1 /* 2 * Copyright (c) 2002, 2015, 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 25 #ifndef SHARE_VM_GC_PARALLEL_PSTASKS_HPP 26 #define SHARE_VM_GC_PARALLEL_PSTASKS_HPP 27 28 #include "memory/allocation.hpp" 29 #include "utilities/growableArray.hpp" 30 31 // 32 // psTasks.hpp is a collection of GCTasks used by the 33 // parallelScavenge collector. 34 // 35 36 class GCTask; 37 class OopClosure; 38 class OopStack; 39 class ObjectStartArray; 40 class ParallelTaskTerminator; 41 class MutableSpace; 42 class PSOldGen; 43 class Thread; 44 class VMThread; 45 46 // 47 // ScavengeRootsTask 48 // 49 // This task scans all the roots of a given type. 50 // 51 // 52 53 class ScavengeRootsTask : public GCTask { 54 public: 55 enum RootType { 56 universe = 1, 57 jni_handles = 2, 58 threads = 3, 59 object_synchronizer = 4, 60 flat_profiler = 5, 61 system_dictionary = 6, 62 class_loader_data = 7, 63 management = 8, 64 jvmti = 9, 65 code_cache = 10 66 }; 67 private: 68 RootType _root_type; 69 public: 70 ScavengeRootsTask(RootType value) : _root_type(value) {} 71 72 char* name() { return (char *)"scavenge-roots-task"; } 73 74 virtual void do_it(GCTaskManager* manager, uint which); 75 }; 76 77 // 78 // ThreadRootsTask 79 // 80 // This task scans the roots of a single thread. This task 81 // enables scanning of thread roots in parallel. 82 // 83 84 class ThreadRootsTask : public GCTask { 85 private: 86 JavaThread* _java_thread; 87 VMThread* _vm_thread; 88 public: 89 ThreadRootsTask(JavaThread* root) : _java_thread(root), _vm_thread(NULL) {} 90 ThreadRootsTask(VMThread* root) : _java_thread(NULL), _vm_thread(root) {} 91 92 char* name() { return (char *)"thread-roots-task"; } 93 94 virtual void do_it(GCTaskManager* manager, uint which); 95 }; 96 97 // 98 // StealTask 99 // 100 // This task is used to distribute work to idle threads. 101 // 102 103 class StealTask : public GCTask { 104 private: 105 ParallelTaskTerminator* const _terminator; 106 public: 107 char* name() { return (char *)"steal-task"; } 108 109 StealTask(ParallelTaskTerminator* t); 110 111 ParallelTaskTerminator* terminator() { return _terminator; } 112 113 virtual void do_it(GCTaskManager* manager, uint which); 114 }; 115 116 // 117 // OldToYoungRootsTask 118 // 119 // This task is used to scan old to young roots in parallel 120 // 121 // A GC thread executing this tasks divides the generation (old gen) 122 // into slices and takes a stripe in the slice as its part of the 123 // work. 124 // 125 // +===============+ slice 0 126 // | stripe 0 | 127 // +---------------+ 128 // | stripe 1 | 129 // +---------------+ 130 // | stripe 2 | 131 // +---------------+ 132 // | stripe 3 | 133 // +===============+ slice 1 134 // | stripe 0 | 135 // +---------------+ 136 // | stripe 1 | 137 // +---------------+ 138 // | stripe 2 | 139 // +---------------+ 140 // | stripe 3 | 141 // +===============+ slice 2 142 // ... 143 // 144 // A task is created for each stripe. In this case there are 4 tasks 145 // created. A GC thread first works on its stripe within slice 0 146 // and then moves to its stripe in the next slice until all stripes 147 // exceed the top of the generation. Note that having fewer GC threads 148 // than stripes works because all the tasks are executed so all stripes 149 // will be covered. In this example if 4 tasks have been created to cover 150 // all the stripes and there are only 3 threads, one of the threads will 151 // get the tasks with the 4th stripe. However, there is a dependence in 152 // PSCardTable::scavenge_contents_parallel() on the number 153 // of tasks created. In scavenge_contents_parallel the distance 154 // to the next stripe is calculated based on the number of tasks. 155 // If the stripe width is ssize, a task's next stripe is at 156 // ssize * number_of_tasks (= slice_stride). In this case after 157 // finishing stripe 0 in slice 0, the thread finds the stripe 0 in slice1 158 // by adding slice_stride to the start of stripe 0 in slice 0 to get 159 // to the start of stride 0 in slice 1. 160 161 class OldToYoungRootsTask : public GCTask { 162 private: 163 PSOldGen* _old_gen; 164 HeapWord* _gen_top; 165 uint _stripe_number; 166 uint _stripe_total; 167 168 public: 169 OldToYoungRootsTask(PSOldGen *old_gen, 170 HeapWord* gen_top, 171 uint stripe_number, 172 uint stripe_total) : 173 _old_gen(old_gen), 174 _gen_top(gen_top), 175 _stripe_number(stripe_number), 176 _stripe_total(stripe_total) { } 177 178 char* name() { return (char *)"old-to-young-roots-task"; } 179 180 virtual void do_it(GCTaskManager* manager, uint which); 181 }; 182 183 #endif // SHARE_VM_GC_PARALLEL_PSTASKS_HPP