1 /* 2 * Copyright (c) 2001, 2014, 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_implementation/g1/g1BlockOffsetTable.inline.hpp" 27 #include "gc_implementation/g1/heapRegion.hpp" 28 #include "memory/space.hpp" 29 #include "oops/oop.inline.hpp" 30 #include "runtime/java.hpp" 31 #include "services/memTracker.hpp" 32 33 34 35 ////////////////////////////////////////////////////////////////////// 36 // G1BlockOffsetSharedArray 37 ////////////////////////////////////////////////////////////////////// 38 39 G1BlockOffsetSharedArray::G1BlockOffsetSharedArray(MemRegion heap, G1RegionToSpaceMapper* storage) : 40 _reserved(), _end(NULL), _listener(), _offset_array(NULL) { 41 42 _reserved = heap; 43 _end = NULL; 44 45 MemRegion bot_reserved = storage->reserved(); 46 47 _offset_array = (u_char*)bot_reserved.start(); 48 _end = _reserved.end(); 49 50 storage->set_mapping_changed_listener(&_listener); 51 52 if (TraceBlockOffsetTable) { 53 gclog_or_tty->print_cr("G1BlockOffsetSharedArray::G1BlockOffsetSharedArray: "); 54 gclog_or_tty->print_cr(" " 55 " rs.base(): " PTR_FORMAT 56 " rs.size(): " SIZE_FORMAT 57 " rs end(): " PTR_FORMAT, 58 p2i(bot_reserved.start()), bot_reserved.byte_size(), p2i(bot_reserved.end())); 59 } 60 } 61 62 bool G1BlockOffsetSharedArray::is_card_boundary(HeapWord* p) const { 63 assert(p >= _reserved.start(), "just checking"); 64 size_t delta = pointer_delta(p, _reserved.start()); 65 return (delta & right_n_bits(LogN_words)) == (size_t)NoBits; 66 } 67 68 ////////////////////////////////////////////////////////////////////// 69 // G1BlockOffsetArray 70 ////////////////////////////////////////////////////////////////////// 71 72 G1BlockOffsetArray::G1BlockOffsetArray(G1BlockOffsetSharedArray* array, 73 MemRegion mr) : 74 G1BlockOffsetTable(mr.start(), mr.end()), 75 _unallocated_block(_bottom), 76 _array(array), _gsp(NULL) { 77 assert(_bottom <= _end, "arguments out of order"); 78 } 79 80 void G1BlockOffsetArray::set_space(G1OffsetTableContigSpace* sp) { 81 _gsp = sp; 82 } 83 84 // The arguments follow the normal convention of denoting 85 // a right-open interval: [start, end) 86 void 87 G1BlockOffsetArray:: set_remainder_to_point_to_start(HeapWord* start, HeapWord* end) { 88 89 if (start >= end) { 90 // The start address is equal to the end address (or to 91 // the right of the end address) so there are not cards 92 // that need to be updated.. 93 return; 94 } 95 96 // Write the backskip value for each region. 97 // 98 // offset 99 // card 2nd 3rd 100 // | +- 1st | | 101 // v v v v 102 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+- 103 // |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ... 104 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+- 105 // 11 19 75 106 // 12 107 // 108 // offset card is the card that points to the start of an object 109 // x - offset value of offset card 110 // 1st - start of first logarithmic region 111 // 0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1 112 // 2nd - start of second logarithmic region 113 // 1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8 114 // 3rd - start of third logarithmic region 115 // 2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64 116 // 117 // integer below the block offset entry is an example of 118 // the index of the entry 119 // 120 // Given an address, 121 // Find the index for the address 122 // Find the block offset table entry 123 // Convert the entry to a back slide 124 // (e.g., with today's, offset = 0x81 => 125 // back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8 126 // Move back N (e.g., 8) entries and repeat with the 127 // value of the new entry 128 // 129 size_t start_card = _array->index_for(start); 130 size_t end_card = _array->index_for(end-1); 131 assert(start ==_array->address_for_index(start_card), "Precondition"); 132 assert(end ==_array->address_for_index(end_card)+N_words, "Precondition"); 133 set_remainder_to_point_to_start_incl(start_card, end_card); // closed interval 134 } 135 136 // Unlike the normal convention in this code, the argument here denotes 137 // a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start() 138 // above. 139 void 140 G1BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card) { 141 if (start_card > end_card) { 142 return; 143 } 144 assert(start_card > _array->index_for(_bottom), "Cannot be first card"); 145 assert(_array->offset_array(start_card-1) <= N_words, 146 "Offset card has an unexpected value"); 147 size_t start_card_for_region = start_card; 148 u_char offset = max_jubyte; 149 for (int i = 0; i < BlockOffsetArray::N_powers; i++) { 150 // -1 so that the the card with the actual offset is counted. Another -1 151 // so that the reach ends in this region and not at the start 152 // of the next. 153 size_t reach = start_card - 1 + (BlockOffsetArray::power_to_cards_back(i+1) - 1); 154 offset = N_words + i; 155 if (reach >= end_card) { 156 _array->set_offset_array(start_card_for_region, end_card, offset); 157 start_card_for_region = reach + 1; 158 break; 159 } 160 _array->set_offset_array(start_card_for_region, reach, offset); 161 start_card_for_region = reach + 1; 162 } 163 assert(start_card_for_region > end_card, "Sanity check"); 164 DEBUG_ONLY(check_all_cards(start_card, end_card);) 165 } 166 167 // The card-interval [start_card, end_card] is a closed interval; this 168 // is an expensive check -- use with care and only under protection of 169 // suitable flag. 170 void G1BlockOffsetArray::check_all_cards(size_t start_card, size_t end_card) const { 171 172 if (end_card < start_card) { 173 return; 174 } 175 guarantee(_array->offset_array(start_card) == N_words, "Wrong value in second card"); 176 for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) { 177 u_char entry = _array->offset_array(c); 178 if (c - start_card > BlockOffsetArray::power_to_cards_back(1)) { 179 guarantee(entry > N_words, 180 err_msg("Should be in logarithmic region - " 181 "entry: %u, " 182 "_array->offset_array(c): %u, " 183 "N_words: %u", 184 (uint)entry, (uint)_array->offset_array(c), (uint)N_words)); 185 } 186 size_t backskip = BlockOffsetArray::entry_to_cards_back(entry); 187 size_t landing_card = c - backskip; 188 guarantee(landing_card >= (start_card - 1), "Inv"); 189 if (landing_card >= start_card) { 190 guarantee(_array->offset_array(landing_card) <= entry, 191 err_msg("Monotonicity - landing_card offset: %u, " 192 "entry: %u", 193 (uint)_array->offset_array(landing_card), (uint)entry)); 194 } else { 195 guarantee(landing_card == start_card - 1, "Tautology"); 196 // Note that N_words is the maximum offset value 197 guarantee(_array->offset_array(landing_card) <= N_words, 198 err_msg("landing card offset: %u, " 199 "N_words: %u", 200 (uint)_array->offset_array(landing_card), (uint)N_words)); 201 } 202 } 203 } 204 205 HeapWord* G1BlockOffsetArray::block_start_unsafe(const void* addr) { 206 assert(_bottom <= addr && addr < _end, 207 "addr must be covered by this Array"); 208 // Must read this exactly once because it can be modified by parallel 209 // allocation. 210 HeapWord* ub = _unallocated_block; 211 if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) { 212 assert(ub < _end, "tautology (see above)"); 213 return ub; 214 } 215 // Otherwise, find the block start using the table. 216 HeapWord* q = block_at_or_preceding(addr, false, 0); 217 return forward_to_block_containing_addr(q, addr); 218 } 219 220 // This duplicates a little code from the above: unavoidable. 221 HeapWord* 222 G1BlockOffsetArray::block_start_unsafe_const(const void* addr) const { 223 assert(_bottom <= addr && addr < _end, 224 "addr must be covered by this Array"); 225 // Must read this exactly once because it can be modified by parallel 226 // allocation. 227 HeapWord* ub = _unallocated_block; 228 if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) { 229 assert(ub < _end, "tautology (see above)"); 230 return ub; 231 } 232 // Otherwise, find the block start using the table. 233 HeapWord* q = block_at_or_preceding(addr, false, 0); 234 HeapWord* n = q + block_size(q); 235 return forward_to_block_containing_addr_const(q, n, addr); 236 } 237 238 239 HeapWord* 240 G1BlockOffsetArray::forward_to_block_containing_addr_slow(HeapWord* q, 241 HeapWord* n, 242 const void* addr) { 243 // We're not in the normal case. We need to handle an important subcase 244 // here: LAB allocation. An allocation previously recorded in the 245 // offset table was actually a lab allocation, and was divided into 246 // several objects subsequently. Fix this situation as we answer the 247 // query, by updating entries as we cross them. 248 249 // If the fist object's end q is at the card boundary. Start refining 250 // with the corresponding card (the value of the entry will be basically 251 // set to 0). If the object crosses the boundary -- start from the next card. 252 size_t n_index = _array->index_for(n); 253 size_t next_index = _array->index_for(n) + !_array->is_card_boundary(n); 254 // Calculate a consistent next boundary. If "n" is not at the boundary 255 // already, step to the boundary. 256 HeapWord* next_boundary = _array->address_for_index(n_index) + 257 (n_index == next_index ? 0 : N_words); 258 assert(next_boundary <= _array->_end, 259 err_msg("next_boundary is beyond the end of the covered region " 260 " next_boundary " PTR_FORMAT " _array->_end " PTR_FORMAT, 261 p2i(next_boundary), p2i(_array->_end))); 262 if (addr >= gsp()->top()) return gsp()->top(); 263 while (next_boundary < addr) { 264 while (n <= next_boundary) { 265 q = n; 266 oop obj = oop(q); 267 if (obj->klass_or_null() == NULL) return q; 268 n += block_size(q); 269 } 270 assert(q <= next_boundary && n > next_boundary, "Consequence of loop"); 271 // [q, n) is the block that crosses the boundary. 272 alloc_block_work2(&next_boundary, &next_index, q, n); 273 } 274 return forward_to_block_containing_addr_const(q, n, addr); 275 } 276 277 // Note that the committed size of the covered space may have changed, 278 // so the table size might also wish to change. 279 void G1BlockOffsetArray::resize(size_t new_word_size) { 280 HeapWord* new_end = _bottom + new_word_size; 281 _end = new_end; // update _end 282 } 283 284 // 285 // threshold_ 286 // | _index_ 287 // v v 288 // +-------+-------+-------+-------+-------+ 289 // | i-1 | i | i+1 | i+2 | i+3 | 290 // +-------+-------+-------+-------+-------+ 291 // ( ^ ] 292 // block-start 293 // 294 void G1BlockOffsetArray::alloc_block_work2(HeapWord** threshold_, size_t* index_, 295 HeapWord* blk_start, HeapWord* blk_end) { 296 // For efficiency, do copy-in/copy-out. 297 HeapWord* threshold = *threshold_; 298 size_t index = *index_; 299 300 assert(blk_start != NULL && blk_end > blk_start, 301 "phantom block"); 302 assert(blk_end > threshold, "should be past threshold"); 303 assert(blk_start <= threshold, "blk_start