changeset 33587:c04a7462b0e6

8139952: Remove UseCMSAdaptiveFreeLists, UseAsyncConcMarkSweepGC, CMSDictionaryChoice, CMSOverflowEarlyRestoration and CMSTestInFreeList Reviewed-by: jwilhelm, ecaspole
author david
date Thu, 22 Oct 2015 08:53:13 +0200
parents df2af0ed648d
children 13edf132ffa0
files hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.cpp hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.hpp hotspot/src/share/vm/gc/cms/concurrentMarkSweepGeneration.cpp hotspot/src/share/vm/gc/cms/concurrentMarkSweepGeneration.hpp hotspot/src/share/vm/gc/cms/vmCMSOperations.hpp hotspot/src/share/vm/gc/shared/generationSpec.cpp hotspot/src/share/vm/runtime/arguments.cpp hotspot/src/share/vm/runtime/globals.hpp
diffstat 8 files changed, 34 insertions(+), 321 deletions(-) [+]
line wrap: on
line diff
--- a/hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.cpp	Wed Oct 21 17:16:02 2015 -0400
+++ b/hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.cpp	Thu Oct 22 08:53:13 2015 +0200
@@ -73,11 +73,7 @@
 }
 
 // Constructor
-CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs,
-  MemRegion mr, bool use_adaptive_freelists,
-  FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) :
-  _dictionaryChoice(dictionaryChoice),
-  _adaptive_freelists(use_adaptive_freelists),
+CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr) :
   _bt(bs, mr),
   // free list locks are in the range of values taken by _lockRank
   // This range currently is [_leaf+2, _leaf+3]
@@ -100,48 +96,17 @@
          "FreeChunk is larger than expected");
   _bt.set_space(this);
   initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
-  // We have all of "mr", all of which we place in the dictionary
-  // as one big chunk. We'll need to decide here which of several
-  // possible alternative dictionary implementations to use. For
-  // now the choice is easy, since we have only one working
-  // implementation, namely, the simple binary tree (splaying
-  // temporarily disabled).
-  switch (dictionaryChoice) {
-    case FreeBlockDictionary<FreeChunk>::dictionaryBinaryTree:
-      _dictionary = new AFLBinaryTreeDictionary(mr);
-      break;
-    case FreeBlockDictionary<FreeChunk>::dictionarySplayTree:
-    case FreeBlockDictionary<FreeChunk>::dictionarySkipList:
-    default:
-      warning("dictionaryChoice: selected option not understood; using"
-              " default BinaryTreeDictionary implementation instead.");
-  }
+
+  _dictionary = new AFLBinaryTreeDictionary(mr);
+
   assert(_dictionary != NULL, "CMS dictionary initialization");
   // The indexed free lists are initially all empty and are lazily
   // filled in on demand. Initialize the array elements to NULL.
   initializeIndexedFreeListArray();
 
-  // Not using adaptive free lists assumes that allocation is first
-  // from the linAB's.  Also a cms perm gen which can be compacted
-  // has to have the klass's klassKlass allocated at a lower
-  // address in the heap than the klass so that the klassKlass is
-  // moved to its new location before the klass is moved.
-  // Set the _refillSize for the linear allocation blocks
-  if (!use_adaptive_freelists) {
-    FreeChunk* fc = _dictionary->get_chunk(mr.word_size(),
-                                           FreeBlockDictionary<FreeChunk>::atLeast);
-    // The small linAB initially has all the space and will allocate
-    // a chunk of any size.
-    HeapWord* addr = (HeapWord*) fc;
-    _smallLinearAllocBlock.set(addr, fc->size() ,
-      1024*SmallForLinearAlloc, fc->size());
-    // Note that _unallocated_block is not updated here.
-    // Allocations from the linear allocation block should
-    // update it.
-  } else {
-    _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc,
-                               SmallForLinearAlloc);
-  }
+  _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc,
+                             SmallForLinearAlloc);
+
   // CMSIndexedFreeListReplenish should be at least 1
   CMSIndexedFreeListReplenish = MAX2((uintx)1, CMSIndexedFreeListReplenish);
   _promoInfo.setSpace(this);
@@ -297,22 +262,7 @@
   MemRegion mr(compaction_top(), end());
   reset(mr);
   // Now refill the linear allocation block(s) if possible.
-  if (_adaptive_freelists) {
-    refillLinearAllocBlocksIfNeeded();
-  } else {
-    // Place as much of mr in the linAB as we can get,
-    // provided it was big enough to go into the dictionary.
-    FreeChunk* fc = dictionary()->find_largest_dict();
-    if (fc != NULL) {
-      assert(fc->size() == mr.word_size(),
-             "Why was the chunk broken up?");
-      removeChunkFromDictionary(fc);
-      HeapWord* addr = (HeapWord*) fc;
-      _smallLinearAllocBlock.set(addr, fc->size() ,
-        1024*SmallForLinearAlloc, fc->size());
-      // Note that _unallocated_block is not updated here.
-    }
-  }
+  refillLinearAllocBlocksIfNeeded();
 }
 
 // Walks the entire dictionary, returning a coterminal
@@ -445,8 +395,7 @@
 
   // dump_memory_block(_smallLinearAllocBlock->_ptr, 128);
 
-  st->print_cr(" _fitStrategy = %s, _adaptive_freelists = %s",
-               _fitStrategy?"true":"false", _adaptive_freelists?"true":"false");
+  st->print_cr(" _fitStrategy = %s", BOOL_TO_STR(_fitStrategy));
 }
 
 void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st)
@@ -617,23 +566,9 @@
       // Now, take this new chunk and add it to the free blocks.
       // Note that the BOT has not yet been updated for this block.
       size_t newFcSize = pointer_delta(value, prevEnd);
-      // XXX This is REALLY UGLY and should be fixed up. XXX
-      if (!_adaptive_freelists && _smallLinearAllocBlock._ptr == NULL) {
-        // Mark the boundary of the new block in BOT
-        _bt.mark_block(prevEnd, value);
-        // put it all in the linAB
-        MutexLockerEx x(parDictionaryAllocLock(),
-                        Mutex::_no_safepoint_check_flag);
-        _smallLinearAllocBlock._ptr = prevEnd;
-        _smallLinearAllocBlock._word_size = newFcSize;
-        repairLinearAllocBlock(&_smallLinearAllocBlock);
-        // Births of chunks put into a LinAB are not recorded.  Births
-        // of chunks as they are allocated out of a LinAB are.
-      } else {
-        // Add the block to the free lists, if possible coalescing it
-        // with the last free block, and update the BOT and census data.
-        addChunkToFreeListsAtEndRecordingStats(prevEnd, newFcSize);
-      }
+      // Add the block to the free lists, if possible coalescing it
+      // with the last free block, and update the BOT and census data.
+      addChunkToFreeListsAtEndRecordingStats(prevEnd, newFcSize);
     }
   }
 }
@@ -1177,11 +1112,7 @@
   assert(size == adjustObjectSize(size),
          "use adjustObjectSize() before calling into allocate()");
 
-  if (_adaptive_freelists) {
-    res = allocate_adaptive_freelists(size);
-  } else {  // non-adaptive free lists
-    res = allocate_non_adaptive_freelists(size);
-  }
+  res = allocate_adaptive_freelists(size);
 
   if (res != NULL) {
     // check that res does lie in this space!
@@ -1203,27 +1134,6 @@
   return res;
 }
 
-HeapWord* CompactibleFreeListSpace::allocate_non_adaptive_freelists(size_t size) {
-  HeapWord* res = NULL;
-  // try and use linear allocation for smaller blocks
-  if (size < _smallLinearAllocBlock._allocation_size_limit) {
-    // if successful, the following also adjusts block offset table
-    res = getChunkFromSmallLinearAllocBlock(size);
-  }
-  // Else triage to indexed lists for smaller sizes
-  if (res == NULL) {
-    if (size < SmallForDictionary) {
-      res = (HeapWord*) getChunkFromIndexedFreeList(size);
-    } else {
-      // else get it from the big dictionary; if even this doesn't
-      // work we are out of luck.
-      res = (HeapWord*)getChunkFromDictionaryExact(size);
-    }
-  }
-
-  return res;
-}
-
 HeapWord* CompactibleFreeListSpace::allocate_adaptive_freelists(size_t size) {
   assert_lock_strong(freelistLock());
   HeapWord* res = NULL;
@@ -1281,9 +1191,6 @@
   // bigLAB or a smallLAB plus refilling a PromotionInfo object.  MinChunkSize
   // is added because the dictionary may over-allocate to avoid fragmentation.
   size_t space = obj_size;
-  if (!_adaptive_freelists) {
-    space = MAX2(space, _smallLinearAllocBlock._refillSize);
-  }
   space += _promoInfo.refillSize() + 2 * MinChunkSize;
   return space;
 }
@@ -1698,11 +1605,7 @@
   size_t size = fc->size();
   _bt.verify_single_block((HeapWord*) fc, size);
   _bt.verify_not_unallocated((HeapWord*) fc, size);
-  if (_adaptive_freelists) {
-    _indexedFreeList[size].return_chunk_at_tail(fc);
-  } else {
-    _indexedFreeList[size].return_chunk_at_head(fc);
-  }
+  _indexedFreeList[size].return_chunk_at_tail(fc);
 #ifndef PRODUCT
   if (CMSCollector::abstract_state() != CMSCollector::Sweeping) {
      _indexedFreeList[size].verify_stats();
@@ -1931,10 +1834,6 @@
 void
 CompactibleFreeListSpace::gc_epilogue() {
   assert_locked();
-  if (PrintGCDetails && Verbose && !_adaptive_freelists) {
-    if (_smallLinearAllocBlock._word_size == 0)
-      warning("CompactibleFreeListSpace(epilogue):: Linear allocation failure");
-  }
   assert(_promoInfo.noPromotions(), "_promoInfo inconsistency");
   _promoInfo.stopTrackingPromotions();
   repairLinearAllocationBlocks();
@@ -2060,13 +1959,6 @@
   }
 }
 
-// Support for concurrent collection policy decisions.
-bool CompactibleFreeListSpace::should_concurrent_collect() const {
-  // In the future we might want to add in fragmentation stats --
-  // including erosion of the "mountain" into this decision as well.
-  return !adaptive_freelists() && linearAllocationWouldFail();
-}
-
 // Support for compaction
 void CompactibleFreeListSpace::prepare_for_compaction(CompactPoint* cp) {
   scan_and_forward(this, cp);
--- a/hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.hpp	Wed Oct 21 17:16:02 2015 -0400
+++ b/hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.hpp	Thu Oct 22 08:53:13 2015 +0200
@@ -138,15 +138,13 @@
   // Linear allocation blocks
   LinearAllocBlock _smallLinearAllocBlock;
 
-  FreeBlockDictionary<FreeChunk>::DictionaryChoice _dictionaryChoice;
   AFLBinaryTreeDictionary* _dictionary;    // Pointer to dictionary for large size blocks
 
   // Indexed array for small size blocks
   AdaptiveFreeList<FreeChunk> _indexedFreeList[IndexSetSize];
 
   // Allocation strategy
-  bool       _fitStrategy;        // Use best fit strategy
-  bool       _adaptive_freelists; // Use adaptive freelists
+  bool _fitStrategy;  // Use best fit strategy
 
   // This is an address close to the largest free chunk in the heap.
   // It is currently assumed to be at the end of the heap.  Free
@@ -204,10 +202,6 @@
   // strategy that attempts to keep the needed number of chunks in each
   // indexed free lists.
   HeapWord* allocate_adaptive_freelists(size_t size);
-  // Allocate from the linear allocation buffers first.  This allocation
-  // strategy assumes maximal coalescing can maintain chunks large enough
-  // to be used as linear allocation buffers.
-  HeapWord* allocate_non_adaptive_freelists(size_t size);
 
   // Gets a chunk from the linear allocation block (LinAB).  If there
   // is not enough space in the LinAB, refills it.
@@ -333,9 +327,7 @@
 
  public:
   // Constructor
-  CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr,
-                           bool use_adaptive_freelists,
-                           FreeBlockDictionary<FreeChunk>::DictionaryChoice);
+  CompactibleFreeListSpace(BlockOffsetSharedArray* bs, MemRegion mr);
   // Accessors
   bool bestFitFirst() { return _fitStrategy == FreeBlockBestFitFirst; }
   FreeBlockDictionary<FreeChunk>* dictionary() const { return _dictionary; }
@@ -349,8 +341,6 @@
   // chunk exists, return NULL.
   FreeChunk* find_chunk_at_end();
 
-  bool adaptive_freelists() const { return _adaptive_freelists; }
-
   void set_collector(CMSCollector* collector) { _collector = collector; }
 
   // Support for parallelization of rescan and marking.
@@ -536,9 +526,6 @@
   void      addChunkAndRepairOffsetTable(HeapWord* chunk, size_t size,
               bool coalesced);
 
-  // Support for decisions regarding concurrent collection policy.
-  bool should_concurrent_collect() const;
-
   // Support for compaction.
   void prepare_for_compaction(CompactPoint* cp);
   void adjust_pointers();
--- a/hotspot/src/share/vm/gc/cms/concurrentMarkSweepGeneration.cpp	Wed Oct 21 17:16:02 2015 -0400
+++ b/hotspot/src/share/vm/gc/cms/concurrentMarkSweepGeneration.cpp	Thu Oct 22 08:53:13 2015 +0200
@@ -190,9 +190,7 @@
 };
 
 ConcurrentMarkSweepGeneration::ConcurrentMarkSweepGeneration(
-     ReservedSpace rs, size_t initial_byte_size,
-     CardTableRS* ct, bool use_adaptive_freelists,
-     FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) :
+     ReservedSpace rs, size_t initial_byte_size, CardTableRS* ct) :
   CardGeneration(rs, initial_byte_size, ct),
   _dilatation_factor(((double)MinChunkSize)/((double)(CollectedHeap::min_fill_size()))),
   _did_compact(false)
@@ -208,9 +206,7 @@
     _numWordsAllocated = 0;
   )
 
-  _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end),
-                                           use_adaptive_freelists,
-                                           dictionaryChoice);
+  _cmsSpace = new CompactibleFreeListSpace(_bts, MemRegion(bottom, end));
   NOT_PRODUCT(debug_cms_space = _cmsSpace;)
   _cmsSpace->_old_gen = this;
 
@@ -1312,13 +1308,6 @@
     }
     return true;
   }
-  if (_cmsSpace->should_concurrent_collect()) {
-    if (PrintGCDetails && Verbose) {
-      gclog_or_tty->print(" %s: collect because cmsSpace says so ",
-        short_name());
-    }
-    return true;
-  }
   return false;
 }
 
@@ -1766,9 +1755,8 @@
     MutexLockerEx hl(Heap_lock, safepoint_check);
     FreelistLocker fll(this);
     MutexLockerEx x(CGC_lock, safepoint_check);
-    if (_foregroundGCIsActive || !UseAsyncConcMarkSweepGC) {
-      // The foreground collector is active or we're
-      // not using asynchronous collections.  Skip this
+    if (_foregroundGCIsActive) {
+      // The foreground collector is. Skip this
       // background collection.
       assert(!_foregroundGCShouldWait, "Should be clear");
       return;
@@ -5214,9 +5202,8 @@
 
   verify_work_stacks_empty();
   // Restore evacuated mark words, if any, used for overflow list links
-  if (!CMSOverflowEarlyRestoration) {
-    restore_preserved_marks_if_any();
-  }
+  restore_preserved_marks_if_any();
+
   verify_overflow_empty();
 }
 
@@ -6186,17 +6173,8 @@
     assert(_mark_stack->isEmpty(), "post-condition (eager drainage)");
     assert(_collector->overflow_list_is_empty(),
            "overflow list was drained above");
-    // We could restore evacuated mark words, if any, used for
-    // overflow list links here because the overflow list is
-    // provably empty here. That would reduce the maximum
-    // size requirements for preserved_{oop,mark}_stack.
-    // But we'll just postpone it until we are all done
-    // so we can just stream through.
-    if (!_concurrent_precleaning && CMSOverflowEarlyRestoration) {
-      _collector->restore_preserved_marks_if_any();
-      assert(_collector->no_preserved_marks(), "No preserved marks");
-    }
-    assert(!CMSOverflowEarlyRestoration || _collector->no_preserved_marks(),
+
+    assert(_collector->no_preserved_marks(),
            "All preserved marks should have been restored above");
   }
 }
@@ -7372,14 +7350,6 @@
 
   set_freeFinger(freeFinger);
   set_freeRangeInFreeLists(freeRangeInFreeLists);
-  if (CMSTestInFreeList) {
-    if (freeRangeInFreeLists) {
-      FreeChunk* fc = (FreeChunk*) freeFinger;
-      assert(fc->is_free(), "A chunk on the free list should be free.");
-      assert(fc->size() > 0, "Free range should have a size");
-      assert(_sp->verify_chunk_in_free_list(fc), "Chunk is not in free lists");
-    }
-  }
 }
 
 // Note that the sweeper runs concurrently with mutators. Thus,
@@ -7532,12 +7502,7 @@
 
 void SweepClosure::do_already_free_chunk(FreeChunk* fc) {
   const size_t size = fc->size();
-  // Chunks that cannot be coalesced are not in the
-  // free lists.
-  if (CMSTestInFreeList && !fc->cantCoalesce()) {
-    assert(_sp->verify_chunk_in_free_list(fc),
-      "free chunk should be in free lists");
-  }
+
   // a chunk that is already free, should not have been
   // marked in the bit map
   HeapWord* const addr = (HeapWord*) fc;
@@ -7550,57 +7515,8 @@
   // See the definition of cantCoalesce().
   if (!fc->cantCoalesce()) {
     // This chunk can potentially be coalesced.
-    if (_sp->adaptive_freelists()) {
-      // All the work is done in
-      do_post_free_or_garbage_chunk(fc, size);
-    } else {  // Not adaptive free lists
-      // this is a free chunk that can potentially be coalesced by the sweeper;
-      if (!inFreeRange()) {
-        // if the next chunk is a free block that can't be coalesced
-        // it doesn't make sense to remove this chunk from the free lists
-        FreeChunk* nextChunk = (FreeChunk*)(addr + size);
-        assert((HeapWord*)nextChunk <= _sp->end(), "Chunk size out of bounds?");
-        if ((HeapWord*)nextChunk < _sp->end() &&     // There is another free chunk to the right ...
-            nextChunk->is_free()               &&     // ... which is free...
-            nextChunk->cantCoalesce()) {             // ... but can't be coalesced
-          // nothing to do
-        } else {
-          // Potentially the start of a new free range:
-          // Don't eagerly remove it from the free lists.
-          // No need to remove it if it will just be put
-          // back again.  (Also from a pragmatic point of view
-          // if it is a free block in a region that is beyond
-          // any allocated blocks, an assertion will fail)
-          // Remember the start of a free run.
-          initialize_free_range(addr, true);
-          // end - can coalesce with next chunk
-        }
-      } else {
-        // the midst of a free range, we are coalescing
-        print_free_block_coalesced(fc);
-        if (CMSTraceSweeper) {
-          gclog_or_tty->print("  -- pick up free block " PTR_FORMAT " (" SIZE_FORMAT ")\n", p2i(fc), size);
-        }
-        // remove it from the free lists
-        _sp->removeFreeChunkFromFreeLists(fc);
-        set_lastFreeRangeCoalesced(true);
-        // If the chunk is being coalesced and the current free range is
-        // in the free lists, remove the current free range so that it
-        // will be returned to the free lists in its entirety - all
-        // the coalesced pieces included.
-        if (freeRangeInFreeLists()) {
-          FreeChunk* ffc = (FreeChunk*) freeFinger();
-          assert(ffc->size() == pointer_delta(addr, freeFinger()),
-            "Size of free range is inconsistent with chunk size.");
-          if (CMSTestInFreeList) {
-            assert(_sp->verify_chunk_in_free_list(ffc),
-              "free range is not in free lists");
-          }
-          _sp->removeFreeChunkFromFreeLists(ffc);
-          set_freeRangeInFreeLists(false);
-        }
-      }
-    }
+    // All the work is done in
+    do_post_free_or_garbage_chunk(fc, size);
     // Note that if the chunk is not coalescable (the else arm
     // below), we unconditionally flush, without needing to do
     // a "lookahead," as we do below.
@@ -7626,46 +7542,11 @@
   HeapWord* const addr = (HeapWord*) fc;
   const size_t size = CompactibleFreeListSpace::adjustObjectSize(oop(addr)->size());
 
-  if (_sp->adaptive_freelists()) {
-    // Verify that the bit map has no bits marked between
-    // addr and purported end of just dead object.
-    _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size);
-
-    do_post_free_or_garbage_chunk(fc, size);
-  } else {
-    if (!inFreeRange()) {
-      // start of a new free range
-      assert(size > 0, "A free range should have a size");
-      initialize_free_range(addr, false);
-    } else {
-      // this will be swept up when we hit the end of the
-      // free range
-      if (CMSTraceSweeper) {
-        gclog_or_tty->print("  -- pick up garbage " PTR_FORMAT " (" SIZE_FORMAT ")\n", p2i(fc), size);
-      }
-      // If the chunk is being coalesced and the current free range is
-      // in the free lists, remove the current free range so that it
-      // will be returned to the free lists in its entirety - all
-      // the coalesced pieces included.
-      if (freeRangeInFreeLists()) {
-        FreeChunk* ffc = (FreeChunk*)freeFinger();
-        assert(ffc->size() == pointer_delta(addr, freeFinger()),
-          "Size of free range is inconsistent with chunk size.");
-        if (CMSTestInFreeList) {
-          assert(_sp->verify_chunk_in_free_list(ffc),
-            "free range is not in free lists");
-        }
-        _sp->removeFreeChunkFromFreeLists(ffc);
-        set_freeRangeInFreeLists(false);
-      }
-      set_lastFreeRangeCoalesced(true);
-    }
-    // this will be swept up when we hit the end of the free range
-
-    // Verify that the bit map has no bits marked between
-    // addr and purported end of just dead object.
-    _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size);
-  }
+  // Verify that the bit map has no bits marked between
+  // addr and purported end of just dead object.
+  _bitMap->verifyNoOneBitsInRange(addr + 1, addr + size);
+  do_post_free_or_garbage_chunk(fc, size);
+
   assert(_limit >= addr + size,
          "A freshly garbage chunk can't possibly straddle over _limit");
   if (inFreeRange()) lookahead_and_flush(fc, size);
@@ -7727,11 +7608,7 @@
   // do_post_free_or_garbage_chunk() should only be called in the case
   // of the adaptive free list allocator.
   const bool fcInFreeLists = fc->is_free();
-  assert(_sp->adaptive_freelists(), "Should only be used in this case.");
   assert((HeapWord*)fc <= _limit, "sweep invariant");
-  if (CMSTestInFreeList && fcInFreeLists) {
-    assert(_sp->verify_chunk_in_free_list(fc), "free chunk is not in free lists");
-  }
 
   if (CMSTraceSweeper) {
     gclog_or_tty->print_cr("  -- pick up another chunk at " PTR_FORMAT " (" SIZE_FORMAT ")", p2i(fc), chunkSize);
@@ -7784,10 +7661,6 @@
       FreeChunk* const ffc = (FreeChunk*)freeFinger();
       assert(ffc->size() == pointer_delta(fc_addr, freeFinger()),
         "Size of free range is inconsistent with chunk size.");
-      if (CMSTestInFreeList) {
-        assert(_sp->verify_chunk_in_free_list(ffc),
-          "Chunk is not in free lists");
-      }
       _sp->coalDeath(ffc->size());
       _sp->removeFreeChunkFromFreeLists(ffc);
       set_freeRangeInFreeLists(false);
@@ -7856,12 +7729,6 @@
   assert(size > 0,
     "A zero sized chunk cannot be added to the free lists.");
   if (!freeRangeInFreeLists()) {
-    if (CMSTestInFreeList) {
-      FreeChunk* fc = (FreeChunk*) chunk;
-      fc->set_size(size);
-      assert(!_sp->verify_chunk_in_free_list(fc),
-        "chunk should not be in free lists yet");
-    }
     if (CMSTraceSweeper) {
       gclog_or_tty->print_cr(" -- add free block " PTR_FORMAT " (" SIZE_FORMAT ") to free lists",
                     p2i(chunk), size);
--- a/hotspot/src/share/vm/gc/cms/concurrentMarkSweepGeneration.hpp	Wed Oct 21 17:16:02 2015 -0400
+++ b/hotspot/src/share/vm/gc/cms/concurrentMarkSweepGeneration.hpp	Thu Oct 22 08:53:13 2015 +0200
@@ -1076,10 +1076,7 @@
   void assert_correct_size_change_locking();
 
  public:
-  ConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size,
-                                CardTableRS* ct,
-                                bool use_adaptive_freelists,
-                                FreeBlockDictionary<FreeChunk>::DictionaryChoice);
+  ConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size, CardTableRS* ct);
 
   // Accessors
   CMSCollector* collector() const { return _collector; }
--- a/hotspot/src/share/vm/gc/cms/vmCMSOperations.hpp	Wed Oct 21 17:16:02 2015 -0400
+++ b/hotspot/src/share/vm/gc/cms/vmCMSOperations.hpp	Thu Oct 22 08:53:13 2015 +0200
@@ -138,7 +138,6 @@
     : VM_GC_Operation(gc_count_before, gc_cause, full_gc_count_before, true /* full */)
   {
     assert(FullGCCount_lock != NULL, "Error");
-    assert(UseAsyncConcMarkSweepGC, "Else will hang caller");
   }
   ~VM_GenCollectFullConcurrent() {}
   virtual VMOp_Type type() const { return VMOp_GenCollectFullConcurrent; }
--- a/hotspot/src/share/vm/gc/shared/generationSpec.cpp	Wed Oct 21 17:16:02 2015 -0400
+++ b/hotspot/src/share/vm/gc/shared/generationSpec.cpp	Thu Oct 22 08:53:13 2015 +0200
@@ -58,9 +58,7 @@
       // else registers with an existing CMSCollector
 
       ConcurrentMarkSweepGeneration* g = NULL;
-      g = new ConcurrentMarkSweepGeneration(rs,
-                 init_size(), remset, UseCMSAdaptiveFreeLists,
-                 (FreeBlockDictionary<FreeChunk>::DictionaryChoice)CMSDictionaryChoice);
+      g = new ConcurrentMarkSweepGeneration(rs, init_size(), remset);
 
       g->initialize_performance_counters();
 
--- a/hotspot/src/share/vm/runtime/arguments.cpp	Wed Oct 21 17:16:02 2015 -0400
+++ b/hotspot/src/share/vm/runtime/arguments.cpp	Thu Oct 22 08:53:13 2015 +0200
@@ -2469,16 +2469,6 @@
     }
   }
 
-  // Note: only executed in non-PRODUCT mode
-  if (!UseAsyncConcMarkSweepGC &&
-      (ExplicitGCInvokesConcurrent ||
-       ExplicitGCInvokesConcurrentAndUnloadsClasses)) {
-    jio_fprintf(defaultStream::error_stream(),
-                "error: +ExplicitGCInvokesConcurrent[AndUnloadsClasses] conflicts"
-                " with -UseAsyncConcMarkSweepGC");
-    status = false;
-  }
-
   if (PrintNMTStatistics) {
 #if INCLUDE_NMT
     if (MemTracker::tracking_level() == NMT_off) {
--- a/hotspot/src/share/vm/runtime/globals.hpp	Wed Oct 21 17:16:02 2015 -0400
+++ b/hotspot/src/share/vm/runtime/globals.hpp	Thu Oct 22 08:53:13 2015 +0200
@@ -1622,12 +1622,6 @@
           "Number of times to retry allocations when "                      \
           "blocked by the GC locker")                                       \
                                                                             \
-  develop(bool, UseCMSAdaptiveFreeLists, true,                              \
-          "Use adaptive free lists in the CMS generation")                  \
-                                                                            \
-  develop(bool, UseAsyncConcMarkSweepGC, true,                              \
-          "Use Asynchronous Concurrent Mark-Sweep GC in the old generation")\
-                                                                            \
   product(bool, UseCMSBestFit, true,                                        \
           "Use CMS best fit allocation strategy")                           \
                                                                             \
@@ -1822,10 +1816,6 @@
           "When CMS class unloading is enabled, the maximum CMS cycle "     \
           "count for which classes may not be unloaded")                    \
                                                                             \
-  develop(intx, CMSDictionaryChoice, 0,                                     \
-          "Use BinaryTreeDictionary as default in the CMS generation")      \
-          range(0, 2)                                                       \
-                                                                            \
   product(uintx, CMSIndexedFreeListReplenish, 4,                            \
           "Replenish an indexed free list with this number of chunks")      \
           range(1, max_uintx)                                               \
@@ -1840,9 +1830,6 @@
   product(bool, CMSLoopWarn, false,                                         \
           "Warn in case of excessive CMS looping")                          \
                                                                             \
-  develop(bool, CMSOverflowEarlyRestoration, false,                         \
-          "Restore preserved marks early")                                  \
-                                                                            \
   /* where does the range max value of (max_jint - 1) come from? */         \
   product(size_t, MarkStackSizeMax, NOT_LP64(4*M) LP64_ONLY(512*M),         \
           "Maximum size of marking stack")                                  \
@@ -2080,10 +2067,6 @@
           "unloading of classes when class unloading is enabled")           \
           range(0, 100)                                                     \
                                                                             \
-  develop(bool, CMSTestInFreeList, false,                                   \
-          "Check if the coalesced range is already in the "                 \
-          "free lists as claimed")                                          \
-                                                                            \
   notproduct(bool, CMSVerifyReturnedBytes, false,                           \
           "Check that all the garbage collected was returned to the "       \
           "free lists")                                                     \