g1CardCounts.hpp revision 8413:92457dfb91bd 
1/*
2 * Copyright (c) 2013, 2015, 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24
25#ifndef SHARE_VM_GC_G1_G1CARDCOUNTS_HPP
26#define SHARE_VM_GC_G1_G1CARDCOUNTS_HPP
27
28#include "gc/g1/g1RegionToSpaceMapper.hpp"
29#include "memory/allocation.hpp"
30#include "memory/virtualspace.hpp"
31#include "utilities/globalDefinitions.hpp"
32
33class CardTableModRefBS;
34class G1CardCounts;
35class G1CollectedHeap;
36class G1RegionToSpaceMapper;
37class HeapRegion;
38
39class 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
55class 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  // Return the number of slots needed for a card counts table
105  // that covers mem_region_words words.
106  static size_t compute_size(size_t mem_region_size_in_words);
107
108  // Returns how many bytes of the heap a single byte of the card counts table
109  // corresponds to.
110  static size_t heap_map_factor();
111
112  void initialize(G1RegionToSpaceMapper* mapper);
113
114  // Increments the refinement count for the given card.
115  // Returns the pre-increment count value.
116  uint add_card_count(jbyte* card_ptr);
117
118  // Returns true if the given count is high enough to be considered
119  // 'hot'; false otherwise.
120  bool is_hot(uint count);
121
122  // Clears the card counts for the cards spanned by the region
123  void clear_region(HeapRegion* hr);
124
125  // Clears the card counts for the cards spanned by the MemRegion
126  void clear_range(MemRegion mr);
127
128  // Clear the entire card counts table during GC.
129  void clear_all();
130};
131
132#endif // SHARE_VM_GC_G1_G1CARDCOUNTS_HPP
133