--- a/src/share/vm/gc_interface/collectedHeap.hpp	Wed Mar 12 00:00:05 2014 +0100
+++ b/src/share/vm/gc_interface/collectedHeap.hpp	Tue Mar 11 18:45:59 2014 -0700
@@ -389,28 +389,21 @@
   // allocation from them and necessitating allocation of new TLABs.
   virtual void ensure_parsability(bool retire_tlabs);
 
-  // Return an estimate of the maximum allocation that could be performed
-  // without triggering any collection or expansion activity.  In a
-  // generational collector, for example, this is probably the largest
-  // allocation that could be supported (without expansion) in the youngest
-  // generation.  It is "unsafe" because no locks are taken; the result
-  // should be treated as an approximation, not a guarantee, for use in
-  // heuristic resizing decisions.
-  virtual size_t unsafe_max_alloc() = 0;
-
   // Section on thread-local allocation buffers (TLABs)
   // If the heap supports thread-local allocation buffers, it should override
   // the following methods:
   // Returns "true" iff the heap supports thread-local allocation buffers.
   // The default is "no".
-  virtual bool supports_tlab_allocation() const {
-    return false;
-  }
+  virtual bool supports_tlab_allocation() const = 0;
+
   // The amount of space available for thread-local allocation buffers.
-  virtual size_t tlab_capacity(Thread *thr) const {
-    guarantee(false, "thread-local allocation buffers not supported");
-    return 0;
-  }
+  virtual size_t tlab_capacity(Thread *thr) const = 0;
+
+  // The amount of used space for thread-local allocation buffers for the given thread.
+  virtual size_t tlab_used(Thread *thr) const = 0;
+
+  virtual size_t max_tlab_size() const;
+
   // An estimate of the maximum allocation that could be performed
   // for thread-local allocation buffers without triggering any
   // collection or expansion activity.