1 /* 2 * Copyright (c) 2005, 2017, 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 "aot/aotLoader.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "code/codeCache.hpp" 31 #include "gc/parallel/gcTaskManager.hpp" 32 #include "gc/parallel/parallelScavengeHeap.inline.hpp" 33 #include "gc/parallel/parMarkBitMap.inline.hpp" 34 #include "gc/parallel/pcTasks.hpp" 35 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 36 #include "gc/parallel/psCompactionManager.inline.hpp" 37 #include "gc/parallel/psMarkSweep.hpp" 38 #include "gc/parallel/psMarkSweepDecorator.hpp" 39 #include "gc/parallel/psOldGen.hpp" 40 #include "gc/parallel/psParallelCompact.inline.hpp" 41 #include "gc/parallel/psPromotionManager.inline.hpp" 42 #include "gc/parallel/psScavenge.hpp" 43 #include "gc/parallel/psYoungGen.hpp" 44 #include "gc/shared/gcCause.hpp" 45 #include "gc/shared/gcHeapSummary.hpp" 46 #include "gc/shared/gcId.hpp" 47 #include "gc/shared/gcLocker.inline.hpp" 48 #include "gc/shared/gcTimer.hpp" 49 #include "gc/shared/gcTrace.hpp" 50 #include "gc/shared/gcTraceTime.inline.hpp" 51 #include "gc/shared/isGCActiveMark.hpp" 52 #include "gc/shared/referencePolicy.hpp" 53 #include "gc/shared/referenceProcessor.hpp" 54 #include "gc/shared/spaceDecorator.hpp" 55 #include "logging/log.hpp" 56 #include "memory/resourceArea.hpp" 57 #include "oops/instanceKlass.inline.hpp" 58 #include "oops/instanceMirrorKlass.inline.hpp" 59 #include "oops/methodData.hpp" 60 #include "oops/objArrayKlass.inline.hpp" 61 #include "oops/oop.inline.hpp" 62 #include "runtime/atomic.hpp" 63 #include "runtime/fprofiler.hpp" 64 #include "runtime/safepoint.hpp" 65 #include "runtime/vmThread.hpp" 66 #include "services/management.hpp" 67 #include "services/memTracker.hpp" 68 #include "services/memoryService.hpp" 69 #include "utilities/events.hpp" 70 #include "utilities/stack.inline.hpp" 71 72 #include <math.h> 73 74 // All sizes are in HeapWords. 75 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words 76 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize; 77 const size_t ParallelCompactData::RegionSizeBytes = 78 RegionSize << LogHeapWordSize; 79 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1; 80 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1; 81 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask; 82 83 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words 84 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize; 85 const size_t ParallelCompactData::BlockSizeBytes = 86 BlockSize << LogHeapWordSize; 87 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1; 88 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1; 89 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask; 90 91 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize; 92 const size_t ParallelCompactData::Log2BlocksPerRegion = 93 Log2RegionSize - Log2BlockSize; 94 95 const ParallelCompactData::RegionData::region_sz_t 96 ParallelCompactData::RegionData::dc_shift = 27; 97 98 const ParallelCompactData::RegionData::region_sz_t 99 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift; 100 101 const ParallelCompactData::RegionData::region_sz_t 102 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift; 103 104 const ParallelCompactData::RegionData::region_sz_t 105 ParallelCompactData::RegionData::los_mask = ~dc_mask; 106 107 const ParallelCompactData::RegionData::region_sz_t 108 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift; 109 110 const ParallelCompactData::RegionData::region_sz_t 111 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift; 112 113 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; 114 115 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; 116 117 double PSParallelCompact::_dwl_mean; 118 double PSParallelCompact::_dwl_std_dev; 119 double PSParallelCompact::_dwl_first_term; 120 double PSParallelCompact::_dwl_adjustment; 121 #ifdef ASSERT 122 bool PSParallelCompact::_dwl_initialized = false; 123 #endif // #ifdef ASSERT 124 125 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size, 126 HeapWord* destination) 127 { 128 assert(src_region_idx != 0, "invalid src_region_idx"); 129 assert(partial_obj_size != 0, "invalid partial_obj_size argument"); 130 assert(destination != NULL, "invalid destination argument"); 131 132 _src_region_idx = src_region_idx; 133 _partial_obj_size = partial_obj_size; 134 _destination = destination; 135 136 // These fields may not be updated below, so make sure they're clear. 137 assert(_dest_region_addr == NULL, "should have been cleared"); 138 assert(_first_src_addr == NULL, "should have been cleared"); 139 140 // Determine the number of destination regions for the partial object. 141 HeapWord* const last_word = destination + partial_obj_size - 1; 142 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 143 HeapWord* const beg_region_addr = sd.region_align_down(destination); 144 HeapWord* const end_region_addr = sd.region_align_down(last_word); 145 146 if (beg_region_addr == end_region_addr) { 147 // One destination region. 148 _destination_count = 1; 149 if (end_region_addr == destination) { 150 // The destination falls on a region boundary, thus the first word of the 151 // partial object will be the first word copied to the destination region. 152 _dest_region_addr = end_region_addr; 153 _first_src_addr = sd.region_to_addr(src_region_idx); 154 } 155 } else { 156 // Two destination regions. When copied, the partial object will cross a 157 // destination region boundary, so a word somewhere within the partial 158 // object will be the first word copied to the second destination region. 159 _destination_count = 2; 160 _dest_region_addr = end_region_addr; 161 const size_t ofs = pointer_delta(end_region_addr, destination); 162 assert(ofs < _partial_obj_size, "sanity"); 163 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs; 164 } 165 } 166 167 void SplitInfo::clear() 168 { 169 _src_region_idx = 0; 170 _partial_obj_size = 0; 171 _destination = NULL; 172 _destination_count = 0; 173 _dest_region_addr = NULL; 174 _first_src_addr = NULL; 175 assert(!is_valid(), "sanity"); 176 } 177 178 #ifdef ASSERT 179 void SplitInfo::verify_clear() 180 { 181 assert(_src_region_idx == 0, "not clear"); 182 assert(_partial_obj_size == 0, "not clear"); 183 assert(_destination == NULL, "not clear"); 184 assert(_destination_count == 0, "not clear"); 185 assert(_dest_region_addr == NULL, "not clear"); 186 assert(_first_src_addr == NULL, "not clear"); 187 } 188 #endif // #ifdef ASSERT 189 190 191 void PSParallelCompact::print_on_error(outputStream* st) { 192 _mark_bitmap.print_on_error(st); 193 } 194 195 #ifndef PRODUCT 196 const char* PSParallelCompact::space_names[] = { 197 "old ", "eden", "from", "to " 198 }; 199 200 void PSParallelCompact::print_region_ranges() { 201 if (!log_develop_is_enabled(Trace, gc, compaction)) { 202 return; 203 } 204 Log(gc, compaction) log; 205 ResourceMark rm; 206 Universe::print_on(log.trace_stream()); 207 log.trace("space bottom top end new_top"); 208 log.trace("------ ---------- ---------- ---------- ----------"); 209 210 for (unsigned int id = 0; id < last_space_id; ++id) { 211 const MutableSpace* space = _space_info[id].space(); 212 log.trace("%u %s " 213 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " 214 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", 215 id, space_names[id], 216 summary_data().addr_to_region_idx(space->bottom()), 217 summary_data().addr_to_region_idx(space->top()), 218 summary_data().addr_to_region_idx(space->end()), 219 summary_data().addr_to_region_idx(_space_info[id].new_top())); 220 } 221 } 222 223 void 224 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c) 225 { 226 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7) 227 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5) 228 229 ParallelCompactData& sd = PSParallelCompact::summary_data(); 230 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0; 231 log_develop_trace(gc, compaction)( 232 REGION_IDX_FORMAT " " PTR_FORMAT " " 233 REGION_IDX_FORMAT " " PTR_FORMAT " " 234 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " " 235 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d", 236 i, p2i(c->data_location()), dci, p2i(c->destination()), 237 c->partial_obj_size(), c->live_obj_size(), 238 c->data_size(), c->source_region(), c->destination_count()); 239 240 #undef REGION_IDX_FORMAT 241 #undef REGION_DATA_FORMAT 242 } 243 244 void 245 print_generic_summary_data(ParallelCompactData& summary_data, 246 HeapWord* const beg_addr, 247 HeapWord* const end_addr) 248 { 249 size_t total_words = 0; 250 size_t i = summary_data.addr_to_region_idx(beg_addr); 251 const size_t last = summary_data.addr_to_region_idx(end_addr); 252 HeapWord* pdest = 0; 253 254 while (i < last) { 255 ParallelCompactData::RegionData* c = summary_data.region(i); 256 if (c->data_size() != 0 || c->destination() != pdest) { 257 print_generic_summary_region(i, c); 258 total_words += c->data_size(); 259 pdest = c->destination(); 260 } 261 ++i; 262 } 263 264 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); 265 } 266 267 void 268 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data, 269 HeapWord* const beg_addr, 270 HeapWord* const end_addr) { 271 ::print_generic_summary_data(summary_data,beg_addr, end_addr); 272 } 273 274 void 275 print_generic_summary_data(ParallelCompactData& summary_data, 276 SpaceInfo* space_info) 277 { 278 if (!log_develop_is_enabled(Trace, gc, compaction)) { 279 return; 280 } 281 282 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { 283 const MutableSpace* space = space_info[id].space(); 284 print_generic_summary_data(summary_data, space->bottom(), 285 MAX2(space->top(), space_info[id].new_top())); 286 } 287 } 288 289 void 290 print_initial_summary_data(ParallelCompactData& summary_data, 291 const MutableSpace* space) { 292 if (space->top() == space->bottom()) { 293 return; 294 } 295 296 const size_t region_size = ParallelCompactData::RegionSize; 297 typedef ParallelCompactData::RegionData RegionData; 298 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top()); 299 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up); 300 const RegionData* c = summary_data.region(end_region - 1); 301 HeapWord* end_addr = c->destination() + c->data_size(); 302 const size_t live_in_space = pointer_delta(end_addr, space->bottom()); 303 304 // Print (and count) the full regions at the beginning of the space. 305 size_t full_region_count = 0; 306 size_t i = summary_data.addr_to_region_idx(space->bottom()); 307 while (i < end_region && summary_data.region(i)->data_size() == region_size) { 308 ParallelCompactData::RegionData* c = summary_data.region(i); 309 log_develop_trace(gc, compaction)( 310 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 311 i, p2i(c->destination()), 312 c->partial_obj_size(), c->live_obj_size(), 313 c->data_size(), c->source_region(), c->destination_count()); 314 ++full_region_count; 315 ++i; 316 } 317 318 size_t live_to_right = live_in_space - full_region_count * region_size; 319 320 double max_reclaimed_ratio = 0.0; 321 size_t max_reclaimed_ratio_region = 0; 322 size_t max_dead_to_right = 0; 323 size_t max_live_to_right = 0; 324 325 // Print the 'reclaimed ratio' for regions while there is something live in 326 // the region or to the right of it. The remaining regions are empty (and 327 // uninteresting), and computing the ratio will result in division by 0. 328 while (i < end_region && live_to_right > 0) { 329 c = summary_data.region(i); 330 HeapWord* const region_addr = summary_data.region_to_addr(i); 331 const size_t used_to_right = pointer_delta(space->top(), region_addr); 332 const size_t dead_to_right = used_to_right - live_to_right; 333 const double reclaimed_ratio = double(dead_to_right) / live_to_right; 334 335 if (reclaimed_ratio > max_reclaimed_ratio) { 336 max_reclaimed_ratio = reclaimed_ratio; 337 max_reclaimed_ratio_region = i; 338 max_dead_to_right = dead_to_right; 339 max_live_to_right = live_to_right; 340 } 341 342 ParallelCompactData::RegionData* c = summary_data.region(i); 343 log_develop_trace(gc, compaction)( 344 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d" 345 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), 346 i, p2i(c->destination()), 347 c->partial_obj_size(), c->live_obj_size(), 348 c->data_size(), c->source_region(), c->destination_count(), 349 reclaimed_ratio, dead_to_right, live_to_right); 350 351 352 live_to_right -= c->data_size(); 353 ++i; 354 } 355 356 // Any remaining regions are empty. Print one more if there is one. 357 if (i < end_region) { 358 ParallelCompactData::RegionData* c = summary_data.region(i); 359 log_develop_trace(gc, compaction)( 360 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 361 i, p2i(c->destination()), 362 c->partial_obj_size(), c->live_obj_size(), 363 c->data_size(), c->source_region(), c->destination_count()); 364 } 365 366 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", 367 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio); 368 } 369 370 void 371 print_initial_summary_data(ParallelCompactData& summary_data, 372 SpaceInfo* space_info) { 373 if (!log_develop_is_enabled(Trace, gc, compaction)) { 374 return; 375 } 376 377 unsigned int id = PSParallelCompact::old_space_id; 378 const MutableSpace* space; 379 do { 380 space = space_info[id].space(); 381 print_initial_summary_data(summary_data, space); 382 } while (++id < PSParallelCompact::eden_space_id); 383 384 do { 385 space = space_info[id].space(); 386 print_generic_summary_data(summary_data, space->bottom(), space->top()); 387 } while (++id < PSParallelCompact::last_space_id); 388 } 389 #endif // #ifndef PRODUCT 390 391 #ifdef ASSERT 392 size_t add_obj_count; 393 size_t add_obj_size; 394 size_t mark_bitmap_count; 395 size_t mark_bitmap_size; 396 #endif // #ifdef ASSERT 397 398 ParallelCompactData::ParallelCompactData() 399 { 400 _region_start = 0; 401 402 _region_vspace = 0; 403 _reserved_byte_size = 0; 404 _region_data = 0; 405 _region_count = 0; 406 407 _block_vspace = 0; 408 _block_data = 0; 409 _block_count = 0; 410 } 411 412 bool ParallelCompactData::initialize(MemRegion covered_region) 413 { 414 _region_start = covered_region.start(); 415 const size_t region_size = covered_region.word_size(); 416 DEBUG_ONLY(_region_end = _region_start + region_size;) 417 418 assert(region_align_down(_region_start) == _region_start, 419 "region start not aligned"); 420 assert((region_size & RegionSizeOffsetMask) == 0, 421 "region size not a multiple of RegionSize"); 422 423 bool result = initialize_region_data(region_size) && initialize_block_data(); 424 return result; 425 } 426 427 PSVirtualSpace* 428 ParallelCompactData::create_vspace(size_t count, size_t element_size) 429 { 430 const size_t raw_bytes = count * element_size; 431 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10); 432 const size_t granularity = os::vm_allocation_granularity(); 433 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity)); 434 435 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : 436 MAX2(page_sz, granularity); 437 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0); 438 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(), 439 rs.size()); 440 441 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 442 443 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); 444 if (vspace != 0) { 445 if (vspace->expand_by(_reserved_byte_size)) { 446 return vspace; 447 } 448 delete vspace; 449 // Release memory reserved in the space. 450 rs.release(); 451 } 452 453 return 0; 454 } 455 456 bool ParallelCompactData::initialize_region_data(size_t region_size) 457 { 458 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize; 459 _region_vspace = create_vspace(count, sizeof(RegionData)); 460 if (_region_vspace != 0) { 461 _region_data = (RegionData*)_region_vspace->reserved_low_addr(); 462 _region_count = count; 463 return true; 464 } 465 return false; 466 } 467 468 bool ParallelCompactData::initialize_block_data() 469 { 470 assert(_region_count != 0, "region data must be initialized first"); 471 const size_t count = _region_count << Log2BlocksPerRegion; 472 _block_vspace = create_vspace(count, sizeof(BlockData)); 473 if (_block_vspace != 0) { 474 _block_data = (BlockData*)_block_vspace->reserved_low_addr(); 475 _block_count = count; 476 return true; 477 } 478 return false; 479 } 480 481 void ParallelCompactData::clear() 482 { 483 memset(_region_data, 0, _region_vspace->committed_size()); 484 memset(_block_data, 0, _block_vspace->committed_size()); 485 } 486 487 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) { 488 assert(beg_region <= _region_count, "beg_region out of range"); 489 assert(end_region <= _region_count, "end_region out of range"); 490 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize"); 491 492 const size_t region_cnt = end_region - beg_region; 493 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData)); 494 495 const size_t beg_block = beg_region * BlocksPerRegion; 496 const size_t block_cnt = region_cnt * BlocksPerRegion; 497 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData)); 498 } 499 500 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const 501 { 502 const RegionData* cur_cp = region(region_idx); 503 const RegionData* const end_cp = region(region_count() - 1); 504 505 HeapWord* result = region_to_addr(region_idx); 506 if (cur_cp < end_cp) { 507 do { 508 result += cur_cp->partial_obj_size(); 509 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp); 510 } 511 return result; 512 } 513 514 void ParallelCompactData::add_obj(HeapWord* addr, size_t len) 515 { 516 const size_t obj_ofs = pointer_delta(addr, _region_start); 517 const size_t beg_region = obj_ofs >> Log2RegionSize; 518 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize; 519 520 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);) 521 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);) 522 523 if (beg_region == end_region) { 524 // All in one region. 525 _region_data[beg_region].add_live_obj(len); 526 return; 527 } 528 529 // First region. 530 const size_t beg_ofs = region_offset(addr); 531 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs); 532 533 Klass* klass = ((oop)addr)->klass(); 534 // Middle regions--completely spanned by this object. 535 for (size_t region = beg_region + 1; region < end_region; ++region) { 536 _region_data[region].set_partial_obj_size(RegionSize); 537 _region_data[region].set_partial_obj_addr(addr); 538 } 539 540 // Last region. 541 const size_t end_ofs = region_offset(addr + len - 1); 542 _region_data[end_region].set_partial_obj_size(end_ofs + 1); 543 _region_data[end_region].set_partial_obj_addr(addr); 544 } 545 546 void 547 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) 548 { 549 assert(region_offset(beg) == 0, "not RegionSize aligned"); 550 assert(region_offset(end) == 0, "not RegionSize aligned"); 551 552 size_t cur_region = addr_to_region_idx(beg); 553 const size_t end_region = addr_to_region_idx(end); 554 HeapWord* addr = beg; 555 while (cur_region < end_region) { 556 _region_data[cur_region].set_destination(addr); 557 _region_data[cur_region].set_destination_count(0); 558 _region_data[cur_region].set_source_region(cur_region); 559 _region_data[cur_region].set_data_location(addr); 560 561 // Update live_obj_size so the region appears completely full. 562 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size(); 563 _region_data[cur_region].set_live_obj_size(live_size); 564 565 ++cur_region; 566 addr += RegionSize; 567 } 568 } 569 570 // Find the point at which a space can be split and, if necessary, record the 571 // split point. 572 // 573 // If the current src region (which overflowed the destination space) doesn't 574 // have a partial object, the split point is at the beginning of the current src 575 // region (an "easy" split, no extra bookkeeping required). 576 // 577 // If the current src region has a partial object, the split point is in the 578 // region where that partial object starts (call it the split_region). If 579 // split_region has a partial object, then the split point is just after that 580 // partial object (a "hard" split where we have to record the split data and 581 // zero the partial_obj_size field). With a "hard" split, we know that the 582 // partial_obj ends within split_region because the partial object that caused 583 // the overflow starts in split_region. If split_region doesn't have a partial 584 // obj, then the split is at the beginning of split_region (another "easy" 585 // split). 586 HeapWord* 587 ParallelCompactData::summarize_split_space(size_t src_region, 588 SplitInfo& split_info, 589 HeapWord* destination, 590 HeapWord* target_end, 591 HeapWord** target_next) 592 { 593 assert(destination <= target_end, "sanity"); 594 assert(destination + _region_data[src_region].data_size() > target_end, 595 "region should not fit into target space"); 596 assert(is_region_aligned(target_end), "sanity"); 597 598 size_t split_region = src_region; 599 HeapWord* split_destination = destination; 600 size_t partial_obj_size = _region_data[src_region].partial_obj_size(); 601 602 if (destination + partial_obj_size > target_end) { 603 // The split point is just after the partial object (if any) in the 604 // src_region that contains the start of the object that overflowed the 605 // destination space. 606 // 607 // Find the start of the "overflow" object and set split_region to the 608 // region containing it. 609 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr(); 610 split_region = addr_to_region_idx(overflow_obj); 611 612 // Clear the source_region field of all destination regions whose first word 613 // came from data after the split point (a non-null source_region field 614 // implies a region must be filled). 615 // 616 // An alternative to the simple loop below: clear during post_compact(), 617 // which uses memcpy instead of individual stores, and is easy to 618 // parallelize. (The downside is that it clears the entire RegionData 619 // object as opposed to just one field.) 620 // 621 // post_compact() would have to clear the summary data up to the highest 622 // address that was written during the summary phase, which would be 623 // 624 // max(top, max(new_top, clear_top)) 625 // 626 // where clear_top is a new field in SpaceInfo. Would have to set clear_top 627 // to target_end. 628 const RegionData* const sr = region(split_region); 629 const size_t beg_idx = 630 addr_to_region_idx(region_align_up(sr->destination() + 631 sr->partial_obj_size())); 632 const size_t end_idx = addr_to_region_idx(target_end); 633 634 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx); 635 for (size_t idx = beg_idx; idx < end_idx; ++idx) { 636 _region_data[idx].set_source_region(0); 637 } 638 639 // Set split_destination and partial_obj_size to reflect the split region. 640 split_destination = sr->destination(); 641 partial_obj_size = sr->partial_obj_size(); 642 } 643 644 // The split is recorded only if a partial object extends onto the region. 645 if (partial_obj_size != 0) { 646 _region_data[split_region].set_partial_obj_size(0); 647 split_info.record(split_region, partial_obj_size, split_destination); 648 } 649 650 // Setup the continuation addresses. 651 *target_next = split_destination + partial_obj_size; 652 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size; 653 654 if (log_develop_is_enabled(Trace, gc, compaction)) { 655 const char * split_type = partial_obj_size == 0 ? "easy" : "hard"; 656 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT, 657 split_type, p2i(source_next), split_region, partial_obj_size); 658 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT, 659 split_type, p2i(split_destination), 660 addr_to_region_idx(split_destination), 661 p2i(*target_next)); 662 663 if (partial_obj_size != 0) { 664 HeapWord* const po_beg = split_info.destination(); 665 HeapWord* const po_end = po_beg + split_info.partial_obj_size(); 666 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT, 667 split_type, 668 p2i(po_beg), addr_to_region_idx(po_beg), 669 p2i(po_end), addr_to_region_idx(po_end)); 670 } 671 } 672 673 return source_next; 674 } 675 676 bool ParallelCompactData::summarize(SplitInfo& split_info, 677 HeapWord* source_beg, HeapWord* source_end, 678 HeapWord** source_next, 679 HeapWord* target_beg, HeapWord* target_end, 680 HeapWord** target_next) 681 { 682 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next; 683 log_develop_trace(gc, compaction)( 684 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT 685 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT, 686 p2i(source_beg), p2i(source_end), p2i(source_next_val), 687 p2i(target_beg), p2i(target_end), p2i(*target_next)); 688 689 size_t cur_region = addr_to_region_idx(source_beg); 690 const size_t end_region = addr_to_region_idx(region_align_up(source_end)); 691 692 HeapWord *dest_addr = target_beg; 693 while (cur_region < end_region) { 694 // The destination must be set even if the region has no data. 695 _region_data[cur_region].set_destination(dest_addr); 696 697 size_t words = _region_data[cur_region].data_size(); 698 if (words > 0) { 699 // If cur_region does not fit entirely into the target space, find a point 700 // at which the source space can be 'split' so that part is copied to the 701 // target space and the rest is copied elsewhere. 702 if (dest_addr + words > target_end) { 703 assert(source_next != NULL, "source_next is NULL when splitting"); 704 *source_next = summarize_split_space(cur_region, split_info, dest_addr, 705 target_end, target_next); 706 return false; 707 } 708 709 // Compute the destination_count for cur_region, and if necessary, update 710 // source_region for a destination region. The source_region field is 711 // updated if cur_region is the first (left-most) region to be copied to a 712 // destination region. 713 // 714 // The destination_count calculation is a bit subtle. A region that has 715 // data that compacts into itself does not count itself as a destination. 716 // This maintains the invariant that a zero count means the region is 717 // available and can be claimed and then filled. 718 uint destination_count = 0; 719 if (split_info.is_split(cur_region)) { 720 // The current region has been split: the partial object will be copied 721 // to one destination space and the remaining data will be copied to 722 // another destination space. Adjust the initial destination_count and, 723 // if necessary, set the source_region field if the partial object will 724 // cross a destination region boundary. 725 destination_count = split_info.destination_count(); 726 if (destination_count == 2) { 727 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr()); 728 _region_data[dest_idx].set_source_region(cur_region); 729 } 730 } 731 732 HeapWord* const last_addr = dest_addr + words - 1; 733 const size_t dest_region_1 = addr_to_region_idx(dest_addr); 734 const size_t dest_region_2 = addr_to_region_idx(last_addr); 735 736 // Initially assume that the destination regions will be the same and 737 // adjust the value below if necessary. Under this assumption, if 738 // cur_region == dest_region_2, then cur_region will be compacted 739 // completely into itself. 740 destination_count += cur_region == dest_region_2 ? 0 : 1; 741 if (dest_region_1 != dest_region_2) { 742 // Destination regions differ; adjust destination_count. 743 destination_count += 1; 744 // Data from cur_region will be copied to the start of dest_region_2. 745 _region_data[dest_region_2].set_source_region(cur_region); 746 } else if (region_offset(dest_addr) == 0) { 747 // Data from cur_region will be copied to the start of the destination 748 // region. 749 _region_data[dest_region_1].set_source_region(cur_region); 750 } 751 752 _region_data[cur_region].set_destination_count(destination_count); 753 _region_data[cur_region].set_data_location(region_to_addr(cur_region)); 754 dest_addr += words; 755 } 756 757 ++cur_region; 758 } 759 760 *target_next = dest_addr; 761 return true; 762 } 763 764 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) { 765 assert(addr != NULL, "Should detect NULL oop earlier"); 766 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap"); 767 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked"); 768 769 // Region covering the object. 770 RegionData* const region_ptr = addr_to_region_ptr(addr); 771 HeapWord* result = region_ptr->destination(); 772 773 // If the entire Region is live, the new location is region->destination + the 774 // offset of the object within in the Region. 775 776 // Run some performance tests to determine if this special case pays off. It 777 // is worth it for pointers into the dense prefix. If the optimization to 778 // avoid pointer updates in regions that only point to the dense prefix is 779 // ever implemented, this should be revisited. 780 if (region_ptr->data_size() == RegionSize) { 781 result += region_offset(addr); 782 return result; 783 } 784 785 // Otherwise, the new location is region->destination + block offset + the 786 // number of live words in the Block that are (a) to the left of addr and (b) 787 // due to objects that start in the Block. 788 789 // Fill in the block table if necessary. This is unsynchronized, so multiple 790 // threads may fill the block table for a region (harmless, since it is 791 // idempotent). 792 if (!region_ptr->blocks_filled()) { 793 PSParallelCompact::fill_blocks(addr_to_region_idx(addr)); 794 region_ptr->set_blocks_filled(); 795 } 796 797 HeapWord* const search_start = block_align_down(addr); 798 const size_t block_offset = addr_to_block_ptr(addr)->offset(); 799 800 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); 801 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr)); 802 result += block_offset + live; 803 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result)); 804 return result; 805 } 806 807 #ifdef ASSERT 808 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) 809 { 810 const size_t* const beg = (const size_t*)vspace->committed_low_addr(); 811 const size_t* const end = (const size_t*)vspace->committed_high_addr(); 812 for (const size_t* p = beg; p < end; ++p) { 813 assert(*p == 0, "not zero"); 814 } 815 } 816 817 void ParallelCompactData::verify_clear() 818 { 819 verify_clear(_region_vspace); 820 verify_clear(_block_vspace); 821 } 822 #endif // #ifdef ASSERT 823 824 STWGCTimer PSParallelCompact::_gc_timer; 825 ParallelOldTracer PSParallelCompact::_gc_tracer; 826 elapsedTimer PSParallelCompact::_accumulated_time; 827 unsigned int PSParallelCompact::_total_invocations = 0; 828 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; 829 jlong PSParallelCompact::_time_of_last_gc = 0; 830 CollectorCounters* PSParallelCompact::_counters = NULL; 831 ParMarkBitMap PSParallelCompact::_mark_bitmap; 832 ParallelCompactData PSParallelCompact::_summary_data; 833 834 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; 835 836 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } 837 838 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) { 839 PSParallelCompact::AdjustPointerClosure closure(_cm); 840 klass->oops_do(&closure); 841 } 842 843 void PSParallelCompact::post_initialize() { 844 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 845 MemRegion mr = heap->reserved_region(); 846 _ref_processor = 847 new ReferenceProcessor(mr, // span 848 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 849 ParallelGCThreads, // mt processing degree 850 true, // mt discovery 851 ParallelGCThreads, // mt discovery degree 852 true, // atomic_discovery 853 &_is_alive_closure); // non-header is alive closure 854 _counters = new CollectorCounters("PSParallelCompact", 1); 855 856 // Initialize static fields in ParCompactionManager. 857 ParCompactionManager::initialize(mark_bitmap()); 858 } 859 860 bool PSParallelCompact::initialize() { 861 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 862 MemRegion mr = heap->reserved_region(); 863 864 // Was the old gen get allocated successfully? 865 if (!heap->old_gen()->is_allocated()) { 866 return false; 867 } 868 869 initialize_space_info(); 870 initialize_dead_wood_limiter(); 871 872 if (!_mark_bitmap.initialize(mr)) { 873 vm_shutdown_during_initialization( 874 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel " 875 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 876 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K)); 877 return false; 878 } 879 880 if (!_summary_data.initialize(mr)) { 881 vm_shutdown_during_initialization( 882 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel " 883 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 884 _summary_data.reserved_byte_size()/K, mr.byte_size()/K)); 885 return false; 886 } 887 888 return true; 889 } 890 891 void PSParallelCompact::initialize_space_info() 892 { 893 memset(&_space_info, 0, sizeof(_space_info)); 894 895 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 896 PSYoungGen* young_gen = heap->young_gen(); 897 898 _space_info[old_space_id].set_space(heap->old_gen()->object_space()); 899 _space_info[eden_space_id].set_space(young_gen->eden_space()); 900 _space_info[from_space_id].set_space(young_gen->from_space()); 901 _space_info[to_space_id].set_space(young_gen->to_space()); 902 903 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); 904 } 905 906 void PSParallelCompact::initialize_dead_wood_limiter() 907 { 908 const size_t max = 100; 909 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; 910 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; 911 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); 912 DEBUG_ONLY(_dwl_initialized = true;) 913 _dwl_adjustment = normal_distribution(1.0); 914 } 915 916 void 917 PSParallelCompact::clear_data_covering_space(SpaceId id) 918 { 919 // At this point, top is the value before GC, new_top() is the value that will 920 // be set at the end of GC. The marking bitmap is cleared to top; nothing 921 // should be marked above top. The summary data is cleared to the larger of 922 // top & new_top. 923 MutableSpace* const space = _space_info[id].space(); 924 HeapWord* const bot = space->bottom(); 925 HeapWord* const top = space->top(); 926 HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); 927 928 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); 929 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top)); 930 _mark_bitmap.clear_range(beg_bit, end_bit); 931 932 const size_t beg_region = _summary_data.addr_to_region_idx(bot); 933 const size_t end_region = 934 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top)); 935 _summary_data.clear_range(beg_region, end_region); 936 937 // Clear the data used to 'split' regions. 938 SplitInfo& split_info = _space_info[id].split_info(); 939 if (split_info.is_valid()) { 940 split_info.clear(); 941 } 942 DEBUG_ONLY(split_info.verify_clear();) 943 } 944 945 void PSParallelCompact::pre_compact() 946 { 947 // Update the from & to space pointers in space_info, since they are swapped 948 // at each young gen gc. Do the update unconditionally (even though a 949 // promotion failure does not swap spaces) because an unknown number of young 950 // collections will have swapped the spaces an unknown number of times. 951 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer); 952 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 953 _space_info[from_space_id].set_space(heap->young_gen()->from_space()); 954 _space_info[to_space_id].set_space(heap->young_gen()->to_space()); 955 956 DEBUG_ONLY(add_obj_count = add_obj_size = 0;) 957 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;) 958 959 // Increment the invocation count 960 heap->increment_total_collections(true); 961 962 // We need to track unique mark sweep invocations as well. 963 _total_invocations++; 964 965 heap->print_heap_before_gc(); 966 heap->trace_heap_before_gc(&_gc_tracer); 967 968 // Fill in TLABs 969 heap->accumulate_statistics_all_tlabs(); 970 heap->ensure_parsability(true); // retire TLABs 971 972 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 973 HandleMark hm; // Discard invalid handles created during verification 974 Universe::verify("Before GC"); 975 } 976 977 // Verify object start arrays 978 if (VerifyObjectStartArray && 979 VerifyBeforeGC) { 980 heap->old_gen()->verify_object_start_array(); 981 } 982 983 DEBUG_ONLY(mark_bitmap()->verify_clear();) 984 DEBUG_ONLY(summary_data().verify_clear();) 985 986 // Have worker threads release resources the next time they run a task. 987 gc_task_manager()->release_all_resources(); 988 989 ParCompactionManager::reset_all_bitmap_query_caches(); 990 } 991 992 void PSParallelCompact::post_compact() 993 { 994 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer); 995 996 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 997 // Clear the marking bitmap, summary data and split info. 998 clear_data_covering_space(SpaceId(id)); 999 // Update top(). Must be done after clearing the bitmap and summary data. 1000 _space_info[id].publish_new_top(); 1001 } 1002 1003 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1004 MutableSpace* const from_space = _space_info[from_space_id].space(); 1005 MutableSpace* const to_space = _space_info[to_space_id].space(); 1006 1007 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1008 bool eden_empty = eden_space->is_empty(); 1009 if (!eden_empty) { 1010 eden_empty = absorb_live_data_from_eden(heap->size_policy(), 1011 heap->young_gen(), heap->old_gen()); 1012 } 1013 1014 // Update heap occupancy information which is used as input to the soft ref 1015 // clearing policy at the next gc. 1016 Universe::update_heap_info_at_gc(); 1017 1018 bool young_gen_empty = eden_empty && from_space->is_empty() && 1019 to_space->is_empty(); 1020 1021 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set()); 1022 MemRegion old_mr = heap->old_gen()->reserved(); 1023 if (young_gen_empty) { 1024 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 1025 } else { 1026 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 1027 } 1028 1029 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1030 ClassLoaderDataGraph::purge(); 1031 MetaspaceAux::verify_metrics(); 1032 1033 CodeCache::gc_epilogue(); 1034 JvmtiExport::gc_epilogue(); 1035 1036 #if defined(COMPILER2) || INCLUDE_JVMCI 1037 DerivedPointerTable::update_pointers(); 1038 #endif 1039 1040 ref_processor()->enqueue_discovered_references(NULL); 1041 1042 if (ZapUnusedHeapArea) { 1043 heap->gen_mangle_unused_area(); 1044 } 1045 1046 // Update time of last GC 1047 reset_millis_since_last_gc(); 1048 } 1049 1050 HeapWord* 1051 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, 1052 bool maximum_compaction) 1053 { 1054 const size_t region_size = ParallelCompactData::RegionSize; 1055 const ParallelCompactData& sd = summary_data(); 1056 1057 const MutableSpace* const space = _space_info[id].space(); 1058 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 1059 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom()); 1060 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up); 1061 1062 // Skip full regions at the beginning of the space--they are necessarily part 1063 // of the dense prefix. 1064 size_t full_count = 0; 1065 const RegionData* cp; 1066 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) { 1067 ++full_count; 1068 } 1069 1070 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1071 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1072 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; 1073 if (maximum_compaction || cp == end_cp || interval_ended) { 1074 _maximum_compaction_gc_num = total_invocations(); 1075 return sd.region_to_addr(cp); 1076 } 1077 1078 HeapWord* const new_top = _space_info[id].new_top(); 1079 const size_t space_live = pointer_delta(new_top, space->bottom()); 1080 const size_t space_used = space->used_in_words(); 1081 const size_t space_capacity = space->capacity_in_words(); 1082 1083 const double cur_density = double(space_live) / space_capacity; 1084 const double deadwood_density = 1085 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; 1086 const size_t deadwood_goal = size_t(space_capacity * deadwood_density); 1087 1088 if (TraceParallelOldGCDensePrefix) { 1089 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, 1090 cur_density, deadwood_density, deadwood_goal); 1091 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1092 "space_cap=" SIZE_FORMAT, 1093 space_live, space_used, 1094 space_capacity); 1095 } 1096 1097 // XXX - Use binary search? 1098 HeapWord* dense_prefix = sd.region_to_addr(cp); 1099 const RegionData* full_cp = cp; 1100 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1); 1101 while (cp < end_cp) { 1102 HeapWord* region_destination = cp->destination(); 1103 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination); 1104 if (TraceParallelOldGCDensePrefix && Verbose) { 1105 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " 1106 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8), 1107 sd.region(cp), p2i(region_destination), 1108 p2i(dense_prefix), cur_deadwood); 1109 } 1110 1111 if (cur_deadwood >= deadwood_goal) { 1112 // Found the region that has the correct amount of deadwood to the left. 1113 // This typically occurs after crossing a fairly sparse set of regions, so 1114 // iterate backwards over those sparse regions, looking for the region 1115 // that has the lowest density of live objects 'to the right.' 1116 size_t space_to_left = sd.region(cp) * region_size; 1117 size_t live_to_left = space_to_left - cur_deadwood; 1118 size_t space_to_right = space_capacity - space_to_left; 1119 size_t live_to_right = space_live - live_to_left; 1120 double density_to_right = double(live_to_right) / space_to_right; 1121 while (cp > full_cp) { 1122 --cp; 1123 const size_t prev_region_live_to_right = live_to_right - 1124 cp->data_size(); 1125 const size_t prev_region_space_to_right = space_to_right + region_size; 1126 double prev_region_density_to_right = 1127 double(prev_region_live_to_right) / prev_region_space_to_right; 1128 if (density_to_right <= prev_region_density_to_right) { 1129 return dense_prefix; 1130 } 1131 if (TraceParallelOldGCDensePrefix && Verbose) { 1132 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " 1133 "pc_d2r=%10.8f", sd.region(cp), density_to_right, 1134 prev_region_density_to_right); 1135 } 1136 dense_prefix -= region_size; 1137 live_to_right = prev_region_live_to_right; 1138 space_to_right = prev_region_space_to_right; 1139 density_to_right = prev_region_density_to_right; 1140 } 1141 return dense_prefix; 1142 } 1143 1144 dense_prefix += region_size; 1145 ++cp; 1146 } 1147 1148 return dense_prefix; 1149 } 1150 1151 #ifndef PRODUCT 1152 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, 1153 const SpaceId id, 1154 const bool maximum_compaction, 1155 HeapWord* const addr) 1156 { 1157 const size_t region_idx = summary_data().addr_to_region_idx(addr); 1158 RegionData* const cp = summary_data().region(region_idx); 1159 const MutableSpace* const space = _space_info[id].space(); 1160 HeapWord* const new_top = _space_info[id].new_top(); 1161 1162 const size_t space_live = pointer_delta(new_top, space->bottom()); 1163 const size_t dead_to_left = pointer_delta(addr, cp->destination()); 1164 const size_t space_cap = space->capacity_in_words(); 1165 const double dead_to_left_pct = double(dead_to_left) / space_cap; 1166 const size_t live_to_right = new_top - cp->destination(); 1167 const size_t dead_to_right = space->top() - addr - live_to_right; 1168 1169 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " 1170 "spl=" SIZE_FORMAT " " 1171 "d2l=" SIZE_FORMAT " d2l%%=%6.4f " 1172 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT 1173 " ratio=%10.8f", 1174 algorithm, p2i(addr), region_idx, 1175 space_live, 1176 dead_to_left, dead_to_left_pct, 1177 dead_to_right, live_to_right, 1178 double(dead_to_right) / live_to_right); 1179 } 1180 #endif // #ifndef PRODUCT 1181 1182 // Return a fraction indicating how much of the generation can be treated as 1183 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution 1184 // based on the density of live objects in the generation to determine a limit, 1185 // which is then adjusted so the return value is min_percent when the density is 1186 // 1. 1187 // 1188 // The following table shows some return values for a different values of the 1189 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and 1190 // min_percent is 1. 1191 // 1192 // fraction allowed as dead wood 1193 // ----------------------------------------------------------------- 1194 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 1195 // ------- ---------- ---------- ---------- ---------- ---------- ---------- 1196 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1197 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1198 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1199 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1200 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1201 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1202 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1203 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1204 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1205 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1206 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 1207 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1208 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1209 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1210 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1211 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1212 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1213 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1214 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1215 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1216 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1217 1218 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) 1219 { 1220 assert(_dwl_initialized, "uninitialized"); 1221 1222 // The raw limit is the value of the normal distribution at x = density. 1223 const double raw_limit = normal_distribution(density); 1224 1225 // Adjust the raw limit so it becomes the minimum when the density is 1. 1226 // 1227 // First subtract the adjustment value (which is simply the precomputed value 1228 // normal_distribution(1.0)); this yields a value of 0 when the density is 1. 1229 // Then add the minimum value, so the minimum is returned when the density is 1230 // 1. Finally, prevent negative values, which occur when the mean is not 0.5. 1231 const double min = double(min_percent) / 100.0; 1232 const double limit = raw_limit - _dwl_adjustment + min; 1233 return MAX2(limit, 0.0); 1234 } 1235 1236 ParallelCompactData::RegionData* 1237 PSParallelCompact::first_dead_space_region(const RegionData* beg, 1238 const RegionData* end) 1239 { 1240 const size_t region_size = ParallelCompactData::RegionSize; 1241 ParallelCompactData& sd = summary_data(); 1242 size_t left = sd.region(beg); 1243 size_t right = end > beg ? sd.region(end) - 1 : left; 1244 1245 // Binary search. 1246 while (left < right) { 1247 // Equivalent to (left + right) / 2, but does not overflow. 1248 const size_t middle = left + (right - left) / 2; 1249 RegionData* const middle_ptr = sd.region(middle); 1250 HeapWord* const dest = middle_ptr->destination(); 1251 HeapWord* const addr = sd.region_to_addr(middle); 1252 assert(dest != NULL, "sanity"); 1253 assert(dest <= addr, "must move left"); 1254 1255 if (middle > left && dest < addr) { 1256 right = middle - 1; 1257 } else if (middle < right && middle_ptr->data_size() == region_size) { 1258 left = middle + 1; 1259 } else { 1260 return middle_ptr; 1261 } 1262 } 1263 return sd.region(left); 1264 } 1265 1266 ParallelCompactData::RegionData* 1267 PSParallelCompact::dead_wood_limit_region(const RegionData* beg, 1268 const RegionData* end, 1269 size_t dead_words) 1270 { 1271 ParallelCompactData& sd = summary_data(); 1272 size_t left = sd.region(beg); 1273 size_t right = end > beg ? sd.region(end) - 1 : left; 1274 1275 // Binary search. 1276 while (left < right) { 1277 // Equivalent to (left + right) / 2, but does not overflow. 1278 const size_t middle = left + (right - left) / 2; 1279 RegionData* const middle_ptr = sd.region(middle); 1280 HeapWord* const dest = middle_ptr->destination(); 1281 HeapWord* const addr = sd.region_to_addr(middle); 1282 assert(dest != NULL, "sanity"); 1283 assert(dest <= addr, "must move left"); 1284 1285 const size_t dead_to_left = pointer_delta(addr, dest); 1286 if (middle > left && dead_to_left > dead_words) { 1287 right = middle - 1; 1288 } else if (middle < right && dead_to_left < dead_words) { 1289 left = middle + 1; 1290 } else { 1291 return middle_ptr; 1292 } 1293 } 1294 return sd.region(left); 1295 } 1296 1297 // The result is valid during the summary phase, after the initial summarization 1298 // of each space into itself, and before final summarization. 1299 inline double 1300 PSParallelCompact::reclaimed_ratio(const RegionData* const cp, 1301 HeapWord* const bottom, 1302 HeapWord* const top, 1303 HeapWord* const new_top) 1304 { 1305 ParallelCompactData& sd = summary_data(); 1306 1307 assert(cp != NULL, "sanity"); 1308 assert(bottom != NULL, "sanity"); 1309 assert(top != NULL, "sanity"); 1310 assert(new_top != NULL, "sanity"); 1311 assert(top >= new_top, "summary data problem?"); 1312 assert(new_top > bottom, "space is empty; should not be here"); 1313 assert(new_top >= cp->destination(), "sanity"); 1314 assert(top >= sd.region_to_addr(cp), "sanity"); 1315 1316 HeapWord* const destination = cp->destination(); 1317 const size_t dense_prefix_live = pointer_delta(destination, bottom); 1318 const size_t compacted_region_live = pointer_delta(new_top, destination); 1319 const size_t compacted_region_used = pointer_delta(top, 1320 sd.region_to_addr(cp)); 1321 const size_t reclaimable = compacted_region_used - compacted_region_live; 1322 1323 const double divisor = dense_prefix_live + 1.25 * compacted_region_live; 1324 return double(reclaimable) / divisor; 1325 } 1326 1327 // Return the address of the end of the dense prefix, a.k.a. the start of the 1328 // compacted region. The address is always on a region boundary. 1329 // 1330 // Completely full regions at the left are skipped, since no compaction can 1331 // occur in those regions. Then the maximum amount of dead wood to allow is 1332 // computed, based on the density (amount live / capacity) of the generation; 1333 // the region with approximately that amount of dead space to the left is 1334 // identified as the limit region. Regions between the last completely full 1335 // region and the limit region are scanned and the one that has the best 1336 // (maximum) reclaimed_ratio() is selected. 1337 HeapWord* 1338 PSParallelCompact::compute_dense_prefix(const SpaceId id, 1339 bool maximum_compaction) 1340 { 1341 const size_t region_size = ParallelCompactData::RegionSize; 1342 const ParallelCompactData& sd = summary_data(); 1343 1344 const MutableSpace* const space = _space_info[id].space(); 1345 HeapWord* const top = space->top(); 1346 HeapWord* const top_aligned_up = sd.region_align_up(top); 1347 HeapWord* const new_top = _space_info[id].new_top(); 1348 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top); 1349 HeapWord* const bottom = space->bottom(); 1350 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom); 1351 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 1352 const RegionData* const new_top_cp = 1353 sd.addr_to_region_ptr(new_top_aligned_up); 1354 1355 // Skip full regions at the beginning of the space--they are necessarily part 1356 // of the dense prefix. 1357 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp); 1358 assert(full_cp->destination() == sd.region_to_addr(full_cp) || 1359 space->is_empty(), "no dead space allowed to the left"); 1360 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1, 1361 "region must have dead space"); 1362 1363 // The gc number is saved whenever a maximum compaction is done, and used to 1364 // determine when the maximum compaction interval has expired. This avoids 1365 // successive max compactions for different reasons. 1366 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1367 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1368 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || 1369 total_invocations() == HeapFirstMaximumCompactionCount; 1370 if (maximum_compaction || full_cp == top_cp || interval_ended) { 1371 _maximum_compaction_gc_num = total_invocations(); 1372 return sd.region_to_addr(full_cp); 1373 } 1374 1375 const size_t space_live = pointer_delta(new_top, bottom); 1376 const size_t space_used = space->used_in_words(); 1377 const size_t space_capacity = space->capacity_in_words(); 1378 1379 const double density = double(space_live) / double(space_capacity); 1380 const size_t min_percent_free = MarkSweepDeadRatio; 1381 const double limiter = dead_wood_limiter(density, min_percent_free); 1382 const size_t dead_wood_max = space_used - space_live; 1383 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), 1384 dead_wood_max); 1385 1386 if (TraceParallelOldGCDensePrefix) { 1387 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1388 "space_cap=" SIZE_FORMAT, 1389 space_live, space_used, 1390 space_capacity); 1391 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f " 1392 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, 1393 density, min_percent_free, limiter, 1394 dead_wood_max, dead_wood_limit); 1395 } 1396 1397 // Locate the region with the desired amount of dead space to the left. 1398 const RegionData* const limit_cp = 1399 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit); 1400 1401 // Scan from the first region with dead space to the limit region and find the 1402 // one with the best (largest) reclaimed ratio. 1403 double best_ratio = 0.0; 1404 const RegionData* best_cp = full_cp; 1405 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) { 1406 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); 1407 if (tmp_ratio > best_ratio) { 1408 best_cp = cp; 1409 best_ratio = tmp_ratio; 1410 } 1411 } 1412 1413 return sd.region_to_addr(best_cp); 1414 } 1415 1416 void PSParallelCompact::summarize_spaces_quick() 1417 { 1418 for (unsigned int i = 0; i < last_space_id; ++i) { 1419 const MutableSpace* space = _space_info[i].space(); 1420 HeapWord** nta = _space_info[i].new_top_addr(); 1421 bool result = _summary_data.summarize(_space_info[i].split_info(), 1422 space->bottom(), space->top(), NULL, 1423 space->bottom(), space->end(), nta); 1424 assert(result, "space must fit into itself"); 1425 _space_info[i].set_dense_prefix(space->bottom()); 1426 } 1427 } 1428 1429 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) 1430 { 1431 HeapWord* const dense_prefix_end = dense_prefix(id); 1432 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end); 1433 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); 1434 if (dead_space_crosses_boundary(region, dense_prefix_bit)) { 1435 // Only enough dead space is filled so that any remaining dead space to the 1436 // left is larger than the minimum filler object. (The remainder is filled 1437 // during the copy/update phase.) 1438 // 1439 // The size of the dead space to the right of the boundary is not a 1440 // concern, since compaction will be able to use whatever space is 1441 // available. 1442 // 1443 // Here '||' is the boundary, 'x' represents a don't care bit and a box 1444 // surrounds the space to be filled with an object. 1445 // 1446 // In the 32-bit VM, each bit represents two 32-bit words: 1447 // +---+ 1448 // a) beg_bits: ... x x x | 0 | || 0 x x ... 1449 // end_bits: ... x x x | 0 | || 0 x x ... 1450 // +---+ 1451 // 1452 // In the 64-bit VM, each bit represents one 64-bit word: 1453 // +------------+ 1454 // b) beg_bits: ... x x x | 0 || 0 | x x ... 1455 // end_bits: ... x x 1 | 0 || 0 | x x ... 1456 // +------------+ 1457 // +-------+ 1458 // c) beg_bits: ... x x | 0 0 | || 0 x x ... 1459 // end_bits: ... x 1 | 0 0 | || 0 x x ... 1460 // +-------+ 1461 // +-----------+ 1462 // d) beg_bits: ... x | 0 0 0 | || 0 x x ... 1463 // end_bits: ... 1 | 0 0 0 | || 0 x x ... 1464 // +-----------+ 1465 // +-------+ 1466 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... 1467 // end_bits: ... 0 0 | 0 0 | || 0 x x ... 1468 // +-------+ 1469 1470 // Initially assume case a, c or e will apply. 1471 size_t obj_len = CollectedHeap::min_fill_size(); 1472 HeapWord* obj_beg = dense_prefix_end - obj_len; 1473 1474 #ifdef _LP64 1475 if (MinObjAlignment > 1) { // object alignment > heap word size 1476 // Cases a, c or e. 1477 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { 1478 // Case b above. 1479 obj_beg = dense_prefix_end - 1; 1480 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && 1481 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { 1482 // Case d above. 1483 obj_beg = dense_prefix_end - 3; 1484 obj_len = 3; 1485 } 1486 #endif // #ifdef _LP64 1487 1488 CollectedHeap::fill_with_object(obj_beg, obj_len); 1489 _mark_bitmap.mark_obj(obj_beg, obj_len); 1490 _summary_data.add_obj(obj_beg, obj_len); 1491 assert(start_array(id) != NULL, "sanity"); 1492 start_array(id)->allocate_block(obj_beg); 1493 } 1494 } 1495 1496 void 1497 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) 1498 { 1499 assert(id < last_space_id, "id out of range"); 1500 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(), 1501 "should have been reset in summarize_spaces_quick()"); 1502 1503 const MutableSpace* space = _space_info[id].space(); 1504 if (_space_info[id].new_top() != space->bottom()) { 1505 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); 1506 _space_info[id].set_dense_prefix(dense_prefix_end); 1507 1508 #ifndef PRODUCT 1509 if (TraceParallelOldGCDensePrefix) { 1510 print_dense_prefix_stats("ratio", id, maximum_compaction, 1511 dense_prefix_end); 1512 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); 1513 print_dense_prefix_stats("density", id, maximum_compaction, addr); 1514 } 1515 #endif // #ifndef PRODUCT 1516 1517 // Recompute the summary data, taking into account the dense prefix. If 1518 // every last byte will be reclaimed, then the existing summary data which 1519 // compacts everything can be left in place. 1520 if (!maximum_compaction && dense_prefix_end != space->bottom()) { 1521 // If dead space crosses the dense prefix boundary, it is (at least 1522 // partially) filled with a dummy object, marked live and added to the 1523 // summary data. This simplifies the copy/update phase and must be done 1524 // before the final locations of objects are determined, to prevent 1525 // leaving a fragment of dead space that is too small to fill. 1526 fill_dense_prefix_end(id); 1527 1528 // Compute the destination of each Region, and thus each object. 1529 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); 1530 _summary_data.summarize(_space_info[id].split_info(), 1531 dense_prefix_end, space->top(), NULL, 1532 dense_prefix_end, space->end(), 1533 _space_info[id].new_top_addr()); 1534 } 1535 } 1536 1537 if (log_develop_is_enabled(Trace, gc, compaction)) { 1538 const size_t region_size = ParallelCompactData::RegionSize; 1539 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); 1540 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end); 1541 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); 1542 HeapWord* const new_top = _space_info[id].new_top(); 1543 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top); 1544 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); 1545 log_develop_trace(gc, compaction)( 1546 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " 1547 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " 1548 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, 1549 id, space->capacity_in_words(), p2i(dense_prefix_end), 1550 dp_region, dp_words / region_size, 1551 cr_words / region_size, p2i(new_top)); 1552 } 1553 } 1554 1555 #ifndef PRODUCT 1556 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id, 1557 HeapWord* dst_beg, HeapWord* dst_end, 1558 SpaceId src_space_id, 1559 HeapWord* src_beg, HeapWord* src_end) 1560 { 1561 log_develop_trace(gc, compaction)( 1562 "Summarizing %d [%s] into %d [%s]: " 1563 "src=" PTR_FORMAT "-" PTR_FORMAT " " 1564 SIZE_FORMAT "-" SIZE_FORMAT " " 1565 "dst=" PTR_FORMAT "-" PTR_FORMAT " " 1566 SIZE_FORMAT "-" SIZE_FORMAT, 1567 src_space_id, space_names[src_space_id], 1568 dst_space_id, space_names[dst_space_id], 1569 p2i(src_beg), p2i(src_end), 1570 _summary_data.addr_to_region_idx(src_beg), 1571 _summary_data.addr_to_region_idx(src_end), 1572 p2i(dst_beg), p2i(dst_end), 1573 _summary_data.addr_to_region_idx(dst_beg), 1574 _summary_data.addr_to_region_idx(dst_end)); 1575 } 1576 #endif // #ifndef PRODUCT 1577 1578 void PSParallelCompact::summary_phase(ParCompactionManager* cm, 1579 bool maximum_compaction) 1580 { 1581 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer); 1582 1583 #ifdef ASSERT 1584 if (TraceParallelOldGCMarkingPhase) { 1585 tty->print_cr("add_obj_count=" SIZE_FORMAT " " 1586 "add_obj_bytes=" SIZE_FORMAT, 1587 add_obj_count, add_obj_size * HeapWordSize); 1588 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " " 1589 "mark_bitmap_bytes=" SIZE_FORMAT, 1590 mark_bitmap_count, mark_bitmap_size * HeapWordSize); 1591 } 1592 #endif // #ifdef ASSERT 1593 1594 // Quick summarization of each space into itself, to see how much is live. 1595 summarize_spaces_quick(); 1596 1597 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self"); 1598 NOT_PRODUCT(print_region_ranges()); 1599 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1600 1601 // The amount of live data that will end up in old space (assuming it fits). 1602 size_t old_space_total_live = 0; 1603 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1604 old_space_total_live += pointer_delta(_space_info[id].new_top(), 1605 _space_info[id].space()->bottom()); 1606 } 1607 1608 MutableSpace* const old_space = _space_info[old_space_id].space(); 1609 const size_t old_capacity = old_space->capacity_in_words(); 1610 if (old_space_total_live > old_capacity) { 1611 // XXX - should also try to expand 1612 maximum_compaction = true; 1613 } 1614 1615 // Old generations. 1616 summarize_space(old_space_id, maximum_compaction); 1617 1618 // Summarize the remaining spaces in the young gen. The initial target space 1619 // is the old gen. If a space does not fit entirely into the target, then the 1620 // remainder is compacted into the space itself and that space becomes the new 1621 // target. 1622 SpaceId dst_space_id = old_space_id; 1623 HeapWord* dst_space_end = old_space->end(); 1624 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr(); 1625 for (unsigned int id = eden_space_id; id < last_space_id; ++id) { 1626 const MutableSpace* space = _space_info[id].space(); 1627 const size_t live = pointer_delta(_space_info[id].new_top(), 1628 space->bottom()); 1629 const size_t available = pointer_delta(dst_space_end, *new_top_addr); 1630 1631 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end, 1632 SpaceId(id), space->bottom(), space->top());) 1633 if (live > 0 && live <= available) { 1634 // All the live data will fit. 1635 bool done = _summary_data.summarize(_space_info[id].split_info(), 1636 space->bottom(), space->top(), 1637 NULL, 1638 *new_top_addr, dst_space_end, 1639 new_top_addr); 1640 assert(done, "space must fit into old gen"); 1641 1642 // Reset the new_top value for the space. 1643 _space_info[id].set_new_top(space->bottom()); 1644 } else if (live > 0) { 1645 // Attempt to fit part of the source space into the target space. 1646 HeapWord* next_src_addr = NULL; 1647 bool done = _summary_data.summarize(_space_info[id].split_info(), 1648 space->bottom(), space->top(), 1649 &next_src_addr, 1650 *new_top_addr, dst_space_end, 1651 new_top_addr); 1652 assert(!done, "space should not fit into old gen"); 1653 assert(next_src_addr != NULL, "sanity"); 1654 1655 // The source space becomes the new target, so the remainder is compacted 1656 // within the space itself. 1657 dst_space_id = SpaceId(id); 1658 dst_space_end = space->end(); 1659 new_top_addr = _space_info[id].new_top_addr(); 1660 NOT_PRODUCT(summary_phase_msg(dst_space_id, 1661 space->bottom(), dst_space_end, 1662 SpaceId(id), next_src_addr, space->top());) 1663 done = _summary_data.summarize(_space_info[id].split_info(), 1664 next_src_addr, space->top(), 1665 NULL, 1666 space->bottom(), dst_space_end, 1667 new_top_addr); 1668 assert(done, "space must fit when compacted into itself"); 1669 assert(*new_top_addr <= space->top(), "usage should not grow"); 1670 } 1671 } 1672 1673 log_develop_trace(gc, compaction)("Summary_phase: after final summarization"); 1674 NOT_PRODUCT(print_region_ranges()); 1675 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1676 } 1677 1678 // This method should contain all heap-specific policy for invoking a full 1679 // collection. invoke_no_policy() will only attempt to compact the heap; it 1680 // will do nothing further. If we need to bail out for policy reasons, scavenge 1681 // before full gc, or any other specialized behavior, it needs to be added here. 1682 // 1683 // Note that this method should only be called from the vm_thread while at a 1684 // safepoint. 1685 // 1686 // Note that the all_soft_refs_clear flag in the collector policy 1687 // may be true because this method can be called without intervening 1688 // activity. For example when the heap space is tight and full measure 1689 // are being taken to free space. 1690 void PSParallelCompact::invoke(bool maximum_heap_compaction) { 1691 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 1692 assert(Thread::current() == (Thread*)VMThread::vm_thread(), 1693 "should be in vm thread"); 1694 1695 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1696 GCCause::Cause gc_cause = heap->gc_cause(); 1697 assert(!heap->is_gc_active(), "not reentrant"); 1698 1699 PSAdaptiveSizePolicy* policy = heap->size_policy(); 1700 IsGCActiveMark mark; 1701 1702 if (ScavengeBeforeFullGC) { 1703 PSScavenge::invoke_no_policy(); 1704 } 1705 1706 const bool clear_all_soft_refs = 1707 heap->collector_policy()->should_clear_all_soft_refs(); 1708 1709 PSParallelCompact::invoke_no_policy(clear_all_soft_refs || 1710 maximum_heap_compaction); 1711 } 1712 1713 // This method contains no policy. You should probably 1714 // be calling invoke() instead. 1715 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { 1716 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 1717 assert(ref_processor() != NULL, "Sanity"); 1718 1719 if (GCLocker::check_active_before_gc()) { 1720 return false; 1721 } 1722 1723 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1724 1725 GCIdMark gc_id_mark; 1726 _gc_timer.register_gc_start(); 1727 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 1728 1729 TimeStamp marking_start; 1730 TimeStamp compaction_start; 1731 TimeStamp collection_exit; 1732 1733 GCCause::Cause gc_cause = heap->gc_cause(); 1734 PSYoungGen* young_gen = heap->young_gen(); 1735 PSOldGen* old_gen = heap->old_gen(); 1736 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 1737 1738 // The scope of casr should end after code that can change 1739 // CollectorPolicy::_should_clear_all_soft_refs. 1740 ClearedAllSoftRefs casr(maximum_heap_compaction, 1741 heap->collector_policy()); 1742 1743 if (ZapUnusedHeapArea) { 1744 // Save information needed to minimize mangling 1745 heap->record_gen_tops_before_GC(); 1746 } 1747 1748 // Make sure data structures are sane, make the heap parsable, and do other 1749 // miscellaneous bookkeeping. 1750 pre_compact(); 1751 1752 PreGCValues pre_gc_values(heap); 1753 1754 // Get the compaction manager reserved for the VM thread. 1755 ParCompactionManager* const vmthread_cm = 1756 ParCompactionManager::manager_array(gc_task_manager()->workers()); 1757 1758 { 1759 ResourceMark rm; 1760 HandleMark hm; 1761 1762 // Set the number of GC threads to be used in this collection 1763 gc_task_manager()->set_active_gang(); 1764 gc_task_manager()->task_idle_workers(); 1765 1766 GCTraceCPUTime tcpu; 1767 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true); 1768 1769 heap->pre_full_gc_dump(&_gc_timer); 1770 1771 TraceCollectorStats tcs(counters()); 1772 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 1773 1774 if (TraceOldGenTime) accumulated_time()->start(); 1775 1776 // Let the size policy know we're starting 1777 size_policy->major_collection_begin(); 1778 1779 CodeCache::gc_prologue(); 1780 1781 #if defined(COMPILER2) || INCLUDE_JVMCI 1782 DerivedPointerTable::clear(); 1783 #endif 1784 1785 ref_processor()->enable_discovery(); 1786 ref_processor()->setup_policy(maximum_heap_compaction); 1787 1788 bool marked_for_unloading = false; 1789 1790 marking_start.update(); 1791 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer); 1792 1793 bool max_on_system_gc = UseMaximumCompactionOnSystemGC 1794 && GCCause::is_user_requested_gc(gc_cause); 1795 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc); 1796 1797 #if defined(COMPILER2) || INCLUDE_JVMCI 1798 assert(DerivedPointerTable::is_active(), "Sanity"); 1799 DerivedPointerTable::set_active(false); 1800 #endif 1801 1802 // adjust_roots() updates Universe::_intArrayKlassObj which is 1803 // needed by the compaction for filling holes in the dense prefix. 1804 adjust_roots(vmthread_cm); 1805 1806 compaction_start.update(); 1807 compact(); 1808 1809 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be 1810 // done before resizing. 1811 post_compact(); 1812 1813 // Let the size policy know we're done 1814 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 1815 1816 if (UseAdaptiveSizePolicy) { 1817 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 1818 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 1819 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 1820 1821 // Don't check if the size_policy is ready here. Let 1822 // the size_policy check that internally. 1823 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 1824 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 1825 // Swap the survivor spaces if from_space is empty. The 1826 // resize_young_gen() called below is normally used after 1827 // a successful young GC and swapping of survivor spaces; 1828 // otherwise, it will fail to resize the young gen with 1829 // the current implementation. 1830 if (young_gen->from_space()->is_empty()) { 1831 young_gen->from_space()->clear(SpaceDecorator::Mangle); 1832 young_gen->swap_spaces(); 1833 } 1834 1835 // Calculate optimal free space amounts 1836 assert(young_gen->max_size() > 1837 young_gen->from_space()->capacity_in_bytes() + 1838 young_gen->to_space()->capacity_in_bytes(), 1839 "Sizes of space in young gen are out-of-bounds"); 1840 1841 size_t young_live = young_gen->used_in_bytes(); 1842 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 1843 size_t old_live = old_gen->used_in_bytes(); 1844 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 1845 size_t max_old_gen_size = old_gen->max_gen_size(); 1846 size_t max_eden_size = young_gen->max_size() - 1847 young_gen->from_space()->capacity_in_bytes() - 1848 young_gen->to_space()->capacity_in_bytes(); 1849 1850 // Used for diagnostics 1851 size_policy->clear_generation_free_space_flags(); 1852 1853 size_policy->compute_generations_free_space(young_live, 1854 eden_live, 1855 old_live, 1856 cur_eden, 1857 max_old_gen_size, 1858 max_eden_size, 1859 true /* full gc*/); 1860 1861 size_policy->check_gc_overhead_limit(young_live, 1862 eden_live, 1863 max_old_gen_size, 1864 max_eden_size, 1865 true /* full gc*/, 1866 gc_cause, 1867 heap->collector_policy()); 1868 1869 size_policy->decay_supplemental_growth(true /* full gc*/); 1870 1871 heap->resize_old_gen( 1872 size_policy->calculated_old_free_size_in_bytes()); 1873 1874 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 1875 size_policy->calculated_survivor_size_in_bytes()); 1876 } 1877 1878 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 1879 } 1880 1881 if (UsePerfData) { 1882 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 1883 counters->update_counters(); 1884 counters->update_old_capacity(old_gen->capacity_in_bytes()); 1885 counters->update_young_capacity(young_gen->capacity_in_bytes()); 1886 } 1887 1888 heap->resize_all_tlabs(); 1889 1890 // Resize the metaspace capacity after a collection 1891 MetaspaceGC::compute_new_size(); 1892 1893 if (TraceOldGenTime) { 1894 accumulated_time()->stop(); 1895 } 1896 1897 young_gen->print_used_change(pre_gc_values.young_gen_used()); 1898 old_gen->print_used_change(pre_gc_values.old_gen_used()); 1899 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used()); 1900 1901 // Track memory usage and detect low memory 1902 MemoryService::track_memory_usage(); 1903 heap->update_counters(); 1904 gc_task_manager()->release_idle_workers(); 1905 1906 heap->post_full_gc_dump(&_gc_timer); 1907 } 1908 1909 #ifdef ASSERT 1910 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) { 1911 ParCompactionManager* const cm = 1912 ParCompactionManager::manager_array(int(i)); 1913 assert(cm->marking_stack()->is_empty(), "should be empty"); 1914 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i); 1915 } 1916 #endif // ASSERT 1917 1918 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 1919 HandleMark hm; // Discard invalid handles created during verification 1920 Universe::verify("After GC"); 1921 } 1922 1923 // Re-verify object start arrays 1924 if (VerifyObjectStartArray && 1925 VerifyAfterGC) { 1926 old_gen->verify_object_start_array(); 1927 } 1928 1929 if (ZapUnusedHeapArea) { 1930 old_gen->object_space()->check_mangled_unused_area_complete(); 1931 } 1932 1933 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 1934 1935 collection_exit.update(); 1936 1937 heap->print_heap_after_gc(); 1938 heap->trace_heap_after_gc(&_gc_tracer); 1939 1940 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 1941 marking_start.ticks(), compaction_start.ticks(), 1942 collection_exit.ticks()); 1943 gc_task_manager()->print_task_time_stamps(); 1944 1945 #ifdef TRACESPINNING 1946 ParallelTaskTerminator::print_termination_counts(); 1947 #endif 1948 1949 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 1950 1951 _gc_timer.register_gc_end(); 1952 1953 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id)); 1954 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 1955 1956 return true; 1957 } 1958 1959 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 1960 PSYoungGen* young_gen, 1961 PSOldGen* old_gen) { 1962 MutableSpace* const eden_space = young_gen->eden_space(); 1963 assert(!eden_space->is_empty(), "eden must be non-empty"); 1964 assert(young_gen->virtual_space()->alignment() == 1965 old_gen->virtual_space()->alignment(), "alignments do not match"); 1966 1967 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 1968 return false; 1969 } 1970 1971 // Both generations must be completely committed. 