jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp@e7d0505c8a30

8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: jwilhelm, brutisso

     1 /*

     2  * Copyright (c) 2001, 2012, 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.

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    23  */

    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP

    26 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP

    28 #include "gc_implementation/shared/concurrentGCThread.hpp"

    30 // The Concurrent Mark GC Thread (could be several in the future).

    31 // This is copied from the Concurrent Mark Sweep GC Thread

    32 // Still under construction.

    34 class ConcurrentMark;

    36 class ConcurrentMarkThread: public ConcurrentGCThread {

    37   friend class VMStructs;

    39   double _vtime_start;  // Initial virtual time.

    40   double _vtime_accum;  // Accumulated virtual time.

    42   double _vtime_mark_accum;

    44  public:

    45   virtual void run();

    47  private:

    48   ConcurrentMark*                  _cm;

    49   volatile bool                    _started;

    50   volatile bool                    _in_progress;

    52   void sleepBeforeNextCycle();

    54   static SurrogateLockerThread*         _slt;

    56  public:

    57   // Constructor

    58   ConcurrentMarkThread(ConcurrentMark* cm);

    60   static void makeSurrogateLockerThread(TRAPS);

    61   static SurrogateLockerThread* slt() { return _slt; }

    63   // Printing

    64   void print_on(outputStream* st) const;

    65   void print() const;

    67   // Total virtual time so far.

    68   double vtime_accum();

    69   // Marking virtual time so far

    70   double vtime_mark_accum();

    72   ConcurrentMark* cm()     { return _cm; }

    74   void set_started()       { assert(!_in_progress, "cycle in progress"); _started = true;  }

    75   void clear_started()     { assert(_in_progress, "must be starting a cycle"); _started = false; }

    76   bool started()           { return _started;  }

    78   void set_in_progress()   { assert(_started, "must be starting a cycle"); _in_progress = true;  }

    79   void clear_in_progress() { assert(!_started, "must not be starting a new cycle"); _in_progress = false; }

    80   bool in_progress()       { return _in_progress;  }

    82   // This flag returns true from the moment a marking cycle is

    83   // initiated (during the initial-mark pause when started() is set)

    84   // to the moment when the cycle completes (just after the next

    85   // marking bitmap has been cleared and in_progress() is

    86   // cleared). While this flag is true we will not start another cycle

    87   // so that cycles do not overlap. We cannot use just in_progress()

    88   // as the CM thread might take some time to wake up before noticing

    89   // that started() is set and set in_progress().

    90   bool during_cycle()      { return started() || in_progress(); }

    92   // shutdown

    93   void stop();

    94 };

    96 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP

Mercurial > jdk8-mips64-public > hotspot / file revision

src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp@e7d0505c8a30

src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp