/* * Copyright (c) 2002, 2015, 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. * */ #ifndef SHARE_VM_GC_PARALLEL_PSTASKS_HPP #define SHARE_VM_GC_PARALLEL_PSTASKS_HPP #include "memory/allocation.hpp" #include "utilities/growableArray.hpp" // // psTasks.hpp is a collection of GCTasks used by the // parallelScavenge collector. // class GCTask; class OopClosure; class OopStack; class ObjectStartArray; class ParallelTaskTerminator; class MutableSpace; class PSOldGen; class Thread; class VMThread; // // ScavengeRootsTask // // This task scans all the roots of a given type. // // class ScavengeRootsTask : public GCTask { public: enum RootType { universe = 1, jni_handles = 2, threads = 3, object_synchronizer = 4, flat_profiler = 5, system_dictionary = 6, class_loader_data = 7, management = 8, jvmti = 9, code_cache = 10 }; private: RootType _root_type; public: ScavengeRootsTask(RootType value) : _root_type(value) {} char* name() { return (char *)"scavenge-roots-task"; } virtual void do_it(GCTaskManager* manager, uint which); }; // // ThreadRootsTask // // This task scans the roots of a single thread. This task // enables scanning of thread roots in parallel. // class ThreadRootsTask : public GCTask { private: JavaThread* _java_thread; VMThread* _vm_thread; public: ThreadRootsTask(JavaThread* root) : _java_thread(root), _vm_thread(NULL) {} ThreadRootsTask(VMThread* root) : _java_thread(NULL), _vm_thread(root) {} char* name() { return (char *)"thread-roots-task"; } virtual void do_it(GCTaskManager* manager, uint which); }; // // StealTask // // This task is used to distribute work to idle threads. // class StealTask : public GCTask { private: ParallelTaskTerminator* const _terminator; public: char* name() { return (char *)"steal-task"; } StealTask(ParallelTaskTerminator* t); ParallelTaskTerminator* terminator() { return _terminator; } virtual void do_it(GCTaskManager* manager, uint which); }; // // OldToYoungRootsTask // // This task is used to scan old to young roots in parallel // // A GC thread executing this tasks divides the generation (old gen) // into slices and takes a stripe in the slice as its part of the // work. // // +===============+ slice 0 // | stripe 0 | // +---------------+ // | stripe 1 | // +---------------+ // | stripe 2 | // +---------------+ // | stripe 3 | // +===============+ slice 1 // | stripe 0 | // +---------------+ // | stripe 1 | // +---------------+ // | stripe 2 | // +---------------+ // | stripe 3 | // +===============+ slice 2 // ... // // A task is created for each stripe. In this case there are 4 tasks // created. A GC thread first works on its stripe within slice 0 // and then moves to its stripe in the next slice until all stripes // exceed the top of the generation. Note that having fewer GC threads // than stripes works because all the tasks are executed so all stripes // will be covered. In this example if 4 tasks have been created to cover // all the stripes and there are only 3 threads, one of the threads will // get the tasks with the 4th stripe. However, there is a dependence in // PSCardTable::scavenge_contents_parallel() on the number // of tasks created. In scavenge_contents_parallel the distance // to the next stripe is calculated based on the number of tasks. // If the stripe width is ssize, a task's next stripe is at // ssize * number_of_tasks (= slice_stride). In this case after // finishing stripe 0 in slice 0, the thread finds the stripe 0 in slice1 // by adding slice_stride to the start of stripe 0 in slice 0 to get // to the start of stride 0 in slice 1. class OldToYoungRootsTask : public GCTask { private: PSOldGen* _old_gen; HeapWord* _gen_top; uint _stripe_number; uint _stripe_total; public: OldToYoungRootsTask(PSOldGen *old_gen, HeapWord* gen_top, uint stripe_number, uint stripe_total) : _old_gen(old_gen), _gen_top(gen_top), _stripe_number(stripe_number), _stripe_total(stripe_total) { } char* name() { return (char *)"old-to-young-roots-task"; } virtual void do_it(GCTaskManager* manager, uint which); }; #endif // SHARE_VM_GC_PARALLEL_PSTASKS_HPP