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 package org.openjdk.bench.vm.compiler; 24 25 import org.openjdk.jmh.annotations.Benchmark; 26 import org.openjdk.jmh.annotations.BenchmarkMode; 27 import org.openjdk.jmh.annotations.Mode; 28 import org.openjdk.jmh.annotations.OutputTimeUnit; 29 import org.openjdk.jmh.annotations.Scope; 30 import org.openjdk.jmh.annotations.Setup; 31 import org.openjdk.jmh.annotations.State; 32 33 import java.util.Random; 34 import java.util.concurrent.TimeUnit; 35 36 @BenchmarkMode(Mode.AverageTime) 37 @OutputTimeUnit(TimeUnit.NANOSECONDS) 38 @State(Scope.Thread) 39 public class WriteBarrier { 40 41 // For array references 42 public static final int NUM_REFERENCES_SMALL = 32; 43 public static final int NUM_REFERENCES_LARGE = 2048; 44 45 // For array update tests 46 private Object[] theArraySmall; 47 private Object[] realReferencesSmall; 48 private Object[] nullReferencesSmall; 49 private int[] indicesSmall; 50 51 private Object[] theArrayLarge; 52 private Object[] realReferencesLarge; 53 private Object[] nullReferencesLarge; 54 private int[] indicesLarge; 55 56 // For field update tests 57 public Referencer head = null; 58 public Referencer tail = null; 59 60 // For random number generation 61 private int m_w; 62 private int m_z; 63 64 // For field references 65 public class Referencer { 66 Referencer next = null; Referencer()67 Referencer() { 68 this.next = null; 69 } append(Referencer r)70 void append(Referencer r) { 71 this.next = r; 72 } clear()73 void clear() { 74 this.next = null; 75 } 76 } 77 78 @Setup setup()79 public void setup() { 80 theArraySmall = new Object[NUM_REFERENCES_SMALL]; 81 realReferencesSmall = new Object[NUM_REFERENCES_SMALL]; 82 nullReferencesSmall = new Object[NUM_REFERENCES_SMALL]; 83 indicesSmall = new int[NUM_REFERENCES_SMALL]; 84 85 theArrayLarge = new Object[NUM_REFERENCES_LARGE]; 86 realReferencesLarge = new Object[NUM_REFERENCES_LARGE]; 87 nullReferencesLarge = new Object[NUM_REFERENCES_LARGE]; 88 indicesLarge = new int[NUM_REFERENCES_LARGE]; 89 90 m_w = (int) System.currentTimeMillis(); 91 Random random = new Random(); 92 m_z = random.nextInt(10000) + 1; 93 94 for (int i = 0; i < NUM_REFERENCES_SMALL; i++) { 95 indicesSmall[i] = get_random() % (NUM_REFERENCES_SMALL - 1); 96 realReferencesSmall[i] = new Object(); 97 } 98 99 for (int i = 0; i < NUM_REFERENCES_LARGE; i++) { 100 indicesLarge[i] = get_random() % (NUM_REFERENCES_LARGE - 1); 101 realReferencesLarge[i] = new Object(); 102 } 103 104 // Build a small linked structure 105 this.head = new Referencer(); 106 this.tail = new Referencer(); 107 this.head.append(this.tail); 108 109 // This will (hopefully) promote objects to old space 110 // Run with -XX:+DisableExplicitGC to keep 111 // objects in young space 112 System.gc(); 113 } 114 get_random()115 private int get_random() { 116 m_z = 36969 * (m_z & 65535) + (m_z >> 16); 117 m_w = 18000 * (m_w & 65535) + (m_w >> 16); 118 return Math.abs((m_z << 16) + m_w); /* 32-bit result */ 119 } 120 121 @Benchmark testArrayWriteBarrierFastPathRealSmall()122 public void testArrayWriteBarrierFastPathRealSmall() { 123 for (int i = 0; i < NUM_REFERENCES_SMALL; i++) { 124 theArraySmall[indicesSmall[NUM_REFERENCES_SMALL - i - 1]] = realReferencesSmall[indicesSmall[i]]; 125 } 126 } 127 128 @Benchmark testArrayWriteBarrierFastPathNullSmall()129 public void testArrayWriteBarrierFastPathNullSmall() { 130 for (int i = 0; i < NUM_REFERENCES_SMALL; i++) { 131 theArraySmall[indicesSmall[NUM_REFERENCES_SMALL - i - 1]] = nullReferencesSmall[indicesSmall[i]]; 132 } 133 } 134 135 @Benchmark testArrayWriteBarrierFastPathRealLarge()136 public void testArrayWriteBarrierFastPathRealLarge() { 137 for (int i = 0; i < NUM_REFERENCES_LARGE; i++) { 138 theArrayLarge[indicesLarge[NUM_REFERENCES_LARGE - i - 1]] = realReferencesLarge[indicesLarge[i]]; 139 } 140 } 141 142 @Benchmark testArrayWriteBarrierFastPathNullLarge()143 public void testArrayWriteBarrierFastPathNullLarge() { 144 for (int i = 0; i < NUM_REFERENCES_LARGE; i++) { 145 theArrayLarge[indicesLarge[NUM_REFERENCES_LARGE - i - 1]] = nullReferencesLarge[indicesLarge[i]]; 146 } 147 } 148 149 @Benchmark() testFieldWriteBarrierFastPath()150 public void testFieldWriteBarrierFastPath() { 151 // Shuffle everything around 152 this.tail.append(this.head); 153 this.head.clear(); 154 this.head.append(this.tail); 155 this.tail.clear(); 156 } 157 } 158