1 /*
   2  * Copyright (c) 2013, 2014, 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 "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
  29 #include "memory/allocation.hpp"
  30 #include "runtime/virtualspace.hpp"
  31 #include "utilities/globalDefinitions.hpp"
  32 
  33 class CardTableModRefBS;
  34 class G1CardCounts;
  35 class G1CollectedHeap;
  36 class G1RegionToSpaceMapper;
  37 class HeapRegion;
  38 
  39 class G1CardCountsMappingChangedListener : public G1MappingChangedListener {
  40  private:
  41   G1CardCounts* _counts;
  42  public:
  43   void set_cardcounts(G1CardCounts* counts) { _counts = counts; }
  44 
  45   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
  46 };
  47 
  48 // Table to track the number of times a card has been refined. Once
  49 // a card has been refined a certain number of times, it is
  50 // considered 'hot' and its refinement is delayed by inserting the
  51 // card into the hot card cache. The card will then be refined when
  52 // it is evicted from the hot card cache, or when the hot card cache
  53 // is 'drained' during the next evacuation pause.
  54 
  55 class G1CardCounts: public CHeapObj<mtGC> {
  56   G1CardCountsMappingChangedListener _listener;
  57 
  58   G1CollectedHeap* _g1h;
  59 
  60   // The table of counts
  61   jubyte* _card_counts;
  62 
  63   // Max capacity of the reserved space for the counts table
  64   size_t _reserved_max_card_num;
  65 
  66   // CardTable bottom.
  67   const jbyte* _ct_bot;
  68 
  69   // Barrier set
  70   CardTableModRefBS* _ct_bs;
  71 
  72   // Returns true if the card counts table has been reserved.
  73   bool has_reserved_count_table() { return _card_counts != NULL; }
  74 
  75   // Returns true if the card counts table has been reserved and committed.
  76   bool has_count_table() {
  77     return has_reserved_count_table();
  78   }
  79 
  80   size_t ptr_2_card_num(const jbyte* card_ptr) {
  81     assert(card_ptr >= _ct_bot,
  82            err_msg("Invalid card pointer: "
  83                    "card_ptr: " PTR_FORMAT ", "
  84                    "_ct_bot: " PTR_FORMAT,
  85                    p2i(card_ptr), p2i(_ct_bot)));
  86     size_t card_num = pointer_delta(card_ptr, _ct_bot, sizeof(jbyte));
  87     assert(card_num < _reserved_max_card_num,
  88            err_msg("card pointer out of range: " PTR_FORMAT, p2i(card_ptr)));
  89     return card_num;
  90   }
  91 
  92   jbyte* card_num_2_ptr(size_t card_num) {
  93     assert(card_num < _reserved_max_card_num,
  94            err_msg("card num out of range: "SIZE_FORMAT, card_num));
  95     return (jbyte*) (_ct_bot + card_num);
  96   }
  97 
  98   // Clear the counts table for the given (exclusive) index range.
  99   void clear_range(size_t from_card_num, size_t to_card_num);
 100 
 101  public:
 102   G1CardCounts(G1CollectedHeap* g1h);
 103 
 104   void initialize(G1RegionToSpaceMapper* mapper);
 105 
 106   // Increments the refinement count for the given card.
 107   // Returns the pre-increment count value.
 108   uint add_card_count(jbyte* card_ptr);
 109 
 110   // Returns true if the given count is high enough to be considered
 111   // 'hot'; false otherwise.
 112   bool is_hot(uint count);
 113 
 114   // Clears the card counts for the cards spanned by the region
 115   void clear_region(HeapRegion* hr);
 116 
 117   // Clears the card counts for the cards spanned by the MemRegion
 118   void clear_range(MemRegion mr);
 119 
 120   // Clear the entire card counts table during GC.
 121   void clear_all();
 122 };
 123 
 124 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP