rev 57601 : [mq]: metaspace-improvement
1 /* 2 * Copyright (c) 2018, 2019, 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 #include "precompiled.hpp" 25 26 27 #include "logging/log.hpp" 28 #include "memory/metaspace/constants.hpp" 29 #include "memory/metaspace/chunkAllocSequence.hpp" 30 #include "memory/metaspace/chunkLevel.hpp" 31 #include "memory/metaspace/chunkManager.hpp" 32 #include "memory/metaspace/metachunk.hpp" 33 #include "memory/metaspace/metaspaceStatistics.hpp" 34 #include "memory/metaspace/virtualSpaceNode.hpp" 35 #include "memory/metaspace/virtualSpaceList.hpp" 36 #include "runtime/mutexLocker.hpp" 37 #include "utilities/debug.hpp" 38 #include "utilities/globalDefinitions.hpp" 39 40 namespace metaspace { 41 42 43 // Return a single chunk to the freelist and adjust accounting. No merge is attempted. 44 void ChunkManager::return_chunk_simple(Metachunk* c) { 45 DEBUG_ONLY(c->verify(false)); 46 const chklvl_t lvl = c->level(); 47 _chunks[lvl].add(c); 48 _total_word_size.increment_by(c->word_size()); 49 _committed_word_size.increment_by(c->committed_words()); 50 } 51 52 // Take a single chunk from the given freelist and adjust counters. Returns NULL 53 // if there is no fitting chunk for this level. 54 Metachunk* ChunkManager::remove_first_chunk_at_level(chklvl_t l) { 55 DEBUG_ONLY(chklvl::check_valid_level(l);) 56 Metachunk* c = _chunks[l].remove_first(); 57 if (c != NULL) { 58 _total_word_size.decrement_by(c->word_size()); 59 _committed_word_size.decrement_by(c->committed_words()); 60 } 61 return c; 62 } 63 64 // Creates a chunk manager with a given name (which is for debug purposes only) 65 // and an associated space list which will be used to request new chunks from 66 // (see get_chunk()) 67 ChunkManager::ChunkManager(const char* name, VirtualSpaceList* space_list) 68 : _vslist(space_list), 69 _name(name), 70 _chunks() 71 { 72 } 73 74 // Given a chunk we are about to handout to the caller, make sure it is committed 75 // according to constants::committed_words_on_fresh_chunks 76 bool ChunkManager::commit_chunk_before_handout(Metachunk* c) { 77 const size_t must_be_committed = MIN2(c->word_size(), constants::committed_words_on_fresh_chunks); 78 return c->ensure_committed(must_be_committed); 79 } 80 81 #ifdef ASSERT 82 // Given a splinters array returned from a split operation, check that it meets expectations 83 static void check_splinters_array(Metachunk* splinters[chklvl::NUM_CHUNK_LEVELS], chklvl_t min, chklvl_t max) { 84 // The array shall contain splinters in the range [min, max] and nothing outside. The chunk levels for 85 // the chunks must match too. 86 for (chklvl_t l = chklvl::ROOT_CHUNK_LEVEL; l <= chklvl::HIGHEST_CHUNK_LEVEL; l ++) { 87 if (l >= min && l < max) { 88 assert(splinters[l] != NULL, "Missing splinters"); 89 assert(splinters[l]->level() == l, "Unexpected level"); 90 splinters[l]->verify(false); 91 } else { 92 assert(splinters[l] == NULL, "Unexpected splinters"); 93 } 94 } 95 } 96 #endif 97 98 99 // Given a chunk which must be outside of a freelist and must be free, split it to 100 // meet a target level and return it. Splinters are added to the freelist. 101 Metachunk* ChunkManager::split_chunk_and_add_splinters(Metachunk* c, chklvl_t target_level) { 102 103 assert(c->is_free() && c->level() > target_level, "Invalid chunk for splitting"); 104 DEBUG_ONLY(chklvl::check_valid_level(target_level);) 105 106 const chklvl_t orig_level = c->level(); 107 Metachunk* splinters[chklvl::NUM_CHUNK_LEVELS] = { 0 }; 108 c = c->vsnode()->split(target_level, c, splinters); 109 110 // Splitting should never fail. 111 assert(c != NULL, "Split failed"); 112 assert(c->level() == target_level, "Sanity"); 113 DEBUG_ONLY(c->verify(false)); 114 DEBUG_ONLY(check_splinters_array(splinters, orig_level + 1, target_level);) 115 116 // Return splinters to freelist. 117 for (chklvl_t l = orig_level + 1; l <= target_level; l ++) { 118 return_chunk_simple(splinters[l]); 119 } 120 121 return c; 122 } 123 124 // Get a chunk and be smart about it. 125 // - 1) Attempt to find a free chunk of exactly the pref_level level 126 // - 2) Failing that, attempt to find a chunk smaller or equal the minimal level. 127 // - 3) Failing that, attempt to find a free chunk of larger size and split it. 128 // - 4) Failing that, attempt to allocate a new chunk from the connected virtual space. 129 // - Failing that, give up and return NULL. 130 // Note: this is not guaranteed to return a *committed* chunk. The chunk manager will 131 // attempt to commit the returned chunk according to constants::committed_words_on_fresh_chunks; 132 // but this may fail if we hit a commit limit. In that case, a partly uncommit chunk 133 // will be returned, and the commit is attempted again when we allocate from the chunk's 134 // uncommitted area. See also Metachunk::allocate. 135 Metachunk* ChunkManager::get_chunk(chklvl_t min_level, chklvl_t pref_level) { 136 137 assert_lock_strong(MetaspaceExpand_lock); 138 DEBUG_ONLY(chklvl::check_valid_level(min_level);) 139 DEBUG_ONLY(chklvl::check_valid_level(pref_level);) 140 141 Metachunk* c = NULL; 142 143 // 1) Attempt to find a free chunk of exactly the pref_level level 144 c = remove_first_chunk_at_level(pref_level); 145 146 // 2) Failing that, attempt to find a chunk smaller or equal the minimal level. 147 if (c == NULL) { 148 for (chklvl_t lvl = pref_level + 1; lvl <= min_level; lvl ++) { 149 c = remove_first_chunk_at_level(lvl); 150 if (c != NULL) { 151 break; 152 } 153 } 154 } 155 156 // 3) Failing that, attempt to find a free chunk of larger size and split it. 157 if (c == NULL) { 158 for (chklvl_t lvl = pref_level - 1; lvl >= chklvl::ROOT_CHUNK_LEVEL; lvl --) { 159 c = remove_first_chunk_at_level(lvl); 160 if (c != NULL) { 161 // Split chunk; add splinters to freelist 162 c = split_chunk_and_add_splinters(c, pref_level); 163 break; 164 } 165 } 166 } 167 168 // 4) Failing that, attempt to allocate a new chunk from the connected virtual space. 169 if (c == NULL) { 170 171 c = _vslist->allocate_root_chunk(); 172 173 // This should always work. Note that getting the root chunk may not mean we committed memory. 174 assert(c != NULL, "Unexpected"); 175 176 // Split this root chunk to the desired chunk size. 177 c = split_chunk_and_add_splinters(c, pref_level); 178 179 } 180 181 // Note that we should at this point have a chunk; should always work. If we hit 182 // a commit limit in the meantime, the chunk may still be uncommitted, but the chunk 183 // itself should exist now. 184 assert(c != NULL, "Unexpected"); 185 186 // Before returning the chunk, attempt to commit it according to the handout rules. 187 // If that fails, we ignore the error and return the uncommitted chunk. 188 if (commit_chunk_before_handout(c) == false) { 189 log_info(gc, metaspace)("Failed to commit chunk prior to handout."); 190 } 191 192 DEBUG_ONLY(verify(false);) 193 194 return c; 195 196 } // ChunkManager::get_chunk 197 198 199 // Return a single chunk to the ChunkManager and adjust accounting. May merge chunk 200 // with neighbors. 201 // Happens after a Classloader was unloaded and releases its metaspace chunks. 202 // !! Note: this may invalidate the chunk. Do not access the chunk after 203 // this function returns !! 204 void ChunkManager::return_chunk(Metachunk* c) { 205 206 assert_lock_strong(MetaspaceExpand_lock); 207 DEBUG_ONLY(c->verify(false);) 208 209 const chklvl_t orig_lvl = c->level(); 210 211 int num_merged[chklvl::NUM_CHUNK_LEVELS] = { 0 }; 212 Metachunk* c2 = c->vsnode()->merge(c, num_merged); 213 214 if (c2 != NULL) { 215 DEBUG_ONLY(c2->verify(false)); 216 217 // We did merge chunks and now have a bigger chunk. 218 assert(c2->level() < orig_lvl, "Sanity"); 219 220 // Adjust counters - the merged-in chunks have been removed from the free lists, but the counters 221 // in this chunk manager must be adjusted too. 222 size_t size_chunks_removed = 0; 223 for (chklvl_t l = chklvl::ROOT_CHUNK_LEVEL; l <= chklvl::HIGHEST_CHUNK_LEVEL; l ++) { 224 if (num_merged[l] > 0) { 225 // Since we have a binary tree, we should exactly see one merge per level. 226 assert(num_merged[l] == 1, "sanity"); 227 _chunks[l].dec_counter_by(1); 228 size_chunks_removed += chklvl::word_size_for_level(l); 229 } 230 } 231 _total_word_size.decrement_by(size_chunks_removed); 232 233 c = c2; 234 } 235 236 return_chunk_simple(c); 237 238 } 239 240 241 ChunkManager* ChunkManager::_chunkmanager_class = NULL; 242 ChunkManager* ChunkManager::_chunkmanager_nonclass = NULL; 243 244 void ChunkManager::set_chunkmanager_class(ChunkManager* cm) { 245 assert(_chunkmanager_class == NULL, "Sanity"); 246 _chunkmanager_class = cm; 247 } 248 249 void ChunkManager::set_chunkmanager_nonclass(ChunkManager* cm) { 250 assert(_chunkmanager_nonclass == NULL, "Sanity"); 251 _chunkmanager_nonclass = cm; 252 } 253 254 255 // Update statistics. 256 void ChunkManager::add_to_statistics(ChunkManagerStatistics* out) const { 257 258 for (chklvl_t l = chklvl::ROOT_CHUNK_LEVEL; l <= chklvl::HIGHEST_CHUNK_LEVEL; l ++) { 259 out->num_chunks[l] += _chunks[l].size(); 260 } 261 262 } 263 264 #ifdef ASSERT 265 266 void ChunkManager::verify(bool slow) const { 267 268 size_t word_size = 0; 269 size_t committed_word_size = 0; 270 for (chklvl_t l = chklvl::LOWEST_CHUNK_LEVEL; 271 l <= chklvl::HIGHEST_CHUNK_LEVEL; l ++) 272 { 273 const Metachunk* c = _chunks[l].first(); 274 int num = 0; 275 while (c) { 276 assert(c->level() == l, "Wrong level"); 277 assert(c->is_free(), "Chunk is not free."); 278 num ++; 279 committed_word_size += c->committed_words(); 280 c->verify(slow); 281 c = c->next(); 282 } 283 assert(num == _chunks[l].size(), "Sanity"); 284 word_size += num * chklvl::word_size_for_level(l); 285 } 286 _total_word_size.check(word_size); 287 _committed_word_size.check(committed_word_size); 288 289 } 290 291 #endif // ASSERT 292 293 294 } // namespace metaspace 295 296 297 --- EOF ---