1 /* 2 * Copyright (c) 2005, 2021, 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 "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/javaClasses.inline.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "classfile/symbolTable.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "code/codeCache.hpp" 32 #include "compiler/oopMap.hpp" 33 #include "gc/parallel/parallelArguments.hpp" 34 #include "gc/parallel/parallelScavengeHeap.inline.hpp" 35 #include "gc/parallel/parMarkBitMap.inline.hpp" 36 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 37 #include "gc/parallel/psCompactionManager.inline.hpp" 38 #include "gc/parallel/psOldGen.hpp" 39 #include "gc/parallel/psParallelCompact.inline.hpp" 40 #include "gc/parallel/psPromotionManager.inline.hpp" 41 #include "gc/parallel/psRootType.hpp" 42 #include "gc/parallel/psScavenge.hpp" 43 #include "gc/parallel/psStringDedup.hpp" 44 #include "gc/parallel/psYoungGen.hpp" 45 #include "gc/shared/gcCause.hpp" 46 #include "gc/shared/gcHeapSummary.hpp" 47 #include "gc/shared/gcId.hpp" 48 #include "gc/shared/gcLocker.hpp" 49 #include "gc/shared/gcTimer.hpp" 50 #include "gc/shared/gcTrace.hpp" 51 #include "gc/shared/gcTraceTime.inline.hpp" 52 #include "gc/shared/isGCActiveMark.hpp" 53 #include "gc/shared/oopStorage.inline.hpp" 54 #include "gc/shared/oopStorageSet.inline.hpp" 55 #include "gc/shared/oopStorageSetParState.inline.hpp" 56 #include "gc/shared/referencePolicy.hpp" 57 #include "gc/shared/referenceProcessor.hpp" 58 #include "gc/shared/referenceProcessorPhaseTimes.hpp" 59 #include "gc/shared/spaceDecorator.inline.hpp" 60 #include "gc/shared/taskTerminator.hpp" 61 #include "gc/shared/weakProcessor.inline.hpp" 62 #include "gc/shared/workerPolicy.hpp" 63 #include "gc/shared/workerThread.hpp" 64 #include "gc/shared/workerUtils.hpp" 65 #include "logging/log.hpp" 66 #include "memory/iterator.inline.hpp" 67 #include "memory/metaspaceUtils.hpp" 68 #include "memory/resourceArea.hpp" 69 #include "memory/universe.hpp" 70 #include "oops/access.inline.hpp" 71 #include "oops/flatArrayKlass.inline.hpp" 72 #include "oops/instanceClassLoaderKlass.inline.hpp" 73 #include "oops/instanceKlass.inline.hpp" 74 #include "oops/instanceMirrorKlass.inline.hpp" 75 #include "oops/methodData.hpp" 76 #include "oops/objArrayKlass.inline.hpp" 77 #include "oops/oop.inline.hpp" 78 #include "runtime/atomic.hpp" 79 #include "runtime/handles.inline.hpp" 80 #include "runtime/java.hpp" 81 #include "runtime/safepoint.hpp" 82 #include "runtime/vmThread.hpp" 83 #include "services/memTracker.hpp" 84 #include "services/memoryService.hpp" 85 #include "utilities/align.hpp" 86 #include "utilities/debug.hpp" 87 #include "utilities/events.hpp" 88 #include "utilities/formatBuffer.hpp" 89 #include "utilities/macros.hpp" 90 #include "utilities/stack.inline.hpp" 91 #if INCLUDE_JVMCI 92 #include "jvmci/jvmci.hpp" 93 #endif 94 95 #include <math.h> 96 97 // All sizes are in HeapWords. 98 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words 99 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize; 100 const size_t ParallelCompactData::RegionSizeBytes = 101 RegionSize << LogHeapWordSize; 102 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1; 103 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1; 104 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask; 105 106 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words 107 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize; 108 const size_t ParallelCompactData::BlockSizeBytes = 109 BlockSize << LogHeapWordSize; 110 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1; 111 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1; 112 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask; 113 114 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize; 115 const size_t ParallelCompactData::Log2BlocksPerRegion = 116 Log2RegionSize - Log2BlockSize; 117 118 const ParallelCompactData::RegionData::region_sz_t 119 ParallelCompactData::RegionData::dc_shift = 27; 120 121 const ParallelCompactData::RegionData::region_sz_t 122 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift; 123 124 const ParallelCompactData::RegionData::region_sz_t 125 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift; 126 127 const ParallelCompactData::RegionData::region_sz_t 128 ParallelCompactData::RegionData::los_mask = ~dc_mask; 129 130 const ParallelCompactData::RegionData::region_sz_t 131 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift; 132 133 const ParallelCompactData::RegionData::region_sz_t 134 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift; 135 136 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; 137 138 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer; 139 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; 140 141 double PSParallelCompact::_dwl_mean; 142 double PSParallelCompact::_dwl_std_dev; 143 double PSParallelCompact::_dwl_first_term; 144 double PSParallelCompact::_dwl_adjustment; 145 #ifdef ASSERT 146 bool PSParallelCompact::_dwl_initialized = false; 147 #endif // #ifdef ASSERT 148 149 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size, 150 HeapWord* destination) 151 { 152 assert(src_region_idx != 0, "invalid src_region_idx"); 153 assert(partial_obj_size != 0, "invalid partial_obj_size argument"); 154 assert(destination != NULL, "invalid destination argument"); 155 156 _src_region_idx = src_region_idx; 157 _partial_obj_size = partial_obj_size; 158 _destination = destination; 159 160 // These fields may not be updated below, so make sure they're clear. 161 assert(_dest_region_addr == NULL, "should have been cleared"); 162 assert(_first_src_addr == NULL, "should have been cleared"); 163 164 // Determine the number of destination regions for the partial object. 165 HeapWord* const last_word = destination + partial_obj_size - 1; 166 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 167 HeapWord* const beg_region_addr = sd.region_align_down(destination); 168 HeapWord* const end_region_addr = sd.region_align_down(last_word); 169 170 if (beg_region_addr == end_region_addr) { 171 // One destination region. 172 _destination_count = 1; 173 if (end_region_addr == destination) { 174 // The destination falls on a region boundary, thus the first word of the 175 // partial object will be the first word copied to the destination region. 176 _dest_region_addr = end_region_addr; 177 _first_src_addr = sd.region_to_addr(src_region_idx); 178 } 179 } else { 180 // Two destination regions. When copied, the partial object will cross a 181 // destination region boundary, so a word somewhere within the partial 182 // object will be the first word copied to the second destination region. 183 _destination_count = 2; 184 _dest_region_addr = end_region_addr; 185 const size_t ofs = pointer_delta(end_region_addr, destination); 186 assert(ofs < _partial_obj_size, "sanity"); 187 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs; 188 } 189 } 190 191 void SplitInfo::clear() 192 { 193 _src_region_idx = 0; 194 _partial_obj_size = 0; 195 _destination = NULL; 196 _destination_count = 0; 197 _dest_region_addr = NULL; 198 _first_src_addr = NULL; 199 assert(!is_valid(), "sanity"); 200 } 201 202 #ifdef ASSERT 203 void SplitInfo::verify_clear() 204 { 205 assert(_src_region_idx == 0, "not clear"); 206 assert(_partial_obj_size == 0, "not clear"); 207 assert(_destination == NULL, "not clear"); 208 assert(_destination_count == 0, "not clear"); 209 assert(_dest_region_addr == NULL, "not clear"); 210 assert(_first_src_addr == NULL, "not clear"); 211 } 212 #endif // #ifdef ASSERT 213 214 215 void PSParallelCompact::print_on_error(outputStream* st) { 216 _mark_bitmap.print_on_error(st); 217 } 218 219 #ifndef PRODUCT 220 const char* PSParallelCompact::space_names[] = { 221 "old ", "eden", "from", "to " 222 }; 223 224 void PSParallelCompact::print_region_ranges() { 225 if (!log_develop_is_enabled(Trace, gc, compaction)) { 226 return; 227 } 228 Log(gc, compaction) log; 229 ResourceMark rm; 230 LogStream ls(log.trace()); 231 Universe::print_on(&ls); 232 log.trace("space bottom top end new_top"); 233 log.trace("------ ---------- ---------- ---------- ----------"); 234 235 for (unsigned int id = 0; id < last_space_id; ++id) { 236 const MutableSpace* space = _space_info[id].space(); 237 log.trace("%u %s " 238 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " 239 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", 240 id, space_names[id], 241 summary_data().addr_to_region_idx(space->bottom()), 242 summary_data().addr_to_region_idx(space->top()), 243 summary_data().addr_to_region_idx(space->end()), 244 summary_data().addr_to_region_idx(_space_info[id].new_top())); 245 } 246 } 247 248 void 249 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c) 250 { 251 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7) 252 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5) 253 254 ParallelCompactData& sd = PSParallelCompact::summary_data(); 255 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0; 256 log_develop_trace(gc, compaction)( 257 REGION_IDX_FORMAT " " PTR_FORMAT " " 258 REGION_IDX_FORMAT " " PTR_FORMAT " " 259 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " " 260 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d", 261 