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   // Helper routine.
  98   // Returns the number of cards that can be counted by the given committed
  99   // table size, with a maximum of the number of cards spanned by the max
 100   // capacity of the heap.
 101   size_t committed_to_card_num(size_t committed_size) {
 102     return MIN2(_reserved_max_card_num, committed_size / sizeof(jbyte));
 103   }
 104 
 105   // Clear the counts table for the given (exclusive) index range.
 106   void clear_range(size_t from_card_num, size_t to_card_num);
 107 
 108  public:
 109   G1CardCounts(G1CollectedHeap* g1h);
 110   ~G1CardCounts();
 111 
 112   void initialize();
 113 
 114   // Resize the committed space for the card counts table in
 115   // response to a resize of the committed space for the heap.
 116   void resize(size_t heap_capacity);
 117 
 118   // Increments the refinement count for the given card.
 119   // Returns the pre-increment count value.
 120   uint add_card_count(jbyte* card_ptr);
 121 
 122   // Returns true if the given count is high enough to be considered
 123   // 'hot'; false otherwise.
 124   bool is_hot(uint count);
 125 
 126   // Clears the card counts for the cards spanned by the region
 127   void clear_region(HeapRegion* hr);
 128 
 129   // Clear the entire card counts table during GC.
 130   // Updates the policy stats with the duration.
 131   void clear_all();
 132 };
 133 
 134 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP