changeset 4539:e341c460dcbf

7176479: G1: JVM crashes on T5-8 system with 1.5 TB heap Summary: Refactor G1's hot card cache and card counts table into their own files. Simplify the card counts table, including removing the encoding of the card index in each entry. The card counts table now has a 1:1 correspondence with the cards spanned by heap. Space for the card counts table is reserved from virtual memory (rather than C heap) during JVM startup and is committed/expanded when the heap is expanded. Changes were also reviewed-by Vitaly Davidovich. Reviewed-by: jmasa
author johnc
date Fri, 31 May 2013 12:18:33 -0700
parents d2e053ead2e6
children cd6a08cb2b86
files src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp src/share/vm/gc_implementation/g1/g1CardCounts.cpp src/share/vm/gc_implementation/g1/g1CardCounts.hpp src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp src/share/vm/gc_implementation/g1/g1GCPhaseTimes.cpp src/share/vm/gc_implementation/g1/g1GCPhaseTimes.hpp src/share/vm/gc_implementation/g1/g1HotCardCache.cpp src/share/vm/gc_implementation/g1/g1HotCardCache.hpp src/share/vm/gc_implementation/g1/g1RemSet.cpp src/share/vm/gc_implementation/g1/g1RemSet.hpp src/share/vm/gc_implementation/g1/g1_globals.hpp src/share/vm/runtime/arguments.cpp
diffstat 13 files changed, 806 insertions(+), 829 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp	Fri May 31 12:18:33 2013 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2013, 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
@@ -26,40 +26,12 @@
 #include "gc_implementation/g1/concurrentG1Refine.hpp"
 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
-#include "gc_implementation/g1/g1CollectorPolicy.hpp"
-#include "gc_implementation/g1/g1GCPhaseTimes.hpp"
-#include "gc_implementation/g1/g1RemSet.hpp"
-#include "gc_implementation/g1/heapRegionSeq.inline.hpp"
-#include "memory/space.inline.hpp"
-#include "runtime/atomic.hpp"
-#include "runtime/java.hpp"
-#include "utilities/copy.hpp"
+#include "gc_implementation/g1/g1HotCardCache.hpp"
 
-// Possible sizes for the card counts cache: odd primes that roughly double in size.
-// (See jvmtiTagMap.cpp).
-
-#define MAX_SIZE ((size_t) -1)
-
-size_t ConcurrentG1Refine::_cc_cache_sizes[] = {
-          16381,    32771,    76831,    150001,   307261,
-         614563,  1228891,  2457733,   4915219,  9830479,
-       19660831, 39321619, 78643219, 157286461,  MAX_SIZE
-  };
-
-ConcurrentG1Refine::ConcurrentG1Refine() :
-  _card_counts(NULL), _card_epochs(NULL),
-  _n_card_counts(0), _max_cards(0), _max_n_card_counts(0),
-  _cache_size_index(0), _expand_card_counts(false),
-  _hot_cache(NULL),
-  _def_use_cache(false), _use_cache(false),
-  // We initialize the epochs of the array to 0. By initializing
-  // _n_periods to 1 and not 0 we automatically invalidate all the
-  // entries on the array. Otherwise we might accidentally think that
-  // we claimed a card that was in fact never set (see CR7033292).
-  _n_periods(1),
-  _threads(NULL), _n_threads(0)
+ConcurrentG1Refine::ConcurrentG1Refine(G1CollectedHeap* g1h) :
+  _threads(NULL), _n_threads(0),
+  _hot_card_cache(g1h)
 {
-
   // Ergomonically select initial concurrent refinement parameters
   if (FLAG_IS_DEFAULT(G1ConcRefinementGreenZone)) {
     FLAG_SET_DEFAULT(G1ConcRefinementGreenZone, MAX2<int>(ParallelGCThreads, 1));
@@ -75,13 +47,17 @@
     FLAG_SET_DEFAULT(G1ConcRefinementRedZone, yellow_zone() * 2);
   }
   set_red_zone(MAX2<int>(G1ConcRefinementRedZone, yellow_zone()));
+
   _n_worker_threads = thread_num();
   // We need one extra thread to do the young gen rset size sampling.
   _n_threads = _n_worker_threads + 1;
+
   reset_threshold_step();
 
   _threads = NEW_C_HEAP_ARRAY(ConcurrentG1RefineThread*, _n_threads, mtGC);
+
   int worker_id_offset = (int)DirtyCardQueueSet::num_par_ids();
+
   ConcurrentG1RefineThread *next = NULL;
   for (int i = _n_threads - 1; i >= 0; i--) {
     ConcurrentG1RefineThread* t = new ConcurrentG1RefineThread(this, next, worker_id_offset, i);
@@ -100,74 +76,8 @@
   }
 }
 
-int ConcurrentG1Refine::thread_num() {
-  return MAX2<int>((G1ConcRefinementThreads > 0) ? G1ConcRefinementThreads : ParallelGCThreads, 1);
-}
-
 void ConcurrentG1Refine::init() {
-  if (G1ConcRSLogCacheSize > 0) {
-    _g1h = G1CollectedHeap::heap();
-
-    _max_cards = _g1h->max_capacity() >> CardTableModRefBS::card_shift;
-    _max_n_card_counts = _max_cards * G1MaxHotCardCountSizePercent / 100;
-
-    size_t max_card_num = ((size_t)1 << (sizeof(unsigned)*BitsPerByte-1)) - 1;
-    guarantee(_max_cards < max_card_num, "card_num representation");
-
-    // We need _n_card_counts to be less than _max_n_card_counts here
-    // so that the expansion call (below) actually allocates the
-    // _counts and _epochs arrays.
-    assert(_n_card_counts == 0, "pre-condition");
-    assert(_max_n_card_counts > 0, "pre-condition");
-
-    // Find the index into cache size array that is of a size that's
-    // large enough to hold desired_sz.
-    size_t desired_sz = _max_cards / InitialCacheFraction;
-    int desired_sz_index = 0;
-    while (_cc_cache_sizes[desired_sz_index] < desired_sz) {
-      desired_sz_index += 1;
-      assert(desired_sz_index <  MAX_CC_CACHE_INDEX, "invariant");
-    }
-    assert(desired_sz_index <  MAX_CC_CACHE_INDEX, "invariant");
-
-    // If the desired_sz value is between two sizes then
-    // _cc_cache_sizes[desired_sz_index-1] < desired_sz <= _cc_cache_sizes[desired_sz_index]
-    // we will start with the lower size in the optimistic expectation that
-    // we will not need to expand up. Note desired_sz_index could also be 0.
-    if (desired_sz_index > 0 &&
-        _cc_cache_sizes[desired_sz_index] > desired_sz) {
-      desired_sz_index -= 1;
-    }
-
-    if (!expand_card_count_cache(desired_sz_index)) {
-      // Allocation was unsuccessful - exit
-      vm_exit_during_initialization("Could not reserve enough space for card count cache");
-    }
-    assert(_n_card_counts > 0, "post-condition");
-    assert(_cache_size_index == desired_sz_index, "post-condition");
-
-    Copy::fill_to_bytes(&_card_counts[0],
-                        _n_card_counts * sizeof(CardCountCacheEntry));
-    Copy::fill_to_bytes(&_card_epochs[0], _n_card_counts * sizeof(CardEpochCacheEntry));
-
-    ModRefBarrierSet* bs = _g1h->mr_bs();
-    guarantee(bs->is_a(BarrierSet::CardTableModRef), "Precondition");
-    _ct_bs = (CardTableModRefBS*)bs;
-    _ct_bot = _ct_bs->byte_for_const(_g1h->reserved_region().start());
-
-    _def_use_cache = true;
-    _use_cache = true;
-    _hot_cache_size = (1 << G1ConcRSLogCacheSize);
-    _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);
-    _n_hot = 0;
-    _hot_cache_idx = 0;
-
-    // For refining the cards in the hot cache in parallel
-    int n_workers = (ParallelGCThreads > 0 ?
-                        _g1h->workers()->total_workers() : 1);
-    _hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / n_workers);
-    _hot_cache_par_claimed_idx = 0;
-  }
+  _hot_card_cache.initialize();
 }
 
 void ConcurrentG1Refine::stop() {
@@ -188,17 +98,6 @@
 }
 
 ConcurrentG1Refine::~ConcurrentG1Refine() {
-  if (G1ConcRSLogCacheSize > 0) {
-    // Please see the comment in allocate_card_count_cache
-    // for why we call os::malloc() and os::free() directly.
-    assert(_card_counts != NULL, "Logic");
-    os::free(_card_counts, mtGC);
-    assert(_card_epochs != NULL, "Logic");
-    os::free(_card_epochs, mtGC);
-
-    assert(_hot_cache != NULL, "Logic");
-    FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC);
-  }
   if (_threads != NULL) {
     for (int i = 0; i < _n_threads; i++) {
       delete _threads[i];
@@ -215,317 +114,10 @@
   }
 }
 
