1/* 2 * Copyright (c) 2002, 2017, 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 36class GCTask; 37class OopClosure; 38class OopStack; 39class ObjectStartArray; 40class ParallelTaskTerminator; 41class MutableSpace; 42class PSOldGen; 43class Thread; 44class VMThread; 45 46// 47// ScavengeRootsTask 48// 49// This task scans all the roots of a given type. 50// 51// 52 53class ScavengeRootsTask : public GCTask { 54 public: 55 enum RootType { 56 universe = 1, 57 jni_handles = 2, 58 threads = 3, 59 object_synchronizer = 4, 60 system_dictionary = 5, 61 class_loader_data = 6, 62 management = 7, 63 jvmti = 8, 64 code_cache = 9 65 }; 66 private: 67 RootType _root_type; 68 public: 69 ScavengeRootsTask(RootType value) : _root_type(value) {} 70 71 char* name() { return (char *)"scavenge-roots-task"; } 72 73 virtual void do_it(GCTaskManager* manager, uint which); 74}; 75 76// 77// ThreadRootsTask 78// 79// This task scans the roots of a single thread. This task 80// enables scanning of thread roots in parallel. 81// 82 83class ThreadRootsTask : public GCTask { 84 private: 85 JavaThread* _java_thread; 86 VMThread* _vm_thread; 87 public: 88 ThreadRootsTask(JavaThread* root) : _java_thread(root), _vm_thread(NULL) {} 89 ThreadRootsTask(VMThread* root) : _java_thread(NULL), _vm_thread(root) {} 90 91 char* name() { return (char *)"thread-roots-task"; } 92 93 virtual void do_it(GCTaskManager* manager, uint which); 94}; 95 96// 97// StealTask 98// 99// This task is used to distribute work to idle threads. 100// 101 102class StealTask : public GCTask { 103 private: 104 ParallelTaskTerminator* const _terminator; 105 public: 106 char* name() { return (char *)"steal-task"; } 107 108 StealTask(ParallelTaskTerminator* t); 109 110 ParallelTaskTerminator* terminator() { return _terminator; } 111 112 virtual void do_it(GCTaskManager* manager, uint which); 113}; 114 115// 116// OldToYoungRootsTask 117// 118// This task is used to scan old to young roots in parallel 119// 120// A GC thread executing this tasks divides the generation (old gen) 121// into slices and takes a stripe in the slice as its part of the 122// work. 123// 124// +===============+ slice 0 125// | stripe 0 | 126// +---------------+ 127// | stripe 1 | 128// +---------------+ 129// | stripe 2 | 130// +---------------+ 131// | stripe 3 | 132// +===============+ slice 1 133// | stripe 0 | 134// +---------------+ 135// | stripe 1 | 136// +---------------+ 137// | stripe 2 | 138// +---------------+ 139// | stripe 3 | 140// +===============+ slice 2 141// ... 142// 143// A task is created for each stripe. In this case there are 4 tasks 144// created. A GC thread first works on its stripe within slice 0 145// and then moves to its stripe in the next slice until all stripes 146// exceed the top of the generation. Note that having fewer GC threads 147// than stripes works because all the tasks are executed so all stripes 148// will be covered. In this example if 4 tasks have been created to cover 149// all the stripes and there are only 3 threads, one of the threads will 150// get the tasks with the 4th stripe. However, there is a dependence in 151// CardTableExtension::scavenge_contents_parallel() on the number 152// of tasks created. In scavenge_contents_parallel the distance 153// to the next stripe is calculated based on the number of tasks. 154// If the stripe width is ssize, a task's next stripe is at 155// ssize * number_of_tasks (= slice_stride). In this case after 156// finishing stripe 0 in slice 0, the thread finds the stripe 0 in slice1 157// by adding slice_stride to the start of stripe 0 in slice 0 to get 158// to the start of stride 0 in slice 1. 159 160class OldToYoungRootsTask : public GCTask { 161 private: 162 PSOldGen* _old_gen; 163 HeapWord* _gen_top; 164 uint _stripe_number; 165 uint _stripe_total; 166 167 public: 168 OldToYoungRootsTask(PSOldGen *old_gen, 169 HeapWord* gen_top, 170 uint stripe_number, 171 uint stripe_total) : 172 _old_gen(old_gen), 173 _gen_top(gen_top), 174 _stripe_number(stripe_number), 175 _stripe_total(stripe_total) { } 176 177 char* name() { return (char *)"old-to-young-roots-task"; } 178 179 virtual void do_it(GCTaskManager* manager, uint which); 180}; 181 182#endif // SHARE_VM_GC_PARALLEL_PSTASKS_HPP 183