 
 uint G1Policy::update_young_list_max_and_target_length() {
-  return update_young_list_max_and_target_length(_analytics->predict_rs_lengths());
+  return update_young_list_max_and_target_length(_analytics->predict_rs_length());
 }
 
-uint G1Policy::update_young_list_max_and_target_length(size_t rs_lengths) {
-  uint unbounded_target_length = update_young_list_target_length(rs_lengths);
+uint G1Policy::update_young_list_max_and_target_length(size_t rs_length) {
+  uint unbounded_target_length = update_young_list_target_length(rs_length);
   update_max_gc_locker_expansion();
   return unbounded_target_length;
 }
 
-uint G1Policy::update_young_list_target_length(size_t rs_lengths) {
-  YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
+uint G1Policy::update_young_list_target_length(size_t rs_length) {
+  YoungTargetLengths young_lengths = young_list_target_lengths(rs_length);
   _young_list_target_length = young_lengths.first;
 
   return young_lengths.second;
 }
 
-G1Policy::YoungTargetLengths G1Policy::young_list_target_lengths(size_t rs_lengths) const {
+G1Policy::YoungTargetLengths G1Policy::young_list_target_lengths(size_t rs_length) const {
   YoungTargetLengths result;
 
   // Calculate the absolute and desired min bounds first.
@@ -256,7 +256,7 @@
   if (use_adaptive_young_list_length()) {
     if (collector_state()->in_young_only_phase()) {
       young_list_target_length =
-                        calculate_young_list_target_length(rs_lengths,
+                        calculate_young_list_target_length(rs_length,
                                                            base_min_length,
                                                            desired_min_length,
                                                            desired_max_length);
@@ -301,7 +301,7 @@
 }
 
 uint
-G1Policy::calculate_young_list_target_length(size_t rs_lengths,
+G1Policy::calculate_young_list_target_length(size_t rs_length,
                                                     uint base_min_length,
                                                     uint desired_min_length,
                                                     uint desired_max_length) const {
@@ -326,8 +326,8 @@
   const double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
   const double survivor_regions_evac_time = predict_survivor_regions_evac_time();
   const size_t pending_cards = _analytics->predict_pending_cards();
-  const size_t adj_rs_lengths = rs_lengths + _analytics->predict_rs_length_diff();
-  const size_t scanned_cards = _analytics->predict_card_num(adj_rs_lengths, true /* for_young_gc */);
+  const size_t adj_rs_length = rs_length + _analytics->predict_rs_length_diff();
+  const size_t scanned_cards = _analytics->predict_card_num(adj_rs_length, true /* for_young_gc */);
   const double base_time_ms =
     predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
     survivor_regions_evac_time;
@@ -414,25 +414,25 @@
   return survivor_regions_evac_time;
 }
 
-void G1Policy::revise_young_list_target_length_if_necessary(size_t rs_lengths) {
+void G1Policy::revise_young_list_target_length_if_necessary(size_t rs_length) {
   guarantee(use_adaptive_young_list_length(), "should not call this otherwise" );
 
-  if (rs_lengths > _rs_lengths_prediction) {
+  if (rs_length > _rs_length_prediction) {
     // add 10% to avoid having to recalculate often
-    size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
-    update_rs_lengths_prediction(rs_lengths_prediction);
+    size_t rs_length_prediction = rs_length * 1100 / 1000;
+    update_rs_length_prediction(rs_length_prediction);
 
-    update_young_list_max_and_target_length(rs_lengths_prediction);
+    update_young_list_max_and_target_length(rs_length_prediction);
   }
 }
 
-void G1Policy::update_rs_lengths_prediction() {
-  update_rs_lengths_prediction(_analytics->predict_rs_lengths());
+void G1Policy::update_rs_length_prediction() {
+  update_rs_length_prediction(_analytics->predict_rs_length());
 }
 
-void G1Policy::update_rs_lengths_prediction(size_t prediction) {
+void G1Policy::update_rs_length_prediction(size_t prediction) {
   if (collector_state()->in_young_only_phase() && use_adaptive_young_list_length()) {
-    _rs_lengths_prediction = prediction;
+    _rs_length_prediction = prediction;
   }
 }
 
@@ -471,7 +471,7 @@
   // Reset survivors SurvRateGroup.
   _survivor_surv_rate_group->reset();
   update_young_list_max_and_target_length();
-  update_rs_lengths_prediction();
+  update_rs_length_prediction();
 
   _bytes_allocated_in_old_since_last_gc = 0;
 
@@ -692,29 +692,29 @@
       _analytics->report_cost_per_remset_card_ms(cost_per_remset_card_ms, this_pause_was_young_only);
     }
 