i, p2i(c->data_location()), dci, p2i(c->destination()), 262 c->partial_obj_size(), c->live_obj_size(), 263 c->data_size(), c->source_region(), c->destination_count()); 264 265 #undef REGION_IDX_FORMAT 266 #undef REGION_DATA_FORMAT 267 } 268 269 void 270 print_generic_summary_data(ParallelCompactData& summary_data, 271 HeapWord* const beg_addr, 272 HeapWord* const end_addr) 273 { 274 size_t total_words = 0; 275 size_t i = summary_data.addr_to_region_idx(beg_addr); 276 const size_t last = summary_data.addr_to_region_idx(end_addr); 277 HeapWord* pdest = 0; 278 279 while (i < last) { 280 ParallelCompactData::RegionData* c = summary_data.region(i); 281 if (c->data_size() != 0 || c->destination() != pdest) { 282 print_generic_summary_region(i, c); 283 total_words += c->data_size(); 284 pdest = c->destination(); 285 } 286 ++i; 287 } 288 289 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); 290 } 291 292 void 293 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data, 294 HeapWord* const beg_addr, 295 HeapWord* const end_addr) { 296 ::print_generic_summary_data(summary_data,beg_addr, end_addr); 297 } 298 299 void 300 print_generic_summary_data(ParallelCompactData& summary_data, 301 SpaceInfo* space_info) 302 { 303 if (!log_develop_is_enabled(Trace, gc, compaction)) { 304 return; 305 } 306 307 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { 308 const MutableSpace* space = space_info[id].space(); 309 print_generic_summary_data(summary_data, space->bottom(), 310 MAX2(space->top(), space_info[id].new_top())); 311 } 312 } 313 314 void 315 print_initial_summary_data(ParallelCompactData& summary_data, 316 const MutableSpace* space) { 317 if (space->top() == space->bottom()) { 318 return; 319 } 320 321 const size_t region_size = ParallelCompactData::RegionSize; 322 typedef ParallelCompactData::RegionData RegionData; 323 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top()); 324 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up); 325 const RegionData* c = summary_data.region(end_region - 1); 326 HeapWord* end_addr = c->destination() + c->data_size(); 327 const size_t live_in_space = pointer_delta(end_addr, space->bottom()); 328 329 // Print (and count) the full regions at the beginning of the space. 330 size_t full_region_count = 0; 331 size_t i = summary_data.addr_to_region_idx(space->bottom()); 332 while (i < end_region && summary_data.region(i)->data_size() == region_size) { 333 ParallelCompactData::RegionData* c = summary_data.region(i); 334 log_develop_trace(gc, compaction)( 335 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 336 i, p2i(c->destination()), 337 c->partial_obj_size(), c->live_obj_size(), 338 c->data_size(), c->source_region(), c->destination_count()); 339 ++full_region_count; 340 ++i; 341 } 342 343 size_t live_to_right = live_in_space - full_region_count * region_size; 344 345 double max_reclaimed_ratio = 0.0; 346 size_t max_reclaimed_ratio_region = 0; 347 size_t max_dead_to_right = 0; 348 size_t max_live_to_right = 0; 349 350 // Print the 'reclaimed ratio' for regions while there is something live in 351 // the region or to the right of it. The remaining regions are empty (and 352 // uninteresting), and computing the ratio will result in division by 0. 353 while (i < end_region && live_to_right > 0) { 354 c = summary_data.region(i); 355 HeapWord* const region_addr = summary_data.region_to_addr(i); 356 const size_t used_to_right = pointer_delta(space->top(), region_addr); 357 const size_t dead_to_right = used_to_right - live_to_right; 358 const double reclaimed_ratio = double(dead_to_right) / live_to_right; 359 360 if (reclaimed_ratio > max_reclaimed_ratio) { 361 max_reclaimed_ratio = reclaimed_ratio; 362 max_reclaimed_ratio_region = i; 363 max_dead_to_right = dead_to_right; 364 max_live_to_right = live_to_right; 365 } 366 367 ParallelCompactData::RegionData* c = summary_data.region(i); 368 log_develop_trace(gc, compaction)( 369 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d" 370 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), 371 i, p2i(c->destination()), 372 c->partial_obj_size(), c->live_obj_size(), 373 c->data_size(), c->source_region(), c->destination_count(), 374 reclaimed_ratio, dead_to_right, live_to_right); 375 376 377 live_to_right -= c->data_size(); 378 ++i; 379 } 380 381 // Any remaining regions are empty. Print one more if there is one. 382 if (i < end_region) { 383 ParallelCompactData::RegionData* c = summary_data.region(i); 384 log_develop_trace(gc, compaction)( 385 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 386 i, p2i(c->destination()), 387 c->partial_obj_size(), c->live_obj_size(), 388 c->data_size(), c->source_region(), c->destination_count()); 389 } 390 391 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", 392 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio); 393 } 394 395 void 396 print_initial_summary_data(ParallelCompactData& summary_data, 397 SpaceInfo* space_info) { 398 if (!log_develop_is_enabled(Trace, gc, compaction)) { 399 return; 400 } 401 402 unsigned int id = PSParallelCompact::old_space_id; 403 const MutableSpace* space; 404 do { 405 space = space_info[id].space(); 406 print_initial_summary_data(summary_data, space); 407 } while (++id < PSParallelCompact::eden_space_id); 408 409 do { 410 space = space_info[id].space(); 411 print_generic_summary_data(summary_data, space->bottom(), space->top()); 412 } while (++id < PSParallelCompact::last_space_id); 413 } 414 #endif // #ifndef PRODUCT 415 416 ParallelCompactData::ParallelCompactData() : 417 _region_start(NULL), 418 DEBUG_ONLY(_region_end(NULL) COMMA) 419 _region_vspace(NULL), 420 _reserved_byte_size(0), 421 _region_data(NULL), 422 _region_count(0), 423 _block_vspace(NULL), 424 _block_data(NULL), 425 _block_count(0) {} 426 427 bool ParallelCompactData::initialize(MemRegion covered_region) 428 { 429 _region_start = covered_region.start(); 430 const size_t region_size = covered_region.word_size(); 431 DEBUG_ONLY(_region_end = _region_start + region_size;) 432 433 assert(region_align_down(_region_start) == _region_start, 434 "region start not aligned"); 435 assert((region_size & RegionSizeOffsetMask) == 0, 436 "region size not a multiple of RegionSize"); 437 438 bool result = initialize_region_data(region_size) && initialize_block_data(); 439 return result; 440 } 441 442 PSVirtualSpace* 443 ParallelCompactData::create_vspace(size_t count, size_t element_size) 444 { 445 const size_t raw_bytes = count * element_size; 446 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10); 447 const size_t granularity = os::vm_allocation_granularity(); 448 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity)); 449 450 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : 451 MAX2(page_sz, granularity); 452 ReservedSpace rs(_reserved_byte_size, rs_align, page_sz); 453 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(), 454 rs.size()); 455 456 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 457 458 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); 459 if (vspace != 0) { 460 if (vspace->expand_by(_reserved_byte_size)) { 461 return vspace; 462 } 463 delete vspace; 464 // Release memory reserved in the space. 465 rs.release(); 466 } 467 468 return 0; 469 } 470 471 bool ParallelCompactData::initialize_region_data(size_t region_size) 472 { 473 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize; 474 _region_vspace = create_vspace(count, sizeof(RegionData)); 475 if (_region_vspace != 0) { 476 _region_data = (RegionData*)_region_vspace->reserved_low_addr(); 477 _region_count = count; 478 return true; 479 } 480 return false; 481 } 482 483 bool ParallelCompactData::initialize_block_data() 484 { 485 assert(_region_count != 0, "region data must be initialized first"); 486 const size_t count = _region_count << Log2BlocksPerRegion; 487 _block_vspace = create_vspace(count, sizeof(BlockData)); 488 if (_block_vspace != 0) { 489 _block_data = (BlockData*)_block_vspace->reserved_low_addr(); 490 _block_count = count; 491 return true; 492 } 493 return false; 494 } 495 496 void ParallelCompactData::clear() 497 { 498 memset(_region_data, 0, _region_vspace->committed_size()); 499 memset(_block_data, 0, _block_vspace->committed_size()); 500 } 501 502 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) { 503 assert(beg_region <= _region_count, "beg_region out of range"); 504 assert(end_region <= _region_count, "end_region out of range"); 505 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize"); 506 507 const size_t region_cnt = end_region - beg_region; 508 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData)); 509 510 const size_t beg_block = beg_region * BlocksPerRegion; 511 const size_t block_cnt = region_cnt * BlocksPerRegion; 512 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData)); 513 } 514 515 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const 516 { 517 const RegionData* cur_cp = region(region_idx); 518 const RegionData* const end_cp = region(region_count() - 1); 519 520 HeapWord* result = region_to_addr(region_idx); 521 if (cur_cp < end_cp) { 522 do { 523 result += cur_cp->partial_obj_size(); 524 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp); 525 } 526 return result; 527 } 528 529 void ParallelCompactData::add_obj(HeapWord* addr, size_t len) 530 { 531 const size_t obj_ofs = pointer_delta(addr, _region_start); 532 const size_t beg_region = obj_ofs >> Log2RegionSize; 533 // end_region is inclusive 534 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize; 535 536 if (beg_region == end_region) { 537 // All in one region. 538 _region_data[beg_region].add_live_obj(len); 539 return; 540 } 541 542 // First region. 543 const size_t beg_ofs = region_offset(addr); 544 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs); 545 546 // Middle regions--completely spanned by this object. 547 for (size_t region = beg_region + 1; region < end_region; ++region) { 548 _region_data[region].set_partial_obj_size(RegionSize); 549 _region_data[region].set_partial_obj_addr(addr); 550 } 551 552 // Last region. 553 const size_t end_ofs = region_offset(addr + len - 1); 554 _region_data[end_region].set_partial_obj_size(end_ofs + 1); 555 _region_data[end_region].set_partial_obj_addr(addr); 556 } 557 558 void 559 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) 560 { 561 assert(is_region_aligned(beg), "not RegionSize aligned"); 562 assert(is_region_aligned(end), "not RegionSize aligned"); 563 564 size_t cur_region = addr_to_region_idx(beg); 565 const size_t end_region = addr_to_region_idx(end); 566 HeapWord* addr = beg; 567 while (cur_region < end_region) { 568 _region_data[cur_region].set_destination(addr); 569 _region_data[cur_region].set_destination_count(0); 570 _region_data[cur_region].set_source_region(cur_region); 571 _region_data[cur_region].set_data_location(addr); 572 573 // Update live_obj_size so the region appears completely full. 574 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size(); 575 _region_data[cur_region].set_live_obj_size(live_size); 576 577 ++cur_region; 578 addr += RegionSize; 579 } 580 } 581 582 // Find the point at which a space can be split and, if necessary, record the 583 // split point. 584 // 585 // If the current src region (which overflowed the destination space) doesn't 586 // have a partial object, the split point is at the beginning of the current src 587 // region (an "easy" split, no extra bookkeeping required). 588 // 589 // If the current src region has a partial object, the split point is in the 590 // region where that partial object starts (call it the split_region). If 591 // split_region has a partial object, then the split point is just after that 592 // partial object (a "hard" split where we have to record the split data and 593 // zero the partial_obj_size field). With a "hard" split, we know that the 594 // partial_obj ends within split_region because the partial object that caused 595 // the overflow starts in split_region. If split_region doesn't have a partial 596 // obj, then the split is at the beginning of split_region (another "easy" 597 // split). 598 HeapWord* 599 ParallelCompactData::summarize_split_space(size_t src_region, 600 SplitInfo& split_info, 601 HeapWord* destination, 602 HeapWord* target_end, 603 HeapWord** target_next) 604 { 605 assert(destination <= target_end, "sanity"); 606 assert(destination + _region_data[src_region].data_size() > target_end, 607 "region should not fit into target space"); 608 assert(is_region_aligned(target_end), "sanity"); 609 610 size_t split_region = src_region; 611 HeapWord* split_destination = destination; 612 size_t partial_obj_size = _region_data[src_region].partial_obj_size(); 613 614 if (destination + partial_obj_size > target_end) { 615 // The split point is just after the partial object (if any) in the 616 // src_region that contains the start of the object that overflowed the 617 // destination space. 618 // 619 // Find the start of the "overflow" object and set split_region to the 620 // region containing it. 621 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr(); 622 split_region = addr_to_region_idx(overflow_obj); 623 624 // Clear the source_region field of all destination regions whose first word 625 // came from data after the split point (a non-null source_region field 626 // implies a region must be filled). 627 // 628 // An alternative to the simple loop below: clear during post_compact(), 629 // which uses memcpy instead of individual stores, and is easy to 630 // parallelize. (The downside is that it clears the entire RegionData 631 // object as opposed to just one field.) 