-bool ConcurrentG1Refine::is_young_card(jbyte* card_ptr) {
-  HeapWord* start = _ct_bs->addr_for(card_ptr);
-  HeapRegion* r = _g1h->heap_region_containing(start);
-  if (r != NULL && r->is_young()) {
-    return true;
-  }
-  // This card is not associated with a heap region
-  // so can't be young.
-  return false;
-}
-
-jbyte* ConcurrentG1Refine::add_card_count(jbyte* card_ptr, int* count, bool* defer) {
-  unsigned new_card_num = ptr_2_card_num(card_ptr);
-  unsigned bucket = hash(new_card_num);
-  assert(0 <= bucket && bucket < _n_card_counts, "Bounds");
-
-  CardCountCacheEntry* count_ptr = &_card_counts[bucket];
-  CardEpochCacheEntry* epoch_ptr = &_card_epochs[bucket];
-
-  // We have to construct a new entry if we haven't updated the counts
-  // during the current period, or if the count was updated for a
-  // different card number.
-  unsigned int new_epoch = (unsigned int) _n_periods;
-  julong new_epoch_entry = make_epoch_entry(new_card_num, new_epoch);
-
-  while (true) {
-    // Fetch the previous epoch value
-    julong prev_epoch_entry = epoch_ptr->_value;
-    julong cas_res;
-
-    if (extract_epoch(prev_epoch_entry) != new_epoch) {
-      // This entry has not yet been updated during this period.
-      // Note: we update the epoch value atomically to ensure
-      // that there is only one winner that updates the cached
-      // card_ptr value even though all the refine threads share
-      // the same epoch value.
-
-      cas_res = (julong) Atomic::cmpxchg((jlong) new_epoch_entry,
-                                         (volatile jlong*)&epoch_ptr->_value,
-                                         (jlong) prev_epoch_entry);
-
-      if (cas_res == prev_epoch_entry) {
-        // We have successfully won the race to update the
-        // epoch and card_num value. Make it look like the
-        // count and eviction count were previously cleared.
-        count_ptr->_count = 1;
-        count_ptr->_evict_count = 0;
-        *count = 0;
-        // We can defer the processing of card_ptr
-        *defer = true;
-        return card_ptr;
-      }
-      // We did not win the race to update the epoch field, so some other
-      // thread must have done it. The value that gets returned by CAS
-      // should be the new epoch value.
-      assert(extract_epoch(cas_res) == new_epoch, "unexpected epoch");
-      // We could 'continue' here or just re-read the previous epoch value
-      prev_epoch_entry = epoch_ptr->_value;
-    }
-
-    // The epoch entry for card_ptr has been updated during this period.
-    unsigned old_card_num = extract_card_num(prev_epoch_entry);
-
-    // The card count that will be returned to caller
-    *count = count_ptr->_count;
-
-    // Are we updating the count for the same card?
-    if (new_card_num == old_card_num) {
-      // Same card - just update the count. We could have more than one
-      // thread racing to update count for the current card. It should be
-      // OK not to use a CAS as the only penalty should be some missed
-      // increments of the count which delays identifying the card as "hot".
-
-      if (*count < max_jubyte) count_ptr->_count++;
-      // We can defer the processing of card_ptr
-      *defer = true;
-      return card_ptr;
-    }
-
-    // Different card - evict old card info
-    if (count_ptr->_evict_count < max_jubyte) count_ptr->_evict_count++;
-    if (count_ptr->_evict_count > G1CardCountCacheExpandThreshold) {
-      // Trigger a resize the next time we clear
-      _expand_card_counts = true;
-    }
-
-    cas_res = (julong) Atomic::cmpxchg((jlong) new_epoch_entry,
-                                       (volatile jlong*)&epoch_ptr->_value,
-                                       (jlong) prev_epoch_entry);
-
-    if (cas_res == prev_epoch_entry) {
-      // We successfully updated the card num value in the epoch entry
-      count_ptr->_count = 0; // initialize counter for new card num
-      jbyte* old_card_ptr = card_num_2_ptr(old_card_num);
-
-      // Even though the region containg the card at old_card_num was not
-      // in the young list when old_card_num was recorded in the epoch
-      // cache it could have been added to the free list and subsequently
-      // added to the young list in the intervening time. See CR 6817995.
-      // We do not deal with this case here - it will be handled in
-      // HeapRegion::oops_on_card_seq_iterate_careful after it has been
-      // determined that the region containing the card has been allocated
-      // to, and it's safe to check the young type of the region.
-
-      // We do not want to defer processing of card_ptr in this case
-      // (we need to refine old_card_ptr and card_ptr)
-      *defer = false;
-      return old_card_ptr;
-    }
-    // Someone else beat us - try again.
-  }
-}
-
-jbyte* ConcurrentG1Refine::cache_insert(jbyte* card_ptr, bool* defer) {
-  int count;
-  jbyte* cached_ptr = add_card_count(card_ptr, &count, defer);
-  assert(cached_ptr != NULL, "bad cached card ptr");
-
-  // We've just inserted a card pointer into the card count cache
-  // and got back the card that we just inserted or (evicted) the
-  // previous contents of that count slot.
-
-  // The card we got back could be in a young region. When the
-  // returned card (if evicted) was originally inserted, we had
-  // determined that its containing region was not young. However
-  // it is possible for the region to be freed during a cleanup
-  // pause, then reallocated and tagged as young which will result
-  // in the returned card residing in a young region.
-  //
-  // We do not deal with this case here - the change from non-young
-  // to young could be observed at any time - it will be handled in
-  // HeapRegion::oops_on_card_seq_iterate_careful after it has been
-  // determined that the region containing the card has been allocated
-  // to.
-
-  // The card pointer we obtained from card count cache is not hot
-  // so do not store it in the cache; return it for immediate
-  // refining.
-  if (count < G1ConcRSHotCardLimit) {
-    return cached_ptr;
-  }
-
-  // Otherwise, the pointer we got from the _card_counts cache is hot.
-  jbyte* res = NULL;
-  MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag);
-  if (_n_hot == _hot_cache_size) {
-    res = _hot_cache[_hot_cache_idx];
-    _n_hot--;
-  }
-  // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx.
-  _hot_cache[_hot_cache_idx] = cached_ptr;
-  _hot_cache_idx++;
-  if (_hot_cache_idx == _hot_cache_size) _hot_cache_idx = 0;
-  _n_hot++;
-
-  // The card obtained from the hot card cache could be in a young
-  // region. See above on how this can happen.
-
-  return res;
-}
-
-void ConcurrentG1Refine::clean_up_cache(int worker_i,
-                                        G1RemSet* g1rs,
-                                        DirtyCardQueue* into_cset_dcq) {
-  assert(!use_cache(), "cache should be disabled");
-  int start_idx;
-
-  while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once
-    int end_idx = start_idx + _hot_cache_par_chunk_size;
-
-    if (start_idx ==
-        Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {
-      // The current worker has successfully claimed the chunk [start_idx..end_idx)
-      end_idx = MIN2(end_idx, _n_hot);
-      for (int i = start_idx; i < end_idx; i++) {
-        jbyte* entry = _hot_cache[i];
-        if (entry != NULL) {
-          if (g1rs->concurrentRefineOneCard(entry, worker_i, true)) {
-            // 'entry' contains references that point into the current
-            // collection set. We need to record 'entry' in the DCQS
-            // that's used for that purpose.
-            //
-            // The only time we care about recording cards that contain
-            // references that point into the collection set is during
-            // RSet updating while within an evacuation pause.
-            // In this case worker_i should be the id of a GC worker thread
-            assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
-            assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "incorrect worker id");
-            into_cset_dcq->enqueue(entry);
-          }
-        }
-      }
-    }
-  }
-}
-
-// The arrays used to hold the card counts and the epochs must have
-// a 1:1 correspondence. Hence they are allocated and freed together
-// Returns true if the allocations of both the counts and epochs
-// were successful; false otherwise.
-bool ConcurrentG1Refine::allocate_card_count_cache(size_t n,
-                                                   CardCountCacheEntry** counts,
-                                                   CardEpochCacheEntry** epochs) {
-  // We call the allocation/free routines directly for the counts
-  // and epochs arrays. The NEW_C_HEAP_ARRAY/FREE_C_HEAP_ARRAY
-  // macros call AllocateHeap and FreeHeap respectively.
-  // AllocateHeap will call vm_exit_out_of_memory in the event
-  // of an allocation failure and abort the JVM. With the
-  // _counts/epochs arrays we only need to abort the JVM if the
-  // initial allocation of these arrays fails.
-  //
-  // Additionally AllocateHeap/FreeHeap do some tracing of
-  // allocate/free calls so calling one without calling the
-  // other can cause inconsistencies in the tracing. So we
-  // call neither.
-
-  assert(*counts == NULL, "out param");
-  assert(*epochs == NULL, "out param");
-
-  size_t counts_size = n * sizeof(CardCountCacheEntry);
-  size_t epochs_size = n * sizeof(CardEpochCacheEntry);
-
-  *counts = (CardCountCacheEntry*) os::malloc(counts_size, mtGC);
-  if (*counts == NULL) {
-    // allocation was unsuccessful
-    return false;
-  }
-
-  *epochs = (CardEpochCacheEntry*) os::malloc(epochs_size, mtGC);
-  if (*epochs == NULL) {
-    // allocation was unsuccessful - free counts array
-    assert(*counts != NULL, "must be");
-    os::free(*counts, mtGC);
-    *counts = NULL;
-    return false;
-  }
-
-  // We successfully allocated both counts and epochs
-  return true;
-}
-
-// Returns true if the card counts/epochs cache was
-// successfully expanded; false otherwise.
-bool ConcurrentG1Refine::expand_card_count_cache(int cache_size_idx) {
-  // Can we expand the card count and epoch tables?
-  if (_n_card_counts < _max_n_card_counts) {
-    assert(cache_size_idx >= 0 && cache_size_idx  < MAX_CC_CACHE_INDEX, "oob");
-
-    size_t cache_size = _cc_cache_sizes[cache_size_idx];
-    // Make sure we don't go bigger than we will ever need
-    cache_size = MIN2(cache_size, _max_n_card_counts);
-
-    // Should we expand the card count and card epoch tables?
-    if (cache_size > _n_card_counts) {
-      // We have been asked to allocate new, larger, arrays for
-      // the card counts and the epochs. Attempt the allocation
-      // of both before we free the existing arrays in case
-      // the allocation is unsuccessful...
-      CardCountCacheEntry* counts = NULL;
-      CardEpochCacheEntry* epochs = NULL;
-
-      if (allocate_card_count_cache(cache_size, &counts, &epochs)) {
-        // Allocation was successful.
-        // We can just free the old arrays; we're
-        // not interested in preserving the contents
-        if (_card_counts != NULL) os::free(_card_counts, mtGC);
-        if (_card_epochs != NULL) os::free(_card_epochs, mtGC);
-
-        // Cache the size of the arrays and the index that got us there.
-        _n_card_counts = cache_size;
-        _cache_size_index = cache_size_idx;
-
-        _card_counts = counts;
-        _card_epochs = epochs;
-
-        // We successfully allocated/expanded the caches.
-        return true;
-      }
-    }
-  }
-
-  // We did not successfully expand the caches.
-  return false;
-}
-
-void ConcurrentG1Refine::clear_and_record_card_counts() {
-  if (G1ConcRSLogCacheSize == 0) {
-    return;
-  }
-
-  double start = os::elapsedTime();
-
-  if (_expand_card_counts) {
-    int new_idx = _cache_size_index + 1;
-
-    if (expand_card_count_cache(new_idx)) {
-      // Allocation was successful and  _n_card_counts has
-      // been updated to the new size. We only need to clear
-      // the epochs so we don't read a bogus epoch value
-      // when inserting a card into the hot card cache.
-      Copy::fill_to_bytes(&_card_epochs[0], _n_card_counts * sizeof(CardEpochCacheEntry));
-    }
-    _expand_card_counts = false;
-  }
-
-  int this_epoch = (int) _n_periods;
-  assert((this_epoch+1) <= max_jint, "to many periods");
-  // Update epoch
-  _n_periods++;
-  double cc_clear_time_ms = (os::elapsedTime() - start) * 1000;
-  _g1h->g1_policy()->phase_times()->record_cc_clear_time_ms(cc_clear_time_ms);
+int ConcurrentG1Refine::thread_num() {
+  int n_threads = (G1ConcRefinementThreads > 0) ? G1ConcRefinementThreads
+                                                : ParallelGCThreads;
+  return MAX2<int>(n_threads, 1);
 }
 
 void ConcurrentG1Refine::print_worker_threads_on(outputStream* st) const {
--- a/src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp	Fri May 31 12:18:33 2013 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2013, 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
@@ -25,13 +25,15 @@
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP
 
+#include "gc_implementation/g1/g1HotCardCache.hpp"
 #include "memory/allocation.hpp"
-#include "memory/cardTableModRefBS.hpp"
 #include "runtime/thread.hpp"
 #include "utilities/globalDefinitions.hpp"
 
 // Forward decl
 class ConcurrentG1RefineThread;
+class G1CollectedHeap;
+class G1HotCardCache;
 class G1RemSet;
 
 class ConcurrentG1Refine: public CHeapObj<mtGC> {
@@ -61,141 +63,14 @@
 
   int _thread_threshold_step;
 
+  // We delay the refinement of 'hot' cards using the hot card cache.
+  G1HotCardCache _hot_card_cache;
+
   // Reset the threshold step value based of the current zone boundaries.
   void reset_threshold_step();
 
-  // The cache for card refinement.
-  bool   _use_cache;
-  bool   _def_use_cache;
-
-  size_t _n_periods;    // Used as clearing epoch
-
-  // An evicting cache of the number of times each card
-  // is accessed. Reduces, but does not eliminate, the amount
-  // of duplicated processing of dirty cards.
-
-  enum SomePrivateConstants {
-    epoch_bits           = 32,
-    card_num_shift       = epoch_bits,
-    epoch_mask           = AllBits,
-    card_num_mask        = AllBits,
-
-    // The initial cache size is approximately this fraction
-    // of a maximal cache (i.e. the size needed for all cards
-    // in the heap)
-    InitialCacheFraction = 512
-  };
-
-  const static julong card_num_mask_in_place =
-                        (julong) card_num_mask << card_num_shift;
-
-  typedef struct {
-    julong _value;      // |  card_num   |  epoch   |
-  } CardEpochCacheEntry;
-
-  julong make_epoch_entry(unsigned int card_num, unsigned int epoch) {
-    assert(0 <= card_num && card_num < _max_cards, "Bounds");
-    assert(0 <= epoch && epoch <= _n_periods, "must be");
-
-    return ((julong) card_num << card_num_shift) | epoch;
-  }
-
-  unsigned int extract_epoch(julong v) {
-    return (v & epoch_mask);
-  }
-
-  unsigned int extract_card_num(julong v) {
-    return (v & card_num_mask_in_place) >> card_num_shift;
-  }
-
-  typedef struct {
-    unsigned char _count;
-    unsigned char _evict_count;
-  } CardCountCacheEntry;
-
-  CardCountCacheEntry* _card_counts;
-  CardEpochCacheEntry* _card_epochs;
-
-  // The current number of buckets in the card count cache
-  size_t _n_card_counts;
-
-  // The number of cards for the entire reserved heap
-  size_t _max_cards;
-
-  // The max number of buckets for the card counts and epochs caches.
-  // This is the maximum that the counts and epochs will grow to.
-  // It is specified as a fraction or percentage of _max_cards using
-  // G1MaxHotCardCountSizePercent.
-  size_t _max_n_card_counts;
-
-  // Possible sizes of the cache: odd primes that roughly double in size.
-  // (See jvmtiTagMap.cpp).
-  enum {
-    MAX_CC_CACHE_INDEX = 15    // maximum index into the cache size array.
-  };
-
-  static size_t _cc_cache_sizes[MAX_CC_CACHE_INDEX];
-
-  // The index in _cc_cache_sizes corresponding to the size of
-  // _card_counts.
-  int _cache_size_index;
-
-  bool _expand_card_counts;
-
-  const jbyte* _ct_bot;
-
-  jbyte**      _hot_cache;
-  int          _hot_cache_size;
-  int          _n_hot;
-  int          _hot_cache_idx;
-
-  int          _hot_cache_par_chunk_size;
-  volatile int _hot_cache_par_claimed_idx;
-
-  // Needed to workaround 6817995
-  CardTableModRefBS* _ct_bs;
-  G1CollectedHeap*   _g1h;
-
-  // Helper routine for expand_card_count_cache().
-  // The arrays used to hold the card counts and the epochs must have
-  // a 1:1 correspondence. Hence they are allocated and freed together.
-  // Returns true if the allocations of both the counts and epochs
-  // were successful; false otherwise.
-  bool allocate_card_count_cache(size_t n,
-                                 CardCountCacheEntry** counts,
-                                 CardEpochCacheEntry** epochs);
-
-  // Expands the arrays that hold the card counts and epochs
-  // to the cache size at index. Returns true if the expansion/
-  // allocation was successful; false otherwise.
-  bool expand_card_count_cache(int index);
-
-  // hash a given key (index of card_ptr) with the specified size
-  static unsigned int hash(size_t key, size_t size) {
-    return (unsigned int) (key % size);
-  }
-
-  // hash a given key (index of card_ptr)
-  unsigned int hash(size_t key) {
-    return hash(key, _n_card_counts);
-  }
-
-  unsigned int ptr_2_card_num(jbyte* card_ptr) {
-    return (unsigned int) (card_ptr - _ct_bot);
-  }
-
-  jbyte* card_num_2_ptr(unsigned int card_num) {
-    return (jbyte*) (_ct_bot + card_num);
-  }
-
-  // Returns the count of this card after incrementing it.
-  jbyte* add_card_count(jbyte* card_ptr, int* count, bool* defer);
-
-  // Returns true if this card is in a young region
-  bool is_young_card(jbyte* card_ptr);
-
  public:
-  ConcurrentG1Refine();
+  ConcurrentG1Refine(G1CollectedHeap* g1h);
   ~ConcurrentG1Refine();
 
   void init(); // Accomplish some initialization that has to wait.
@@ -206,34 +81,6 @@
   // Iterate over the conc refine threads
   void threads_do(ThreadClosure *tc);
 
-  // If this is the first entry for the slot, writes into the cache and
-  // returns NULL.  If it causes an eviction, returns the evicted pointer.
-  // Otherwise, its a cache hit, and returns NULL.
-  jbyte* cache_insert(jbyte* card_ptr, bool* defer);
-
-  // Process the cached entries.
-  void clean_up_cache(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);
-
-  // Set up for parallel processing of the cards in the hot cache
-  void clear_hot_cache_claimed_index() {
-    _hot_cache_par_claimed_idx = 0;
-  }
-
-  // Discard entries in the hot cache.
-  void clear_hot_cache() {
-    _hot_cache_idx = 0; _n_hot = 0;
-  }
-
-  bool hot_cache_is_empty() { return _n_hot == 0; }
-
-  bool use_cache() { return _use_cache; }
-  void set_use_cache(bool b) {
-    if (b) _use_cache = _def_use_cache;
-    else   _use_cache = false;
-  }
-
-  void clear_and_record_card_counts();
-
   static int thread_num();
 
   void print_worker_threads_on(outputStream* st) const;
@@ -250,6 +97,8 @@
   int worker_thread_num() const { return _n_worker_threads; }
 
   int thread_threshold_step() const { return _thread_threshold_step; }
+
+  G1HotCardCache* hot_card_cache() { return &_hot_card_cache; }
 };
 
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/g1/g1CardCounts.cpp	Fri May 31 12:18:33 2013 -0700
@@ -0,0 +1,212 @@
+/*
+ * Copyright (c) 2013, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc_implementation/g1/g1CardCounts.hpp"
+#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
+#include "gc_implementation/g1/g1CollectorPolicy.hpp"
+#include "gc_implementation/g1/g1GCPhaseTimes.hpp"
+#include "memory/cardTableModRefBS.hpp"
+#include "services/memTracker.hpp"
+#include "utilities/copy.hpp"
+
+void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) {
+  if (has_count_table()) {
+    check_card_num(from_card_num,
+                   err_msg("from card num out of range: "SIZE_FORMAT, from_card_num));
+    assert(from_card_num < to_card_num,
+           err_msg("Wrong order? from: " SIZE_FORMAT ", to: "SIZE_FORMAT,
+                   from_card_num, to_card_num));
+    assert(to_card_num <= _committed_max_card_num,
+           err_msg("to card num out of range: "
+                   "to: "SIZE_FORMAT ", "
+                   "max: "SIZE_FORMAT,
+                   to_card_num, _committed_max_card_num));
+
+    to_card_num = MIN2(_committed_max_card_num, to_card_num);
+
+    Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num));
+  }
+}
+
+G1CardCounts::G1CardCounts(G1CollectedHeap *g1h):
+  _g1h(g1h), _card_counts(NULL),
+  _reserved_max_card_num(0), _committed_max_card_num(0),
+  _committed_size(0) {}
+
+void G1CardCounts::initialize() {
+  assert(_g1h->max_capacity() > 0, "initialization order");
+  assert(_g1h->capacity() == 0, "initialization order");
+
+  if (G1ConcRSHotCardLimit > 0) {
+    // The max value we can store in the counts table is
+    // max_jubyte. Guarantee the value of the hot
+    // threshold limit is no more than this.
+    guarantee(G1ConcRSHotCardLimit <= max_jubyte, "sanity");
+
+    ModRefBarrierSet* bs = _g1h->mr_bs();
+    guarantee(bs->is_a(BarrierSet::CardTableModRef), "Precondition");
+    _ct_bs = (CardTableModRefBS*)bs;
+    _ct_bot = _ct_bs->byte_for_const(_g1h->reserved_region().start());
+
+    // Allocate/Reserve the counts table
+    size_t reserved_bytes = _g1h->max_capacity();
+    _reserved_max_card_num = reserved_bytes >> CardTableModRefBS::card_shift;
+
+    size_t reserved_size = _reserved_max_card_num * sizeof(jbyte);
+    ReservedSpace rs(ReservedSpace::allocation_align_size_up(reserved_size));
+    if (!rs.is_reserved()) {
+      warning("Could not reserve enough space for the card counts table");
+      guarantee(!has_reserved_count_table(), "should be NULL");
+      return;
+    }
+
+    MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
+
+    _card_counts_storage.initialize(rs, 0);
+    _card_counts = (jubyte*) _card_counts_storage.low();
+  }
+}
+
+void G1CardCounts::resize(size_t heap_capacity) {
+  // Expand the card counts table to handle a heap with the given capacity.
+
+  if (!has_reserved_count_table()) {
+    // Don't expand if we failed to reserve the card counts table.
+    return;
+  }
+
+  assert(_committed_size ==
+         ReservedSpace::allocation_align_size_up(_committed_size),
+         err_msg("Unaligned? committed_size: " SIZE_FORMAT, _committed_size));
+
+  // Verify that the committed space for the card counts
+  // matches our committed max card num.
+  size_t prev_committed_size = _committed_size;
+  size_t prev_committed_card_num = prev_committed_size / sizeof(jbyte);
+  assert(prev_committed_card_num == _committed_max_card_num,
+         err_msg("Card mismatch: "
+                 "prev: " SIZE_FORMAT ", "
+                 "committed: "SIZE_FORMAT,
+                 prev_committed_card_num, _committed_max_card_num));
+
+  size_t new_size = (heap_capacity >> CardTableModRefBS::card_shift) * sizeof(jbyte);
+  size_t new_committed_size = ReservedSpace::allocation_align_size_up(new_size);
+  size_t new_committed_card_num =
+                MIN2(_reserved_max_card_num, new_committed_size / sizeof(jbyte));
+
+  if (_committed_max_card_num < new_committed_card_num) {
+    // we need to expand the backing store for the card counts
+    size_t expand_size = new_committed_size - prev_committed_size;
+
+    if (!_card_counts_storage.expand_by(expand_size)) {
+      warning("Card counts table backing store commit failure");
+      return;
+    }
+    assert(_card_counts_storage.committed_size() == new_committed_size,
+           "expansion commit failure");
+
+    _committed_size = new_committed_size;
+    _committed_max_card_num = new_committed_card_num;
+
+    clear_range(prev_committed_card_num, _committed_max_card_num);
+  }
+}
+
+uint G1CardCounts::add_card_count(jbyte* card_ptr) {
+  // Returns the number of times the card has been refined.
+  // If we failed to reserve/commit the counts table, return 0.
+  // If card_ptr is beyond the committed end of the counts table,
+  // return 0.
+  // Otherwise return the actual count.
+  // Unless G1ConcRSHotCardLimit has been set appropriately,
+  // returning 0 will result in the card being considered
+  // cold and will be refined immediately.
+  uint count = 0;
+  if (has_count_table()) {
+    size_t card_num = ptr_2_card_num(card_ptr);
+    if (card_num < _committed_max_card_num) {
+      count = (uint) _card_counts[card_num];
+      if (count < G1ConcRSHotCardLimit) {
+        _card_counts[card_num] += 1;
+      }
+      assert(_card_counts[card_num] <= G1ConcRSHotCardLimit,
+             err_msg("Refinement count overflow? "
+                     "new count: "UINT32_FORMAT,
+                     (uint) _card_counts[card_num]));
+    }
+  }
+  return count;
+}
+
+bool G1CardCounts::is_hot(uint count) {
+  return (count >= G1ConcRSHotCardLimit);
+}
+
+void G1CardCounts::clear_region(HeapRegion* hr) {
+  assert(!hr->isHumongous(), "Should have been cleared");
+  if (has_count_table()) {
+    HeapWord* bottom = hr->bottom();
+
+    // We use the last address in hr as hr could be the
+    // last region in the heap. In which case trying to find
+    // the card for hr->end() will be an OOB accesss to the
+    // card table.
+    HeapWord* last = hr->end() - 1;
+    assert(_g1h->g1_committed().contains(last),
+           err_msg("last not in committed: "
+                   "last: " PTR_FORMAT ", "
+                   "committed: [" PTR_FORMAT ", " PTR_FORMAT ")",
+                   last,
+                   _g1h->g1_committed().start(),
+                   _g1h->g1_committed().end()));
+
+    const jbyte* from_card_ptr = _ct_bs->byte_for_const(bottom);
+    const jbyte* last_card_ptr = _ct_bs->byte_for_const(last);
+
+#ifdef ASSERT
+    HeapWord* start_addr = _ct_bs->addr_for(from_card_ptr);
+    assert(start_addr == hr->bottom(), "alignment");
+    HeapWord* last_addr = _ct_bs->addr_for(last_card_ptr);
+    assert((last_addr + CardTableModRefBS::card_size_in_words) == hr->end(), "alignment");
+#endif // ASSERT
+
+    // Clear the counts for the (exclusive) card range.
+    size_t from_card_num = ptr_2_card_num(from_card_ptr);
+    size_t to_card_num = ptr_2_card_num(last_card_ptr) + 1;
+    clear_range(from_card_num, to_card_num);
+  }
+}
+
+void G1CardCounts::clear_all() {
+  assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise");
+  clear_range((size_t)0, _committed_max_card_num);
+}
+
+G1CardCounts::~G1CardCounts() {
+  if (has_reserved_count_table()) {
+    _card_counts_storage.release();
+  }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/g1/g1CardCounts.hpp	Fri May 31 12:18:33 2013 -0700
@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2013, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP
+
+#include "memory/allocation.hpp"
+#include "runtime/virtualspace.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+class CardTableModRefBS;
+class G1CollectedHeap;
+class HeapRegion;
+
+// Table to track the number of times a card has been refined. Once
+// a card has been refined a certain number of times, it is
+// considered 'hot' and its refinement is delayed by inserting the
+// card into the hot card cache. The card will then be refined when
+// it is evicted from the hot card cache, or when the hot card cache
+// is 'drained' during the next evacuation pause.
+
+class G1CardCounts: public CHeapObj<mtGC> {
+  G1CollectedHeap* _g1h;
+
+  // The table of counts
+  jubyte* _card_counts;
+
+  // Max capacity of the reserved space for the counts table
+  size_t _reserved_max_card_num;
+
+  // Max capacity of the committed space for the counts table
+  size_t _committed_max_card_num;
+
+  // Size of committed space for the counts table
+  size_t _committed_size;
+
+  // CardTable bottom.
+  const jbyte* _ct_bot;
+
+  // Barrier set
+  CardTableModRefBS* _ct_bs;
+
+  // The virtual memory backing the counts table
+  VirtualSpace _card_counts_storage;
+
+  // Returns true if the card counts table has been reserved.
+  bool has_reserved_count_table() { return _card_counts != NULL; }
+
+  // Returns true if the card counts table has been reserved and committed.
+  bool has_count_table() {
+    return has_reserved_count_table() && _committed_max_card_num > 0;
+  }
+
+  void check_card_num(size_t card_num, const char* msg) {
+    assert(card_num >= 0 && card_num < _committed_max_card_num, msg);
+  }
+
+  size_t ptr_2_card_num(const jbyte* card_ptr) {
+    assert(card_ptr >= _ct_bot,
+           err_msg("Inavalied card pointer: "
+                   "card_ptr: " PTR_FORMAT ", "
+                   "_ct_bot: " PTR_FORMAT,
+                   card_ptr, _ct_bot));
+    size_t card_num = pointer_delta(card_ptr, _ct_bot, sizeof(jbyte));
+    check_card_num(card_num,
+                   err_msg("card pointer out of range: " PTR_FORMAT, card_ptr));
+    return card_num;
+  }
+
+  jbyte* card_num_2_ptr(size_t card_num) {
+    check_card_num(card_num,
+                   err_msg("card num out of range: "SIZE_FORMAT, card_num));
+    return (jbyte*) (_ct_bot + card_num);
+  }
+
+  // Clear the counts table for the given (exclusive) index range.
+  void clear_range(size_t from_card_num, size_t to_card_num);
+
+ public:
+  G1CardCounts(G1CollectedHeap* g1h);
+  ~G1CardCounts();
+
+  void initialize();
+
+  // Resize the committed space for the card counts table in
+  // response to a resize of the committed space for the heap.
+  void resize(size_t heap_capacity);
+
+  // Increments the refinement count for the given card.
+  // Returns the pre-increment count value.
+  uint add_card_count(jbyte* card_ptr);
+
+  // Returns true if the given count is high enough to be considered
+  // 'hot'; false otherwise.
+  bool is_hot(uint count);
+
+  // Clears the card counts for the cards spanned by the region
+  void clear_region(HeapRegion* hr);
+
+  // Clear the entire card counts table during GC.
+  // Updates the policy stats with the duration.
+  void clear_all();
+};
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Fri May 31 12:18:33 2013 -0700
@@ -101,7 +101,7 @@
     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
   {}
   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
-    bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
+    bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
     // This path is executed by the concurrent refine or mutator threads,
     // concurrently, and so we do not care if card_ptr contains references
     // that point into the collection set.
@@ -1439,9 +1439,10 @@
         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
       }
 
-      if (_cg1r->use_cache()) {
-        _cg1r->clear_and_record_card_counts();
-        _cg1r->clear_hot_cache();
+      G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
+      if (hot_card_cache->use_cache()) {
+        hot_card_cache->reset_card_counts();
+        hot_card_cache->reset_hot_cache();
       }
 
       // Rebuild remembered sets of all regions.
@@ -1760,6 +1761,8 @@
   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
   // Tell the BOT about the update.
   _bot_shared->resize(_g1_committed.word_size());
+  // Tell the hot card cache about the update
+  _cg1r->hot_card_cache()->resize_card_counts(capacity());
 }
 
 bool G1CollectedHeap::expand(size_t expand_bytes) {
@@ -2004,7 +2007,7 @@
   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
 
-  _cg1r = new ConcurrentG1Refine();
+  _cg1r = new ConcurrentG1Refine(this);
 
   // Reserve the maximum.
   PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
@@ -2107,6 +2110,9 @@
                   (HeapWord*) _g1_reserved.end(),
                   _expansion_regions);
 
+  // Do later initialization work for concurrent refinement.
+  _cg1r->init();
+
   // 6843694 - ensure that the maximum region index can fit
   // in the remembered set structures.
   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
@@ -2124,20 +2130,20 @@
 
   _g1h = this;
 
-   _in_cset_fast_test_length = max_regions();
-   _in_cset_fast_test_base =
+  _in_cset_fast_test_length = max_regions();
+  _in_cset_fast_test_base =
                    NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
 
-   // We're biasing _in_cset_fast_test to avoid subtracting the
-   // beginning of the heap every time we want to index; basically
-   // it's the same with what we do with the card table.
-   _in_cset_fast_test = _in_cset_fast_test_base -
+  // We're biasing _in_cset_fast_test to avoid subtracting the
+  // beginning of the heap every time we want to index; basically
+  // it's the same with what we do with the card table.
+  _in_cset_fast_test = _in_cset_fast_test_base -
                ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
 
-   // Clear the _cset_fast_test bitmap in anticipation of adding
-   // regions to the incremental collection set for the first
-   // evacuation pause.
-   clear_cset_fast_test();
+  // Clear the _cset_fast_test bitmap in anticipation of adding
+  // regions to the incremental collection set for the first
+  // evacuation pause.
+  clear_cset_fast_test();
 
   // Create the ConcurrentMark data structure and thread.
   // (Must do this late, so that "max_regions" is defined.)
@@ -2195,9 +2201,6 @@
   // counts and that mechanism.
   SpecializationStats::clear();
 
-  // Do later initialization work for concurrent refinement.
-  _cg1r->init();
-
   // Here we allocate the dummy full region that is required by the
   // G1AllocRegion class. If we don't pass an address in the reserved
   // space here, lots of asserts fire.
@@ -2356,7 +2359,8 @@
                                                  bool concurrent,
                                                  int worker_i) {
   // Clean cards in the hot card cache
-  concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
+  G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
+  hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
 
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   int n_completed_buffers = 0;
@@ -5683,8 +5687,11 @@
   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
 
   g1_rem_set()->prepare_for_oops_into_collection_set_do();
-  concurrent_g1_refine()->set_use_cache(false);
-  concurrent_g1_refine()->clear_hot_cache_claimed_index();
+
+  // Disable the hot card cache.
+  G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
+  hot_card_cache->reset_hot_cache_claimed_index();
+  hot_card_cache->set_use_cache(false);
 
   uint n_workers;
   if (G1CollectedHeap::use_parallel_gc_threads()) {
@@ -5766,8 +5773,11 @@
   release_gc_alloc_regions(n_workers, evacuation_info);
   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
 
-  concurrent_g1_refine()->clear_hot_cache();
-  concurrent_g1_refine()->set_use_cache(true);
+  // Reset and re-enable the hot card cache.
+  // Note the counts for the cards in the regions in the
+  // collection set are reset when the collection set is freed.
+  hot_card_cache->reset_hot_cache();
+  hot_card_cache->set_use_cache(true);
 
   finalize_for_evac_failure();
 
@@ -5829,6 +5839,12 @@
   assert(!hr->is_empty(), "the region should not be empty");
   assert(free_list != NULL, "pre-condition");
 
+  // Clear the card counts for this region.
+  // Note: we only need to do this if the region is not young
+  // (since we don't refine cards in young regions).
+  if (!hr->is_young()) {
+    _cg1r->hot_card_cache()->reset_card_counts(hr);
+  }
   *pre_used += hr->used();
   hr->hr_clear(par, true /* clear_space */);
   free_list->add_as_head(hr);
--- a/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.cpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.cpp	Fri May 31 12:18:33 2013 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 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
@@ -155,11 +155,6 @@
 
 G1GCPhaseTimes::G1GCPhaseTimes(uint max_gc_threads) :
   _max_gc_threads(max_gc_threads),
-  _min_clear_cc_time_ms(-1.0),
-  _max_clear_cc_time_ms(-1.0),
-  _cur_clear_cc_time_ms(0.0),
-  _cum_clear_cc_time_ms(0.0),
-  _num_cc_clears(0L),
   _last_gc_worker_start_times_ms(_max_gc_threads, "%.1lf", false),
   _last_ext_root_scan_times_ms(_max_gc_threads, "%.1lf"),
   _last_satb_filtering_times_ms(_max_gc_threads, "%.1lf"),
@@ -212,11 +207,11 @@
     _last_gc_worker_times_ms.set(i, worker_time);
 
     double worker_known_time = _last_ext_root_scan_times_ms.get(i) +
-      _last_satb_filtering_times_ms.get(i) +
-      _last_update_rs_times_ms.get(i) +
-      _last_scan_rs_times_ms.get(i) +
-      _last_obj_copy_times_ms.get(i) +
-      _last_termination_times_ms.get(i);
+                               _last_satb_filtering_times_ms.get(i) +
+                               _last_update_rs_times_ms.get(i) +
+                               _last_scan_rs_times_ms.get(i) +
+                               _last_obj_copy_times_ms.get(i) +
+                               _last_termination_times_ms.get(i);
 
     double worker_other_time = worker_time - worker_known_time;
     _last_gc_worker_other_times_ms.set(i, worker_other_time);
@@ -285,15 +280,6 @@
   }
   print_stats(1, "Code Root Fixup", _cur_collection_code_root_fixup_time_ms);
   print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
-  if (Verbose && G1Log::finest()) {
-    print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
-    print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
-    print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
-    print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
-    if (_num_cc_clears > 0) {
-      print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
-    }
-  }
   double misc_time_ms = pause_time_sec * MILLIUNITS - accounted_time_ms();
   print_stats(1, "Other", misc_time_ms);
   if (_cur_verify_before_time_ms > 0.0) {
@@ -311,19 +297,3 @@
     print_stats(2, "Verify After", _cur_verify_after_time_ms);
   }
 }
-
-void G1GCPhaseTimes::record_cc_clear_time_ms(double ms) {
-  if (!(Verbose && G1Log::finest())) {
-    return;
-  }
-
-  if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms) {
-    _min_clear_cc_time_ms = ms;
-  }
-  if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms) {
-    _max_clear_cc_time_ms = ms;
-  }
-  _cur_clear_cc_time_ms = ms;
-  _cum_clear_cc_time_ms += ms;
-  _num_cc_clears++;
-}
--- a/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.hpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.hpp	Fri May 31 12:18:33 2013 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 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
@@ -133,13 +133,6 @@
   double _cur_ref_proc_time_ms;
   double _cur_ref_enq_time_ms;
 
-  // Card Table Count Cache stats
-  double _min_clear_cc_time_ms;         // min
-  double _max_clear_cc_time_ms;         // max
-  double _cur_clear_cc_time_ms;         // clearing time during current pause
-  double _cum_clear_cc_time_ms;         // cumulative clearing time
-  jlong  _num_cc_clears;                // number of times the card count cache has been cleared
-
   double _cur_collection_start_sec;
   double _root_region_scan_wait_time_ms;
 
@@ -227,8 +220,6 @@
     _root_region_scan_wait_time_ms = time_ms;
   }
 
-  void record_cc_clear_time_ms(double ms);
-
   void record_young_free_cset_time_ms(double time_ms) {
     _recorded_young_free_cset_time_ms = time_ms;
   }
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/g1/g1HotCardCache.cpp	Fri May 31 12:18:33 2013 -0700
@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2013, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc_implementation/g1/dirtyCardQueue.hpp"
+#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
+#include "gc_implementation/g1/g1HotCardCache.hpp"
+#include "gc_implementation/g1/g1RemSet.hpp"
+#include "gc_implementation/g1/heapRegion.hpp"
+#include "runtime/atomic.hpp"
+
+G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
+  _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}
+
+void G1HotCardCache::initialize() {
+  if (default_use_cache()) {
+    _use_cache = true;
+
+    _hot_cache_size = (1 << G1ConcRSLogCacheSize);
+    _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);
+
+    _n_hot = 0;
+    _hot_cache_idx = 0;
+
+    // For refining the cards in the hot cache in parallel
+    int n_workers = (ParallelGCThreads > 0 ?
+                        _g1h->workers()->total_workers() : 1);
+    _hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / n_workers);
+    _hot_cache_par_claimed_idx = 0;
+
+    _card_counts.initialize();
+  }
+}
+
+G1HotCardCache::~G1HotCardCache() {
+  if (default_use_cache()) {
+    assert(_hot_cache != NULL, "Logic");
+    FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC);
+  }
+}
+
+jbyte* G1HotCardCache::insert(jbyte* card_ptr) {
+  uint count = _card_counts.add_card_count(card_ptr);
+  if (!_card_counts.is_hot(count)) {
+    // The card is not hot so do not store it in the cache;
+    // return it for immediate refining.
+    return card_ptr;
+  }
+
+  // Otherwise, the card is hot.
+  jbyte* res = NULL;
+  MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag);
+  if (_n_hot == _hot_cache_size) {
+    res = _hot_cache[_hot_cache_idx];
+    _n_hot--;
+  }
+
+  // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx.
+  _hot_cache[_hot_cache_idx] = card_ptr;
+  _hot_cache_idx++;
+
+  if (_hot_cache_idx == _hot_cache_size) {
+    // Wrap around
+    _hot_cache_idx = 0;
+  }
+  _n_hot++;
+
+  return res;
+}
+
+void G1HotCardCache::drain(int worker_i,
+                           G1RemSet* g1rs,
+                           DirtyCardQueue* into_cset_dcq) {
+  if (!default_use_cache()) {
+    assert(_hot_cache == NULL, "Logic");
+    return;
+  }
+
+  assert(_hot_cache != NULL, "Logic");
+  assert(!use_cache(), "cache should be disabled");
+  int start_idx;
+
+  while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once
+    int end_idx = start_idx + _hot_cache_par_chunk_size;
+
+    if (start_idx ==
+        Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {
+      // The current worker has successfully claimed the chunk [start_idx..end_idx)
+      end_idx = MIN2(end_idx, _n_hot);
+      for (int i = start_idx; i < end_idx; i++) {
+        jbyte* card_ptr = _hot_cache[i];
+        if (card_ptr != NULL) {
+          if (g1rs->refine_card(card_ptr, worker_i, true)) {
+            // The part of the heap spanned by the card contains references
+            // that point into the current collection set.
+            // We need to record the card pointer in the DirtyCardQueueSet
+            // that we use for such cards.
+            //
+            // The only time we care about recording cards that contain
+            // references that point into the collection set is during
+            // RSet updating while within an evacuation pause.
+            // In this case worker_i should be the id of a GC worker thread
+            assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
+            assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads),
+                   err_msg("incorrect worker id: "INT32_FORMAT, worker_i));
+
+            into_cset_dcq->enqueue(card_ptr);
+          }
+        }
+      }
+    }
+  }
+  // The existing entries in the hot card cache, which were just refined
+  // above, are discarded prior to re-enabling the cache near the end of the GC.
+}
+
+void G1HotCardCache::resize_card_counts(size_t heap_capacity) {
+  _card_counts.resize(heap_capacity);
+}
+
+void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
+  _card_counts.clear_region(hr);
+}
+
+void G1HotCardCache::reset_card_counts() {
+  _card_counts.clear_all();
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/g1/g1HotCardCache.hpp	Fri May 31 12:18:33 2013 -0700
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2013, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
+
+#include "gc_implementation/g1/g1_globals.hpp"
+#include "gc_implementation/g1/g1CardCounts.hpp"
+#include "memory/allocation.hpp"
+#include "runtime/safepoint.hpp"
+#include "runtime/thread.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+class DirtyCardQueue;
+class G1CollectedHeap;
+class G1RemSet;
+class HeapRegion;
+
+// An evicting cache of cards that have been logged by the G1 post
+// write barrier. Placing a card in the cache delays the refinement
+// of the card until the card is evicted, or the cache is drained
+// during the next evacuation pause.
+//
+// The first thing the G1 post write barrier does is to check whether
+// the card containing the updated pointer is already dirty and, if
+// so, skips the remaining code in the barrier.
+//
+// Delaying the refinement of a card will make the card fail the
+// first is_dirty check in the write barrier, skipping the remainder
+// of the write barrier.
+//
+// This can significantly reduce the overhead of the write barrier
+// code, increasing throughput.
+
+class G1HotCardCache: public CHeapObj<mtGC> {
+  G1CollectedHeap*   _g1h;
+
+  // The card cache table
+  jbyte**      _hot_cache;
+
+  int          _hot_cache_size;
+  int          _n_hot;
+  int          _hot_cache_idx;
+
+  int          _hot_cache_par_chunk_size;
+  volatile int _hot_cache_par_claimed_idx;
+
+  bool         _use_cache;
+
+  G1CardCounts _card_counts;
+
+  bool default_use_cache() const {
+    return (G1ConcRSLogCacheSize > 0);
+  }
+
+ public:
+  G1HotCardCache(G1CollectedHeap* g1h);
+  ~G1HotCardCache();
+
+  void initialize();
+
+  bool use_cache() { return _use_cache; }
+
+  void set_use_cache(bool b) {
+    _use_cache = (b ? default_use_cache() : false);
+  }
+
+  // Returns the card to be refined or NULL.
+  //
+  // Increments the count for given the card. if the card is not 'hot',
+  // it is returned for immediate refining. Otherwise the card is
+  // added to the hot card cache.
+  // If there is enough room in the hot card cache for the card we're
+  // adding, NULL is returned and no further action in needed.
+  // If we evict a card from the cache to make room for the new card,
+  // the evicted card is then returned for refinement.
+  jbyte* insert(jbyte* card_ptr);
+
+  // Refine the cards that have delayed as a result of
+  // being in the cache.
+  void drain(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);
+
+  // Set up for parallel processing of the cards in the hot cache
+  void reset_hot_cache_claimed_index() {
+    _hot_cache_par_claimed_idx = 0;
+  }
+
+  // Resets the hot card cache and discards the entries.
+  void reset_hot_cache() {
+    assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
+    assert(Thread::current()->is_VM_thread(), "Current thread should be the VMthread");
+    _hot_cache_idx = 0; _n_hot = 0;
+  }
+
+  bool hot_cache_is_empty() { return _n_hot == 0; }
+
+  // Resizes the card counts table to match the given capacity
+  void resize_card_counts(size_t heap_capacity);
+
+  // Zeros the values in the card counts table for entire committed heap
+  void reset_card_counts();
+
+  // Zeros the values in the card counts table for the given region
+  void reset_card_counts(HeapRegion* hr);
+};
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1HOTCARDCACHE_HPP
--- a/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Fri May 31 12:18:33 2013 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2013, 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
@@ -29,6 +29,7 @@
 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
+#include "gc_implementation/g1/g1HotCardCache.hpp"
 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
 #include "gc_implementation/g1/g1RemSet.inline.hpp"
@@ -248,7 +249,7 @@
     assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
     assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "should be a GC worker");
 
-    if (_g1rs->concurrentRefineOneCard(card_ptr, worker_i, true)) {
+    if (_g1rs->refine_card(card_ptr, worker_i, true)) {
       // 'card_ptr' contains references that point into the collection
       // set. We need to record the card in the DCQS
       // (G1CollectedHeap::into_cset_dirty_card_queue_set())
@@ -289,9 +290,6 @@
 #if CARD_REPEAT_HISTO
   ct_freq_update_histo_and_reset();
 #endif
-  if (worker_i == 0) {
-    _cg1r->clear_and_record_card_counts();
-  }
 
   // We cache the value of 'oc' closure into the appropriate slot in the
   // _cset_rs_update_cl for this worker
@@ -380,7 +378,10 @@
     assert(r != NULL, "unexpected null");
 
     // Scan oops in the card looking for references into the collection set
-    HeapWord* end   = _ct_bs->addr_for(card_ptr + 1);
+    // Don't use addr_for(card_ptr + 1) which can ask for
+    // a card beyond the heap.  This is not safe without a perm
+    // gen.
+    HeapWord* end   = start + CardTableModRefBS::card_size_in_words;
     MemRegion scanRegion(start, end);
 
     UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
@@ -394,7 +395,7 @@
     //   RSet updating,
     // * the post-write barrier shouldn't be logging updates to young
     //   regions (but there is a situation where this can happen - see
-    //   the comment in G1RemSet::concurrentRefineOneCard below -
+    //   the comment in G1RemSet::refine_card() below -
     //   that should not be applicable here), and
     // * during actual RSet updating, the filtering of cards in young
     //   regions in HeapRegion::oops_on_card_seq_iterate_careful is
@@ -500,8 +501,6 @@
                                        claim_val);
 }
 
-
-
 G1TriggerClosure::G1TriggerClosure() :
   _triggered(false) { }
 
@@ -522,15 +521,98 @@
   _record_refs_into_cset(record_refs_into_cset),
   _push_ref_cl(push_ref_cl), _worker_i(worker_i) { }
 
-bool G1RemSet::concurrentRefineOneCard_impl(jbyte* card_ptr, int worker_i,
-                                                   bool check_for_refs_into_cset) {
+// Returns true if the given card contains references that point
+// into the collection set, if we're checking for such references;
+// false otherwise.
+
+bool G1RemSet::refine_card(jbyte* card_ptr, int worker_i,
+                           bool check_for_refs_into_cset) {
+
+  // If the card is no longer dirty, nothing to do.
+  if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
+    // No need to return that this card contains refs that point
+    // into the collection set.
+    return false;
+  }
+
   // Construct the region representing the card.
   HeapWord* start = _ct_bs->addr_for(card_ptr);
   // And find the region containing it.
   HeapRegion* r = _g1->heap_region_containing(start);
-  assert(r != NULL, "unexpected null");
+  if (r == NULL) {
+    guarantee(_g1->is_in_permanent(start), "Or else where?");
+    // Again no need to return that this card contains refs that
+    // point into the collection set.
+    return false;  // Not in the G1 heap (might be in perm, for example.)
+  }
 
-  HeapWord* end   = _ct_bs->addr_for(card_ptr + 1);
+  // Why do we have to check here whether a card is on a young region,
+  // given that we dirty young regions and, as a result, the
+  // post-barrier is supposed to filter them out and never to enqueue
+  // them? When we allocate a new region as the "allocation region" we
+  // actually dirty its cards after we release the lock, since card
+  // dirtying while holding the lock was a performance bottleneck. So,
+  // as a result, it is possible for other threads to actually
+  // allocate objects in the region (after the acquire the lock)
+  // before all the cards on the region are dirtied. This is unlikely,
+  // and it doesn't happen often, but it can happen. So, the extra
+  // check below filters out those cards.
+  if (r->is_young()) {
+    return false;
+  }
+
+  // While we are processing RSet buffers during the collection, we
+  // actually don't want to scan any cards on the collection set,
+  // since we don't want to update remebered sets with entries that
+  // point into the collection set, given that live objects from the
+  // collection set are about to move and such entries will be stale
+  // very soon. This change also deals with a reliability issue which
+  // involves scanning a card in the collection set and coming across
+  // an array that was being chunked and looking malformed. Note,
+  // however, that if evacuation fails, we have to scan any objects
+  // that were not moved and create any missing entries.
+  if (r->in_collection_set()) {
+    return false;
+  }
+
+  // The result from the hot card cache insert call is either:
+  //   * pointer to the current card
+  //     (implying that the current card is not 'hot'),
+  //   * null
+  //     (meaning we had inserted the card ptr into the "hot" card cache,
+  //     which had some headroom),
+  //   * a pointer to a "hot" card that was evicted from the "hot" cache.
+  //
+
+  G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
+  if (hot_card_cache->use_cache()) {
+    assert(!check_for_refs_into_cset, "sanity");
+    assert(!SafepointSynchronize::is_at_safepoint(), "sanity");
+
+    card_ptr = hot_card_cache->insert(card_ptr);
+    if (card_ptr == NULL) {
+      // There was no eviction. Nothing to do.
+      return false;
+    }
+
+    start = _ct_bs->addr_for(card_ptr);
+    r = _g1->heap_region_containing(start);
+    if (r == NULL) {
+      guarantee(_g1->is_in_permanent(start), "Or else where?");
+      // Not in the G1 heap
+      return false;
+    }
+
+    // Checking whether the region we got back from the cache
+    // is young here is inappropriate. The region could have been
+    // freed, reallocated and tagged as young while in the cache.
+    // Hence we could see its young type change at any time.
+  }
+
+  // Don't use addr_for(card_ptr + 1) which can ask for
+  // a card beyond the heap.  This is not safe without a perm
+  // gen at the upper end of the heap.
+  HeapWord* end   = start + CardTableModRefBS::card_size_in_words;
   MemRegion dirtyRegion(start, end);
 
 #if CARD_REPEAT_HISTO
@@ -605,143 +687,17 @@
     _conc_refine_cards++;
   }
 
-  return trigger_cl.triggered();
-}
+  // This gets set to true if the card being refined has
+  // references that point into the collection set.
+  bool has_refs_into_cset = trigger_cl.triggered();
 
-bool G1RemSet::concurrentRefineOneCard(jbyte* card_ptr, int worker_i,
-                                              bool check_for_refs_into_cset) {
-  // If the card is no longer dirty, nothing to do.
-  if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
-    // No need to return that this card contains refs that point
-    // into the collection set.
-    return false;
-  }
+  // We should only be detecting that the card contains references
+  // that point into the collection set if the current thread is
+  // a GC worker thread.
+  assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(),
+           "invalid result at non safepoint");
 
-  // Construct the region representing the card.
-  HeapWord* start = _ct_bs->addr_for(card_ptr);
-  // And find the region containing it.
-  HeapRegion* r = _g1->heap_region_containing(start);
-  if (r == NULL) {
-    guarantee(_g1->is_in_permanent(start), "Or else where?");
-    // Again no need to return that this card contains refs that
-    // point into the collection set.
-    return false;  // Not in the G1 heap (might be in perm, for example.)
-  }
-  // Why do we have to check here whether a card is on a young region,
-  // given that we dirty young regions and, as a result, the
-  // post-barrier is supposed to filter them out and never to enqueue
-  // them? When we allocate a new region as the "allocation region" we
-  // actually dirty its cards after we release the lock, since card
-  // dirtying while holding the lock was a performance bottleneck. So,
-  // as a result, it is possible for other threads to actually
-  // allocate objects in the region (after the acquire the lock)
-  // before all the cards on the region are dirtied. This is unlikely,
-  // and it doesn't happen often, but it can happen. So, the extra
-  // check below filters out those cards.
-  if (r->is_young()) {
-    return false;
-  }
-  // While we are processing RSet buffers during the collection, we
-  // actually don't want to scan any cards on the collection set,
-  // since we don't want to update remebered sets with entries that
-  // point into the collection set, given that live objects from the
-  // collection set are about to move and such entries will be stale
-  // very soon. This change also deals with a reliability issue which
-  // involves scanning a card in the collection set and coming across
-  // an array that was being chunked and looking malformed. Note,
-  // however, that if evacuation fails, we have to scan any objects
-  // that were not moved and create any missing entries.
-  if (r->in_collection_set()) {
-    return false;
-  }
-
-  // Should we defer processing the card?
-  //
-  // Previously the result from the insert_cache call would be
-  // either card_ptr (implying that card_ptr was currently "cold"),
-  // null (meaning we had inserted the card ptr into the "hot"
-  // cache, which had some headroom), or a "hot" card ptr
-  // extracted from the "hot" cache.
-  //
-  // Now that the _card_counts cache in the ConcurrentG1Refine
-  // instance is an evicting hash table, the result we get back
-  // could be from evicting the card ptr in an already occupied
-  // bucket (in which case we have replaced the card ptr in the
-  // bucket with card_ptr and "defer" is set to false). To avoid
-  // having a data structure (updates to which would need a lock)
-  // to hold these unprocessed dirty cards, we need to immediately
-  // process card_ptr. The actions needed to be taken on return
-  // from cache_insert are summarized in the following table:
-  //
-  // res      defer   action
-  // --------------------------------------------------------------
-  // null     false   card evicted from _card_counts & replaced with
-  //                  card_ptr; evicted ptr added to hot cache.
-  //                  No need to process res; immediately process card_ptr
-  //
-  // null     true    card not evicted from _card_counts; card_ptr added
-  //                  to hot cache.
-  //                  Nothing to do.
-  //
-  // non-null false   card evicted from _card_counts & replaced with
-  //                  card_ptr; evicted ptr is currently "cold" or
-  //                  caused an eviction from the hot cache.
-  //                  Immediately process res; process card_ptr.
-  //
-  // non-null true    card not evicted from _card_counts; card_ptr is
-  //                  currently cold, or caused an eviction from hot
-  //                  cache.
-  //                  Immediately process res; no need to process card_ptr.
-
-
-  jbyte* res = card_ptr;
-  bool defer = false;
-
-  // This gets set to true if the card being refined has references
-  // that point into the collection set.
-  bool oops_into_cset = false;
-
-  if (_cg1r->use_cache()) {
-    jbyte* res = _cg1r->cache_insert(card_ptr, &defer);
-    if (res != NULL && (res != card_ptr || defer)) {
-      start = _ct_bs->addr_for(res);
-      r = _g1->heap_region_containing(start);
-      if (r == NULL) {
-        assert(_g1->is_in_permanent(start), "Or else where?");
-      } else {
-        // Checking whether the region we got back from the cache
-        // is young here is inappropriate. The region could have been
-        // freed, reallocated and tagged as young while in the cache.
-        // Hence we could see its young type change at any time.
-        //
-        // Process card pointer we get back from the hot card cache. This
-        // will check whether the region containing the card is young
-        // _after_ checking that the region has been allocated from.
-        oops_into_cset = concurrentRefineOneCard_impl(res, worker_i,
-                                                      false /* check_for_refs_into_cset */);
-        // The above call to concurrentRefineOneCard_impl is only
-        // performed if the hot card cache is enabled. This cache is
-        // disabled during an evacuation pause - which is the only
-        // time when we need know if the card contains references
-        // that point into the collection set. Also when the hot card
-        // cache is enabled, this code is executed by the concurrent
-        // refine threads - rather than the GC worker threads - and
-        // concurrentRefineOneCard_impl will return false.
-        assert(!oops_into_cset, "should not see true here");
-      }
-    }
-  }
-
-  if (!defer) {
-    oops_into_cset =
-      concurrentRefineOneCard_impl(card_ptr, worker_i, check_for_refs_into_cset);
-    // We should only be detecting that the card contains references
-    // that point into the collection set if the current thread is
-    // a GC worker thread.
-    assert(!oops_into_cset || SafepointSynchronize::is_at_safepoint(),
-           "invalid result at non safepoint");
-  }
-  return oops_into_cset;
+  return has_refs_into_cset;
 }
 
 class HRRSStatsIter: public HeapRegionClosure {
@@ -844,13 +800,16 @@
       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
       dcqs.concatenate_logs();
     }
-    bool cg1r_use_cache = _cg1r->use_cache();
-    _cg1r->set_use_cache(false);
+
+    G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
+    bool use_hot_card_cache = hot_card_cache->use_cache();
+    hot_card_cache->set_use_cache(false);
+
     DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
     updateRS(&into_cset_dcq, 0);
     _g1->into_cset_dirty_card_queue_set().clear();
-    _cg1r->set_use_cache(cg1r_use_cache);
 
+    hot_card_cache->set_use_cache(use_hot_card_cache);
     assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
   }
 }
--- a/src/share/vm/gc_implementation/g1/g1RemSet.hpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/gc_implementation/g1/g1RemSet.hpp	Fri May 31 12:18:33 2013 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2013, 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
@@ -66,14 +66,6 @@
   // references into the collection set.
   OopsInHeapRegionClosure** _cset_rs_update_cl;
 
-  // The routine that performs the actual work of refining a dirty
-  // card.
-  // If check_for_refs_into_refs is true then a true result is returned
-  // if the card contains oops that have references into the current
-  // collection set.
-  bool concurrentRefineOneCard_impl(jbyte* card_ptr, int worker_i,
-                                    bool check_for_refs_into_cset);
-
 public:
   // This is called to reset dual hash tables after the gc pause
   // is finished and the initial hash table is no longer being
@@ -90,8 +82,7 @@
   // function can be helpful in partitioning the work to be done. It
   // should be the same as the "i" passed to the calling thread's
   // work(i) function. In the sequential case this param will be ingored.
-  void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
-                                   int worker_i);
+  void oops_into_collection_set_do(OopsInHeapRegionClosure* blk, int worker_i);
 
   // Prepare for and cleanup after an oops_into_collection_set_do
   // call.  Must call each of these once before and after (in sequential
@@ -124,14 +115,13 @@
   void scrub_par(BitMap* region_bm, BitMap* card_bm,
                  uint worker_num, int claim_val);
 
-  // Refine the card corresponding to "card_ptr".  If "sts" is non-NULL,
-  // join and leave around parts that must be atomic wrt GC.  (NULL means
-  // being done at a safepoint.)
+  // Refine the card corresponding to "card_ptr".
   // If check_for_refs_into_cset is true, a true result is returned
   // if the given card contains oops that have references into the
   // current collection set.
-  virtual bool concurrentRefineOneCard(jbyte* card_ptr, int worker_i,
-                                       bool check_for_refs_into_cset);
+  virtual bool refine_card(jbyte* card_ptr,
+                           int worker_i,
+                           bool check_for_refs_into_cset);
 
   // Print any relevant summary info.
   virtual void print_summary_info();
--- a/src/share/vm/gc_implementation/g1/g1_globals.hpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/gc_implementation/g1/g1_globals.hpp	Fri May 31 12:18:33 2013 -0700
@@ -166,16 +166,12 @@
           "Select green, yellow and red zones adaptively to meet the "      \
           "the pause requirements.")                                        \
                                                                             \
-  develop(intx, G1ConcRSLogCacheSize, 10,                                   \
+  product(uintx, G1ConcRSLogCacheSize, 10,                                  \
           "Log base 2 of the length of conc RS hot-card cache.")            \
                                                                             \
-  develop(intx, G1ConcRSHotCardLimit, 4,                                    \
+  product(uintx, G1ConcRSHotCardLimit, 4,                                   \
           "The threshold that defines (>=) a hot card.")                    \
                                                                             \
-  develop(intx, G1MaxHotCardCountSizePercent, 25,                           \
-          "The maximum size of the hot card count cache as a "              \
-          "percentage of the number of cards for the maximum heap.")        \
-                                                                            \
   develop(bool, G1PrintOopAppls, false,                                     \
           "When true, print applications of closures to external locs.")    \
                                                                             \
@@ -250,10 +246,6 @@
           "If non-0 is the number of parallel rem set update threads, "     \
           "otherwise the value is determined ergonomically.")               \
                                                                             \
-  develop(intx, G1CardCountCacheExpandThreshold, 16,                        \
-          "Expand the card count cache if the number of collisions for "    \
-          "a particular entry exceeds this value.")                         \
-                                                                            \
   develop(bool, G1VerifyCTCleanup, false,                                   \
           "Verify card table cleanup.")                                     \
                                                                             \
--- a/src/share/vm/runtime/arguments.cpp	Fri May 31 08:00:19 2013 -0700
+++ b/src/share/vm/runtime/arguments.cpp	Fri May 31 12:18:33 2013 -0700
@@ -1939,6 +1939,10 @@
                                         "G1RefProcDrainInterval");
     status = status && verify_min_value((intx)G1ConcMarkStepDurationMillis, 1,
                                         "G1ConcMarkStepDurationMillis");
+    status = status && verify_interval(G1ConcRSHotCardLimit, 0, max_jubyte,
+                                       "G1ConcRSHotCardLimit");
+    status = status && verify_interval(G1ConcRSLogCacheSize, 0, 31,
+                                       "G1ConcRSLogCacheSize");
   }
 #endif