jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp@eda078b01c65 (annotated)

src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp@eda078b01c65 (annotated)

src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp

Mon, 27 May 2013 15:22:59 +0200

author: stefank
date: Mon, 27 May 2013 15:22:59 +0200
changeset 5194: eda078b01c65
parent 4128: f81a7c0c618d
child 6198: 55fb97c4c58d
permissions: -rw-r--r--

8015268: NPG: 2.5% regression in young GC times on CRM Sales Opty
Summary: Split SystemDictionary and ClassLoaderDataGraph root processing to help load balancing.
Reviewed-by: tschatzl, johnc

 /*
  * Copyright (c) 2002, 2010, 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_IMPLEMENTATION_PARALLELSCAVENGE_PSTASKS_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_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
 // CardTableExtension::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* _gen;
   HeapWord* _gen_top;
   uint _stripe_number;
   uint _stripe_total;
  public:
   OldToYoungRootsTask(PSOldGen *gen,
                       HeapWord* gen_top,
                       uint stripe_number,
                       uint stripe_total) :
     _gen(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_IMPLEMENTATION_PARALLELSCAVENGE_PSTASKS_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp@eda078b01c65 (annotated)

src/share/vm/gc_implementation/parallelScavenge/psTasks.hpp