632 // 633 // post_compact() would have to clear the summary data up to the highest 634 // address that was written during the summary phase, which would be 635 // 636 // max(top, max(new_top, clear_top)) 637 // 638 // where clear_top is a new field in SpaceInfo. Would have to set clear_top 639 // to target_end. 640 const RegionData* const sr = region(split_region); 641 const size_t beg_idx = 642 addr_to_region_idx(region_align_up(sr->destination() + 643 sr->partial_obj_size())); 644 const size_t end_idx = addr_to_region_idx(target_end); 645 646 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx); 647 for (size_t idx = beg_idx; idx < end_idx; ++idx) { 648 _region_data[idx].set_source_region(0); 649 } 650 651 // Set split_destination and partial_obj_size to reflect the split region. 652 split_destination = sr->destination(); 653 partial_obj_size = sr->partial_obj_size(); 654 } 655 656 // The split is recorded only if a partial object extends onto the region. 657 if (partial_obj_size != 0) { 658 _region_data[split_region].set_partial_obj_size(0); 659 split_info.record(split_region, partial_obj_size, split_destination); 660 } 661 662 // Setup the continuation addresses. 663 *target_next = split_destination + partial_obj_size; 664 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size; 665 666 if (log_develop_is_enabled(Trace, gc, compaction)) { 667 const char * split_type = partial_obj_size == 0 ? "easy" : "hard"; 668 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT, 669 split_type, p2i(source_next), split_region, partial_obj_size); 670 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT, 671 split_type, p2i(split_destination), 672 addr_to_region_idx(split_destination), 673 p2i(*target_next)); 674 675 if (partial_obj_size != 0) { 676 HeapWord* const po_beg = split_info.destination(); 677 HeapWord* const po_end = po_beg + split_info.partial_obj_size(); 678 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT, 679 split_type, 680 p2i(po_beg), addr_to_region_idx(po_beg), 681 p2i(po_end), addr_to_region_idx(po_end)); 682 } 683 } 684 685 return source_next; 686 } 687 688 bool ParallelCompactData::summarize(SplitInfo& split_info, 689 HeapWord* source_beg, HeapWord* source_end, 690 HeapWord** source_next, 691 HeapWord* target_beg, HeapWord* target_end, 692 HeapWord** target_next) 693 { 694 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next; 695 log_develop_trace(gc, compaction)( 696 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT 697 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT, 698 p2i(source_beg), p2i(source_end), p2i(source_next_val), 699 p2i(target_beg), p2i(target_end), p2i(*target_next)); 700 701 size_t cur_region = addr_to_region_idx(source_beg); 702 const size_t end_region = addr_to_region_idx(region_align_up(source_end)); 703 704 HeapWord *dest_addr = target_beg; 705 while (cur_region < end_region) { 706 // The destination must be set even if the region has no data. 707 _region_data[cur_region].set_destination(dest_addr); 708 709 size_t words = _region_data[cur_region].data_size(); 710 if (words > 0) { 711 // If cur_region does not fit entirely into the target space, find a point 712 // at which the source space can be 'split' so that part is copied to the 713 // target space and the rest is copied elsewhere. 714 if (dest_addr + words > target_end) { 715 assert(source_next != NULL, "source_next is NULL when splitting"); 716 *source_next = summarize_split_space(cur_region, split_info, dest_addr, 717 target_end, target_next); 718 return false; 719 } 720 721 // Compute the destination_count for cur_region, and if necessary, update 722 // source_region for a destination region. The source_region field is 723 // updated if cur_region is the first (left-most) region to be copied to a 724 // destination region. 725 // 726 // The destination_count calculation is a bit subtle. A region that has 727 // data that compacts into itself does not count itself as a destination. 728 // This maintains the invariant that a zero count means the region is 729 // available and can be claimed and then filled. 730 uint destination_count = 0; 731 if (split_info.is_split(cur_region)) { 732 // The current region has been split: the partial object will be copied 733 // to one destination space and the remaining data will be copied to 734 // another destination space. Adjust the initial destination_count and, 735 // if necessary, set the source_region field if the partial object will 736 // cross a destination region boundary. 737 destination_count = split_info.destination_count(); 738 if (destination_count == 2) { 739 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr()); 740 _region_data[dest_idx].set_source_region(cur_region); 741 } 742 } 743 744 HeapWord* const last_addr = dest_addr + words - 1; 745 const size_t dest_region_1 = addr_to_region_idx(dest_addr); 746 const size_t dest_region_2 = addr_to_region_idx(last_addr); 747 748 // Initially assume that the destination regions will be the same and 749 // adjust the value below if necessary. Under this assumption, if 750 // cur_region == dest_region_2, then cur_region will be compacted 751 // completely into itself. 752 destination_count += cur_region == dest_region_2 ? 0 : 1; 753 if (dest_region_1 != dest_region_2) { 754 // Destination regions differ; adjust destination_count. 755 destination_count += 1; 756 // Data from cur_region will be copied to the start of dest_region_2. 757 _region_data[dest_region_2].set_source_region(cur_region); 758 } else if (is_region_aligned(dest_addr)) { 759 // Data from cur_region will be copied to the start of the destination 760 // region. 761 _region_data[dest_region_1].set_source_region(cur_region); 762 } 763 764 _region_data[cur_region].set_destination_count(destination_count); 765 _region_data[cur_region].set_data_location(region_to_addr(cur_region)); 766 dest_addr += words; 767 } 768 769 ++cur_region; 770 } 771 772 *target_next = dest_addr; 773 return true; 774 } 775 776 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) const { 777 assert(addr != NULL, "Should detect NULL oop earlier"); 778 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap"); 779 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked"); 780 781 // Region covering the object. 782 RegionData* const region_ptr = addr_to_region_ptr(addr); 783 HeapWord* result = region_ptr->destination(); 784 785 // If the entire Region is live, the new location is region->destination + the 786 // offset of the object within in the Region. 787 788 // Run some performance tests to determine if this special case pays off. It 789 // is worth it for pointers into the dense prefix. If the optimization to 790 // avoid pointer updates in regions that only point to the dense prefix is 791 // ever implemented, this should be revisited. 792 if (region_ptr->data_size() == RegionSize) { 793 result += region_offset(addr); 794 return result; 795 } 796 797 // Otherwise, the new location is region->destination + block offset + the 798 // number of live words in the Block that are (a) to the left of addr and (b) 799 // due to objects that start in the Block. 800 801 // Fill in the block table if necessary. This is unsynchronized, so multiple 802 // threads may fill the block table for a region (harmless, since it is 803 // idempotent). 804 if (!region_ptr->blocks_filled()) { 805 PSParallelCompact::fill_blocks(addr_to_region_idx(addr)); 806 region_ptr->set_blocks_filled(); 807 } 808 809 HeapWord* const search_start = block_align_down(addr); 810 const size_t block_offset = addr_to_block_ptr(addr)->offset(); 811 812 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); 813 const size_t live = bitmap->live_words_in_range(cm, search_start, cast_to_oop(addr)); 814 result += block_offset + live; 815 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result)); 816 return result; 817 } 818 819 #ifdef ASSERT 820 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) 821 { 822 const size_t* const beg = (const size_t*)vspace->committed_low_addr(); 823 const size_t* const end = (const size_t*)vspace->committed_high_addr(); 824 for (const size_t* p = beg; p < end; ++p) { 825 assert(*p == 0, "not zero"); 826 } 827 } 828 829 void ParallelCompactData::verify_clear() 830 { 831 verify_clear(_region_vspace); 832 verify_clear(_block_vspace); 833 } 834 #endif // #ifdef ASSERT 835 836 STWGCTimer PSParallelCompact::_gc_timer; 837 ParallelOldTracer PSParallelCompact::_gc_tracer; 838 elapsedTimer PSParallelCompact::_accumulated_time; 839 unsigned int PSParallelCompact::_total_invocations = 0; 840 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; 841 CollectorCounters* PSParallelCompact::_counters = NULL; 842 ParMarkBitMap PSParallelCompact::_mark_bitmap; 843 ParallelCompactData PSParallelCompact::_summary_data; 844 845 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; 846 847 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } 848 849 void PSParallelCompact::post_initialize() { 850 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 851 _span_based_discoverer.set_span(heap->reserved_region()); 852 _ref_processor = 853 new ReferenceProcessor(&_span_based_discoverer, 854 ParallelGCThreads, // mt processing degree 855 ParallelGCThreads, // mt discovery degree 856 false, // concurrent_discovery 857 &_is_alive_closure); // non-header is alive closure 858 859 _counters = new CollectorCounters("Parallel full collection pauses", 1); 860 861 // Initialize static fields in ParCompactionManager. 