diff -r a7bfa4e20897 -r faa43d41b739 hotspot/src/share/vm/gc_implementation/shared/plab.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/shared/plab.hpp	Wed Apr 15 11:42:20 2015 -0400
@@ -0,0 +1,197 @@
+/*
+ * Copyright (c) 2001, 2015, 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_SHARED_PLAB_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_SHARED_PLAB_HPP
+
+#include "gc_implementation/shared/gcUtil.hpp"
+#include "memory/allocation.hpp"
+#include "runtime/atomic.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+// Forward declarations.
+class PLABStats;
+
+// A per-thread allocation buffer used during GC.
+class PLAB: public CHeapObj<mtGC> {
+protected:
+  char      head[32];
+  size_t    _word_sz;          // In HeapWord units
+  HeapWord* _bottom;
+  HeapWord* _top;
+  HeapWord* _end;           // Last allocatable address + 1
+  HeapWord* _hard_end;      // _end + AlignmentReserve
+  // In support of ergonomic sizing of PLAB's
+  size_t    _allocated;     // in HeapWord units
+  size_t    _wasted;        // in HeapWord units
+  char      tail[32];
+  static size_t AlignmentReserve;
+
+  // Force future allocations to fail and queries for contains()
+  // to return false. Returns the amount of unused space in this PLAB.
+  size_t invalidate() {
+    _end    = _hard_end;
+    size_t remaining = pointer_delta(_end, _top);  // Calculate remaining space.
+    _top    = _end;      // Force future allocations to fail.
+    _bottom = _end;      // Force future contains() queries to return false.
+    return remaining;
+  }
+
+  // Fill in remaining space with a dummy object and invalidate the PLAB. Returns
+  // the amount of remaining space.
+  size_t retire_internal();
+
+public:
+  // Initializes the buffer to be empty, but with the given "word_sz".
+  // Must get initialized with "set_buf" for an allocation to succeed.
+  PLAB(size_t word_sz);
+  virtual ~PLAB() {}
+
+  // Minimum PLAB size.
+  static size_t min_size();
+  // Maximum PLAB size.
+  static size_t max_size();
+
+  // If an allocation of the given "word_sz" can be satisfied within the
+  // buffer, do the allocation, returning a pointer to the start of the
+  // allocated block.  If the allocation request cannot be satisfied,
+  // return NULL.
+  HeapWord* allocate(size_t word_sz) {
+    HeapWord* res = _top;
+    if (pointer_delta(_end, _top) >= word_sz) {
+      _top = _top + word_sz;
+      return res;
+    } else {
+      return NULL;
+    }
+  }
+
+  // Allocate the object aligned to "alignment_in_bytes".
+  HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
+
+  // Undo the last allocation in the buffer, which is required to be of the
+  // "obj" of the given "word_sz".
+  void undo_allocation(HeapWord* obj, size_t word_sz) {
+    assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
+    assert(pointer_delta(_top, obj)     == word_sz, "Bad undo");
+    _top = obj;
+  }
+
+  // The total (word) size of the buffer, including both allocated and
+  // unallocated space.
+  size_t word_sz() { return _word_sz; }
+
+  // Should only be done if we are about to reset with a new buffer of the
+  // given size.
+  void set_word_size(size_t new_word_sz) {
+    assert(new_word_sz > AlignmentReserve, "Too small");
+    _word_sz = new_word_sz;
+  }
+
+  // The number of words of unallocated space remaining in the buffer.
+  size_t words_remaining() {
+    assert(_end >= _top, "Negative buffer");
+    return pointer_delta(_end, _top, HeapWordSize);
+  }
+
+  bool contains(void* addr) {
+    return (void*)_bottom <= addr && addr < (void*)_hard_end;
+  }
+
+  // Sets the space of the buffer to be [buf, space+word_sz()).
+  virtual void set_buf(HeapWord* buf) {
+    _bottom   = buf;
+    _top      = _bottom;
+    _hard_end = _bottom + word_sz();
+    _end      = _hard_end - AlignmentReserve;
+    assert(_end >= _top, "Negative buffer");
+    // In support of ergonomic sizing
+    _allocated += word_sz();
+  }
+
+  // Flush allocation statistics into the given PLABStats supporting ergonomic
+  // sizing of PLAB's and retire the current buffer. To be called at the end of
+  // GC.
+  void flush_and_retire_stats(PLABStats* stats);
+
+  // Fills in the unallocated portion of the buffer with a garbage object and updates
+  // statistics. To be called during GC.
+  virtual void retire();
+
+  void print() PRODUCT_RETURN;
+};
+
+// PLAB book-keeping.
+class PLABStats VALUE_OBJ_CLASS_SPEC {
+  size_t _allocated;      // Total allocated
+  size_t _wasted;         // of which wasted (internal fragmentation)
+  size_t _unused;         // Unused in last buffer
+  size_t _desired_plab_sz;// Output of filter (below), suitably trimmed and quantized
+  AdaptiveWeightedAverage
+         _filter;         // Integrator with decay
+
+  void reset() {
+    _allocated = 0;
+    _wasted    = 0;
+    _unused    = 0;
+  }
+ public:
+  PLABStats(size_t desired_plab_sz_, unsigned wt) :
+    _allocated(0),
+    _wasted(0),
+    _unused(0),
+    _desired_plab_sz(desired_plab_sz_),
+    _filter(wt)
+  { }
+
+  static const size_t min_size() {
+    return PLAB::min_size();
+  }
+
+  static const size_t max_size() {
+    return PLAB::max_size();
+  }
+
+  size_t desired_plab_sz() {
+    return _desired_plab_sz;
+  }
+
+  // Updates the current desired PLAB size. Computes the new desired PLAB size,
+  // updates _desired_plab_sz and clears sensor accumulators.
+  void adjust_desired_plab_sz(uint no_of_gc_workers);
+
+  void add_allocated(size_t v) {
+    Atomic::add_ptr(v, &_allocated);
+  }
+
+  void add_unused(size_t v) {
+    Atomic::add_ptr(v, &_unused);
+  }
+
+  void add_wasted(size_t v) {
+    Atomic::add_ptr(v, &_wasted);
+  }
+};
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_PLAB_HPP