1 /*

     2  * Copyright (c) 2016, 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_G1_G1HEAPSIZINGPOLICY_HPP

    26 #define SHARE_VM_GC_G1_G1HEAPSIZINGPOLICY_HPP

    27 

    28 #include "memory/allocation.hpp"

    29 

    30 class G1Analytics;

    31 class G1CollectedHeap;

    32 

    33 class G1HeapSizingPolicy: public CHeapObj<mtGC> {

    34   // MinOverThresholdForGrowth must be less than the number of recorded

    35   // pause times in G1Analytics, representing the minimum number of pause

    36   // time ratios that exceed GCTimeRatio before a heap expansion will be triggered.

    37   const static uint MinOverThresholdForGrowth = 4;

    38 

    39   const G1CollectedHeap* _g1;

    40   const G1Analytics* _analytics;

    41 

    42   const uint _num_prev_pauses_for_heuristics;

    43   // Ratio check data for determining if heap growth is necessary.

    44   uint _ratio_over_threshold_count;

    45   double _ratio_over_threshold_sum;

    46   uint _pauses_since_start;

    47 

    48 

    49 protected:

    50   G1HeapSizingPolicy(const G1CollectedHeap* g1, const G1Analytics* analytics);

    51 public:

    52 

    53   // If an expansion would be appropriate, because recent GC overhead had

    54   // exceeded the desired limit, return an amount to expand by.

    55   virtual size_t expansion_amount();

    56 

    57   // Clear ratio tracking data used by expansion_amount().

    58   void clear_ratio_check_data();

    59 

    60   static G1HeapSizingPolicy* create(const G1CollectedHeap* g1, const G1Analytics* analytics);

    61 };

    62 

    63 #endif // SRC_SHARE_VM_GC_G1_G1HEAPSIZINGPOLICY_HPP