1 /* 2 * Copyright (c) 2001, 2010, 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_CONCURRENTG1REFINE_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP 27 28 #include "memory/allocation.hpp" 29 #include "memory/cardTableModRefBS.hpp" 30 #include "runtime/thread.hpp" 31 #include "utilities/globalDefinitions.hpp" 32 33 // Forward decl 34 class ConcurrentG1RefineThread; 35 class G1RemSet; 36 37 class ConcurrentG1Refine: public CHeapObj { 38 ConcurrentG1RefineThread** _threads; 39 int _n_threads; 40 int _n_worker_threads; 41 /* 42 * The value of the update buffer queue length falls into one of 3 zones: 43 * green, yellow, red. If the value is in [0, green) nothing is 44 * done, the buffers are left unprocessed to enable the caching effect of the 45 * dirtied cards. In the yellow zone [green, yellow) the concurrent refinement 46 * threads are gradually activated. In [yellow, red) all threads are 47 * running. If the length becomes red (max queue length) the mutators start 48 * processing the buffers. 49 * 50 * There are some interesting cases (when G1UseAdaptiveConcRefinement 51 * is turned off): 52 * 1) green = yellow = red = 0. In this case the mutator will process all 53 * buffers. Except for those that are created by the deferred updates 54 * machinery during a collection. 55 * 2) green = 0. Means no caching. Can be a good way to minimize the 56 * amount of time spent updating rsets during a collection. 57 */ 58 int _green_zone; 59 int _yellow_zone; 60 int _red_zone; 61 62 int _thread_threshold_step; 63 64 // Reset the threshold step value based of the current zone boundaries. 65 void reset_threshold_step(); 66 67 // The cache for card refinement. 68 bool _use_cache; 69 bool _def_use_cache; 70 71 size_t _n_periods; // Used as clearing epoch 72 73 // An evicting cache of the number of times each card 74 // is accessed. Reduces, but does not eliminate, the amount 75 // of duplicated processing of dirty cards. 76 77 enum SomePrivateConstants { 78 epoch_bits = 32, 79 card_num_shift = epoch_bits, 80 epoch_mask = AllBits, 81 card_num_mask = AllBits, 82 83 // The initial cache size is approximately this fraction 84 // of a maximal cache (i.e. the size needed for all cards 85 // in the heap) 86 InitialCacheFraction = 512 87 }; 88 89 const static julong card_num_mask_in_place = 90 (julong) card_num_mask << card_num_shift; 91 92 typedef struct { 93 julong _value; // | card_num | epoch | 94 } CardEpochCacheEntry; 95 96 julong make_epoch_entry(unsigned int card_num, unsigned int epoch) { 97 assert(0 <= card_num && card_num < _max_n_card_counts, "Bounds"); 98 assert(0 <= epoch && epoch <= _n_periods, "must be"); 99 100 return ((julong) card_num << card_num_shift) | epoch; 101 } 102 103 unsigned int extract_epoch(julong v) { 104 return (v & epoch_mask); 105 } 106 107 unsigned int extract_card_num(julong v) { 108 return (v & card_num_mask_in_place) >> card_num_shift; 109 } 110 111 typedef struct { 112 unsigned char _count; 113 unsigned char _evict_count; 114 } CardCountCacheEntry; 115 116 CardCountCacheEntry* _card_counts; 117 CardEpochCacheEntry* _card_epochs; 118 119 // The current number of buckets in the card count cache 120 unsigned _n_card_counts; 121 122 // The max number of buckets required for the number of 123 // cards for the entire reserved heap 124 unsigned _max_n_card_counts; 125 126 // Possible sizes of the cache: odd primes that roughly double in size. 127 // (See jvmtiTagMap.cpp). 128 static int _cc_cache_sizes[]; 129 130 // The index in _cc_cache_sizes corresponding to the size of 131 // _card_counts. 132 int _cache_size_index; 133 134 bool _expand_card_counts; 135 136 const jbyte* _ct_bot; 137 138 jbyte** _hot_cache; 139 int _hot_cache_size; 140 int _n_hot; 141 int _hot_cache_idx; 142 143 int _hot_cache_par_chunk_size; 144 volatile int _hot_cache_par_claimed_idx; 145 146 // Needed to workaround 6817995 147 CardTableModRefBS* _ct_bs; 148 G1CollectedHeap* _g1h; 149 150 // Expands the array that holds the card counts to the next size up 151 void expand_card_count_cache(); 152 153 // hash a given key (index of card_ptr) with the specified size 154 static unsigned int hash(size_t key, int size) { 155 return (unsigned int) key % size; 156 } 157 158 // hash a given key (index of card_ptr) 159 unsigned int hash(size_t key) { 160 return hash(key, _n_card_counts); 161 } 162 163 unsigned ptr_2_card_num(jbyte* card_ptr) { 164 return (unsigned) (card_ptr - _ct_bot); 165 } 166 167 jbyte* card_num_2_ptr(unsigned card_num) { 168 return (jbyte*) (_ct_bot + card_num); 169 } 170 171 // Returns the count of this card after incrementing it. 172 jbyte* add_card_count(jbyte* card_ptr, int* count, bool* defer); 173 174 // Returns true if this card is in a young region 175 bool is_young_card(jbyte* card_ptr); 176 177 public: 178 ConcurrentG1Refine(); 179 ~ConcurrentG1Refine(); 180 181 void init(); // Accomplish some initialization that has to wait. 182 void stop(); 183 184 void reinitialize_threads(); 185 186 // Iterate over the conc refine threads 187 void threads_do(ThreadClosure *tc); 188 189 // If this is the first entry for the slot, writes into the cache and 190 // returns NULL. If it causes an eviction, returns the evicted pointer. 191 // Otherwise, its a cache hit, and returns NULL. 192 jbyte* cache_insert(jbyte* card_ptr, bool* defer); 193 194 // Process the cached entries. 195 void clean_up_cache(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq); 196 197 // Set up for parallel processing of the cards in the hot cache 198 void clear_hot_cache_claimed_index() { 199 _hot_cache_par_claimed_idx = 0; 200 } 201 202 // Discard entries in the hot cache. 203 void clear_hot_cache() { 204 _hot_cache_idx = 0; _n_hot = 0; 205 } 206 207 bool hot_cache_is_empty() { return _n_hot == 0; } 208 209 bool use_cache() { return _use_cache; } 210 void set_use_cache(bool b) { 211 if (b) _use_cache = _def_use_cache; 212 else _use_cache = false; 213 } 214 215 void clear_and_record_card_counts(); 216 217 static int thread_num(); 218 219 void print_worker_threads_on(outputStream* st) const; 220 221 void set_green_zone(int x) { _green_zone = x; } 222 void set_yellow_zone(int x) { _yellow_zone = x; } 223 void set_red_zone(int x) { _red_zone = x; } 224 225 int green_zone() const { return _green_zone; } 226 int yellow_zone() const { return _yellow_zone; } 227 int red_zone() const { return _red_zone; } 228 229 int total_thread_num() const { return _n_threads; } 230 int worker_thread_num() const { return _n_worker_threads; } 231 232 int thread_threshold_step() const { return _thread_threshold_step; } 233 }; 234 235 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP