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/g1/g1CollectorPolicy.hpp" 29 #include "gc/g1/g1GCPhaseTimes.hpp" 30 #include "gc/shared/cardTableModRefBS.hpp" 31 #include "services/memTracker.hpp" 32 #include "utilities/copy.hpp" 33 34 void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 35 if (zero_filled) { 36 return; 37 } 38 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords); 39 _counts->clear_range(mr); 40 } 41 42 size_t G1CardCounts::compute_size(size_t mem_region_size_in_words) { 43 // We keep card counts for every card, so the size of the card counts table must 44 // be the same as the card table. 45 return G1SATBCardTableLoggingModRefBS::compute_size(mem_region_size_in_words); 46 } 47 48 size_t G1CardCounts::heap_map_factor() { 49 // See G1CardCounts::compute_size() why we reuse the card table value. 50 return G1SATBCardTableLoggingModRefBS::heap_map_factor(); 51 } 52 53 void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) { 54 if (has_count_table()) { 55 assert(from_card_num < to_card_num, 56 "Wrong order? from: " SIZE_FORMAT ", to: " SIZE_FORMAT, 57 from_card_num, to_card_num); 58 Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num)); 59 } 60 } 61 62 G1CardCounts::G1CardCounts(G1CollectedHeap *g1h): 63 _listener(), _g1h(g1h), _card_counts(NULL), _reserved_max_card_num(0) { 64 _listener.set_cardcounts(this); 65 } 66 67 void G1CardCounts::initialize(G1RegionToSpaceMapper* mapper) { 68 assert(_g1h->max_capacity() > 0, "initialization order"); 69 assert(_g1h->capacity() == 0, "initialization order"); 70 71 if (G1ConcRSHotCardLimit > 0) { 72 // The max value we can store in the counts table is 73 // max_jubyte. Guarantee the value of the hot 74 // threshold limit is no more than this. 75 guarantee(G1ConcRSHotCardLimit <= max_jubyte, "sanity"); 76 77 _ct_bs = _g1h->g1_barrier_set(); 78 _ct_bot = _ct_bs->byte_for_const(_g1h->reserved_region().start()); 79 80 _card_counts = (jubyte*) mapper->reserved().start(); 81 _reserved_max_card_num = mapper->reserved().byte_size(); 82 mapper->set_mapping_changed_listener(&_listener); 83 } 84 } 85 86 uint G1CardCounts::add_card_count(jbyte* card_ptr) { 87 // Returns the number of times the card has been refined. 88 // If we failed to reserve/commit the counts table, return 0. 89 // If card_ptr is beyond the committed end of the counts table, 90 // return 0. 91 // Otherwise return the actual count. 92 // Unless G1ConcRSHotCardLimit has been set appropriately, 93 // returning 0 will result in the card being considered 94 // cold and will be refined immediately. 95 uint count = 0; 96 if (has_count_table()) { 97 size_t card_num = ptr_2_card_num(card_ptr); 98 assert(card_num < _reserved_max_card_num, 99 "Card " SIZE_FORMAT " outside of card counts table (max size " SIZE_FORMAT ")", 100 card_num, _reserved_max_card_num); 101 count = (uint) _card_counts[card_num]; 102 if (count < G1ConcRSHotCardLimit) { 103 _card_counts[card_num] = 104 (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit)); 105 } 106 } 107 return count; 108 } 109 110 bool G1CardCounts::is_hot(uint count) { 111 return (count >= G1ConcRSHotCardLimit); 112 } 113 114 void G1CardCounts::clear_region(HeapRegion* hr) { 115 MemRegion mr(hr->bottom(), hr->end()); 116 clear_range(mr); 117 } 118 119 void G1CardCounts::clear_range(MemRegion mr) { 120 if (has_count_table()) { 121 const jbyte* from_card_ptr = _ct_bs->byte_for_const(mr.start()); 122 // We use the last address in the range as the range could represent the 123 // last region in the heap. In which case trying to find the card will be an 124 // OOB access to the card table. 125 const jbyte* last_card_ptr = _ct_bs->byte_for_const(mr.last()); 126 127 #ifdef ASSERT 128 HeapWord* start_addr = _ct_bs->addr_for(from_card_ptr); 129 assert(start_addr == mr.start(), "MemRegion start must be aligned to a card."); 130 HeapWord* last_addr = _ct_bs->addr_for(last_card_ptr); 131 assert((last_addr + CardTableModRefBS::card_size_in_words) == mr.end(), "MemRegion end must be aligned to a card."); 132 #endif // ASSERT 133 134 // Clear the counts for the (exclusive) card range. 135 size_t from_card_num = ptr_2_card_num(from_card_ptr); 136 size_t to_card_num = ptr_2_card_num(last_card_ptr) + 1; 137 clear_range(from_card_num, to_card_num); 138 } 139 } 140 141 class G1CardCountsClearClosure : public HeapRegionClosure { 142 private: 143 G1CardCounts* _card_counts; 144 public: 145 G1CardCountsClearClosure(G1CardCounts* card_counts) : 146 HeapRegionClosure(), _card_counts(card_counts) { } 147 148 149 virtual bool doHeapRegion(HeapRegion* r) { 150 _card_counts->clear_region(r); 151 return false; 152 } 153 }; 154 155 void G1CardCounts::clear_all() { 156 assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise"); 157 G1CardCountsClearClosure cl(this); 158 _g1h->heap_region_iterate(&cl); 159 }