-    if (_max_rs_lengths > 0) {
+    if (_max_rs_length > 0) {
       double cards_per_entry_ratio =
-        (double) remset_cards_scanned / (double) _max_rs_lengths;
+        (double) remset_cards_scanned / (double) _max_rs_length;
       _analytics->report_cards_per_entry_ratio(cards_per_entry_ratio, this_pause_was_young_only);
     }
 
-    // This is defensive. For a while _max_rs_lengths could get
-    // smaller than _recorded_rs_lengths which was causing
+    // This is defensive. For a while _max_rs_length could get
+    // smaller than _recorded_rs_length which was causing
     // rs_length_diff to get very large and mess up the RSet length
     // predictions. The reason was unsafe concurrent updates to the
-    // _inc_cset_recorded_rs_lengths field which the code below guards
+    // _inc_cset_recorded_rs_length field which the code below guards
     // against (see CR 7118202). This bug has now been fixed (see CR
     // 7119027). However, I'm still worried that
-    // _inc_cset_recorded_rs_lengths might still end up somewhat
+    // _inc_cset_recorded_rs_length might still end up somewhat
     // inaccurate. The concurrent refinement thread calculates an
     // RSet's length concurrently with other CR threads updating it
     // which might cause it to calculate the length incorrectly (if,
     // say, it's in mid-coarsening). So I'll leave in the defensive
     // conditional below just in case.
     size_t rs_length_diff = 0;
-    size_t recorded_rs_lengths = _collection_set->recorded_rs_lengths();
-    if (_max_rs_lengths > recorded_rs_lengths) {
-      rs_length_diff = _max_rs_lengths - recorded_rs_lengths;
+    size_t recorded_rs_length = _collection_set->recorded_rs_length();
+    if (_max_rs_length > recorded_rs_length) {
+      rs_length_diff = _max_rs_length - recorded_rs_length;
     }
     _analytics->report_rs_length_diff((double) rs_length_diff);
 
@@ -745,7 +745,7 @@
     // During mixed gc we do not use them for young gen sizing.
     if (this_pause_was_young_only) {
       _analytics->report_pending_cards((double) _pending_cards);
-      _analytics->report_rs_lengths((double) _max_rs_lengths);
+      _analytics->report_rs_length((double) _max_rs_length);
     }
   }
 
@@ -757,7 +757,7 @@
 
   _free_regions_at_end_of_collection = _g1h->num_free_regions();
 
-  update_rs_lengths_prediction();
+  update_rs_length_prediction();
 
   // Do not update dynamic IHOP due to G1 periodic collection as it is highly likely
   // that in this case we are not running in a "normal" operating mode.
@@ -889,7 +889,7 @@
 }
 
 double G1Policy::predict_base_elapsed_time_ms(size_t pending_cards) const {
-  size_t rs_length = _analytics->predict_rs_lengths() + _analytics->predict_rs_length_diff();
+  size_t rs_length = _analytics->predict_rs_length() + _analytics->predict_rs_length_diff();
   size_t card_num = _analytics->predict_card_num(rs_length, collector_state()->in_young_only_phase());
   return predict_base_elapsed_time_ms(pending_cards, card_num);
 }
--- a/src/hotspot/share/gc/g1/g1Policy.hpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1Policy.hpp	Wed Aug 07 10:29:07 2019 +0200
@@ -96,9 +96,9 @@
 
   uint _free_regions_at_end_of_collection;
 
-  size_t _max_rs_lengths;
+  size_t _max_rs_length;
 
-  size_t _rs_lengths_prediction;
+  size_t _rs_length_prediction;
 
   size_t _pending_cards;
 
@@ -132,8 +132,8 @@
     hr->install_surv_rate_group(_survivor_surv_rate_group);
   }
 
-  void record_max_rs_lengths(size_t rs_lengths) {
-    _max_rs_lengths = rs_lengths;
+  void record_max_rs_length(size_t rs_length) {
+    _max_rs_length = rs_length;
   }
 
   double predict_base_elapsed_time_ms(size_t pending_cards) const;
@@ -194,17 +194,17 @@
   double _mark_cleanup_start_sec;
 
   // Updates the internal young list maximum and target lengths. Returns the
-  // unbounded young list target length.
+  // unbounded young list target length. If no rs_length parameter is passed,
+  // predict the RS length using the prediction model, otherwise use the
+  // given rs_length as the prediction.
   uint update_young_list_max_and_target_length();
-  uint update_young_list_max_and_target_length(size_t rs_lengths);
+  uint update_young_list_max_and_target_length(size_t rs_length);
 
   // Update the young list target length either by setting it to the
   // desired fixed value or by calculating it using G1's pause
-  // prediction model. If no rs_lengths parameter is passed, predict
-  // the RS lengths using the prediction model, otherwise use the
-  // given rs_lengths as the prediction.
+  // prediction model.
   // Returns the unbounded young list target length.
-  uint update_young_list_target_length(size_t rs_lengths);
+  uint update_young_list_target_length(size_t rs_length);
 
   // Calculate and return the minimum desired young list target
   // length. This is the minimum desired young list length according
@@ -217,12 +217,12 @@
   uint calculate_young_list_desired_max_length() const;
 
   // Calculate and return the maximum young list target length that
-  // can fit into the pause time goal. The parameters are: rs_lengths
+  // can fit into the pause time goal. The parameters are: rs_length
   // represent the prediction of how large the young RSet lengths will
   // be, base_min_length is the already existing number of regions in
   // the young list, min_length and max_length are the desired min and
   // max young list length according to the user's inputs.
-  uint calculate_young_list_target_length(size_t rs_lengths,
+  uint calculate_young_list_target_length(size_t rs_length,
                                           uint base_min_length,
                                           uint desired_min_length,
                                           uint desired_max_length) const;
@@ -230,10 +230,10 @@
   // Result of the bounded_young_list_target_length() method, containing both the
   // bounded as well as the unbounded young list target lengths in this order.
   typedef Pair<uint, uint, StackObj> YoungTargetLengths;
-  YoungTargetLengths young_list_target_lengths(size_t rs_lengths) const;
+  YoungTargetLengths young_list_target_lengths(size_t rs_length) const;
 
-  void update_rs_lengths_prediction();
-  void update_rs_lengths_prediction(size_t prediction);
+  void update_rs_length_prediction();
+  void update_rs_length_prediction(size_t prediction);
 
   // Check whether a given young length (young_length) fits into the
   // given target pause time and whether the prediction for the amount
@@ -295,10 +295,10 @@
 
   G1GCPhaseTimes* phase_times() const { return _phase_times; }
 
-  // Check the current value of the young list RSet lengths and
+  // Check the current value of the young list RSet length and
   // compare it against the last prediction. If the current value is
   // higher, recalculate the young list target length prediction.
-  void revise_young_list_target_length_if_necessary(size_t rs_lengths);
+  void revise_young_list_target_length_if_necessary(size_t rs_length);
 
   // This should be called after the heap is resized.
   void record_new_heap_size(uint new_number_of_regions);
--- a/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp	Wed Aug 07 10:29:07 2019 +0200
@@ -110,7 +110,7 @@
   }
 
   while (!should_terminate()) {
-    sample_young_list_rs_lengths();
+    sample_young_list_rs_length();
 
     if (os::supports_vtime()) {
       _vtime_accum = (os::elapsedVTime() - vtime_start);
@@ -132,14 +132,14 @@
 class G1YoungRemSetSamplingClosure : public HeapRegionClosure {
   SuspendibleThreadSetJoiner* _sts;
   size_t _regions_visited;
-  size_t _sampled_rs_lengths;
+  size_t _sampled_rs_length;
 public:
   G1YoungRemSetSamplingClosure(SuspendibleThreadSetJoiner* sts) :
-    HeapRegionClosure(), _sts(sts), _regions_visited(0), _sampled_rs_lengths(0) { }
+    HeapRegionClosure(), _sts(sts), _regions_visited(0), _sampled_rs_length(0) { }
 
   virtual bool do_heap_region(HeapRegion* r) {
     size_t rs_length = r->rem_set()->occupied();
-    _sampled_rs_lengths += rs_length;
+    _sampled_rs_length += rs_length;
 
     // Update the collection set policy information for this region
     G1CollectedHeap::heap()->collection_set()->update_young_region_prediction(r, rs_length);
@@ -158,10 +158,10 @@
     return false;
   }
 
-  size_t sampled_rs_lengths() const { return _sampled_rs_lengths; }
+  size_t sampled_rs_length() const { return _sampled_rs_length; }
 };
 
-void G1YoungRemSetSamplingThread::sample_young_list_rs_lengths() {
+void G1YoungRemSetSamplingThread::sample_young_list_rs_length() {
   SuspendibleThreadSetJoiner sts;
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
   G1Policy* policy = g1h->policy();
@@ -173,7 +173,7 @@
     g1cs->iterate(&cl);
 
     if (cl.is_complete()) {
-      policy->revise_young_list_target_length_if_necessary(cl.sampled_rs_lengths());
+      policy->revise_young_list_target_length_if_necessary(cl.sampled_rs_length());
     }
   }
 }
--- a/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.hpp	Tue Aug 06 15:03:48 2019 -0400
+++ b/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.hpp	Wed Aug 07 10:29:07 2019 +0200
@@ -47,7 +47,7 @@
 
   double _vtime_accum;  // Accumulated virtual time.
 
-  void sample_young_list_rs_lengths();
+  void sample_young_list_rs_length();
 
   void run_service();
   void check_for_periodic_gc();