1972 if (young_gen->virtual_space()->uncommitted_size() != 0) { 1973 return false; 1974 } 1975 if (old_gen->virtual_space()->uncommitted_size() != 0) { 1976 return false; 1977 } 1978 1979 // Figure out how much to take from eden. Include the average amount promoted 1980 // in the total; otherwise the next young gen GC will simply bail out to a 1981 // full GC. 1982 const size_t alignment = old_gen->virtual_space()->alignment(); 1983 const size_t eden_used = eden_space->used_in_bytes(); 1984 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 1985 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 1986 const size_t eden_capacity = eden_space->capacity_in_bytes(); 1987 1988 if (absorb_size >= eden_capacity) { 1989 return false; // Must leave some space in eden. 1990 } 1991 1992 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 1993 if (new_young_size < young_gen->min_gen_size()) { 1994 return false; // Respect young gen minimum size. 1995 } 1996 1997 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 1998 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 1999 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 2000 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 2001 absorb_size / K, 2002 eden_capacity / K, (eden_capacity - absorb_size) / K, 2003 young_gen->from_space()->used_in_bytes() / K, 2004 young_gen->to_space()->used_in_bytes() / K, 2005 young_gen->capacity_in_bytes() / K, new_young_size / K); 2006 2007 // Fill the unused part of the old gen. 2008 MutableSpace* const old_space = old_gen->object_space(); 2009 HeapWord* const unused_start = old_space->top(); 2010 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 2011 2012 if (unused_words > 0) { 2013 if (unused_words < CollectedHeap::min_fill_size()) { 2014 return false; // If the old gen cannot be filled, must give up. 2015 } 2016 CollectedHeap::fill_with_objects(unused_start, unused_words); 2017 } 2018 2019 // Take the live data from eden and set both top and end in the old gen to 2020 // eden top. (Need to set end because reset_after_change() mangles the region 2021 // from end to virtual_space->high() in debug builds). 2022 HeapWord* const new_top = eden_space->top(); 2023 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 2024 absorb_size); 2025 young_gen->reset_after_change(); 2026 old_space->set_top(new_top); 2027 old_space->set_end(new_top); 2028 old_gen->reset_after_change(); 2029 2030 // Update the object start array for the filler object and the data from eden. 2031 ObjectStartArray* const start_array = old_gen->start_array(); 2032 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 2033 start_array->allocate_block(p); 2034 } 2035 2036 // Could update the promoted average here, but it is not typically updated at 2037 // full GCs and the value to use is unclear. Something like 2038 // 2039 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 2040 2041 size_policy->set_bytes_absorbed_from_eden(absorb_size); 2042 return true; 2043 } 2044 2045 GCTaskManager* const PSParallelCompact::gc_task_manager() { 2046 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 2047 "shouldn't return NULL"); 2048 return ParallelScavengeHeap::gc_task_manager(); 2049 } 2050 2051 void PSParallelCompact::marking_phase(ParCompactionManager* cm, 2052 bool maximum_heap_compaction, 2053 ParallelOldTracer *gc_tracer) { 2054 // Recursively traverse all live objects and mark them 2055 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer); 2056 2057 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2058 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2059 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2060 TaskQueueSetSuper* qset = ParCompactionManager::stack_array(); 2061 ParallelTaskTerminator terminator(active_gc_threads, qset); 2062 2063 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm); 2064 ParCompactionManager::FollowStackClosure follow_stack_closure(cm); 2065 2066 // Need new claim bits before marking starts. 2067 ClassLoaderDataGraph::clear_claimed_marks(); 2068 2069 { 2070 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer); 2071 2072 ParallelScavengeHeap::ParStrongRootsScope psrs; 2073 2074 GCTaskQueue* q = GCTaskQueue::create(); 2075 2076 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe)); 2077 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles)); 2078 // We scan the thread roots in parallel 2079 Threads::create_thread_roots_marking_tasks(q); 2080 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer)); 2081 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler)); 2082 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management)); 2083 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary)); 2084 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data)); 2085 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti)); 2086 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache)); 2087 2088 if (active_gc_threads > 1) { 2089 for (uint j = 0; j < active_gc_threads; j++) { 2090 q->enqueue(new StealMarkingTask(&terminator)); 2091 } 2092 } 2093 2094 gc_task_manager()->execute_and_wait(q); 2095 } 2096 2097 // Process reference objects found during marking 2098 { 2099 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 2100 2101 ReferenceProcessorStats stats; 2102 if (ref_processor()->processing_is_mt()) { 2103 RefProcTaskExecutor task_executor; 2104 stats = ref_processor()->process_discovered_references( 2105 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, 2106 &task_executor, &_gc_timer); 2107 } else { 2108 stats = ref_processor()->process_discovered_references( 2109 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL, 2110 &_gc_timer); 2111 } 2112 2113 gc_tracer->report_gc_reference_stats(stats); 2114 } 2115 2116 // This is the point where the entire marking should have completed. 2117 assert(cm->marking_stacks_empty(), "Marking should have completed"); 2118 2119 { 2120 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer); 2121 2122 // Follow system dictionary roots and unload classes. 2123 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), &_gc_timer); 2124 2125 // Unload nmethods. 2126 CodeCache::do_unloading(is_alive_closure(), purged_class); 2127 2128 // Prune dead klasses from subklass/sibling/implementor lists. 2129 Klass::clean_weak_klass_links(is_alive_closure()); 2130 } 2131 2132 { 2133 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer); 2134 // Delete entries for dead interned strings. 2135 StringTable::unlink(is_alive_closure()); 2136 } 2137 2138 { 2139 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer); 2140 // Clean up unreferenced symbols in symbol table. 2141 SymbolTable::unlink(); 2142 } 2143 2144 _gc_tracer.report_object_count_after_gc(is_alive_closure()); 2145 } 2146 2147 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) { 2148 // Adjust the pointers to reflect the new locations 2149 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer); 2150 2151 // Need new claim bits when tracing through and adjusting pointers. 2152 ClassLoaderDataGraph::clear_claimed_marks(); 2153 2154 PSParallelCompact::AdjustPointerClosure oop_closure(cm); 2155 PSParallelCompact::AdjustKlassClosure klass_closure(cm); 2156 2157 // General strong roots. 2158 Universe::oops_do(&oop_closure); 2159 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles 2160 Threads::oops_do(&oop_closure, NULL); 2161 ObjectSynchronizer::oops_do(&oop_closure); 2162 FlatProfiler::oops_do(&oop_closure); 2163 Management::oops_do(&oop_closure); 2164 JvmtiExport::oops_do(&oop_closure); 2165 SystemDictionary::oops_do(&oop_closure); 2166 ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true); 2167 2168 // Now adjust pointers in remaining weak roots. (All of which should 2169 // have been cleared if they pointed to non-surviving objects.) 2170 // Global (weak) JNI handles 2171 JNIHandles::weak_oops_do(&oop_closure); 2172 2173 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations); 2174 CodeCache::blobs_do(&adjust_from_blobs); 2175 AOTLoader::oops_do(&oop_closure); 2176 StringTable::oops_do(&oop_closure); 2177 ref_processor()->weak_oops_do(&oop_closure); 2178 // Roots were visited so references into the young gen in roots 2179 // may have been scanned. Process them also. 2180 // Should the reference processor have a span that excludes 2181 // young gen objects? 2182 PSScavenge::reference_processor()->weak_oops_do(&oop_closure); 2183 } 2184 2185 // Helper class to print 8 region numbers per line and then print the total at the end. 2186 class FillableRegionLogger : public StackObj { 2187 private: 2188 Log(gc, compaction) log; 2189 static const int LineLength = 8; 2190 size_t _regions[LineLength]; 2191 int _next_index; 2192 bool _enabled; 2193 size_t _total_regions; 2194 public: 2195 FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { } 2196 ~FillableRegionLogger() { 2197 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions); 2198 } 2199 2200 void print_line() { 2201 if (!_enabled || _next_index == 0) { 2202 return; 2203 } 2204 FormatBuffer<> line("Fillable: "); 2205 for (int i = 0; i < _next_index; i++) { 2206 line.append(" " SIZE_FORMAT_W(7), _regions[i]); 2207 } 2208 log.trace("%s", line.buffer()); 2209 _next_index = 0; 2210 } 2211 2212 void handle(size_t region) { 2213 if (!_enabled) { 2214 return; 2215 } 2216 _regions[_next_index++] = region; 2217 if (_next_index == LineLength) { 2218 print_line(); 2219 } 2220 _total_regions++; 2221 } 2222 }; 2223 2224 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q, 2225 uint parallel_gc_threads) 2226 { 2227 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer); 2228 2229 // Find the threads that are active 2230 unsigned int which = 0; 2231 2232 // Find all regions that are available (can be filled immediately) and 2233 // distribute them to the thread stacks. The iteration is done in reverse 2234 // order (high to low) so the regions will be removed in ascending order. 2235 2236 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 2237 2238 which = 0; 2239 // id + 1 is used to test termination so unsigned can 2240 // be used with an old_space_id == 0. 2241 FillableRegionLogger region_logger; 2242 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) { 2243 SpaceInfo* const space_info = _space_info + id; 2244 MutableSpace* const space = space_info->space(); 2245 HeapWord* const new_top = space_info->new_top(); 2246 2247 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix()); 2248 const size_t end_region = 2249 sd.addr_to_region_idx(sd.region_align_up(new_top)); 2250 2251 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) { 2252 if (sd.region(cur)->claim_unsafe()) { 2253 ParCompactionManager* cm = ParCompactionManager::manager_array(which); 2254 cm->region_stack()->push(cur); 2255 region_logger.handle(cur); 2256 // Assign regions to tasks in round-robin fashion. 2257 if (++which == parallel_gc_threads) { 2258 which = 0; 2259 } 2260 } 2261 } 2262 region_logger.print_line(); 2263 } 2264 } 2265 2266 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 2267 2268 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q, 2269 uint parallel_gc_threads) { 2270 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer); 2271 2272 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2273 2274 // Iterate over all the spaces adding tasks for updating 2275 // regions in the dense prefix. Assume that 1 gc thread 2276 // will work on opening the gaps and the remaining gc threads 2277 // will work on the dense prefix. 2278 unsigned int space_id; 2279 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) { 2280 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); 2281 const MutableSpace* const space = _space_info[space_id].space(); 2282 2283 if (dense_prefix_end == space->bottom()) { 2284 // There is no dense prefix for this space. 2285 continue; 2286 } 2287 2288 // The dense prefix is before this region. 2289 size_t region_index_end_dense_prefix = 2290 sd.addr_to_region_idx(dense_prefix_end); 2291 RegionData* const dense_prefix_cp = 2292 sd.region(region_index_end_dense_prefix); 2293 assert(dense_prefix_end == space->end() || 2294 dense_prefix_cp->available() || 2295 dense_prefix_cp->claimed(), 2296 "The region after the dense prefix should always be ready to fill"); 2297 2298 size_t region_index_start = sd.addr_to_region_idx(space->bottom()); 2299 2300 // Is there dense prefix work? 2301 size_t total_dense_prefix_regions = 2302 region_index_end_dense_prefix - region_index_start; 2303 // How many regions of the dense prefix should be given to 2304 // each thread? 2305 if (total_dense_prefix_regions > 0) { 2306 uint tasks_for_dense_prefix = 1; 2307 if (total_dense_prefix_regions <= 2308 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { 2309 // Don't over partition. This assumes that 2310 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value 2311 // so there are not many regions to process. 2312 tasks_for_dense_prefix = parallel_gc_threads; 2313 } else { 2314 // Over partition 2315 tasks_for_dense_prefix = parallel_gc_threads * 2316 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; 2317 } 2318 size_t regions_per_thread = total_dense_prefix_regions / 2319 tasks_for_dense_prefix; 2320 // Give each thread at least 1 region. 2321 if (regions_per_thread == 0) { 2322 regions_per_thread = 1; 2323 } 2324 2325 for (uint k = 0; k < tasks_for_dense_prefix; k++) { 2326 if (region_index_start >= region_index_end_dense_prefix) { 2327 break; 2328 } 2329 // region_index_end is not processed 2330 size_t region_index_end = MIN2(region_index_start + regions_per_thread, 2331 region_index_end_dense_prefix); 2332 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2333 region_index_start, 2334 region_index_end)); 2335 region_index_start = region_index_end; 2336 } 2337 } 2338 // This gets any part of the dense prefix that did not 2339 // fit evenly. 2340 if (region_index_start < region_index_end_dense_prefix) { 2341 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2342 region_index_start, 2343 region_index_end_dense_prefix)); 2344 } 2345 } 2346 } 2347 2348 void PSParallelCompact::enqueue_region_stealing_tasks( 2349 GCTaskQueue* q, 2350 ParallelTaskTerminator* terminator_ptr, 2351 uint parallel_gc_threads) { 2352 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer); 2353 2354 // Once a thread has drained it's stack, it should try to steal regions from 2355 // other threads. 2356 for (uint j = 0; j < parallel_gc_threads; j++) { 2357 q->enqueue(new CompactionWithStealingTask(terminator_ptr)); 2358 } 2359 } 2360 2361 #ifdef ASSERT 2362 // Write a histogram of the number of times the block table was filled for a 2363 // region. 2364 void PSParallelCompact::write_block_fill_histogram() 2365 { 2366 if (!log_develop_is_enabled(Trace, gc, compaction)) { 2367 return; 2368 } 2369 2370 Log(gc, compaction) log; 2371 ResourceMark rm; 2372 outputStream* out = log.trace_stream(); 2373 2374 typedef ParallelCompactData::RegionData rd_t; 2375 ParallelCompactData& sd = summary_data(); 2376 2377 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2378 MutableSpace* const spc = _space_info[id].space(); 2379 if (spc->bottom() != spc->top()) { 2380 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom()); 2381 HeapWord* const top_aligned_up = sd.region_align_up(spc->top()); 2382 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up); 2383 2384 size_t histo[5] = { 0, 0, 0, 0, 0 }; 2385 const size_t histo_len = sizeof(histo) / sizeof(size_t); 2386 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t)); 2387 2388 for (const rd_t* cur = beg; cur < end; ++cur) { 2389 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)]; 2390 } 2391 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt); 2392 for (size_t i = 0; i < histo_len; ++i) { 2393 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%", 2394 histo[i], 100.0 * histo[i] / region_cnt); 2395 } 2396 out->cr(); 2397 } 2398 } 2399 } 2400 #endif // #ifdef ASSERT 2401 2402 void PSParallelCompact::compact() { 2403 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer); 2404 2405 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2406 PSOldGen* old_gen = heap->old_gen(); 2407 old_gen->start_array()->reset(); 2408 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2409 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2410 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2411 ParallelTaskTerminator terminator(active_gc_threads, qset); 2412 2413 GCTaskQueue* q = GCTaskQueue::create(); 2414 prepare_region_draining_tasks(q, active_gc_threads); 2415 enqueue_dense_prefix_tasks(q, active_gc_threads); 2416 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads); 2417 2418 { 2419 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer); 2420 2421 gc_task_manager()->execute_and_wait(q); 2422 2423 #ifdef ASSERT 2424 // Verify that all regions have been processed before the deferred updates. 2425 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2426 verify_complete(SpaceId(id)); 2427 } 2428 #endif 2429 } 2430 2431 { 2432 // Update the deferred objects, if any. Any compaction manager can be used. 2433 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer); 2434 ParCompactionManager* cm = ParCompactionManager::manager_array(0); 2435 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2436 update_deferred_objects(cm, SpaceId(id)); 2437 } 2438 } 2439 2440 DEBUG_ONLY(write_block_fill_histogram()); 2441 } 2442 2443 #ifdef ASSERT 2444 void PSParallelCompact::verify_complete(SpaceId space_id) { 2445 // All Regions between space bottom() to new_top() should be marked as filled 2446 // and all Regions between new_top() and top() should be available (i.e., 2447 // should have been emptied). 2448 ParallelCompactData& sd = summary_data(); 2449 SpaceInfo si = _space_info[space_id]; 2450 HeapWord* new_top_addr = sd.region_align_up(si.new_top()); 2451 HeapWord* old_top_addr = sd.region_align_up(si.space()->top()); 2452 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom()); 2453 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr); 2454 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr); 2455 2456 bool issued_a_warning = false; 2457 2458 size_t cur_region; 2459 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) { 2460 const RegionData* const c = sd.region(cur_region); 2461 if (!c->completed()) { 2462 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u", 2463 cur_region, c->destination_count()); 2464 issued_a_warning = true; 2465 } 2466 } 2467 2468 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) { 2469 const RegionData* const c = sd.region(cur_region); 2470 if (!c->available()) { 2471 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u", 2472 cur_region, c->destination_count()); 2473 issued_a_warning = true; 2474 } 2475 } 2476 2477 if (issued_a_warning) { 2478 print_region_ranges(); 2479 } 2480 } 2481 #endif // #ifdef ASSERT 2482 2483 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) { 2484 _start_array->allocate_block(addr); 2485 compaction_manager()->update_contents(oop(addr)); 2486 } 2487 2488 // Update interior oops in the ranges of regions [beg_region, end_region). 2489 void 2490 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 2491 SpaceId space_id, 2492 size_t beg_region, 2493 size_t end_region) { 2494 ParallelCompactData& sd = summary_data(); 2495 ParMarkBitMap* const mbm = mark_bitmap(); 2496 2497 HeapWord* beg_addr = sd.region_to_addr(beg_region); 2498 HeapWord* const end_addr = sd.region_to_addr(end_region); 2499 assert(beg_region <= end_region, "bad region range"); 2500 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); 2501 2502 #ifdef ASSERT 2503 // Claim the regions to avoid triggering an assert when they are marked as 2504 // filled. 2505 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) { 2506 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed"); 2507 } 2508 #endif // #ifdef ASSERT 2509 2510 if (beg_addr != space(space_id)->bottom()) { 2511 // Find the first live object or block of dead space that *starts* in this 2512 // range of regions. If a partial object crosses onto the region, skip it; 2513 // it will be marked for 'deferred update' when the object head is 2514 // processed. If dead space crosses onto the region, it is also skipped; it 2515 // will be filled when the prior region is processed. If neither of those 2516 // apply, the first word in the region is the start of a live object or dead 2517 // space. 2518 assert(beg_addr > space(space_id)->bottom(), "sanity"); 2519 const RegionData* const cp = sd.region(beg_region); 2520 if (cp->partial_obj_size() != 0) { 2521 beg_addr = sd.partial_obj_end(beg_region); 2522 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) { 2523 beg_addr = mbm->find_obj_beg(beg_addr, end_addr); 2524 } 2525 } 2526 2527 if (beg_addr < end_addr) { 2528 // A live object or block of dead space starts in this range of Regions. 2529 HeapWord* const dense_prefix_end = dense_prefix(space_id); 2530 2531 // Create closures and iterate. 2532 UpdateOnlyClosure update_closure(mbm, cm, space_id); 2533 FillClosure fill_closure(cm, space_id); 2534 ParMarkBitMap::IterationStatus status; 2535 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, 2536 dense_prefix_end); 2537 if (status == ParMarkBitMap::incomplete) { 2538 update_closure.do_addr(update_closure.source()); 2539 } 2540 } 2541 2542 // Mark the regions as filled. 2543 RegionData* const beg_cp = sd.region(beg_region); 2544 RegionData* const end_cp = sd.region(end_region); 2545 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) { 2546 cp->set_completed(); 2547 } 2548 } 2549 2550 // Return the SpaceId for the space containing addr. If addr is not in the 2551 // heap, last_space_id is returned. In debug mode it expects the address to be 2552 // in the heap and asserts such. 2553 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) { 2554 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap"); 2555 2556 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2557 if (_space_info[id].space()->contains(addr)) { 2558 return SpaceId(id); 2559 } 2560 } 2561 2562 assert(false, "no space contains the addr"); 2563 return last_space_id; 2564 } 2565 2566 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm, 2567 SpaceId id) { 2568 assert(id < last_space_id, "bad space id"); 2569 2570 ParallelCompactData& sd = summary_data(); 2571 const SpaceInfo* const space_info = _space_info + id; 2572 ObjectStartArray* const start_array = space_info->start_array(); 2573 2574 const MutableSpace* const space = space_info->space(); 2575 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set"); 2576 HeapWord* const beg_addr = space_info->dense_prefix(); 2577 HeapWord* const end_addr = sd.region_align_up(space_info->new_top()); 2578 2579 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr); 2580 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr); 2581 const RegionData* cur_region; 2582 for (cur_region = beg_region; cur_region < end_region; ++cur_region) { 2583 HeapWord* const addr = cur_region->deferred_obj_addr(); 2584 if (addr != NULL) { 2585 if (start_array != NULL) { 2586 start_array->allocate_block(addr); 2587 } 2588 cm->update_contents(oop(addr)); 2589 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr))); 2590 } 2591 } 2592 } 2593 2594 // Skip over count live words starting from beg, and return the address of the 2595 // next live word. Unless marked, the word corresponding to beg is assumed to 2596 // be dead. Callers must either ensure beg does not correspond to the middle of 2597 // an object, or account for those live words in some other way. Callers must 2598 // also ensure that there are enough live words in the range [beg, end) to skip. 2599 HeapWord* 2600 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count) 2601 { 2602 assert(count > 0, "sanity"); 2603 2604 ParMarkBitMap* m = mark_bitmap(); 2605 idx_t bits_to_skip = m->words_to_bits(count); 2606 idx_t cur_beg = m->addr_to_bit(beg); 2607 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end)); 2608 2609 do { 2610 cur_beg = m->find_obj_beg(cur_beg, search_end); 2611 idx_t cur_end = m->find_obj_end(cur_beg, search_end); 2612 const size_t obj_bits = cur_end - cur_beg + 1; 2613 if (obj_bits > bits_to_skip) { 2614 return m->bit_to_addr(cur_beg + bits_to_skip); 2615 } 2616 bits_to_skip -= obj_bits; 2617 cur_beg = cur_end + 1; 2618 } while (bits_to_skip > 0); 2619 2620 // Skipping the desired number of words landed just past the end of an object. 2621 // Find the start of the next object. 2622 cur_beg = m->find_obj_beg(cur_beg, search_end); 2623 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip"); 2624 return m->bit_to_addr(cur_beg); 2625 } 2626 2627 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr, 2628 SpaceId src_space_id, 2629 size_t src_region_idx) 2630 { 2631 assert(summary_data().is_region_aligned(dest_addr), "not aligned"); 2632 2633 const SplitInfo& split_info = _space_info[src_space_id].split_info(); 2634 if (split_info.dest_region_addr() == dest_addr) { 2635 // The partial object ending at the split point contains the first word to 2636 // be copied to dest_addr. 2637 return split_info.first_src_addr(); 2638 } 2639 2640 const ParallelCompactData& sd = summary_data(); 2641 ParMarkBitMap* const bitmap = mark_bitmap(); 2642 const size_t RegionSize = ParallelCompactData::RegionSize; 2643 2644 assert(sd.is_region_aligned(dest_addr), "not aligned"); 2645 const RegionData* const src_region_ptr = sd.region(src_region_idx); 2646 const size_t partial_obj_size = src_region_ptr->partial_obj_size(); 2647 HeapWord* const src_region_destination = src_region_ptr->destination(); 2648 2649 assert(dest_addr >= src_region_destination, "wrong src region"); 2650 assert(src_region_ptr->data_size() > 0, "src region cannot be empty"); 2651 2652 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx); 2653 HeapWord* const src_region_end = src_region_beg + RegionSize; 2654 2655 HeapWord* addr = src_region_beg; 2656 if (dest_addr == src_region_destination) { 2657 // Return the first live word in the source region. 2658 if (partial_obj_size == 0) { 2659 addr = bitmap->find_obj_beg(addr, src_region_end); 2660 assert(addr < src_region_end, "no objects start in src region"); 2661 } 2662 return addr; 2663 } 2664 2665 // Must skip some live data. 2666 size_t words_to_skip = dest_addr - src_region_destination; 2667 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region"); 2668 2669 if (partial_obj_size >= words_to_skip) { 2670 // All the live words to skip are part of the partial object. 2671 addr += words_to_skip; 2672 if (partial_obj_size == words_to_skip) { 2673 // Find the first live word past the partial object. 2674 addr = bitmap->find_obj_beg(addr, src_region_end); 2675 assert(addr < src_region_end, "wrong src region"); 2676 } 2677 return addr; 2678 } 2679 2680 // Skip over the partial object (if any). 2681 if (partial_obj_size != 0) { 2682 words_to_skip -= partial_obj_size; 2683 addr += partial_obj_size; 2684 } 2685 2686 // Skip over live words due to objects that start in the region. 2687 addr = skip_live_words(addr, src_region_end, words_to_skip); 2688 assert(addr < src_region_end, "wrong src region"); 2689 return addr; 2690 } 2691 2692 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, 2693 SpaceId src_space_id, 2694 size_t beg_region, 2695 HeapWord* end_addr) 2696 { 2697 ParallelCompactData& sd = summary_data(); 2698 2699 #ifdef ASSERT 2700 MutableSpace* const src_space = _space_info[src_space_id].space(); 2701 HeapWord* const beg_addr = sd.region_to_addr(beg_region); 2702 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(), 2703 "src_space_id does not match beg_addr"); 2704 assert(src_space->contains(end_addr) || end_addr == src_space->end(), 2705 "src_space_id does not match end_addr"); 2706 #endif // #ifdef ASSERT 2707 2708 RegionData* const beg = sd.region(beg_region); 2709 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr)); 2710 2711 // Regions up to new_top() are enqueued if they become available. 2712 HeapWord* const new_top = _space_info[src_space_id].new_top(); 2713 RegionData* const enqueue_end = 2714 sd.addr_to_region_ptr(sd.region_align_up(new_top)); 2715 2716 for (RegionData* cur = beg; cur < end; ++cur) { 2717 assert(cur->data_size() > 0, "region must have live data"); 2718 cur->decrement_destination_count(); 2719 if (cur < enqueue_end && cur->available() && cur->claim()) { 2720 cm->push_region(sd.region(cur)); 2721 } 2722 } 2723 } 2724 2725 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure, 2726 SpaceId& src_space_id, 2727 HeapWord*& src_space_top, 2728 HeapWord* end_addr) 2729 { 2730 typedef ParallelCompactData::RegionData RegionData; 2731 2732 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2733 const size_t region_size = ParallelCompactData::RegionSize; 2734 2735 size_t src_region_idx = 0; 2736 2737 // Skip empty regions (if any) up to the top of the space. 2738 HeapWord* const src_aligned_up = sd.region_align_up(end_addr); 2739 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up); 2740 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top); 2741 const RegionData* const top_region_ptr = 2742 sd.addr_to_region_ptr(top_aligned_up); 2743 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) { 2744 ++src_region_ptr; 2745 } 2746 2747 if (src_region_ptr < top_region_ptr) { 2748 // The next source region is in the current space. Update src_region_idx 2749 // and the source address to match src_region_ptr. 2750 src_region_idx = sd.region(src_region_ptr); 2751 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx); 2752 if (src_region_addr > closure.source()) { 2753 closure.set_source(src_region_addr); 2754 } 2755 return src_region_idx; 2756 } 2757 2758 // Switch to a new source space and find the first non-empty region. 2759 unsigned int space_id = src_space_id + 1; 2760 assert(space_id < last_space_id, "not enough spaces"); 2761 2762 HeapWord* const destination = closure.destination(); 2763 2764 do { 2765 MutableSpace* space = _space_info[space_id].space(); 2766 HeapWord* const bottom = space->bottom(); 2767 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom); 2768 2769 // Iterate over the spaces that do not compact into themselves. 2770 if (bottom_cp->destination() != bottom) { 2771 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 2772 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 2773 2774 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) { 2775 if (src_cp->live_obj_size() > 0) { 2776 // Found it. 2777 assert(src_cp->destination() == destination, 2778 "first live obj in the space must match the destination"); 2779 assert(src_cp->partial_obj_size() == 0, 2780 "a space cannot begin with a partial obj"); 2781 2782 src_space_id = SpaceId(space_id); 2783 src_space_top = space->top(); 2784 const size_t src_region_idx = sd.region(src_cp); 2785 closure.set_source(sd.region_to_addr(src_region_idx)); 2786 return src_region_idx; 2787 } else { 2788 assert(src_cp->data_size() == 0, "sanity"); 2789 } 2790 } 2791 } 2792 } while (++space_id < last_space_id); 2793 2794 assert(false, "no source region was found"); 2795 return 0; 2796 } 2797 2798 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx) 2799 { 2800 typedef ParMarkBitMap::IterationStatus IterationStatus; 2801 const size_t RegionSize = ParallelCompactData::RegionSize; 2802 ParMarkBitMap* const bitmap = mark_bitmap(); 2803 ParallelCompactData& sd = summary_data(); 2804 RegionData* const region_ptr = sd.region(region_idx); 2805 2806 // Get the items needed to construct the closure. 2807 HeapWord* dest_addr = sd.region_to_addr(region_idx); 2808 SpaceId dest_space_id = space_id(dest_addr); 2809 ObjectStartArray* start_array = _space_info[dest_space_id].start_array(); 2810 HeapWord* new_top = _space_info[dest_space_id].new_top(); 2811 assert(dest_addr < new_top, "sanity"); 2812 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize); 2813 2814 // Get the source region and related info. 2815 size_t src_region_idx = region_ptr->source_region(); 2816 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx)); 2817 HeapWord* src_space_top = _space_info[src_space_id].space()->top(); 2818 2819 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 2820 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx)); 2821 2822 // Adjust src_region_idx to prepare for decrementing destination counts (the 2823 // destination count is not decremented when a region is copied to itself). 2824 if (src_region_idx == region_idx) { 2825 src_region_idx += 1; 2826 } 2827 2828 if (bitmap->is_unmarked(closure.source())) { 2829 // The first source word is in the middle of an object; copy the remainder 2830 // of the object or as much as will fit. The fact that pointer updates were 2831 // deferred will be noted when the object header is processed. 2832 HeapWord* const old_src_addr = closure.source(); 2833 closure.copy_partial_obj(); 2834 if (closure.is_full()) { 2835 decrement_destination_counts(cm, src_space_id, src_region_idx, 2836 closure.source()); 2837 region_ptr->set_deferred_obj_addr(NULL); 2838 region_ptr->set_completed(); 2839 return; 2840 } 2841 2842 HeapWord* const end_addr = sd.region_align_down(closure.source()); 2843 if (sd.region_align_down(old_src_addr) != end_addr) { 2844 // The partial object was copied from more than one source region. 2845 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2846 2847 // Move to the next source region, possibly switching spaces as well. All 2848 // args except end_addr may be modified. 2849 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2850 end_addr); 2851 } 2852 } 2853 2854 do { 2855 HeapWord* const cur_addr = closure.source(); 2856 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1), 2857 src_space_top); 2858 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr); 2859 2860 if (status == ParMarkBitMap::incomplete) { 2861 // The last obj that starts in the source region does not end in the 2862 // region. 2863 assert(closure.source() < end_addr, "sanity"); 2864 HeapWord* const obj_beg = closure.source(); 2865 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(), 2866 src_space_top); 2867 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end); 2868 if (obj_end < range_end) { 2869 // The end was found; the entire object will fit. 2870 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end)); 2871 assert(status != ParMarkBitMap::would_overflow, "sanity"); 2872 } else { 2873 // The end was not found; the object will not fit. 2874 assert(range_end < src_space_top, "obj cannot cross space boundary"); 2875 status = ParMarkBitMap::would_overflow; 2876 } 2877 } 2878 2879 if (status == ParMarkBitMap::would_overflow) { 2880 // The last object did not fit. Note that interior oop updates were 2881 // deferred, then copy enough of the object to fill the region. 2882 region_ptr->set_deferred_obj_addr(closure.destination()); 2883 status = closure.copy_until_full(); // copies from closure.source() 2884 2885 decrement_destination_counts(cm, src_space_id, src_region_idx, 2886 closure.source()); 2887 region_ptr->set_completed(); 2888 return; 2889 } 2890 2891 if (status == ParMarkBitMap::full) { 2892 decrement_destination_counts(cm, src_space_id, src_region_idx, 2893 closure.source()); 2894 region_ptr->set_deferred_obj_addr(NULL); 2895 region_ptr->set_completed(); 2896 return; 2897 } 2898 2899 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2900 2901 // Move to the next source region, possibly switching spaces as well. All 2902 // args except end_addr may be modified. 2903 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2904 end_addr); 2905 } while (true); 2906 } 2907 2908 void PSParallelCompact::fill_blocks(size_t region_idx) 2909 { 2910 // Fill in the block table elements for the specified region. Each block 2911 // table element holds the number of live words in the region that are to the 2912 // left of the first object that starts in the block. Thus only blocks in 2913 // which an object starts need to be filled. 2914 // 2915 // The algorithm scans the section of the bitmap that corresponds to the 2916 // region, keeping a running total of the live words. When an object start is 2917 // found, if it's the first to start in the block that contains it, the 2918 // current total is written to the block table element. 2919 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize; 2920 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize; 2921 const size_t RegionSize = ParallelCompactData::RegionSize; 2922 2923 ParallelCompactData& sd = summary_data(); 2924 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size(); 2925 if (partial_obj_size >= RegionSize) { 2926 return; // No objects start in this region. 2927 } 2928 2929 // Ensure the first loop iteration decides that the block has changed. 2930 size_t cur_block = sd.block_count(); 2931 2932 const ParMarkBitMap* const bitmap = mark_bitmap(); 2933 2934 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment; 2935 assert((size_t)1 << Log2BitsPerBlock == 2936 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity"); 2937 2938 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize); 2939 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize); 2940 size_t live_bits = bitmap->words_to_bits(partial_obj_size); 2941 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end); 2942 while (beg_bit < range_end) { 2943 const size_t new_block = beg_bit >> Log2BitsPerBlock; 2944 if (new_block != cur_block) { 2945 cur_block = new_block; 2946 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits)); 2947 } 2948 2949 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end); 2950 if (end_bit < range_end - 1) { 2951 live_bits += end_bit - beg_bit + 1; 2952 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end); 2953 } else { 2954 return; 2955 } 2956 } 2957 } 2958 2959 void 2960 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) { 2961 const MutableSpace* sp = space(space_id); 2962 if (sp->is_empty()) { 2963 return; 2964 } 2965 2966 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2967 ParMarkBitMap* const bitmap = mark_bitmap(); 2968 HeapWord* const dp_addr = dense_prefix(space_id); 2969 HeapWord* beg_addr = sp->bottom(); 2970 HeapWord* end_addr = sp->top(); 2971 2972 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix"); 2973 2974 const size_t beg_region = sd.addr_to_region_idx(beg_addr); 2975 const size_t dp_region = sd.addr_to_region_idx(dp_addr); 2976 if (beg_region < dp_region) { 2977 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region); 2978 } 2979 2980 // The destination of the first live object that starts in the region is one 2981 // past the end of the partial object entering the region (if any). 2982 HeapWord* const dest_addr = sd.partial_obj_end(dp_region); 2983 HeapWord* const new_top = _space_info[space_id].new_top(); 2984 assert(new_top >= dest_addr, "bad new_top value"); 2985 const size_t words = pointer_delta(new_top, dest_addr); 2986 2987 if (words > 0) { 2988 ObjectStartArray* start_array = _space_info[space_id].start_array(); 2989 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 2990 2991 ParMarkBitMap::IterationStatus status; 2992 status = bitmap->iterate(&closure, dest_addr, end_addr); 2993 assert(status == ParMarkBitMap::full, "iteration not complete"); 2994 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr, 2995 "live objects skipped because closure is full"); 2996 } 2997 } 2998 2999 jlong PSParallelCompact::millis_since_last_gc() { 3000 // We need a monotonically non-decreasing time in ms but 3001 // os::javaTimeMillis() does not guarantee monotonicity. 3002 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3003 jlong ret_val = now - _time_of_last_gc; 3004 // XXX See note in genCollectedHeap::millis_since_last_gc(). 3005 if (ret_val < 0) { 3006 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 3007 return 0; 3008 } 3009 return ret_val; 3010 } 3011 3012 void PSParallelCompact::reset_millis_since_last_gc() { 3013 // We need a monotonically non-decreasing time in ms but 3014 // os::javaTimeMillis() does not guarantee monotonicity. 3015 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3016 } 3017 3018 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() 3019 { 3020 if (source() != destination()) { 3021 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3022 Copy::aligned_conjoint_words(source(), destination(), words_remaining()); 3023 } 3024 update_state(words_remaining()); 3025 assert(is_full(), "sanity"); 3026 return ParMarkBitMap::full; 3027 } 3028 3029 void MoveAndUpdateClosure::copy_partial_obj() 3030 { 3031 size_t words = words_remaining(); 3032 3033 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end()); 3034 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end); 3035 if (end_addr < range_end) { 3036 words = bitmap()->obj_size(source(), end_addr); 3037 } 3038 3039 // This test is necessary; if omitted, the pointer updates to a partial object 3040 // that crosses the dense prefix boundary could be overwritten. 3041 if (source() != destination()) { 3042 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3043 Copy::aligned_conjoint_words(source(), destination(), words); 3044 } 3045 update_state(words); 3046 } 3047 3048 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3049 PSParallelCompact::AdjustPointerClosure closure(cm); 3050 oop_oop_iterate_oop_maps<true>(obj, &closure); 3051 } 3052 3053 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3054 InstanceKlass::oop_pc_update_pointers(obj, cm); 3055 3056 PSParallelCompact::AdjustPointerClosure closure(cm); 3057 oop_oop_iterate_statics<true>(obj, &closure); 3058 } 3059 3060 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3061 InstanceKlass::oop_pc_update_pointers(obj, cm); 3062 } 3063 3064 #ifdef ASSERT 3065 template <class T> static void trace_reference_gc(const char *s, oop obj, 3066 T* referent_addr, 3067 T* next_addr, 3068 T* discovered_addr) { 3069 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj)); 3070 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3071 p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL); 3072 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3073 p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL); 3074 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3075 p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL); 3076 } 3077 #endif 3078 3079 template <class T> 3080 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) { 3081 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj); 3082 PSParallelCompact::adjust_pointer(referent_addr, cm); 3083 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj); 3084 PSParallelCompact::adjust_pointer(next_addr, cm); 3085 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj); 3086 PSParallelCompact::adjust_pointer(discovered_addr, cm); 3087 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj, 3088 referent_addr, next_addr, discovered_addr);) 3089 } 3090 3091 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3092 InstanceKlass::oop_pc_update_pointers(obj, cm); 3093 3094 if (UseCompressedOops) { 3095 oop_pc_update_pointers_specialized<narrowOop>(obj, cm); 3096 } else { 3097 oop_pc_update_pointers_specialized<oop>(obj, cm); 3098 } 3099 } 3100 3101 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3102 assert(obj->is_objArray(), "obj must be obj array"); 3103 PSParallelCompact::AdjustPointerClosure closure(cm); 3104 oop_oop_iterate_elements<true>(objArrayOop(obj), &closure); 3105 } 3106 3107 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3108 assert(obj->is_typeArray(),"must be a type array"); 3109 } 3110 3111 ParMarkBitMapClosure::IterationStatus 3112 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) { 3113 assert(destination() != NULL, "sanity"); 3114 assert(bitmap()->obj_size(addr) == words, "bad size"); 3115 3116 _source = addr; 3117 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) == 3118 destination(), "wrong destination"); 3119 3120 if (words > words_remaining()) { 3121 return ParMarkBitMap::would_overflow; 3122 } 3123 3124 // The start_array must be updated even if the object is not moving. 3125 if (_start_array != NULL) { 3126 _start_array->allocate_block(destination()); 3127 } 3128 3129 if (destination() != source()) { 3130 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3131 Copy::aligned_conjoint_words(source(), destination(), words); 3132 } 3133 3134 oop moved_oop = (oop) destination(); 3135 compaction_manager()->update_contents(moved_oop); 3136 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop)); 3137 3138 update_state(words); 3139 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity"); 3140 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete; 3141 } 3142 3143 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm, 3144 ParCompactionManager* cm, 3145 PSParallelCompact::SpaceId space_id) : 3146 ParMarkBitMapClosure(mbm, cm), 3147 _space_id(space_id), 3148 _start_array(PSParallelCompact::start_array(space_id)) 3149 { 3150 } 3151 3152 // Updates the references in the object to their new values. 3153 ParMarkBitMapClosure::IterationStatus 3154 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) { 3155 do_addr(addr); 3156 return ParMarkBitMap::incomplete; 3157 } 3158 3159 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : 3160 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), 3161 _start_array(PSParallelCompact::start_array(space_id)) 3162 { 3163 assert(space_id == PSParallelCompact::old_space_id, 3164 "cannot use FillClosure in the young gen"); 3165 } 3166 3167 ParMarkBitMapClosure::IterationStatus 3168 FillClosure::do_addr(HeapWord* addr, size_t size) { 3169 CollectedHeap::fill_with_objects(addr, size); 3170 HeapWord* const end = addr + size; 3171 do { 3172 _start_array->allocate_block(addr); 3173 addr += oop(addr)->size(); 3174 } while (addr < end); 3175 return ParMarkBitMap::incomplete; 3176 }