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changeset 3351:be398bba40e9

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Merge
author stefank
date Fri, 17 Feb 2012 13:23:29 +0100
parents f9961b6498f9 (current diff) 23c0eb012d6f (diff)
children d3384450b649
files
diffstat 28 files changed, 834 insertions(+), 672 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -6092,7 +6092,11 @@
   _inter_sweep_timer.reset();
   _inter_sweep_timer.start();
 
-  update_time_of_last_gc(os::javaTimeMillis());
+  // We need to use a monotonically non-deccreasing time in ms
+  // or we will see time-warp warnings and os::javaTimeMillis()
+  // does not guarantee monotonicity.
+  jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
+  update_time_of_last_gc(now);
 
   // NOTE on abstract state transitions:
   // Mutators allocate-live and/or mark the mod-union table dirty
--- a/src/share/vm/gc_implementation/g1/collectionSetChooser.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/collectionSetChooser.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -48,6 +48,8 @@
 
 #ifndef PRODUCT
 bool CSetChooserCache::verify() {
+  guarantee(false, "CSetChooserCache::verify(): don't call this any more");
+
   int index = _first;
   HeapRegion *prev = NULL;
   for (int i = 0; i < _occupancy; ++i) {
@@ -75,6 +77,8 @@
 #endif // PRODUCT
 
 void CSetChooserCache::insert(HeapRegion *hr) {
+  guarantee(false, "CSetChooserCache::insert(): don't call this any more");
+
   assert(!is_full(), "cache should not be empty");
   hr->calc_gc_efficiency();
 
@@ -104,6 +108,9 @@
 }
 
 HeapRegion *CSetChooserCache::remove_first() {
+  guarantee(false, "CSetChooserCache::remove_first(): "
+                   "don't call this any more");
+
   if (_occupancy > 0) {
     assert(_cache[_first] != NULL, "cache should have at least one region");
     HeapRegion *ret = _cache[_first];
@@ -118,16 +125,35 @@
   }
 }
 
-static inline int orderRegions(HeapRegion* hr1, HeapRegion* hr2) {
+// Even though we don't use the GC efficiency in our heuristics as
+// much as we used to, we still order according to GC efficiency. This
+// will cause regions with a lot of live objects and large RSets to
+// end up at the end of the array. Given that we might skip collecting
+// the last few old regions, if after a few mixed GCs the remaining
+// have reclaimable bytes under a certain threshold, the hope is that
+// the ones we'll skip are ones with both large RSets and a lot of
+// live objects, not the ones with just a lot of live objects if we
+// ordered according to the amount of reclaimable bytes per region.
+static int orderRegions(HeapRegion* hr1, HeapRegion* hr2) {
   if (hr1 == NULL) {
-    if (hr2 == NULL) return 0;
-    else return 1;
+    if (hr2 == NULL) {
+      return 0;
+    } else {
+      return 1;
+    }
   } else if (hr2 == NULL) {
     return -1;
   }
-  if (hr2->gc_efficiency() < hr1->gc_efficiency()) return -1;
-  else if (hr1->gc_efficiency() < hr2->gc_efficiency()) return 1;
-  else return 0;
+
+  double gc_eff1 = hr1->gc_efficiency();
+  double gc_eff2 = hr2->gc_efficiency();
+  if (gc_eff1 > gc_eff2) {
+    return -1;
+  } if (gc_eff1 < gc_eff2) {
+    return 1;
+  } else {
+    return 0;
+  }
 }
 
 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
@@ -151,51 +177,61 @@
   //
   _markedRegions((ResourceObj::set_allocation_type((address)&_markedRegions,
                                              ResourceObj::C_HEAP),
-                  100),
-                 true),
-  _curMarkedIndex(0),
-  _numMarkedRegions(0),
-  _unmarked_age_1_returned_as_new(false),
-  _first_par_unreserved_idx(0)
-{}
-
-
+                  100), true /* C_Heap */),
+    _curr_index(0), _length(0),
+    _regionLiveThresholdBytes(0), _remainingReclaimableBytes(0),
+    _first_par_unreserved_idx(0) {
+  _regionLiveThresholdBytes =
+    HeapRegion::GrainBytes * (size_t) G1OldCSetRegionLiveThresholdPercent / 100;
+}
 
 #ifndef PRODUCT
 bool CollectionSetChooser::verify() {
+  guarantee(_length >= 0, err_msg("_length: %d", _length));
+  guarantee(0 <= _curr_index && _curr_index <= _length,
+            err_msg("_curr_index: %d _length: %d", _curr_index, _length));
   int index = 0;
-  guarantee(_curMarkedIndex <= _numMarkedRegions,
-            "_curMarkedIndex should be within bounds");
-  while (index < _curMarkedIndex) {
-    guarantee(_markedRegions.at(index++) == NULL,
-              "all entries before _curMarkedIndex should be NULL");
+  size_t sum_of_reclaimable_bytes = 0;
+  while (index < _curr_index) {
+    guarantee(_markedRegions.at(index) == NULL,
+              "all entries before _curr_index should be NULL");
+    index += 1;
   }
   HeapRegion *prev = NULL;
-  while (index < _numMarkedRegions) {
+  while (index < _length) {
     HeapRegion *curr = _markedRegions.at(index++);
     guarantee(curr != NULL, "Regions in _markedRegions array cannot be NULL");
     int si = curr->sort_index();
     guarantee(!curr->is_young(), "should not be young!");
+    guarantee(!curr->isHumongous(), "should not be humongous!");
     guarantee(si > -1 && si == (index-1), "sort index invariant");
     if (prev != NULL) {
-      guarantee(orderRegions(prev, curr) != 1, "regions should be sorted");
+      guarantee(orderRegions(prev, curr) != 1,
+                err_msg("GC eff prev: %1.4f GC eff curr: %1.4f",
+                        prev->gc_efficiency(), curr->gc_efficiency()));
     }
+    sum_of_reclaimable_bytes += curr->reclaimable_bytes();
     prev = curr;
   }
-  return _cache.verify();
+  guarantee(sum_of_reclaimable_bytes == _remainingReclaimableBytes,
+            err_msg("reclaimable bytes inconsistent, "
+                    "remaining: "SIZE_FORMAT" sum: "SIZE_FORMAT,
+                    _remainingReclaimableBytes, sum_of_reclaimable_bytes));
+  return true;
 }
 #endif
 
-void
-CollectionSetChooser::fillCache() {
-  while (!_cache.is_full() && (_curMarkedIndex < _numMarkedRegions)) {
-    HeapRegion* hr = _markedRegions.at(_curMarkedIndex);
+void CollectionSetChooser::fillCache() {
+  guarantee(false, "fillCache: don't call this any more");
+
+  while (!_cache.is_full() && (_curr_index < _length)) {
+    HeapRegion* hr = _markedRegions.at(_curr_index);
     assert(hr != NULL,
            err_msg("Unexpected NULL hr in _markedRegions at index %d",
-                   _curMarkedIndex));
-    _curMarkedIndex += 1;
+                   _curr_index));
+    _curr_index += 1;
     assert(!hr->is_young(), "should not be young!");
-    assert(hr->sort_index() == _curMarkedIndex-1, "sort_index invariant");
+    assert(hr->sort_index() == _curr_index-1, "sort_index invariant");
     _markedRegions.at_put(hr->sort_index(), NULL);
     _cache.insert(hr);
     assert(!_cache.is_empty(), "cache should not be empty");
@@ -203,9 +239,7 @@
   assert(verify(), "cache should be consistent");
 }
 
-void
-CollectionSetChooser::sortMarkedHeapRegions() {
-  guarantee(_cache.is_empty(), "cache should be empty");
+void CollectionSetChooser::sortMarkedHeapRegions() {
   // First trim any unused portion of the top in the parallel case.
   if (_first_par_unreserved_idx > 0) {
     if (G1PrintParCleanupStats) {
@@ -217,43 +251,78 @@
     _markedRegions.trunc_to(_first_par_unreserved_idx);
   }
   _markedRegions.sort(orderRegions);
-  assert(_numMarkedRegions <= _markedRegions.length(), "Requirement");
-  assert(_numMarkedRegions == 0
-         || _markedRegions.at(_numMarkedRegions-1) != NULL,
-         "Testing _numMarkedRegions");
-  assert(_numMarkedRegions == _markedRegions.length()
-         || _markedRegions.at(_numMarkedRegions) == NULL,
-         "Testing _numMarkedRegions");
+  assert(_length <= _markedRegions.length(), "Requirement");
+  assert(_length == 0 || _markedRegions.at(_length - 1) != NULL,
+         "Testing _length");
+  assert(_length == _markedRegions.length() ||
+                        _markedRegions.at(_length) == NULL, "Testing _length");
   if (G1PrintParCleanupStats) {
-    gclog_or_tty->print_cr("     Sorted %d marked regions.", _numMarkedRegions);
+    gclog_or_tty->print_cr("     Sorted %d marked regions.", _length);
   }
-  for (int i = 0; i < _numMarkedRegions; i++) {
+  for (int i = 0; i < _length; i++) {
     assert(_markedRegions.at(i) != NULL, "Should be true by sorting!");
     _markedRegions.at(i)->set_sort_index(i);
   }
   if (G1PrintRegionLivenessInfo) {
     G1PrintRegionLivenessInfoClosure cl(gclog_or_tty, "Post-Sorting");
-    for (int i = 0; i < _numMarkedRegions; ++i) {
+    for (int i = 0; i < _length; ++i) {
       HeapRegion* r = _markedRegions.at(i);
       cl.doHeapRegion(r);
     }
   }
-  assert(verify(), "should now be sorted");
+  assert(verify(), "CSet chooser verification");
 }
 
-void
-CollectionSetChooser::addMarkedHeapRegion(HeapRegion* hr) {
+size_t CollectionSetChooser::calcMinOldCSetLength() {
+  // The min old CSet region bound is based on the maximum desired
+  // number of mixed GCs after a cycle. I.e., even if some old regions
+  // look expensive, we should add them to the CSet anyway to make
+  // sure we go through the available old regions in no more than the
+  // maximum desired number of mixed GCs.
+  //
+  // The calculation is based on the number of marked regions we added
+  // to the CSet chooser in the first place, not how many remain, so
+  // that the result is the same during all mixed GCs that follow a cycle.
+
+  const size_t region_num = (size_t) _length;
+  const size_t gc_num = (size_t) G1MaxMixedGCNum;
+  size_t result = region_num / gc_num;
+  // emulate ceiling
+  if (result * gc_num < region_num) {
+    result += 1;
+  }
+  return result;
+}
+
+size_t CollectionSetChooser::calcMaxOldCSetLength() {
+  // The max old CSet region bound is based on the threshold expressed
+  // as a percentage of the heap size. I.e., it should bound the
+  // number of old regions added to the CSet irrespective of how many
+  // of them are available.
+
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+  const size_t region_num = g1h->n_regions();
+  const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
+  size_t result = region_num * perc / 100;
+  // emulate ceiling
+  if (100 * result < region_num * perc) {
+    result += 1;
+  }
+  return result;
+}
+
+void CollectionSetChooser::addMarkedHeapRegion(HeapRegion* hr) {
   assert(!hr->isHumongous(),
          "Humongous regions shouldn't be added to the collection set");
   assert(!hr->is_young(), "should not be young!");
   _markedRegions.append(hr);
-  _numMarkedRegions++;
+  _length++;
+  _remainingReclaimableBytes += hr->reclaimable_bytes();
   hr->calc_gc_efficiency();
 }
 
-void
-CollectionSetChooser::
-prepareForAddMarkedHeapRegionsPar(size_t n_regions, size_t chunkSize) {
+void CollectionSetChooser::prepareForAddMarkedHeapRegionsPar(size_t n_regions,
+                                                             size_t chunkSize) {
   _first_par_unreserved_idx = 0;
   int n_threads = ParallelGCThreads;
   if (UseDynamicNumberOfGCThreads) {
@@ -274,8 +343,7 @@
   _markedRegions.at_put_grow((int)(aligned_n_regions + max_waste - 1), NULL);
 }
 
-jint
-CollectionSetChooser::getParMarkedHeapRegionChunk(jint n_regions) {
+jint CollectionSetChooser::getParMarkedHeapRegionChunk(jint n_regions) {
   // Don't do this assert because this can be called at a point
   // where the loop up stream will not execute again but might
   // try to claim more chunks (loop test has not been done yet).
@@ -287,83 +355,37 @@
   return res - n_regions;
 }
 
-void
-CollectionSetChooser::setMarkedHeapRegion(jint index, HeapRegion* hr) {
+void CollectionSetChooser::setMarkedHeapRegion(jint index, HeapRegion* hr) {
   assert(_markedRegions.at(index) == NULL, "precondition");
   assert(!hr->is_young(), "should not be young!");
   _markedRegions.at_put(index, hr);
   hr->calc_gc_efficiency();
 }
 
-void
-CollectionSetChooser::incNumMarkedHeapRegions(jint inc_by) {
-  (void)Atomic::add(inc_by, &_numMarkedRegions);
-}
-
-void
-CollectionSetChooser::clearMarkedHeapRegions(){
-  for (int i = 0; i < _markedRegions.length(); i++) {
-    HeapRegion* r =   _markedRegions.at(i);
-    if (r != NULL) r->set_sort_index(-1);
+void CollectionSetChooser::updateTotals(jint region_num,
+                                        size_t reclaimable_bytes) {
+  // Only take the lock if we actually need to update the totals.
+  if (region_num > 0) {
+    assert(reclaimable_bytes > 0, "invariant");
+    // We could have just used atomics instead of taking the
+    // lock. However, we currently don't have an atomic add for size_t.
+    MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
+    _length += (int) region_num;
+    _remainingReclaimableBytes += reclaimable_bytes;
+  } else {
+    assert(reclaimable_bytes == 0, "invariant");
   }
-  _markedRegions.clear();
-  _curMarkedIndex = 0;
-  _numMarkedRegions = 0;
-  _cache.clear();
-};
-
-void
-CollectionSetChooser::updateAfterFullCollection() {
-  clearMarkedHeapRegions();
 }
 
-// if time_remaining < 0.0, then this method should try to return
-// a region, whether it fits within the remaining time or not
-HeapRegion*
-CollectionSetChooser::getNextMarkedRegion(double time_remaining,
-                                          double avg_prediction) {
-  G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  G1CollectorPolicy* g1p = g1h->g1_policy();
-  fillCache();
-  if (_cache.is_empty()) {
-    assert(_curMarkedIndex == _numMarkedRegions,
-           "if cache is empty, list should also be empty");
-    ergo_verbose0(ErgoCSetConstruction,
-                  "stop adding old regions to CSet",
-                  ergo_format_reason("cache is empty"));
-    return NULL;
-  }
-
-  HeapRegion *hr = _cache.get_first();
-  assert(hr != NULL, "if cache not empty, first entry should be non-null");
-  double predicted_time = g1h->predict_region_elapsed_time_ms(hr, false);
-
-  if (g1p->adaptive_young_list_length()) {
-    if (time_remaining - predicted_time < 0.0) {
-      g1h->check_if_region_is_too_expensive(predicted_time);
-      ergo_verbose2(ErgoCSetConstruction,
-                    "stop adding old regions to CSet",
-                    ergo_format_reason("predicted old region time higher than remaining time")
-                    ergo_format_ms("predicted old region time")
-                    ergo_format_ms("remaining time"),
-                    predicted_time, time_remaining);
-      return NULL;
-    }
-  } else {
-    double threshold = 2.0 * avg_prediction;
-    if (predicted_time > threshold) {
-      ergo_verbose2(ErgoCSetConstruction,
-                    "stop adding old regions to CSet",
-                    ergo_format_reason("predicted old region time higher than threshold")
-                    ergo_format_ms("predicted old region time")
-                    ergo_format_ms("threshold"),
-                    predicted_time, threshold);
-      return NULL;
+void CollectionSetChooser::clearMarkedHeapRegions() {
+  for (int i = 0; i < _markedRegions.length(); i++) {
+    HeapRegion* r = _markedRegions.at(i);
+    if (r != NULL) {
+      r->set_sort_index(-1);
     }
   }
-
-  HeapRegion *hr2 = _cache.remove_first();
-  assert(hr == hr2, "cache contents should not have changed");
-
-  return hr;
-}
+  _markedRegions.clear();
+  _curr_index = 0;
+  _length = 0;
+  _remainingReclaimableBytes = 0;
+};
--- a/src/share/vm/gc_implementation/g1/collectionSetChooser.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/collectionSetChooser.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -28,28 +28,6 @@
 #include "gc_implementation/g1/heapRegion.hpp"
 #include "utilities/growableArray.hpp"
 
-// We need to sort heap regions by collection desirability.
-// This sorting is currently done in two "stages". An initial sort is
-// done following a cleanup pause as soon as all of the marked but
-// non-empty regions have been identified and the completely empty
-// ones reclaimed.
-// This gives us a global sort on a GC efficiency metric
-// based on predictive data available at that time. However,
-// any of these regions that are collected will only be collected
-// during a future GC pause, by which time it is possible that newer
-// data might allow us to revise and/or refine the earlier
-// pause predictions, leading to changes in expected gc efficiency
-// order. To somewhat mitigate this obsolescence, more so in the
-// case of regions towards the end of the list, which will be
-// picked later, these pre-sorted regions from the _markedRegions
-// array are not used as is, but a small prefix thereof is
-// insertion-sorted again into a small cache, based on more
-// recent remembered set information. Regions are then drawn
-// from this cache to construct the collection set at each
-// incremental GC.
-// This scheme and/or its implementation may be subject to
-// revision in the future.
-
 class CSetChooserCache VALUE_OBJ_CLASS_SPEC {
 private:
   enum {
@@ -103,24 +81,82 @@
 class CollectionSetChooser: public CHeapObj {
 
   GrowableArray<HeapRegion*> _markedRegions;
-  int _curMarkedIndex;
-  int _numMarkedRegions;
-  CSetChooserCache _cache;
+
+  // The index of the next candidate old region to be considered for
+  // addition to the CSet.
+  int _curr_index;
+
+  // The number of candidate old regions added to the CSet chooser.
+  int _length;
 
-  // True iff last collection pause ran of out new "age 0" regions, and
-  // returned an "age 1" region.
-  bool _unmarked_age_1_returned_as_new;
+  CSetChooserCache _cache;
+  jint _first_par_unreserved_idx;
 
-  jint _first_par_unreserved_idx;
+  // If a region has more live bytes than this threshold, it will not
+  // be added to the CSet chooser and will not be a candidate for
+  // collection.
+  size_t _regionLiveThresholdBytes;
+
+  // The sum of reclaimable bytes over all the regions in the CSet chooser.
+  size_t _remainingReclaimableBytes;
 
 public:
 
-  HeapRegion* getNextMarkedRegion(double time_so_far, double avg_prediction);
+  // Return the current candidate region to be considered for
+  // collection without removing it from the CSet chooser.
+  HeapRegion* peek() {
+    HeapRegion* res = NULL;
+    if (_curr_index < _length) {
+      res = _markedRegions.at(_curr_index);
+      assert(res != NULL,
+             err_msg("Unexpected NULL hr in _markedRegions at index %d",
+                     _curr_index));
+    }
+    return res;
+  }
+
+  // Remove the given region from the CSet chooser and move to the
+  // next one. The given region should be the current candidate region
+  // in the CSet chooser.
+  void remove_and_move_to_next(HeapRegion* hr) {
+    assert(hr != NULL, "pre-condition");
+    assert(_curr_index < _length, "pre-condition");
+    assert(_markedRegions.at(_curr_index) == hr, "pre-condition");
+    hr->set_sort_index(-1);
+    _markedRegions.at_put(_curr_index, NULL);
+    assert(hr->reclaimable_bytes() <= _remainingReclaimableBytes,
+           err_msg("remaining reclaimable bytes inconsistent "
+                   "from region: "SIZE_FORMAT" remaining: "SIZE_FORMAT,
+                   hr->reclaimable_bytes(), _remainingReclaimableBytes));
+    _remainingReclaimableBytes -= hr->reclaimable_bytes();
+    _curr_index += 1;
+  }
 
   CollectionSetChooser();
 
   void sortMarkedHeapRegions();
   void fillCache();
+
+  // Determine whether to add the given region to the CSet chooser or
+  // not. Currently, we skip humongous regions (we never add them to
+  // the CSet, we only reclaim them during cleanup) and regions whose
+  // live bytes are over the threshold.
+  bool shouldAdd(HeapRegion* hr) {
+    assert(hr->is_marked(), "pre-condition");
+    assert(!hr->is_young(), "should never consider young regions");
+    return !hr->isHumongous() &&
+            hr->live_bytes() < _regionLiveThresholdBytes;
+  }
+
+  // Calculate the minimum number of old regions we'll add to the CSet
+  // during a mixed GC.
+  size_t calcMinOldCSetLength();
+
+  // Calculate the maximum number of old regions we'll add to the CSet
+  // during a mixed GC.
+  size_t calcMaxOldCSetLength();
+
+  // Serial version.
   void addMarkedHeapRegion(HeapRegion *hr);
 
   // Must be called before calls to getParMarkedHeapRegionChunk.
@@ -133,14 +169,21 @@
   // Set the marked array entry at index to hr.  Careful to claim the index
   // first if in parallel.
   void setMarkedHeapRegion(jint index, HeapRegion* hr);
-  // Atomically increment the number of claimed regions by "inc_by".
-  void incNumMarkedHeapRegions(jint inc_by);
+  // Atomically increment the number of added regions by region_num
+  // and the amount of reclaimable bytes by reclaimable_bytes.
+  void updateTotals(jint region_num, size_t reclaimable_bytes);
 
   void clearMarkedHeapRegions();
 
-  void updateAfterFullCollection();
+  // Return the number of candidate regions that remain to be collected.
+  size_t remainingRegions() { return _length - _curr_index; }
 
-  bool unmarked_age_1_returned_as_new() { return _unmarked_age_1_returned_as_new; }
+  // Determine whether the CSet chooser has more candidate regions or not.
+  bool isEmpty() { return remainingRegions() == 0; }
+
+  // Return the reclaimable bytes that remain to be collected on
+  // all the candidate regions in the CSet chooser.
+  size_t remainingReclaimableBytes () { return _remainingReclaimableBytes; }
 
   // Returns true if the used portion of "_markedRegions" is properly
   // sorted, otherwise asserts false.
@@ -148,9 +191,17 @@
   bool verify(void);
   bool regionProperlyOrdered(HeapRegion* r) {
     int si = r->sort_index();
-    return (si == -1) ||
-      (si > -1 && _markedRegions.at(si) == r) ||
-      (si < -1 && _cache.region_in_cache(r));
+    if (si > -1) {
+      guarantee(_curr_index <= si && si < _length,
+                err_msg("curr: %d sort index: %d: length: %d",
+                        _curr_index, si, _length));
+      guarantee(_markedRegions.at(si) == r,
+                err_msg("sort index: %d at: "PTR_FORMAT" r: "PTR_FORMAT,
+                        si, _markedRegions.at(si), r));
+    } else {
+      guarantee(si == -1, err_msg("sort index: %d", si));
+    }
+    return true;
   }
 #endif
 
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -958,7 +958,7 @@
         should_try_gc = false;
       } else {
         // Read the GC count while still holding the Heap_lock.
-        gc_count_before = SharedHeap::heap()->total_collections();
+        gc_count_before = total_collections();
         should_try_gc = true;
       }
     }
@@ -976,7 +976,7 @@
         // failed to allocate. No point in trying to allocate
         // further. We'll just return NULL.
         MutexLockerEx x(Heap_lock);
-        *gc_count_before_ret = SharedHeap::heap()->total_collections();
+        *gc_count_before_ret = total_collections();
         return NULL;
       }
     } else {
@@ -1031,7 +1031,8 @@
   // the check before we do the actual allocation. The reason for doing it
   // before the allocation is that we avoid having to keep track of the newly
   // allocated memory while we do a GC.
-  if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation", word_size)) {
+  if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
+                                           word_size)) {
     collect(GCCause::_g1_humongous_allocation);
   }
 
@@ -1059,7 +1060,7 @@
         should_try_gc = false;
       } else {
         // Read the GC count while still holding the Heap_lock.
-        gc_count_before = SharedHeap::heap()->total_collections();
+        gc_count_before = total_collections();
         should_try_gc = true;
       }
     }
@@ -1081,7 +1082,7 @@
         // failed to allocate. No point in trying to allocate
         // further. We'll just return NULL.
         MutexLockerEx x(Heap_lock);
-        *gc_count_before_ret = SharedHeap::heap()->total_collections();
+        *gc_count_before_ret = total_collections();
         return NULL;
       }
     } else {
@@ -2311,10 +2312,12 @@
 }
 
 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
-  return
-    ((cause == GCCause::_gc_locker           && GCLockerInvokesConcurrent) ||
-     (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent) ||
-      cause == GCCause::_g1_humongous_allocation);
+  switch (cause) {
+    case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
+    case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
+    case GCCause::_g1_humongous_allocation: return true;
+    default:                                return false;
+  }
 }
 
 #ifndef PRODUCT
@@ -2408,47 +2411,66 @@
 }
 
 void G1CollectedHeap::collect(GCCause::Cause cause) {
-  // The caller doesn't have the Heap_lock
-  assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
+  assert_heap_not_locked();
 
   unsigned int gc_count_before;
   unsigned int full_gc_count_before;
-  {
-    MutexLocker ml(Heap_lock);
-
-    // Read the GC count while holding the Heap_lock
-    gc_count_before = SharedHeap::heap()->total_collections();
-    full_gc_count_before = SharedHeap::heap()->total_full_collections();
-  }
-
-  if (should_do_concurrent_full_gc(cause)) {
-    // Schedule an initial-mark evacuation pause that will start a
-    // concurrent cycle. We're setting word_size to 0 which means that
-    // we are not requesting a post-GC allocation.
-    VM_G1IncCollectionPause op(gc_count_before,
-                               0,     /* word_size */
-                               true,  /* should_initiate_conc_mark */
-                               g1_policy()->max_pause_time_ms(),
-                               cause);
-    VMThread::execute(&op);
-  } else {
-    if (cause == GCCause::_gc_locker
-        DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
-
-      // Schedule a standard evacuation pause. We're setting word_size
-      // to 0 which means that we are not requesting a post-GC allocation.
+  bool retry_gc;
+
+  do {
+    retry_gc = false;
+
+    {
+      MutexLocker ml(Heap_lock);
+
+      // Read the GC count while holding the Heap_lock
+      gc_count_before = total_collections();
+      full_gc_count_before = total_full_collections();
+    }
+
+    if (should_do_concurrent_full_gc(cause)) {
+      // Schedule an initial-mark evacuation pause that will start a
+      // concurrent cycle. We're setting word_size to 0 which means that
+      // we are not requesting a post-GC allocation.
       VM_G1IncCollectionPause op(gc_count_before,
                                  0,     /* word_size */
-                                 false, /* should_initiate_conc_mark */
+                                 true,  /* should_initiate_conc_mark */
                                  g1_policy()->max_pause_time_ms(),
                                  cause);
       VMThread::execute(&op);
+      if (!op.pause_succeeded()) {
+        // Another GC got scheduled and prevented us from scheduling
+        // the initial-mark GC. It's unlikely that the GC that
+        // pre-empted us was also an initial-mark GC. So, we'll retry
+        // the initial-mark GC.
+
+        if (full_gc_count_before == total_full_collections()) {
+          retry_gc = true;
+        } else {
+          // A Full GC happened while we were trying to schedule the
+          // initial-mark GC. No point in starting a new cycle given
+          // that the whole heap was collected anyway.
+        }
+      }
     } else {
-      // Schedule a Full GC.
-      VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
-      VMThread::execute(&op);
+      if (cause == GCCause::_gc_locker
+          DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
+
+        // Schedule a standard evacuation pause. We're setting word_size
+        // to 0 which means that we are not requesting a post-GC allocation.
+        VM_G1IncCollectionPause op(gc_count_before,
+                                   0,     /* word_size */
+                                   false, /* should_initiate_conc_mark */
+                                   g1_policy()->max_pause_time_ms(),
+                                   cause);
+        VMThread::execute(&op);
+      } else {
+        // Schedule a Full GC.
+        VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
+        VMThread::execute(&op);
+      }
     }
-  }
+  } while (retry_gc);
 }
 
 bool G1CollectedHeap::is_in(const void* p) const {
@@ -3149,12 +3171,12 @@
 
     // We apply the relevant closures to all the oops in the
     // system dictionary, the string table and the code cache.
-    const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
+    const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
 
     process_strong_roots(true,      // activate StrongRootsScope
                          true,      // we set "collecting perm gen" to true,
                                     // so we don't reset the dirty cards in the perm gen.
-                         SharedHeap::ScanningOption(so),  // roots scanning options
+                         ScanningOption(so),  // roots scanning options
                          &rootsCl,
                          &blobsCl,
                          &rootsCl);
@@ -3425,16 +3447,6 @@
   }
 }
 
-double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
-                                                       bool young) {
-  return _g1_policy->predict_region_elapsed_time_ms(hr, young);
-}
-
-void G1CollectedHeap::check_if_region_is_too_expensive(double
-                                                           predicted_time_ms) {
-  _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
-}
-
 size_t G1CollectedHeap::pending_card_num() {
   size_t extra_cards = 0;
   JavaThread *curr = Threads::first();
@@ -3706,12 +3718,12 @@
         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
 #endif // YOUNG_LIST_VERBOSE
 
-        g1_policy()->choose_collection_set(target_pause_time_ms);
+        g1_policy()->finalize_cset(target_pause_time_ms);
 
         _cm->note_start_of_gc();
         // We should not verify the per-thread SATB buffers given that
         // we have not filtered them yet (we'll do so during the
-        // GC). We also call this after choose_collection_set() to
+        // GC). We also call this after finalize_cset() to
         // ensure that the CSet has been finalized.
         _cm->verify_no_cset_oops(true  /* verify_stacks */,
                                  true  /* verify_enqueued_buffers */,
@@ -4734,7 +4746,7 @@
 void
 G1CollectedHeap::
 g1_process_strong_roots(bool collecting_perm_gen,
-                        SharedHeap::ScanningOption so,
+                        ScanningOption so,
                         OopClosure* scan_non_heap_roots,
                         OopsInHeapRegionClosure* scan_rs,
                         OopsInGenClosure* scan_perm,
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -770,7 +770,7 @@
   // the "i" of the calling parallel worker thread's work(i) function.
   // In the sequential case this param will be ignored.
   void g1_process_strong_roots(bool collecting_perm_gen,
-                               SharedHeap::ScanningOption so,
+                               ScanningOption so,
                                OopClosure* scan_non_heap_roots,
                                OopsInHeapRegionClosure* scan_rs,
                                OopsInGenClosure* scan_perm,
@@ -1182,6 +1182,12 @@
   bool free_regions_coming() { return _free_regions_coming; }
   void wait_while_free_regions_coming();
 
+  // Determine whether the given region is one that we are using as an
+  // old GC alloc region.
+  bool is_old_gc_alloc_region(HeapRegion* hr) {
+    return hr == _retained_old_gc_alloc_region;
+  }
+
   // Perform a collection of the heap; intended for use in implementing
   // "System.gc".  This probably implies as full a collection as the
   // "CollectedHeap" supports.
@@ -1662,8 +1668,6 @@
 public:
   void stop_conc_gc_threads();
 
-  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();
--- a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -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();
--- a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -312,16 +312,13 @@
   double _recorded_non_young_free_cset_time_ms;
 
   double _sigma;
-  double _expensive_region_limit_ms;
 
   size_t _rs_lengths_prediction;
 
   size_t _known_garbage_bytes;
   double _known_garbage_ratio;
 
-  double sigma() {
-    return _sigma;
-  }
+  double sigma() { return _sigma; }
 
   // A function that prevents us putting too much stock in small sample
   // sets.  Returns a number between 2.0 and 1.0, depending on the number
@@ -491,8 +488,6 @@
            get_new_prediction(_non_young_other_cost_per_region_ms_seq);
   }
 
-  void check_if_region_is_too_expensive(double predicted_time_ms);
-
   double predict_young_collection_elapsed_time_ms(size_t adjustment);
   double predict_base_elapsed_time_ms(size_t pending_cards);
   double predict_base_elapsed_time_ms(size_t pending_cards,
@@ -707,7 +702,6 @@
   // initial-mark work.
   volatile bool _during_initial_mark_pause;
 
-  bool _should_revert_to_young_gcs;
   bool _last_young_gc;
 
   // This set of variables tracks the collector efficiency, in order to
@@ -946,10 +940,17 @@
     return _bytes_copied_during_gc;
   }
 
+  // Determine whether the next GC should be mixed. Called to determine
+  // whether to start mixed GCs or whether to carry on doing mixed
+  // GCs. The two action strings are used in the ergo output when the
+  // method returns true or false.
+  bool next_gc_should_be_mixed(const char* true_action_str,
+                               const char* false_action_str);
+
   // Choose a new collection set.  Marks the chosen regions as being
   // "in_collection_set", and links them together.  The head and number of
   // the collection set are available via access methods.
-  void choose_collection_set(double target_pause_time_ms);
+  void finalize_cset(double target_pause_time_ms);
 
   // The head of the list (via "next_in_collection_set()") representing the
   // current collection set.
--- a/src/share/vm/gc_implementation/g1/g1ErgoVerbose.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/g1ErgoVerbose.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -131,8 +131,8 @@
                              ", " _name_ ": "SIZE_FORMAT" bytes (%1.2f %%)"
 
 // Generates the format string
-#define ergo_format(_action_, _extra_format_)                   \
-  " %1.3f: [G1Ergonomics (%s) " _action_ _extra_format_ "]"
+#define ergo_format(_extra_format_)                           \
+  " %1.3f: [G1Ergonomics (%s) %s" _extra_format_ "]"
 
 // Conditionally, prints an ergonomic decision record. _extra_format_
 // is the format string for the optional items we'd like to print
@@ -145,20 +145,21 @@
 // them to the print method. For convenience, we have wrapper macros
 // below which take a specific number of arguments and set the rest to
 // a default value.
-#define ergo_verbose_common(_tag_, _action_, _extra_format_,            \
+#define ergo_verbose_common(_tag_, _action_, _extra_format_,                \
                             _arg0_, _arg1_, _arg2_, _arg3_, _arg4_, _arg5_) \
-  do {                                                                  \
-    if (G1ErgoVerbose::enabled((_tag_))) {                              \
-      gclog_or_tty->print_cr(ergo_format(_action_, _extra_format_),     \
-                             os::elapsedTime(),                         \
-                             G1ErgoVerbose::to_string((_tag_)),         \
-                             (_arg0_), (_arg1_), (_arg2_),              \
-                             (_arg3_), (_arg4_), (_arg5_));             \
-    }                                                                   \
+  do {                                                                      \
+    if (G1ErgoVerbose::enabled((_tag_))) {                                  \
+      gclog_or_tty->print_cr(ergo_format(_extra_format_),                   \
+                             os::elapsedTime(),                             \
+                             G1ErgoVerbose::to_string((_tag_)),             \
+                             (_action_),                                    \
+                             (_arg0_), (_arg1_), (_arg2_),                  \
+                             (_arg3_), (_arg4_), (_arg5_));                 \
+    }                                                                       \
   } while (0)
 
 
-#define ergo_verbose(_tag_, _action_)                           \
+#define ergo_verbose(_tag_, _action_)                                   \
   ergo_verbose_common(_tag_, _action_, "", 0, 0, 0, 0, 0, 0)
 
 #define ergo_verbose0(_tag_, _action_, _extra_format_)                  \
--- a/src/share/vm/gc_implementation/g1/g1_globals.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/g1_globals.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -297,7 +297,23 @@
                                                                             \
   develop(uintx, G1DefaultMaxNewGenPercent, 80,                             \
           "Percentage (0-100) of the heap size to use as maximum "          \
-          "young gen size.")
+          "young gen size.")                                                \
+                                                                            \
+  develop(uintx, G1OldCSetRegionLiveThresholdPercent, 95,                   \
+          "Threshold for regions to be added to the collection set. "       \
+          "Regions with more live bytes that this will not be collected.")  \
+                                                                            \
+  develop(uintx, G1OldReclaimableThresholdPercent, 1,                       \
+          "Threshold for the remaining old reclaimable bytes, expressed "   \
+          "as a percentage of the heap size. If the old reclaimable bytes " \
+          "are under this we will not collect them with more mixed GCs.")   \
+                                                                            \
+  develop(uintx, G1MaxMixedGCNum, 4,                                        \
+          "The maximum desired number of mixed GCs after a marking cycle.") \
+                                                                            \
+  develop(uintx, G1OldCSetRegionThresholdPercent, 10,                       \
+          "An upper bound for the number of old CSet regions expressed "    \
+          "as a percentage of the heap size.")
 
 G1_FLAGS(DECLARE_DEVELOPER_FLAG, DECLARE_PD_DEVELOPER_FLAG, DECLARE_PRODUCT_FLAG, DECLARE_PD_PRODUCT_FLAG, DECLARE_DIAGNOSTIC_FLAG, DECLARE_EXPERIMENTAL_FLAG, DECLARE_NOTPRODUCT_FLAG, DECLARE_MANAGEABLE_FLAG, DECLARE_PRODUCT_RW_FLAG)
 
--- a/src/share/vm/gc_implementation/g1/heapRegion.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/heapRegion.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -387,13 +387,12 @@
   ct_bs->clear(MemRegion(bottom(), end()));
 }
 
-// <PREDICTION>
 void HeapRegion::calc_gc_efficiency() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  _gc_efficiency = (double) garbage_bytes() /
-                            g1h->predict_region_elapsed_time_ms(this, false);
+  G1CollectorPolicy* g1p = g1h->g1_policy();
+  _gc_efficiency = (double) reclaimable_bytes() /
+                            g1p->predict_region_elapsed_time_ms(this, false);
 }
-// </PREDICTION>
 
 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
   assert(!isHumongous(), "sanity / pre-condition");
--- a/src/share/vm/gc_implementation/g1/heapRegion.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/g1/heapRegion.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -415,6 +415,16 @@
     return used_at_mark_start_bytes - marked_bytes();
   }
 
+  // Return the amount of bytes we'll reclaim if we collect this
+  // region. This includes not only the known garbage bytes in the
+  // region but also any unallocated space in it, i.e., [top, end),
+  // since it will also be reclaimed if we collect the region.
+  size_t reclaimable_bytes() {
+    size_t known_live_bytes = live_bytes();
+    assert(known_live_bytes <= capacity(), "sanity");
+    return capacity() - known_live_bytes;
+  }
+
   // An upper bound on the number of live bytes in the region.
   size_t max_live_bytes() { return used() - garbage_bytes(); }
 
@@ -648,10 +658,8 @@
     init_top_at_mark_start();
   }
 
-  // <PREDICTION>
   void calc_gc_efficiency(void);
   double gc_efficiency() { return _gc_efficiency;}
-  // </PREDICTION>
 
   bool is_young() const     { return _young_type != NotYoung; }
   bool is_survivor() const  { return _young_type == Survivor; }
--- a/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parNew/parNewGeneration.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1042,7 +1042,11 @@
     size_policy->avg_survived()->sample(from()->used());
   }
 
-  update_time_of_last_gc(os::javaTimeMillis());
+  // We need to use a monotonically non-deccreasing time in ms
+  // or we will see time-warp warnings and os::javaTimeMillis()
+  // does not guarantee monotonicity.
+  jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
+  update_time_of_last_gc(now);
 
   SpecializationStats::print();
 
--- a/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -418,25 +418,17 @@
       gc_count = Universe::heap()->total_collections();
 
       result = young_gen()->allocate(size);
-
-      // (1) If the requested object is too large to easily fit in the
-      //     young_gen, or
-      // (2) If GC is locked out via GCLocker, young gen is full and
-      //     the need for a GC already signalled to GCLocker (done
-      //     at a safepoint),
-      // ... then, rather than force a safepoint and (a potentially futile)
-      // collection (attempt) for each allocation, try allocation directly
-      // in old_gen. For case (2) above, we may in the future allow
-      // TLAB allocation directly in the old gen.
       if (result != NULL) {
         return result;
       }
-      if (size >= (young_gen()->eden_space()->capacity_in_words(Thread::current()) / 2)) {
-        result = old_gen()->allocate(size);
-        if (result != NULL) {
-          return result;
-        }
+
+      // If certain conditions hold, try allocating from the old gen.
+      result = mem_allocate_old_gen(size);
+      if (result != NULL) {
+        return result;
       }
+
+      // Failed to allocate without a gc.
       if (GC_locker::is_active_and_needs_gc()) {
         // If this thread is not in a jni critical section, we stall
         // the requestor until the critical section has cleared and
@@ -460,7 +452,6 @@
     }
 
     if (result == NULL) {
-
       // Generate a VM operation
       VM_ParallelGCFailedAllocation op(size, gc_count);
       VMThread::execute(&op);
@@ -523,6 +514,42 @@
   return result;
 }
 
+// A "death march" is a series of ultra-slow allocations in which a full gc is
+// done before each allocation, and after the full gc the allocation still
+// cannot be satisfied from the young gen.  This routine detects that condition;
+// it should be called after a full gc has been done and the allocation
+// attempted from the young gen. The parameter 'addr' should be the result of
+// that young gen allocation attempt.
+void
+ParallelScavengeHeap::death_march_check(HeapWord* const addr, size_t size) {
+  if (addr != NULL) {
+    _death_march_count = 0;  // death march has ended
+  } else if (_death_march_count == 0) {
+    if (should_alloc_in_eden(size)) {
+      _death_march_count = 1;    // death march has started
+    }
+  }
+}
+
+HeapWord* ParallelScavengeHeap::mem_allocate_old_gen(size_t size) {
+  if (!should_alloc_in_eden(size) || GC_locker::is_active_and_needs_gc()) {
+    // Size is too big for eden, or gc is locked out.
+    return old_gen()->allocate(size);
+  }
+
+  // If a "death march" is in progress, allocate from the old gen a limited
+  // number of times before doing a GC.
+  if (_death_march_count > 0) {
+    if (_death_march_count < 64) {
+      ++_death_march_count;
+      return old_gen()->allocate(size);
+    } else {
+      _death_march_count = 0;
+    }
+  }
+  return NULL;
+}
+
 // Failed allocation policy. Must be called from the VM thread, and
 // only at a safepoint! Note that this method has policy for allocation
 // flow, and NOT collection policy. So we do not check for gc collection
@@ -535,27 +562,22 @@
   assert(!Universe::heap()->is_gc_active(), "not reentrant");
   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 
-  size_t mark_sweep_invocation_count = total_invocations();
-
-  // We assume (and assert!) that an allocation at this point will fail
-  // unless we collect.
+  // We assume that allocation in eden will fail unless we collect.
 
   // First level allocation failure, scavenge and allocate in young gen.
   GCCauseSetter gccs(this, GCCause::_allocation_failure);
-  PSScavenge::invoke();
+  const bool invoked_full_gc = PSScavenge::invoke();
   HeapWord* result = young_gen()->allocate(size);
 
   // Second level allocation failure.
   //   Mark sweep and allocate in young generation.
-  if (result == NULL) {
-    // There is some chance the scavenge method decided to invoke mark_sweep.
-    // Don't mark sweep twice if so.
-    if (mark_sweep_invocation_count == total_invocations()) {
-      invoke_full_gc(false);
-      result = young_gen()->allocate(size);
-    }
+  if (result == NULL && !invoked_full_gc) {
+    invoke_full_gc(false);
+    result = young_gen()->allocate(size);
   }
 
+  death_march_check(result, size);
+
   // Third level allocation failure.
   //   After mark sweep and young generation allocation failure,
   //   allocate in old generation.
--- a/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -64,6 +64,7 @@
   // Collection of generations that are adjacent in the
   // space reserved for the heap.
   AdjoiningGenerations* _gens;
+  unsigned int _death_march_count;
 
   static GCTaskManager*          _gc_task_manager;      // The task manager.
 
@@ -71,8 +72,13 @@
   static inline size_t total_invocations();
   HeapWord* allocate_new_tlab(size_t size);
 
+  inline bool should_alloc_in_eden(size_t size) const;
+  inline void death_march_check(HeapWord* const result, size_t size);
+  HeapWord* mem_allocate_old_gen(size_t size);
+
  public:
   ParallelScavengeHeap() : CollectedHeap() {
+    _death_march_count = 0;
     set_alignment(_perm_gen_alignment, intra_heap_alignment());
     set_alignment(_young_gen_alignment, intra_heap_alignment());
     set_alignment(_old_gen_alignment, intra_heap_alignment());
--- a/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,6 +36,12 @@
     PSMarkSweep::total_invocations();
 }
 
+inline bool ParallelScavengeHeap::should_alloc_in_eden(const size_t size) const
+{
+  const size_t eden_size = young_gen()->eden_space()->capacity_in_words();
+  return size < eden_size / 2;
+}
+
 inline void ParallelScavengeHeap::invoke_scavenge()
 {
   PSScavenge::invoke();
--- a/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -100,12 +100,12 @@
 
 // This method contains no policy. You should probably
 // be calling invoke() instead.
-void PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
+bool PSMarkSweep::invoke_no_policy(bool clear_all_softrefs) {
   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
   assert(ref_processor() != NULL, "Sanity");
 
   if (GC_locker::check_active_before_gc()) {
-    return;
+    return false;
   }
 
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
@@ -382,6 +382,8 @@
 #ifdef TRACESPINNING
   ParallelTaskTerminator::print_termination_counts();
 #endif
+
+  return true;
 }
 
 bool PSMarkSweep::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
--- a/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -78,7 +78,7 @@
 
  public:
   static void invoke(bool clear_all_softrefs);
-  static void invoke_no_policy(bool clear_all_softrefs);
+  static bool invoke_no_policy(bool clear_all_softrefs);
 
   static void initialize();
 
--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1993,12 +1993,12 @@
 
 // This method contains no policy. You should probably
 // be calling invoke() instead.
-void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
+bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
   assert(ref_processor() != NULL, "Sanity");
 
   if (GC_locker::check_active_before_gc()) {
-    return;
+    return false;
   }
 
   TimeStamp marking_start;
@@ -2248,6 +2248,8 @@
 #ifdef TRACESPINNING
   ParallelTaskTerminator::print_termination_counts();
 #endif
+
+  return true;
 }
 
 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1057,7 +1057,7 @@
   }
 
   static void invoke(bool maximum_heap_compaction);
-  static void invoke_no_policy(bool maximum_heap_compaction);
+  static bool invoke_no_policy(bool maximum_heap_compaction);
 
   static void post_initialize();
   // Perform initialization for PSParallelCompact that requires
--- a/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -247,167 +247,6 @@
   }
 }
 
-//
-// This method is pretty bulky. It would be nice to split it up
-// into smaller submethods, but we need to be careful not to hurt
-// performance.
-//
-
-oop PSPromotionManager::copy_to_survivor_space(oop o) {
-  assert(PSScavenge::should_scavenge(&o), "Sanity");
-
-  oop new_obj = NULL;
-
-  // NOTE! We must be very careful with any methods that access the mark
-  // in o. There may be multiple threads racing on it, and it may be forwarded
-  // at any time. Do not use oop methods for accessing the mark!
-  markOop test_mark = o->mark();
-
-  // The same test as "o->is_forwarded()"
-  if (!test_mark->is_marked()) {
-    bool new_obj_is_tenured = false;
-    size_t new_obj_size = o->size();
-
-    // Find the objects age, MT safe.
-    int age = (test_mark->has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
-      test_mark->displaced_mark_helper()->age() : test_mark->age();
-
-    // Try allocating obj in to-space (unless too old)
-    if (age < PSScavenge::tenuring_threshold()) {
-      new_obj = (oop) _young_lab.allocate(new_obj_size);
-      if (new_obj == NULL && !_young_gen_is_full) {
-        // Do we allocate directly, or flush and refill?
-        if (new_obj_size > (YoungPLABSize / 2)) {
-          // Allocate this object directly
-          new_obj = (oop)young_space()->cas_allocate(new_obj_size);
-        } else {
-          // Flush and fill
-          _young_lab.flush();
-
-          HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
-          if (lab_base != NULL) {
-            _young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
-            // Try the young lab allocation again.
-            new_obj = (oop) _young_lab.allocate(new_obj_size);
-          } else {
-            _young_gen_is_full = true;
-          }
-        }
-      }
-    }
-
-    // Otherwise try allocating obj tenured
-    if (new_obj == NULL) {
-#ifndef PRODUCT
-      if (Universe::heap()->promotion_should_fail()) {
-        return oop_promotion_failed(o, test_mark);
-      }
-#endif  // #ifndef PRODUCT
-
-      new_obj = (oop) _old_lab.allocate(new_obj_size);
-      new_obj_is_tenured = true;
-
-      if (new_obj == NULL) {
-        if (!_old_gen_is_full) {
-          // Do we allocate directly, or flush and refill?
-          if (new_obj_size > (OldPLABSize / 2)) {
-            // Allocate this object directly
-            new_obj = (oop)old_gen()->cas_allocate(new_obj_size);
-          } else {
-            // Flush and fill
-            _old_lab.flush();
-
-            HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize);
-            if(lab_base != NULL) {
-              _old_lab.initialize(MemRegion(lab_base, OldPLABSize));
-              // Try the old lab allocation again.
-              new_obj = (oop) _old_lab.allocate(new_obj_size);
-            }
-          }
-        }
-
-        // This is the promotion failed test, and code handling.
-        // The code belongs here for two reasons. It is slightly
-        // different thatn the code below, and cannot share the
-        // CAS testing code. Keeping the code here also minimizes
-        // the impact on the common case fast path code.
-
-        if (new_obj == NULL) {
-          _old_gen_is_full = true;
-          return oop_promotion_failed(o, test_mark);
-        }
-      }
-    }
-
-    assert(new_obj != NULL, "allocation should have succeeded");
-
-    // Copy obj
-    Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)new_obj, new_obj_size);
-
-    // Now we have to CAS in the header.
-    if (o->cas_forward_to(new_obj, test_mark)) {
-      // We won any races, we "own" this object.
-      assert(new_obj == o->forwardee(), "Sanity");
-
-      // Increment age if obj still in new generation. Now that
-      // we're dealing with a markOop that cannot change, it is
-      // okay to use the non mt safe oop methods.
-      if (!new_obj_is_tenured) {
-        new_obj->incr_age();
-        assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
-      }
-
-      // Do the size comparison first with new_obj_size, which we
-      // already have. Hopefully, only a few objects are larger than
-      // _min_array_size_for_chunking, and most of them will be arrays.
-      // So, the is->objArray() test would be very infrequent.
-      if (new_obj_size > _min_array_size_for_chunking &&
-          new_obj->is_objArray() &&
-          PSChunkLargeArrays) {
-        // we'll chunk it
-        oop* const masked_o = mask_chunked_array_oop(o);
-        push_depth(masked_o);
-        TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);
-      } else {
-        // we'll just push its contents
-        new_obj->push_contents(this);
-      }
-    }  else {
-      // We lost, someone else "owns" this object
-      guarantee(o->is_forwarded(), "Object must be forwarded if the cas failed.");
-
-      // Try to deallocate the space.  If it was directly allocated we cannot
-      // deallocate it, so we have to test.  If the deallocation fails,
-      // overwrite with a filler object.
-      if (new_obj_is_tenured) {
-        if (!_old_lab.unallocate_object((HeapWord*) new_obj, new_obj_size)) {
-          CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
-        }
-      } else if (!_young_lab.unallocate_object((HeapWord*) new_obj, new_obj_size)) {
-        CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
-      }
-
-      // don't update this before the unallocation!
-      new_obj = o->forwardee();
-    }
-  } else {
-    assert(o->is_forwarded(), "Sanity");
-    new_obj = o->forwardee();
-  }
-
-#ifdef DEBUG
-  // This code must come after the CAS test, or it will print incorrect
-  // information.
-  if (TraceScavenge) {
-    gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (" SIZE_FORMAT ")}",
-       PSScavenge::should_scavenge(&new_obj) ? "copying" : "tenuring",
-       new_obj->blueprint()->internal_name(), o, new_obj, new_obj->size());
-  }
-#endif
-
-  return new_obj;
-}
-
 template <class T> void PSPromotionManager::process_array_chunk_work(
                                                  oop obj,
                                                  int start, int end) {
--- a/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -171,7 +171,7 @@
   void set_old_gen_is_full(bool state) { _old_gen_is_full = state; }
 
   // Promotion methods
-  oop copy_to_survivor_space(oop o);
+  template<bool promote_immediately> oop copy_to_survivor_space(oop o);
   oop oop_promotion_failed(oop obj, markOop obj_mark);
 
   void reset();
--- a/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -61,6 +61,170 @@
   claim_or_forward_internal_depth(p);
 }
 
+//
+// This method is pretty bulky. It would be nice to split it up
+// into smaller submethods, but we need to be careful not to hurt
+// performance.
+//
+template<bool promote_immediately>
+oop PSPromotionManager::copy_to_survivor_space(oop o) {
+  assert(PSScavenge::should_scavenge(&o), "Sanity");
+
+  oop new_obj = NULL;
+
+  // NOTE! We must be very careful with any methods that access the mark
+  // in o. There may be multiple threads racing on it, and it may be forwarded
+  // at any time. Do not use oop methods for accessing the mark!
+  markOop test_mark = o->mark();
+
+  // The same test as "o->is_forwarded()"
+  if (!test_mark->is_marked()) {
+    bool new_obj_is_tenured = false;
+    size_t new_obj_size = o->size();
+
+    if (!promote_immediately) {
+      // Find the objects age, MT safe.
+      int age = (test_mark->has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
+        test_mark->displaced_mark_helper()->age() : test_mark->age();
+
+      // Try allocating obj in to-space (unless too old)
+      if (age < PSScavenge::tenuring_threshold()) {
+        new_obj = (oop) _young_lab.allocate(new_obj_size);
+        if (new_obj == NULL && !_young_gen_is_full) {
+          // Do we allocate directly, or flush and refill?
+          if (new_obj_size > (YoungPLABSize / 2)) {
+            // Allocate this object directly
+            new_obj = (oop)young_space()->cas_allocate(new_obj_size);
+          } else {
+            // Flush and fill
+            _young_lab.flush();
+
+            HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
+            if (lab_base != NULL) {
+              _young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
+              // Try the young lab allocation again.
+              new_obj = (oop) _young_lab.allocate(new_obj_size);
+            } else {
+              _young_gen_is_full = true;
+            }
+          }
+        }
+      }
+    }
+
+    // Otherwise try allocating obj tenured
+    if (new_obj == NULL) {
+#ifndef PRODUCT
+      if (Universe::heap()->promotion_should_fail()) {
+        return oop_promotion_failed(o, test_mark);
+      }
+#endif  // #ifndef PRODUCT
+
+      new_obj = (oop) _old_lab.allocate(new_obj_size);
+      new_obj_is_tenured = true;
+
+      if (new_obj == NULL) {
+        if (!_old_gen_is_full) {
+          // Do we allocate directly, or flush and refill?
+          if (new_obj_size > (OldPLABSize / 2)) {
+            // Allocate this object directly
+            new_obj = (oop)old_gen()->cas_allocate(new_obj_size);
+          } else {
+            // Flush and fill
+            _old_lab.flush();
+
+            HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize);
+            if(lab_base != NULL) {
+              _old_lab.initialize(MemRegion(lab_base, OldPLABSize));
+              // Try the old lab allocation again.
+              new_obj = (oop) _old_lab.allocate(new_obj_size);
+            }
+          }
+        }
+
+        // This is the promotion failed test, and code handling.
+        // The code belongs here for two reasons. It is slightly
+        // different thatn the code below, and cannot share the
+        // CAS testing code. Keeping the code here also minimizes
+        // the impact on the common case fast path code.
+
+        if (new_obj == NULL) {
+          _old_gen_is_full = true;
+          return oop_promotion_failed(o, test_mark);
+        }
+      }
+    }
+
+    assert(new_obj != NULL, "allocation should have succeeded");
+
+    // Copy obj
+    Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)new_obj, new_obj_size);
+
+    // Now we have to CAS in the header.
+    if (o->cas_forward_to(new_obj, test_mark)) {
+      // We won any races, we "own" this object.
+      assert(new_obj == o->forwardee(), "Sanity");
+
+      // Increment age if obj still in new generation. Now that
+      // we're dealing with a markOop that cannot change, it is
+      // okay to use the non mt safe oop methods.
+      if (!new_obj_is_tenured) {
+        new_obj->incr_age();
+        assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
+      }
+
+      // Do the size comparison first with new_obj_size, which we
+      // already have. Hopefully, only a few objects are larger than
+      // _min_array_size_for_chunking, and most of them will be arrays.
+      // So, the is->objArray() test would be very infrequent.
+      if (new_obj_size > _min_array_size_for_chunking &&
+          new_obj->is_objArray() &&
+          PSChunkLargeArrays) {
+        // we'll chunk it
+        oop* const masked_o = mask_chunked_array_oop(o);
+        push_depth(masked_o);
+        TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);
+      } else {
+        // we'll just push its contents
+        new_obj->push_contents(this);
+      }
+    }  else {
+      // We lost, someone else "owns" this object
+      guarantee(o->is_forwarded(), "Object must be forwarded if the cas failed.");
+
+      // Try to deallocate the space.  If it was directly allocated we cannot
+      // deallocate it, so we have to test.  If the deallocation fails,
+      // overwrite with a filler object.
+      if (new_obj_is_tenured) {
+        if (!_old_lab.unallocate_object((HeapWord*) new_obj, new_obj_size)) {
+          CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
+        }
+      } else if (!_young_lab.unallocate_object((HeapWord*) new_obj, new_obj_size)) {
+        CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
+      }
+
+      // don't update this before the unallocation!
+      new_obj = o->forwardee();
+    }
+  } else {
+    assert(o->is_forwarded(), "Sanity");
+    new_obj = o->forwardee();
+  }
+
+#ifdef DEBUG
+  // This code must come after the CAS test, or it will print incorrect
+  // information.
+  if (TraceScavenge) {
+    gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (" SIZE_FORMAT ")}",
+       PSScavenge::should_scavenge(&new_obj) ? "copying" : "tenuring",
+       new_obj->blueprint()->internal_name(), o, new_obj, new_obj->size());
+  }
+#endif
+
+  return new_obj;
+}
+
+
 inline void PSPromotionManager::process_popped_location_depth(StarTask p) {
   if (is_oop_masked(p)) {
     assert(PSChunkLargeArrays, "invariant");
@@ -69,9 +233,9 @@
   } else {
     if (p.is_narrow()) {
       assert(UseCompressedOops, "Error");
-      PSScavenge::copy_and_push_safe_barrier(this, (narrowOop*)p);
+      PSScavenge::copy_and_push_safe_barrier<narrowOop, /*promote_immediately=*/false>(this, p);
     } else {
-      PSScavenge::copy_and_push_safe_barrier(this, (oop*)p);
+      PSScavenge::copy_and_push_safe_barrier<oop, /*promote_immediately=*/false>(this, p);
     }
   }
 }
--- a/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psScavenge.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -24,6 +24,7 @@
 
 #include "precompiled.hpp"
 #include "classfile/symbolTable.hpp"
+#include "code/codeCache.hpp"
 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
 #include "gc_implementation/parallelScavenge/generationSizer.hpp"
@@ -100,7 +101,7 @@
 
     // Weak refs may be visited more than once.
     if (PSScavenge::should_scavenge(p, _to_space)) {
-      PSScavenge::copy_and_push_safe_barrier(_promotion_manager, p);
+      PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p);
     }
   }
   virtual void do_oop(oop* p)       { PSKeepAliveClosure::do_oop_work(p); }
@@ -214,36 +215,41 @@
 //
 // Note that this method should only be called from the vm_thread while
 // at a safepoint!
-void PSScavenge::invoke() {
+bool PSScavenge::invoke() {
   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
   assert(!Universe::heap()->is_gc_active(), "not reentrant");
 
-  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
+  ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 
   PSAdaptiveSizePolicy* policy = heap->size_policy();
   IsGCActiveMark mark;
 
-  bool scavenge_was_done = PSScavenge::invoke_no_policy();
+  const bool scavenge_done = PSScavenge::invoke_no_policy();
+  const bool need_full_gc = !scavenge_done ||
+    policy->should_full_GC(heap->old_gen()->free_in_bytes());
+  bool full_gc_done = false;
 
-  PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
-  if (UsePerfData)
-    counters->update_full_follows_scavenge(0);
-  if (!scavenge_was_done ||
-      policy->should_full_GC(heap->old_gen()->free_in_bytes())) {
-    if (UsePerfData)
-      counters->update_full_follows_scavenge(full_follows_scavenge);
+  if (UsePerfData) {
+    PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
+    const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
+    counters->update_full_follows_scavenge(ffs_val);
+  }
+
+  if (need_full_gc) {
     GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
     CollectorPolicy* cp = heap->collector_policy();
     const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
 
     if (UseParallelOldGC) {
-      PSParallelCompact::invoke_no_policy(clear_all_softrefs);
+      full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
     } else {
-      PSMarkSweep::invoke_no_policy(clear_all_softrefs);
+      full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
     }
   }
+
+  return full_gc_done;
 }
 
 // This method contains no policy. You should probably
@@ -602,6 +608,8 @@
 
     NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
 
+    CodeCache::prune_scavenge_root_nmethods();
+
     // Re-verify object start arrays
     if (VerifyObjectStartArray &&
         VerifyAfterGC) {
--- a/src/share/vm/gc_implementation/parallelScavenge/psScavenge.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psScavenge.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -117,10 +117,9 @@
   // Called by parallelScavengeHeap to init the tenuring threshold
   static void initialize();
 
-  // Scavenge entry point
-  static void invoke();
-  // Return true is a collection was done.  Return
-  // false if the collection was skipped.
+  // Scavenge entry point.  This may invoke a full gc; return true if so.
+  static bool invoke();
+  // Return true if a collection was done; false otherwise.
   static bool invoke_no_policy();
 
   // If an attempt to promote fails, this method is invoked
@@ -135,7 +134,8 @@
   template <class T> static inline bool should_scavenge(T* p, MutableSpace* to_space);
   template <class T> static inline bool should_scavenge(T* p, bool check_to_space);
 
-  template <class T> inline static void copy_and_push_safe_barrier(PSPromotionManager* pm, T* p);
+  template <class T, bool promote_immediately>
+    inline static void copy_and_push_safe_barrier(PSPromotionManager* pm, T* p);
 
   // Is an object in the young generation
   // This assumes that the HeapWord argument is in the heap,
--- a/src/share/vm/gc_implementation/parallelScavenge/psScavenge.inline.hpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psScavenge.inline.hpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -28,6 +28,7 @@
 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
 #include "gc_implementation/parallelScavenge/psPromotionManager.hpp"
+#include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
 
 inline void PSScavenge::save_to_space_top_before_gc() {
@@ -65,7 +66,7 @@
 // Attempt to "claim" oop at p via CAS, push the new obj if successful
 // This version tests the oop* to make sure it is within the heap before
 // attempting marking.
-template <class T>
+template <class T, bool promote_immediately>
 inline void PSScavenge::copy_and_push_safe_barrier(PSPromotionManager* pm,
                                                    T*                  p) {
   assert(should_scavenge(p, true), "revisiting object?");
@@ -73,7 +74,7 @@
   oop o = oopDesc::load_decode_heap_oop_not_null(p);
   oop new_obj = o->is_forwarded()
         ? o->forwardee()
-        : pm->copy_to_survivor_space(o);
+        : pm->copy_to_survivor_space<promote_immediately>(o);
   oopDesc::encode_store_heap_oop_not_null(p, new_obj);
 
   // We cannot mark without test, as some code passes us pointers
@@ -86,7 +87,8 @@
   }
 }
 
-class PSScavengeRootsClosure: public OopClosure {
+template<bool promote_immediately>
+class PSRootsClosure: public OopClosure {
  private:
   PSPromotionManager* _promotion_manager;
 
@@ -94,13 +96,16 @@
   template <class T> void do_oop_work(T *p) {
     if (PSScavenge::should_scavenge(p)) {
       // We never card mark roots, maybe call a func without test?
-      PSScavenge::copy_and_push_safe_barrier(_promotion_manager, p);
+      PSScavenge::copy_and_push_safe_barrier<T, promote_immediately>(_promotion_manager, p);
     }
   }
  public:
-  PSScavengeRootsClosure(PSPromotionManager* pm) : _promotion_manager(pm) { }
-  void do_oop(oop* p)       { PSScavengeRootsClosure::do_oop_work(p); }
-  void do_oop(narrowOop* p) { PSScavengeRootsClosure::do_oop_work(p); }
+  PSRootsClosure(PSPromotionManager* pm) : _promotion_manager(pm) { }
+  void do_oop(oop* p)       { PSRootsClosure::do_oop_work(p); }
+  void do_oop(narrowOop* p) { PSRootsClosure::do_oop_work(p); }
 };
 
+typedef PSRootsClosure</*promote_immediately=*/false> PSScavengeRootsClosure;
+typedef PSRootsClosure</*promote_immediately=*/true> PSPromoteRootsClosure;
+
 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSSCAVENGE_INLINE_HPP
--- a/src/share/vm/gc_implementation/parallelScavenge/psTasks.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/gc_implementation/parallelScavenge/psTasks.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -51,6 +51,7 @@
 
   PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(which);
   PSScavengeRootsClosure roots_closure(pm);
+  PSPromoteRootsClosure  roots_to_old_closure(pm);
 
   switch (_root_type) {
     case universe:
@@ -91,7 +92,7 @@
 
     case code_cache:
       {
-        CodeBlobToOopClosure each_scavengable_code_blob(&roots_closure, /*do_marking=*/ true);
+        CodeBlobToOopClosure each_scavengable_code_blob(&roots_to_old_closure, /*do_marking=*/ true);
         CodeCache::scavenge_root_nmethods_do(&each_scavengable_code_blob);
       }
       break;
--- a/src/share/vm/memory/defNewGeneration.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/memory/defNewGeneration.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -655,7 +655,12 @@
   from()->set_concurrent_iteration_safe_limit(from()->top());
   to()->set_concurrent_iteration_safe_limit(to()->top());
   SpecializationStats::print();
-  update_time_of_last_gc(os::javaTimeMillis());
+
+  // We need to use a monotonically non-deccreasing time in ms
+  // or we will see time-warp warnings and os::javaTimeMillis()
+  // does not guarantee monotonicity.
+  jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
+  update_time_of_last_gc(now);
 }
 
 class RemoveForwardPointerClosure: public ObjectClosure {
--- a/src/share/vm/memory/genMarkSweep.cpp	Wed Feb 15 16:09:49 2012 -0500
+++ b/src/share/vm/memory/genMarkSweep.cpp	Fri Feb 17 13:23:29 2012 +0100
@@ -176,7 +176,11 @@
 
   // Update time of last gc for all generations we collected
   // (which curently is all the generations in the heap).
-  gch->update_time_of_last_gc(os::javaTimeMillis());
+  // We need to use a monotonically non-deccreasing time in ms
+  // or we will see time-warp warnings and os::javaTimeMillis()
+  // does not guarantee monotonicity.
+  jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
+  gch->update_time_of_last_gc(now);
 }
 
 void GenMarkSweep::allocate_stacks() {