--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/gtest/gc/g1/test_g1IHOPControl.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,149 @@
+/*
+ * Copyright (c) 2016, 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.
+ */
+
+#include "precompiled.hpp"
+#include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/g1IHOPControl.hpp"
+#include "gc/g1/g1Predictions.hpp"
+#include "unittest.hpp"
+
+static void test_update(G1IHOPControl* ctrl, double alloc_time,
+                        size_t alloc_amount, size_t young_size,
+                        double mark_time) {
+  for (int i = 0; i < 100; i++) {
+    ctrl->update_allocation_info(alloc_time, alloc_amount, young_size);
+    ctrl->update_marking_length(mark_time);
+  }
+}
+
+// @requires UseG1GC
+TEST_VM(G1StaticIHOPControl, simple) {
+  // Test requires G1
+  if (!UseG1GC) {
+    return;
+  }
+
+  const size_t initial_ihop = 45;
+
+  G1StaticIHOPControl ctrl(initial_ihop);
+  ctrl.update_target_occupancy(100);
+
+  size_t threshold = ctrl.get_conc_mark_start_threshold();
+  EXPECT_EQ(initial_ihop, threshold);
+
+  ctrl.update_allocation_info(100.0, 100, 100);
+  threshold = ctrl.get_conc_mark_start_threshold();
+  EXPECT_EQ(initial_ihop, threshold);
+
+  ctrl.update_marking_length(1000.0);
+  threshold = ctrl.get_conc_mark_start_threshold();
+  EXPECT_EQ(initial_ihop, threshold);
+
+  // Whatever we pass, the IHOP value must stay the same.
+  test_update(&ctrl, 2, 10, 10, 3);
+  threshold = ctrl.get_conc_mark_start_threshold();
+
+  EXPECT_EQ(initial_ihop, threshold);
+
+  test_update(&ctrl, 12, 10, 10, 3);
+  threshold = ctrl.get_conc_mark_start_threshold();
+
+  EXPECT_EQ(initial_ihop, threshold);
+}
+
+// @requires UseG1GC
+TEST_VM(G1AdaptiveIHOPControl, simple) {
+  // Test requires G1
+  if (!UseG1GC) {
+    return;
+  }
+
+  const size_t initial_threshold = 45;
+  const size_t young_size = 10;
+  const size_t target_size = 100;
+
+  // The final IHOP value is always
+  // target_size - (young_size + alloc_amount/alloc_time * marking_time)
+
+  G1Predictions pred(0.95);
+  G1AdaptiveIHOPControl ctrl(initial_threshold, &pred, 0, 0);
+  ctrl.update_target_occupancy(target_size);
+
+  // First "load".
+  const size_t alloc_time1 = 2;
+  const size_t alloc_amount1 = 10;
+  const size_t marking_time1 = 2;
+  const size_t settled_ihop1 = target_size
+          - (young_size + alloc_amount1 / alloc_time1 * marking_time1);
+
+  size_t threshold;
+  threshold = ctrl.get_conc_mark_start_threshold();
+
+  EXPECT_EQ(initial_threshold, threshold);
+
+  for (size_t i = 0; i < G1AdaptiveIHOPNumInitialSamples - 1; i++) {
+    ctrl.update_allocation_info(alloc_time1, alloc_amount1, young_size);
+    ctrl.update_marking_length(marking_time1);
+    // Not enough data yet.
+    threshold = ctrl.get_conc_mark_start_threshold();
+
+    ASSERT_EQ(initial_threshold, threshold) << "on step " << i;
+  }
+
+  test_update(&ctrl, alloc_time1, alloc_amount1, young_size, marking_time1);
+
+  threshold = ctrl.get_conc_mark_start_threshold();
+
+  EXPECT_EQ(settled_ihop1, threshold);
+
+  // Second "load". A bit higher allocation rate.
+  const size_t alloc_time2 = 2;
+  const size_t alloc_amount2 = 30;
+  const size_t marking_time2 = 2;
+  const size_t settled_ihop2 = target_size
+          - (young_size + alloc_amount2 / alloc_time2 * marking_time2);
+
+  test_update(&ctrl, alloc_time2, alloc_amount2, young_size, marking_time2);
+
+  threshold = ctrl.get_conc_mark_start_threshold();
+
+  EXPECT_LT(threshold, settled_ihop1);
+
+  // Third "load". Very high (impossible) allocation rate.
+  const size_t alloc_time3 = 1;
+  const size_t alloc_amount3 = 50;
+  const size_t marking_time3 = 2;
+  const size_t settled_ihop3 = 0;
+
+  test_update(&ctrl, alloc_time3, alloc_amount3, young_size, marking_time3);
+  threshold = ctrl.get_conc_mark_start_threshold();
+
+  EXPECT_EQ(settled_ihop3, threshold);
+
+  // And back to some arbitrary value.
+  test_update(&ctrl, alloc_time2, alloc_amount2, young_size, marking_time2);
+
+  threshold = ctrl.get_conc_mark_start_threshold();
+
+  EXPECT_GT(threshold, settled_ihop3);
+}