1 /*

     2  * Copyright (c) 2013, 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_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP

    26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP

    27 

    28 #include "memory/allocation.hpp"

    29 #include "runtime/virtualspace.hpp"

    30 #include "utilities/globalDefinitions.hpp"

    31 

    32 class CardTableModRefBS;

    33 class G1CollectedHeap;

    34 class HeapRegion;

    35 

    36 // Table to track the number of times a card has been refined. Once

    37 // a card has been refined a certain number of times, it is

    38 // considered 'hot' and its refinement is delayed by inserting the

    39 // card into the hot card cache. The card will then be refined when

    40 // it is evicted from the hot card cache, or when the hot card cache

    41 // is 'drained' during the next evacuation pause.

    42 

    43 class G1CardCounts: public CHeapObj<mtGC> {

    44   G1CollectedHeap* _g1h;

    45 

    46   // The table of counts

    47   jubyte* _card_counts;

    48 

    49   // Max capacity of the reserved space for the counts table

    50   size_t _reserved_max_card_num;

    51 

    52   // Max capacity of the committed space for the counts table

    53   size_t _committed_max_card_num;

    54 

    55   // Size of committed space for the counts table

    56   size_t _committed_size;

    57 

    58   // CardTable bottom.

    59   const jbyte* _ct_bot;

    60 

    61   // Barrier set

    62   CardTableModRefBS* _ct_bs;

    63 

    64   // The virtual memory backing the counts table

    65   VirtualSpace _card_counts_storage;

    66 

    67   // Returns true if the card counts table has been reserved.

    68   bool has_reserved_count_table() { return _card_counts != NULL; }

    69 

    70   // Returns true if the card counts table has been reserved and committed.

    71   bool has_count_table() {

    72     return has_reserved_count_table() && _committed_max_card_num > 0;

    73   }

    74 

    75   void check_card_num(size_t card_num, const char* msg) {

    76     assert(card_num >= 0 && card_num < _committed_max_card_num, msg);

    77   }

    78 

    79   size_t ptr_2_card_num(const jbyte* card_ptr) {

    80     assert(card_ptr >= _ct_bot,

    81            err_msg("Inavalied card pointer: "

    82                    "card_ptr: " PTR_FORMAT ", "

    83                    "_ct_bot: " PTR_FORMAT,

    84                    card_ptr, _ct_bot));

    85     size_t card_num = pointer_delta(card_ptr, _ct_bot, sizeof(jbyte));

    86     check_card_num(card_num,

    87                    err_msg("card pointer out of range: " PTR_FORMAT, card_ptr));

    88     return card_num;

    89   }

    90 

    91   jbyte* card_num_2_ptr(size_t card_num) {

    92     check_card_num(card_num,

    93                    err_msg("card num out of range: "SIZE_FORMAT, card_num));

    94     return (jbyte*) (_ct_bot + card_num);

    95   }

    96 

    97   // Clear the counts table for the given (exclusive) index range.

    98   void clear_range(size_t from_card_num, size_t to_card_num);

    99 

   100  public:

   101   G1CardCounts(G1CollectedHeap* g1h);

   102   ~G1CardCounts();

   103 

   104   void initialize();

   105 

   106   // Resize the committed space for the card counts table in

   107   // response to a resize of the committed space for the heap.

   108   void resize(size_t heap_capacity);

   109 

   110   // Increments the refinement count for the given card.

   111   // Returns the pre-increment count value.

   112   uint add_card_count(jbyte* card_ptr);

   113 

   114   // Returns true if the given count is high enough to be considered

   115   // 'hot'; false otherwise.

   116   bool is_hot(uint count);

   117 

   118   // Clears the card counts for the cards spanned by the region

   119   void clear_region(HeapRegion* hr);

   120 

   121   // Clear the entire card counts table during GC.

   122   // Updates the policy stats with the duration.

   123   void clear_all();

   124 };

   125 

   126 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP