--- a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Wed Jan 18 09:50:16 2012 -0800
+++ b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Wed Feb 15 13:06:53 2012 -0500
@@ -206,7 +206,6 @@
 
   _initiate_conc_mark_if_possible(false),
   _during_initial_mark_pause(false),
-  _should_revert_to_young_gcs(false),
   _last_young_gc(false),
   _last_gc_was_young(false),
 
@@ -295,9 +294,6 @@
   _par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
   _par_last_gc_worker_other_times_ms = new double[_parallel_gc_threads];
 
-  // start conservatively
-  _expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
-
   int index;
   if (ParallelGCThreads == 0)
     index = 0;
@@ -629,16 +625,9 @@
       // possible to maximize how many old regions we can add to it.
     }
   } else {
-    if (gcs_are_young()) {
-      young_list_target_length = _young_list_fixed_length;
-    } else {
-      // A bit arbitrary: during mixed GCs we allocate half
-      // the young regions to try to add old regions to the CSet.
-      young_list_target_length = _young_list_fixed_length / 2;
-      // We choose to accept that we might go under the desired min
-      // length given that we intentionally ask for a smaller young gen.
-      desired_min_length = absolute_min_length;
-    }
+    // The user asked for a fixed young gen so we'll fix the young gen
+    // whether the next GC is young or mixed.
+    young_list_target_length = _young_list_fixed_length;
   }
 
   // Make sure we don't go over the desired max length, nor under the
@@ -872,7 +861,6 @@
   // transitions and make sure we start with young GCs after the Full GC.
   set_gcs_are_young(true);
   _last_young_gc = false;
-  _should_revert_to_young_gcs = false;
   clear_initiate_conc_mark_if_possible();
   clear_during_initial_mark_pause();
   _known_garbage_bytes = 0;
@@ -889,7 +877,7 @@
   // Reset survivors SurvRateGroup.
   _survivor_surv_rate_group->reset();
   update_young_list_target_length();
-  _collectionSetChooser->updateAfterFullCollection();
+  _collectionSetChooser->clearMarkedHeapRegions();
 }
 
 void G1CollectorPolicy::record_stop_world_start() {
@@ -1000,7 +988,6 @@
 }
 
 void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
-  _should_revert_to_young_gcs = false;
   _last_young_gc = true;
   _in_marking_window = false;
 }
@@ -1205,9 +1192,7 @@
   last_pause_included_initial_mark = during_initial_mark_pause();
   if (last_pause_included_initial_mark) {
     record_concurrent_mark_init_end(0.0);
-  }
-
-  if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
+  } else if (!_last_young_gc && need_to_start_conc_mark("end of GC")) {
     // Note: this might have already been set, if during the last
     // pause we decided to start a cycle but at the beginning of
     // this pause we decided to postpone it. That's OK.
@@ -1492,12 +1477,14 @@
   }
 
   if (_last_young_gc) {
+    // This is supposed to to be the "last young GC" before we start
+    // doing mixed GCs. Here we decide whether to start mixed GCs or not.
+
     if (!last_pause_included_initial_mark) {
-      ergo_verbose2(ErgoMixedGCs,
-                    "start mixed GCs",
-                    ergo_format_byte_perc("known garbage"),
-                    _known_garbage_bytes, _known_garbage_ratio * 100.0);
-      set_gcs_are_young(false);
+      if (next_gc_should_be_mixed("start mixed GCs",
+                                  "do not start mixed GCs")) {
+        set_gcs_are_young(false);
+      }
     } else {
       ergo_verbose0(ErgoMixedGCs,
                     "do not start mixed GCs",
@@ -1507,39 +1494,14 @@
   }
 
   if (!_last_gc_was_young) {
-    if (_should_revert_to_young_gcs) {
-      ergo_verbose2(ErgoMixedGCs,
-                    "end mixed GCs",
-                    ergo_format_reason("mixed GCs end requested")
-                    ergo_format_byte_perc("known garbage"),
-                    _known_garbage_bytes, _known_garbage_ratio * 100.0);
-      set_gcs_are_young(true);
-    } else if (_known_garbage_ratio < 0.05) {
-      ergo_verbose3(ErgoMixedGCs,
-               "end mixed GCs",
-               ergo_format_reason("known garbage percent lower than threshold")
-               ergo_format_byte_perc("known garbage")
-               ergo_format_perc("threshold"),
-               _known_garbage_bytes, _known_garbage_ratio * 100.0,
-               0.05 * 100.0);
-      set_gcs_are_young(true);
-    } else if (adaptive_young_list_length() &&
-              (get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) {
-      ergo_verbose5(ErgoMixedGCs,
-                    "end mixed GCs",
-                    ergo_format_reason("current GC efficiency lower than "
-                                       "predicted young GC efficiency")
-                    ergo_format_double("GC efficiency factor")
-                    ergo_format_double("current GC efficiency")
-                    ergo_format_double("predicted young GC efficiency")
-                    ergo_format_byte_perc("known garbage"),
-                    get_gc_eff_factor(), cur_efficiency,
-                    predict_young_gc_eff(),
-                    _known_garbage_bytes, _known_garbage_ratio * 100.0);
+    // This is a mixed GC. Here we decide whether to continue doing
+    // mixed GCs or not.
+
+    if (!next_gc_should_be_mixed("continue mixed GCs",
+                                 "do not continue mixed GCs")) {
       set_gcs_are_young(true);
     }
   }
-  _should_revert_to_young_gcs = false;
 
   if (_last_gc_was_young && !_during_marking) {
     _young_gc_eff_seq->add(cur_efficiency);
@@ -1648,15 +1610,6 @@
 
     _pending_cards_seq->add((double) _pending_cards);
     _rs_lengths_seq->add((double) _max_rs_lengths);
-
-    double expensive_region_limit_ms =
-      (double) MaxGCPauseMillis - predict_constant_other_time_ms();
-    if (expensive_region_limit_ms < 0.0) {
-      // this means that the other time was predicted to be longer than
-      // than the max pause time
-      expensive_region_limit_ms = (double) MaxGCPauseMillis;
-    }
-    _expensive_region_limit_ms = expensive_region_limit_ms;
   }
 
   _in_marking_window = new_in_marking_window;
@@ -1838,13 +1791,11 @@
   if (hr->is_marked())
     bytes_to_copy = hr->max_live_bytes();
   else {
-    guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
-               "invariant" );
+    assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
     int age = hr->age_in_surv_rate_group();
     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
     bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
   }
-
   return bytes_to_copy;
 }
 
@@ -1860,22 +1811,6 @@
   _recorded_rs_lengths = rs_lengths;
 }
 
-void G1CollectorPolicy::check_if_region_is_too_expensive(double
-                                                           predicted_time_ms) {
-  // I don't think we need to do this when in young GC mode since
-  // marking will be initiated next time we hit the soft limit anyway...
-  if (predicted_time_ms > _expensive_region_limit_ms) {
-    ergo_verbose2(ErgoMixedGCs,
-              "request mixed GCs end",
-              ergo_format_reason("predicted region time higher than threshold")
-              ergo_format_ms("predicted region time")
-              ergo_format_ms("threshold"),
-              predicted_time_ms, _expensive_region_limit_ms);
-    // no point in doing another mixed GC
-    _should_revert_to_young_gcs = true;
-  }
-}
-
 void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
                                                double elapsed_ms) {
   _recent_gc_times_ms->add(elapsed_ms);
@@ -2274,12 +2209,12 @@
 }
 
 class KnownGarbageClosure: public HeapRegionClosure {
+  G1CollectedHeap* _g1h;
   CollectionSetChooser* _hrSorted;
 
 public:
   KnownGarbageClosure(CollectionSetChooser* hrSorted) :
-    _hrSorted(hrSorted)
-  {}
+    _g1h(G1CollectedHeap::heap()), _hrSorted(hrSorted) { }
 
   bool doHeapRegion(HeapRegion* r) {
     // We only include humongous regions in collection
@@ -2288,11 +2223,10 @@
 
     // Do we have any marking information for this region?
     if (r->is_marked()) {
-      // We don't include humongous regions in collection
-      // sets because we collect them immediately at the end of a marking
-      // cycle.  We also don't include young regions because we *must*
-      // include them in the next collection pause.
-      if (!r->isHumongous() && !r->is_young()) {
+      // We will skip any region that's currently used as an old GC
+      // alloc region (we should not consider those for collection
+      // before we fill them up).
+      if (_hrSorted->shouldAdd(r) && !_g1h->is_old_gc_alloc_region(r)) {
         _hrSorted->addMarkedHeapRegion(r);
       }
     }
@@ -2301,8 +2235,10 @@
 };
 
 class ParKnownGarbageHRClosure: public HeapRegionClosure {
+  G1CollectedHeap* _g1h;
   CollectionSetChooser* _hrSorted;
   jint _marked_regions_added;
+  size_t _reclaimable_bytes_added;
   jint _chunk_size;
   jint _cur_chunk_idx;
   jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
@@ -2320,6 +2256,7 @@
     assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
     _hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
     _marked_regions_added++;
+    _reclaimable_bytes_added += r->reclaimable_bytes();
     _cur_chunk_idx++;
   }
 
@@ -2327,10 +2264,10 @@
   ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
                            jint chunk_size,
                            int worker) :
-    _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
-    _marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
-    _invokes(0)
-  {}
+      _g1h(G1CollectedHeap::heap()),
+      _hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
+      _marked_regions_added(0), _reclaimable_bytes_added(0),
+      _cur_chunk_idx(0), _cur_chunk_end(0), _invokes(0) { }
 
   bool doHeapRegion(HeapRegion* r) {
     // We only include humongous regions in collection
@@ -2340,17 +2277,17 @@
 
     // Do we have any marking information for this region?
     if (r->is_marked()) {
-      // We don't include humongous regions in collection
-      // sets because we collect them immediately at the end of a marking
-      // cycle.
-      // We also do not include young regions in collection sets
-      if (!r->isHumongous() && !r->is_young()) {
+      // We will skip any region that's currently used as an old GC
+      // alloc region (we should not consider those for collection
+      // before we fill them up).
+      if (_hrSorted->shouldAdd(r) && !_g1h->is_old_gc_alloc_region(r)) {
         add_region(r);
       }
     }
     return false;
   }
   jint marked_regions_added() { return _marked_regions_added; }
+  size_t reclaimable_bytes_added() { return _reclaimable_bytes_added; }
   int invokes() { return _invokes; }
 };
 
@@ -2362,8 +2299,7 @@
   ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
     AbstractGangTask("ParKnownGarbageTask"),
     _hrSorted(hrSorted), _chunk_size(chunk_size),
-    _g1(G1CollectedHeap::heap())
-  {}
+    _g1(G1CollectedHeap::heap()) { }
 
   void work(uint worker_id) {
     ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted,
@@ -2374,7 +2310,9 @@
                                          _g1->workers()->active_workers(),
                                          HeapRegion::InitialClaimValue);
     jint regions_added = parKnownGarbageCl.marked_regions_added();
-    _hrSorted->incNumMarkedHeapRegions(regions_added);
+    size_t reclaimable_bytes_added =
+                                   parKnownGarbageCl.reclaimable_bytes_added();
+    _hrSorted->updateTotals(regions_added, reclaimable_bytes_added);
     if (G1PrintParCleanupStats) {
       gclog_or_tty->print_cr("     Thread %d called %d times, added %d regions to list.",
                  worker_id, parKnownGarbageCl.invokes(), regions_added);
@@ -2658,7 +2596,43 @@
 }
 #endif // !PRODUCT
 
-void G1CollectorPolicy::choose_collection_set(double target_pause_time_ms) {
+bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
+                                                const char* false_action_str) {
+  CollectionSetChooser* cset_chooser = _collectionSetChooser;
+  if (cset_chooser->isEmpty()) {
+    ergo_verbose0(ErgoMixedGCs,
+                  false_action_str,
+                  ergo_format_reason("candidate old regions not available"));
+    return false;
+  }
+  size_t reclaimable_bytes = cset_chooser->remainingReclaimableBytes();
+  size_t capacity_bytes = _g1->capacity();
+  double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
+  double threshold = (double) G1OldReclaimableThresholdPercent;
+  if (perc < threshold) {
+    ergo_verbose4(ErgoMixedGCs,
+              false_action_str,
+              ergo_format_reason("reclaimable percentage lower than threshold")
+              ergo_format_region("candidate old regions")
+              ergo_format_byte_perc("reclaimable")
+              ergo_format_perc("threshold"),
+              cset_chooser->remainingRegions(),
+              reclaimable_bytes, perc, threshold);
+    return false;
+  }
+
+  ergo_verbose4(ErgoMixedGCs,
+                true_action_str,
+                ergo_format_reason("candidate old regions available")
+                ergo_format_region("candidate old regions")
+                ergo_format_byte_perc("reclaimable")
+                ergo_format_perc("threshold"),
+                cset_chooser->remainingRegions(),
+                reclaimable_bytes, perc, threshold);
+  return true;
+}
+
+void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) {
   // Set this here - in case we're not doing young collections.
   double non_young_start_time_sec = os::elapsedTime();
 
@@ -2672,7 +2646,6 @@
 
   double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
   double predicted_pause_time_ms = base_time_ms;
-
   double time_remaining_ms = target_pause_time_ms - base_time_ms;
 
   ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
@@ -2682,22 +2655,6 @@
                 ergo_format_ms("target pause time"),
                 base_time_ms, time_remaining_ms, target_pause_time_ms);
 
-  // the 10% and 50% values are arbitrary...
-  double threshold = 0.10 * target_pause_time_ms;
-  if (time_remaining_ms < threshold) {
-    double prev_time_remaining_ms = time_remaining_ms;
-    time_remaining_ms = 0.50 * target_pause_time_ms;
-    ergo_verbose3(ErgoCSetConstruction,
-                  "adjust remaining time",
-                  ergo_format_reason("remaining time lower than threshold")
-                  ergo_format_ms("remaining time")
-                  ergo_format_ms("threshold")
-                  ergo_format_ms("adjusted remaining time"),
-                  prev_time_remaining_ms, threshold, time_remaining_ms);
-  }
-
-  size_t expansion_bytes = _g1->expansion_regions() * HeapRegion::GrainBytes;
-
   HeapRegion* hr;
   double young_start_time_sec = os::elapsedTime();
 
@@ -2752,78 +2709,97 @@
   non_young_start_time_sec = young_end_time_sec;
 
   if (!gcs_are_young()) {
-    bool should_continue = true;
-    NumberSeq seq;
-    double avg_prediction = 100000000000000000.0; // something very large
-
-    double prev_predicted_pause_time_ms = predicted_pause_time_ms;
-    do {
-      // Note that add_old_region_to_cset() increments the
-      // _old_cset_region_length field and cset_region_length() returns the
-      // sum of _eden_cset_region_length, _survivor_cset_region_length, and
-      // _old_cset_region_length. So, as old regions are added to the
-      // CSet, _old_cset_region_length will be incremented and
-      // cset_region_length(), which is used below, will always reflect
-      // the the total number of regions added up to this point to the CSet.
-
-      hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
-                                                      avg_prediction);
-      if (hr != NULL) {
-        _g1->old_set_remove(hr);
-        double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
-        time_remaining_ms -= predicted_time_ms;
-        predicted_pause_time_ms += predicted_time_ms;
-        add_old_region_to_cset(hr);
-        seq.add(predicted_time_ms);
-        avg_prediction = seq.avg() + seq.sd();
+    CollectionSetChooser* cset_chooser = _collectionSetChooser;
+    assert(cset_chooser->verify(), "CSet Chooser verification - pre");
+    const size_t min_old_cset_length = cset_chooser->calcMinOldCSetLength();
+    const size_t max_old_cset_length = cset_chooser->calcMaxOldCSetLength();
+
+    size_t expensive_region_num = 0;
+    bool check_time_remaining = adaptive_young_list_length();
+    HeapRegion* hr = cset_chooser->peek();
+    while (hr != NULL) {
+      if (old_cset_region_length() >= max_old_cset_length) {
+        // Added maximum number of old regions to the CSet.
+        ergo_verbose2(ErgoCSetConstruction,
+                      "finish adding old regions to CSet",
+                      ergo_format_reason("old CSet region num reached max")
+                      ergo_format_region("old")
+                      ergo_format_region("max"),
+                      old_cset_region_length(), max_old_cset_length);
+        break;
       }
 
-      should_continue = true;
-      if (hr == NULL) {
-        // No need for an ergo verbose message here,
-        // getNextMarkRegion() does this when it returns NULL.
-        should_continue = false;
+      double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
+      if (check_time_remaining) {
+        if (predicted_time_ms > time_remaining_ms) {
+          // Too expensive for the current CSet.
+
+          if (old_cset_region_length() >= min_old_cset_length) {
+            // We have added the minimum number of old regions to the CSet,
+            // we are done with this CSet.
+            ergo_verbose4(ErgoCSetConstruction,
+                          "finish adding old regions to CSet",
+                          ergo_format_reason("predicted time is too high")
+                          ergo_format_ms("predicted time")
+                          ergo_format_ms("remaining time")
+                          ergo_format_region("old")
+                          ergo_format_region("min"),
+                          predicted_time_ms, time_remaining_ms,
+                          old_cset_region_length(), min_old_cset_length);
+            break;
+          }
+
+          // We'll add it anyway given that we haven't reached the
+          // minimum number of old regions.
+          expensive_region_num += 1;
+        }
       } else {
-        if (adaptive_young_list_length()) {
-          if (time_remaining_ms < 0.0) {
-            ergo_verbose1(ErgoCSetConstruction,
-                          "stop adding old regions to CSet",
-                          ergo_format_reason("remaining time is lower than 0")
-                          ergo_format_ms("remaining time"),
-                          time_remaining_ms);
-            should_continue = false;
-          }
-        } else {
-          if (cset_region_length() >= _young_list_fixed_length) {
-            ergo_verbose2(ErgoCSetConstruction,
-                          "stop adding old regions to CSet",
-                          ergo_format_reason("CSet length reached target")
-                          ergo_format_region("CSet")
-                          ergo_format_region("young target"),
-                          cset_region_length(), _young_list_fixed_length);
-            should_continue = false;
-          }
+        if (old_cset_region_length() >= min_old_cset_length) {
+          // In the non-auto-tuning case, we'll finish adding regions
+          // to the CSet if we reach the minimum.
+          ergo_verbose2(ErgoCSetConstruction,
+                        "finish adding old regions to CSet",
+                        ergo_format_reason("old CSet region num reached min")
+                        ergo_format_region("old")
+                        ergo_format_region("min"),
+                        old_cset_region_length(), min_old_cset_length);
+          break;
         }
       }
-    } while (should_continue);
-
-    if (!adaptive_young_list_length() &&
-        cset_region_length() < _young_list_fixed_length) {
-      ergo_verbose2(ErgoCSetConstruction,
-                    "request mixed GCs end",
-                    ergo_format_reason("CSet length lower than target")
-                    ergo_format_region("CSet")
-                    ergo_format_region("young target"),
-                    cset_region_length(), _young_list_fixed_length);
-      _should_revert_to_young_gcs  = true;
+
+      // We will add this region to the CSet.
+      time_remaining_ms -= predicted_time_ms;
+      predicted_pause_time_ms += predicted_time_ms;
+      cset_chooser->remove_and_move_to_next(hr);
+      _g1->old_set_remove(hr);
+      add_old_region_to_cset(hr);
+
+      hr = cset_chooser->peek();
+    }
+    if (hr == NULL) {
+      ergo_verbose0(ErgoCSetConstruction,
+                    "finish adding old regions to CSet",
+                    ergo_format_reason("candidate old regions not available"));
     }
 
-    ergo_verbose2(ErgoCSetConstruction | ErgoHigh,
-                  "add old regions to CSet",
-                  ergo_format_region("old")
-                  ergo_format_ms("predicted old region time"),
-                  old_cset_region_length(),
-                  predicted_pause_time_ms - prev_predicted_pause_time_ms);
+    if (expensive_region_num > 0) {
+      // We print the information once here at the end, predicated on
+      // whether we added any apparently expensive regions or not, to
+      // avoid generating output per region.
+      ergo_verbose4(ErgoCSetConstruction,
+                    "added expensive regions to CSet",
+                    ergo_format_reason("old CSet region num not reached min")
+                    ergo_format_region("old")
+                    ergo_format_region("expensive")
+                    ergo_format_region("min")
+                    ergo_format_ms("remaining time"),
+                    old_cset_region_length(),
+                    expensive_region_num,
+                    min_old_cset_length,
+                    time_remaining_ms);
+    }
+
+    assert(cset_chooser->verify(), "CSet Chooser verification - post");
   }
 
   stop_incremental_cset_building();