should be at or before threshold"); 304 assert(pointer_delta(threshold, blk_start) <= N_words, 305 "offset should be <= BlockOffsetSharedArray::N"); 306 assert(Universe::heap()->is_in_reserved(blk_start), 307 "reference must be into the heap"); 308 assert(Universe::heap()->is_in_reserved(blk_end-1), 309 "limit must be within the heap"); 310 assert(threshold == _array->_reserved.start() + index*N_words, 311 "index must agree with threshold"); 312 313 DEBUG_ONLY(size_t orig_index = index;) 314 315 // Mark the card that holds the offset into the block. Note 316 // that _next_offset_index and _next_offset_threshold are not 317 // updated until the end of this method. 318 _array->set_offset_array(index, threshold, blk_start); 319 320 // We need to now mark the subsequent cards that this blk spans. 321 322 // Index of card on which blk ends. 323 size_t end_index = _array->index_for(blk_end - 1); 324 325 // Are there more cards left to be updated? 326 if (index + 1 <= end_index) { 327 HeapWord* rem_st = _array->address_for_index(index + 1); 328 // Calculate rem_end this way because end_index 329 // may be the last valid index in the covered region. 330 HeapWord* rem_end = _array->address_for_index(end_index) + N_words; 331 set_remainder_to_point_to_start(rem_st, rem_end); 332 } 333 334 index = end_index + 1; 335 // Calculate threshold_ this way because end_index 336 // may be the last valid index in the covered region. 337 threshold = _array->address_for_index(end_index) + N_words; 338 assert(threshold >= blk_end, "Incorrect offset threshold"); 339 340 // index_ and threshold_ updated here. 341 *threshold_ = threshold; 342 *index_ = index; 343 344 #ifdef ASSERT 345 // The offset can be 0 if the block starts on a boundary. That 346 // is checked by an assertion above. 347 size_t start_index = _array->index_for(blk_start); 348 HeapWord* boundary = _array->address_for_index(start_index); 349 assert((_array->offset_array(orig_index) == 0 && 350 blk_start == boundary) || 351 (_array->offset_array(orig_index) > 0 && 352 _array->offset_array(orig_index) <= N_words), 353 err_msg("offset array should have been set - " 354 "orig_index offset: %u, " 355 "blk_start: " PTR_FORMAT ", " 356 "boundary: " PTR_FORMAT, 357 (uint)_array->offset_array(orig_index), 358 p2i(blk_start), p2i(boundary))); 359 for (size_t j = orig_index + 1; j <= end_index; j++) { 360 assert(_array->offset_array(j) > 0 && 361 _array->offset_array(j) <= 362 (u_char) (N_words+BlockOffsetArray::N_powers-1), 363 err_msg("offset array should have been set - " 364 "%u not > 0 OR %u not <= %u", 365 (uint) _array->offset_array(j), 366 (uint) _array->offset_array(j), 367 (uint) (N_words+BlockOffsetArray::N_powers-1))); 368 } 369 #endif 370 } 371 372 bool 373 G1BlockOffsetArray::verify_for_object(HeapWord* obj_start, 374 size_t word_size) const { 375 size_t first_card = _array->index_for(obj_start); 376 size_t last_card = _array->index_for(obj_start + word_size - 1); 377 if (!_array->is_card_boundary(obj_start)) { 378 // If the object is not on a card boundary the BOT entry of the 379 // first card should point to another object so we should not 380 // check that one. 381 first_card += 1; 382 } 383 for (size_t card = first_card; card <= last_card; card += 1) { 384 HeapWord* card_addr = _array->address_for_index(card); 385 HeapWord* block_start = block_start_const(card_addr); 386 if (block_start != obj_start) { 387 gclog_or_tty->print_cr("block start: "PTR_FORMAT" is incorrect - " 388 "card index: "SIZE_FORMAT" " 389 "card addr: "PTR_FORMAT" BOT entry: %u " 390 "obj: "PTR_FORMAT" word size: "SIZE_FORMAT" " 391 "cards: ["SIZE_FORMAT","SIZE_FORMAT"]", 392 p2i(block_start), card, p2i(card_addr), 393 _array->offset_array(card), 394 p2i(obj_start), word_size, first_card, last_card); 395 return false; 396 } 397 } 398 return true; 399 } 400 401 #ifndef PRODUCT 402 void 403 G1BlockOffsetArray::print_on(outputStream* out) { 404 size_t from_index = _array->index_for(_bottom); 405 size_t to_index = _array->index_for(_end); 406 out->print_cr(">> BOT for area ["PTR_FORMAT","PTR_FORMAT") " 407 "cards ["SIZE_FORMAT","SIZE_FORMAT")", 408 p2i(_bottom), p2i(_end), from_index, to_index); 409 for (size_t i = from_index; i < to_index; ++i) { 410 out->print_cr(" entry "SIZE_FORMAT_W(8)" | "PTR_FORMAT" : %3u", 411 i, p2i(_array->address_for_index(i)), 412 (uint) _array->offset_array(i)); 413 } 414 } 415 #endif // !PRODUCT 416 417 ////////////////////////////////////////////////////////////////////// 418 // G1BlockOffsetArrayContigSpace 419 ////////////////////////////////////////////////////////////////////// 420 421 HeapWord* 422 G1BlockOffsetArrayContigSpace::block_start_unsafe(const void* addr) { 423 assert(_bottom <= addr && addr < _end, 424 "addr must be covered by this Array"); 425 HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1); 426 return forward_to_block_containing_addr(q, addr); 427 } 428 429 HeapWord* 430 G1BlockOffsetArrayContigSpace:: 431 block_start_unsafe_const(const void* addr) const { 432 assert(_bottom <= addr && addr < _end, 433 "addr must be covered by this Array"); 434 HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1); 435 HeapWord* n = q + block_size(q); 436 return forward_to_block_containing_addr_const(q, n, addr); 437 } 438 439 G1BlockOffsetArrayContigSpace:: 440 G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array, 441 MemRegion mr) : 442 G1BlockOffsetArray(array, mr) 443 { 444 _next_offset_threshold = NULL; 445 _next_offset_index = 0; 446 } 447 448 HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold_raw() { 449 assert(!Universe::heap()->is_in_reserved(_array->_offset_array), 450 "just checking"); 451 _next_offset_index = _array->index_for_raw(_bottom); 452 _next_offset_index++; 453 _next_offset_threshold = 454 _array->address_for_index_raw(_next_offset_index); 455 return _next_offset_threshold; 456 } 457 458 void G1BlockOffsetArrayContigSpace::zero_bottom_entry_raw() { 459 assert(!Universe::heap()->is_in_reserved(_array->_offset_array), 460 "just checking"); 461 size_t bottom_index = _array->index_for_raw(_bottom); 462 assert(_array->address_for_index_raw(bottom_index) == _bottom, 463 "Precondition of call"); 464 _array->set_offset_array_raw(bottom_index, 0); 465 } 466 467 HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold() { 468 assert(!Universe::heap()->is_in_reserved(_array->_offset_array), 469 "just checking"); 470 _next_offset_index = _array->index_for(_bottom); 471 _next_offset_index++; 472 _next_offset_threshold = 473 _array->address_for_index(_next_offset_index); 474 return _next_offset_threshold; 475 } 476 477 void 478 G1BlockOffsetArrayContigSpace::set_for_starts_humongous(HeapWord* new_top) { 479 assert(new_top <= _end, "_end should have already been updated"); 480 481 // The first BOT entry should have offset 0. 482 reset_bot(); 483 alloc_block(_bottom, new_top); 484 } 485 486 #ifndef PRODUCT 487 void 488 G1BlockOffsetArrayContigSpace::print_on(outputStream* out) { 489 G1BlockOffsetArray::print_on(out); 490 out->print_cr(" next offset threshold: "PTR_FORMAT, p2i(_next_offset_threshold)); 491 out->print_cr(" next offset index: "SIZE_FORMAT, _next_offset_index); 492 } 493 #endif // !PRODUCT