1 /*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23 /*
24 * To change this template, choose Tools | Templates
25 * and open the template in the editor.
26 */
27
28 package org.openjdk.bench.vm.compiler;
29
30 import org.openjdk.jmh.annotations.Benchmark;
31 import org.openjdk.jmh.annotations.BenchmarkMode;
32 import org.openjdk.jmh.annotations.Mode;
33 import org.openjdk.jmh.annotations.OutputTimeUnit;
34 import org.openjdk.jmh.annotations.Scope;
35 import org.openjdk.jmh.annotations.Setup;
36 import org.openjdk.jmh.annotations.State;
37
38 import java.util.Random;
39 import java.util.concurrent.TimeUnit;
40
41 @BenchmarkMode(Mode.AverageTime)
42 @OutputTimeUnit(TimeUnit.NANOSECONDS)
43 @State(Scope.Thread)
44 public class WriteBarrier {
45
46 // For array references
47 public static final int NUM_REFERENCES_SMALL = 32;
48 public static final int NUM_REFERENCES_LARGE = 2048;
49
50 // For array update tests
51 private Object[] theArraySmall;
52 private Object[] realReferencesSmall;
53 private Object[] nullReferencesSmall;
54 private int[] indicesSmall;
55
56 private Object[] theArrayLarge;
57 private Object[] realReferencesLarge;
58 private Object[] nullReferencesLarge;
59 private int[] indicesLarge;
60
61 // For field update tests
62 public Referencer head = null;
63 public Referencer tail = null;
64
65 // For random number generation
66 private int m_w;
67 private int m_z;
68
69 // For field references
70 public class Referencer {
71 Referencer next = null;
72 Referencer() {
73 this.next = null;
74 }
75 void append(Referencer r) {
76 this.next = r;
77 }
78 void clear() {
79 this.next = null;
80 }
81 }
82
83 @Setup
84 public void setup() {
85 theArraySmall = new Object[NUM_REFERENCES_SMALL];
86 realReferencesSmall = new Object[NUM_REFERENCES_SMALL];
87 nullReferencesSmall = new Object[NUM_REFERENCES_SMALL];
88 indicesSmall = new int[NUM_REFERENCES_SMALL];
89
90 theArrayLarge = new Object[NUM_REFERENCES_LARGE];
91 realReferencesLarge = new Object[NUM_REFERENCES_LARGE];
92 nullReferencesLarge = new Object[NUM_REFERENCES_LARGE];
93 indicesLarge = new int[NUM_REFERENCES_LARGE];
94
95 m_w = (int) System.currentTimeMillis();
96 Random random = new Random();
97 m_z = random.nextInt(10000) + 1;
98
99 for (int i = 0; i < NUM_REFERENCES_SMALL; i++) {
100 indicesSmall[i] = get_random() % (NUM_REFERENCES_SMALL - 1);
101 realReferencesSmall[i] = new Object();
102 }
103
104 for (int i = 0; i < NUM_REFERENCES_LARGE; i++) {
105 indicesLarge[i] = get_random() % (NUM_REFERENCES_LARGE - 1);
106 realReferencesLarge[i] = new Object();
107 }
108
109 // Build a small linked structure
110 this.head = new Referencer();
111 this.tail = new Referencer();
112 this.head.append(this.tail);
113
114 // This will (hopefully) promote objects to old space
115 // Run with -XX:+DisableExplicitGC to keep
116 // objects in young space
117 System.gc();
118 }
119
120 private int get_random() {
121 m_z = 36969 * (m_z & 65535) + (m_z >> 16);
122 m_w = 18000 * (m_w & 65535) + (m_w >> 16);
123 return Math.abs((m_z << 16) + m_w); /* 32-bit result */
124 }
125
126 @Benchmark
127 public void testArrayWriteBarrierFastPathRealSmall() {
128 for (int i = 0; i < NUM_REFERENCES_SMALL; i++) {
129 theArraySmall[indicesSmall[NUM_REFERENCES_SMALL - i - 1]] = realReferencesSmall[indicesSmall[i]];
130 }
131 }
132
133 @Benchmark
134 public void testArrayWriteBarrierFastPathNullSmall() {
135 for (int i = 0; i < NUM_REFERENCES_SMALL; i++) {
136 theArraySmall[indicesSmall[NUM_REFERENCES_SMALL - i - 1]] = nullReferencesSmall[indicesSmall[i]];
137 }
138 }
139
140 @Benchmark
141 public void testArrayWriteBarrierFastPathRealLarge() {
142 for (int i = 0; i < NUM_REFERENCES_LARGE; i++) {
143 theArrayLarge[indicesLarge[NUM_REFERENCES_LARGE - i - 1]] = realReferencesLarge[indicesLarge[i]];
144 }
145 }
146
147 @Benchmark
148 public void testArrayWriteBarrierFastPathNullLarge() {
149 for (int i = 0; i < NUM_REFERENCES_LARGE; i++) {
150 theArrayLarge[indicesLarge[NUM_REFERENCES_LARGE - i - 1]] = nullReferencesLarge[indicesLarge[i]];
151 }
152 }
153
154 @Benchmark()
155 public void testFieldWriteBarrierFastPath() {
156 // Shuffle everything around
157 this.tail.append(this.head);
158 this.head.clear();
159 this.head.append(this.tail);
160 this.tail.clear();
161 }
162 }