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. 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 #include "precompiled.hpp" 26 #include "gc/g1/g1CardCounts.hpp" 27 #include "gc/g1/g1CollectedHeap.inline.hpp" 28 #include "gc/shared/cardTableModRefBS.hpp" 29 #include "services/memTracker.hpp" 30 #include "utilities/copy.hpp" 31 32 void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 33 if (zero_filled) { 34 return; 35 } 36 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords); 37 _counts->clear_range(mr); 38 } 39 40 size_t G1CardCounts::compute_size(size_t mem_region_size_in_words) { 41 // We keep card counts for every card, so the size of the card counts table must 42 // be the same as the card table. 43 return G1CardTable::compute_size(mem_region_size_in_words); 44 } 45 46 size_t G1CardCounts::heap_map_factor() { 47 // See G1CardCounts::compute_size() why we reuse the card table value. 48 return G1CardTable::heap_map_factor(); 49 } 50 51 void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) { 52 if (has_count_table()) { 53 assert(from_card_num < to_card_num, 54 "Wrong order? from: " SIZE_FORMAT ", to: " SIZE_FORMAT, 55 from_card_num, to_card_num); 56 Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num)); 57 } 58 } 59 60 G1CardCounts::G1CardCounts(G1CollectedHeap *g1h): 61 _listener(), _g1h(g1h), _card_counts(NULL), _reserved_max_card_num(0) { 62 _listener.set_cardcounts(this); 63 } 64 65 void G1CardCounts::initialize(G1RegionToSpaceMapper* mapper) { 66 assert(_g1h->max_capacity() > 0, "initialization order"); 67 assert(_g1h->capacity() == 0, "initialization order"); 68 69 if (G1ConcRSHotCardLimit > 0) { 70 // The max value we can store in the counts table is 71 // max_jubyte. Guarantee the value of the hot 72 // threshold limit is no more than this. 73 guarantee(G1ConcRSHotCardLimit <= max_jubyte, "sanity"); 74 75 _ct = _g1h->g1_card_table(); 76 _ct_bot = _ct->byte_for_const(_g1h->reserved_region().start()); 77 78 _card_counts = (jubyte*) mapper->reserved().start(); 79 _reserved_max_card_num = mapper->reserved().byte_size(); 80 mapper->set_mapping_changed_listener(&_listener); 81 } 82 } 83 84 uint G1CardCounts::add_card_count(jbyte* card_ptr) { 85 // Returns the number of times the card has been refined. 86 // If we failed to reserve/commit the counts table, return 0. 87 // If card_ptr is beyond the committed end of the counts table, 88 // return 0. 89 // Otherwise return the actual count. 90 // Unless G1ConcRSHotCardLimit has been set appropriately, 91 // returning 0 will result in the card being considered 92 // cold and will be refined immediately. 93 uint count = 0; 94 if (has_count_table()) { 95 size_t card_num = ptr_2_card_num(card_ptr); 96 assert(card_num < _reserved_max_card_num, 97 "Card " SIZE_FORMAT " outside of card counts table (max size " SIZE_FORMAT ")", 98 card_num, _reserved_max_card_num); 99 count = (uint) _card_counts[card_num]; 100 if (count < G1ConcRSHotCardLimit) { 101 _card_counts[card_num] = 102 (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit)); 103 } 104 } 105 return count; 106 } 107 108 bool G1CardCounts::is_hot(uint count) { 109 return (count >= G1ConcRSHotCardLimit); 110 } 111 112 void G1CardCounts::clear_region(HeapRegion* hr) { 113 MemRegion mr(hr->bottom(), hr->end()); 114 clear_range(mr); 115 } 116 117 void G1CardCounts::clear_range(MemRegion mr) { 118 if (has_count_table()) { 119 const jbyte* from_card_ptr = _ct->byte_for_const(mr.start()); 120 // We use the last address in the range as the range could represent the 121 // last region in the heap. In which case trying to find the card will be an 122 // OOB access to the card table. 123 const jbyte* last_card_ptr = _ct->byte_for_const(mr.last()); 124 125 #ifdef ASSERT 126 HeapWord* start_addr = _ct->addr_for(from_card_ptr); 127 assert(start_addr == mr.start(), "MemRegion start must be aligned to a card."); 128 HeapWord* last_addr = _ct->addr_for(last_card_ptr); 129 assert((last_addr + G1CardTable::card_size_in_words) == mr.end(), "MemRegion end must be aligned to a card."); 130 #endif // ASSERT 131 132 // Clear the counts for the (exclusive) card range. 133 size_t from_card_num = ptr_2_card_num(from_card_ptr); 134 size_t to_card_num = ptr_2_card_num(last_card_ptr) + 1; 135 clear_range(from_card_num, to_card_num); 136 } 137 } 138 139 class G1CardCountsClearClosure : public HeapRegionClosure { 140 private: 141 G1CardCounts* _card_counts; 142 public: 143 G1CardCountsClearClosure(G1CardCounts* card_counts) : 144 HeapRegionClosure(), _card_counts(card_counts) { } 145 146 147 virtual bool doHeapRegion(HeapRegion* r) { 148 _card_counts->clear_region(r); 149 return false; 150 } 151 }; 152 153 void G1CardCounts::clear_all() { 154 assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise"); 155 G1CardCountsClearClosure cl(this); 156 _g1h->heap_region_iterate(&cl); 157 }