diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/hotspot/share/gc/g1/g1RemSetSummary.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1RemSetSummary.hpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2013, 2017, 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_G1_G1REMSETSUMMARY_HPP
+#define SHARE_VM_GC_G1_G1REMSETSUMMARY_HPP
+
+#include "utilities/globalDefinitions.hpp"
+#include "utilities/ostream.hpp"
+
+class G1RemSet;
+
+// A G1RemSetSummary manages statistical information about the G1RemSet
+
+class G1RemSetSummary VALUE_OBJ_CLASS_SPEC {
+private:
+  friend class GetRSThreadVTimeClosure;
+
+  G1RemSet* _rem_set;
+
+  size_t _num_conc_refined_cards;
+  size_t _num_processed_buf_mutator;
+  size_t _num_processed_buf_rs_threads;
+
+  size_t _num_coarsenings;
+
+  size_t _num_vtimes;
+  double* _rs_threads_vtimes;
+
+  double _sampling_thread_vtime;
+
+  void set_rs_thread_vtime(uint thread, double value);
+  void set_sampling_thread_vtime(double value) {
+    _sampling_thread_vtime = value;
+  }
+
+  // update this summary with current data from various places
+  void update();
+
+public:
+  G1RemSetSummary();
+  G1RemSetSummary(G1RemSet* remset);
+
+  ~G1RemSetSummary();
+
+  // set the counters in this summary to the values of the others
+  void set(G1RemSetSummary* other);
+  // subtract all counters from the other summary, and set them in the current
+  void subtract_from(G1RemSetSummary* other);
+
+  void print_on(outputStream* out);
+
+  double rs_thread_vtime(uint thread) const;
+
+  double sampling_thread_vtime() const {
+    return _sampling_thread_vtime;
+  }
+
+  size_t num_conc_refined_cards() const {
+    return _num_conc_refined_cards;
+  }
+
+  size_t num_processed_buf_mutator() const {
+    return _num_processed_buf_mutator;
+  }
+
+  size_t num_processed_buf_rs_threads() const {
+    return _num_processed_buf_rs_threads;
+  }
+
+  size_t num_processed_buf_total() const {
+    return num_processed_buf_mutator() + num_processed_buf_rs_threads();
+  }
+
+  size_t num_coarsenings() const {
+    return _num_coarsenings;
+  }
+};
+
+#endif // SHARE_VM_GC_G1_G1REMSETSUMMARY_HPP