--- /dev/null	2019-01-28 17:45:20.000000000 +0800
+++ new/src/share/vm/gc_implementation/g1/g1IHOPControl.hpp	2019-01-28 17:45:19.000000000 +0800
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2015, 2019, 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_G1IHOPCONTROL_HPP
+#define SHARE_VM_GC_G1_G1IHOPCONTROL_HPP
+
+#include "memory/allocation.hpp"
+#include "utilities/numberSeq.hpp"
+
+class G1NewTracer;
+
+// Base class for algorithms that calculate the heap occupancy at which
+// concurrent marking should start. This heap usage threshold should be relative
+// to old gen size.
+class G1IHOPControl : public CHeapObj<mtGC> {
+ protected:
+  // The initial IHOP value relative to the target occupancy.
+  double _initial_ihop_percent;
+  // The target maximum occupancy of the heap. The target occupancy is the number
+  // of bytes when marking should be finished and reclaim started.
+  size_t _target_occupancy;
+
+  // Most recent complete mutator allocation period in seconds.
+  double _last_allocation_time_s;
+  // Amount of bytes allocated during _last_allocation_time_s.
+  size_t _last_allocated_bytes;
+
+  // Initialize an instance with the initial IHOP value in percent. The target
+  // occupancy will be updated at the first heap expansion.
+  G1IHOPControl(double initial_ihop_percent);
+
+  // Most recent time from the end of the initial mark to the start of the first
+  // mixed gc.
+  virtual double last_marking_length_s() const = 0;
+ public:
+  virtual ~G1IHOPControl() { }
+
+  // Get the current non-young occupancy at which concurrent marking should start.
+  virtual size_t get_conc_mark_start_threshold() = 0;
+
+  // Adjust target occupancy.
+  virtual void update_target_occupancy(size_t new_target_occupancy);
+  // Update information about time during which allocations in the Java heap occurred,
+  // how large these allocations were in bytes, and an additional buffer.
+  // The allocations should contain any amount of space made unusable for further
+  // allocation, e.g. any waste caused by TLAB allocation, space at the end of
+  // humongous objects that can not be used for allocation, etc.
+  // Together with the target occupancy, this additional buffer should contain the
+  // difference between old gen size and total heap size at the start of reclamation,
+  // and space required for that reclamation.
+  virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size);
+  // Update the time spent in the mutator beginning from the end of initial mark to
+  // the first mixed gc.
+  virtual void update_marking_length(double marking_length_s) = 0;
+
+  virtual void print();
+  virtual void send_trace_event(G1NewTracer* tracer);
+};
+
+// The returned concurrent mark starting occupancy threshold is a fixed value
+// relative to the maximum heap size.
+class G1StaticIHOPControl : public G1IHOPControl {
+  // Most recent mutator time between the end of initial mark to the start of the
+  // first mixed gc.
+  double _last_marking_length_s;
+ protected:
+  double last_marking_length_s() const { return _last_marking_length_s; }
+ public:
+  G1StaticIHOPControl(double ihop_percent);
+
+  size_t get_conc_mark_start_threshold() {
+    guarantee(_target_occupancy > 0, "Target occupancy must have been initialized.");
+    return (size_t) (_initial_ihop_percent * _target_occupancy / 100.0);
+  }
+
+  virtual void update_marking_length(double marking_length_s) {
+   assert(marking_length_s > 0.0, "Marking length must be larger than zero.");
+    _last_marking_length_s = marking_length_s;
+  }
+};
+#endif // SHARE_VM_GC_G1_G1IHOPCONTROL_HPP