862 ParCompactionManager::initialize(mark_bitmap()); 863 } 864 865 bool PSParallelCompact::initialize() { 866 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 867 MemRegion mr = heap->reserved_region(); 868 869 // Was the old gen get allocated successfully? 870 if (!heap->old_gen()->is_allocated()) { 871 return false; 872 } 873 874 initialize_space_info(); 875 initialize_dead_wood_limiter(); 876 877 if (!_mark_bitmap.initialize(mr)) { 878 vm_shutdown_during_initialization( 879 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel " 880 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 881 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K)); 882 return false; 883 } 884 885 if (!_summary_data.initialize(mr)) { 886 vm_shutdown_during_initialization( 887 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel " 888 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 889 _summary_data.reserved_byte_size()/K, mr.byte_size()/K)); 890 return false; 891 } 892 893 return true; 894 } 895 896 void PSParallelCompact::initialize_space_info() 897 { 898 memset(&_space_info, 0, sizeof(_space_info)); 899 900 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 901 PSYoungGen* young_gen = heap->young_gen(); 902 903 _space_info[old_space_id].set_space(heap->old_gen()->object_space()); 904 _space_info[eden_space_id].set_space(young_gen->eden_space()); 905 _space_info[from_space_id].set_space(young_gen->from_space()); 906 _space_info[to_space_id].set_space(young_gen->to_space()); 907 908 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); 909 } 910 911 void PSParallelCompact::initialize_dead_wood_limiter() 912 { 913 const size_t max = 100; 914 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; 915 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; 916 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); 917 DEBUG_ONLY(_dwl_initialized = true;) 918 _dwl_adjustment = normal_distribution(1.0); 919 } 920 921 void 922 PSParallelCompact::clear_data_covering_space(SpaceId id) 923 { 924 // At this point, top is the value before GC, new_top() is the value that will 925 // be set at the end of GC. The marking bitmap is cleared to top; nothing 926 // should be marked above top. The summary data is cleared to the larger of 927 // top & new_top. 928 MutableSpace* const space = _space_info[id].space(); 929 HeapWord* const bot = space->bottom(); 930 HeapWord* const top = space->top(); 931 HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); 932 933 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); 934 const idx_t end_bit = _mark_bitmap.align_range_end(_mark_bitmap.addr_to_bit(top)); 935 _mark_bitmap.clear_range(beg_bit, end_bit); 936 937 const size_t beg_region = _summary_data.addr_to_region_idx(bot); 938 const size_t end_region = 939 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top)); 940 _summary_data.clear_range(beg_region, end_region); 941 942 // Clear the data used to 'split' regions. 943 SplitInfo& split_info = _space_info[id].split_info(); 944 if (split_info.is_valid()) { 945 split_info.clear(); 946 } 947 DEBUG_ONLY(split_info.verify_clear();) 948 } 949 950 void PSParallelCompact::pre_compact() 951 { 952 // Update the from & to space pointers in space_info, since they are swapped 953 // at each young gen gc. Do the update unconditionally (even though a 954 // promotion failure does not swap spaces) because an unknown number of young 955 // collections will have swapped the spaces an unknown number of times. 956 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer); 957 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 958 _space_info[from_space_id].set_space(heap->young_gen()->from_space()); 959 _space_info[to_space_id].set_space(heap->young_gen()->to_space()); 960 961 // Increment the invocation count 962 heap->increment_total_collections(true); 963 964 // We need to track unique mark sweep invocations as well. 965 _total_invocations++; 966 967 heap->print_heap_before_gc(); 968 heap->trace_heap_before_gc(&_gc_tracer); 969 970 // Fill in TLABs 971 heap->ensure_parsability(true); // retire TLABs 972 973 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 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 ParCompactionManager::reset_all_bitmap_query_caches(); 987 } 988 989 void PSParallelCompact::post_compact() 990 { 991 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer); 992 ParCompactionManager::remove_all_shadow_regions(); 993 994 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 995 // Clear the marking bitmap, summary data and split info. 996 clear_data_covering_space(SpaceId(id)); 997 // Update top(). Must be done after clearing the bitmap and summary data. 998 _space_info[id].publish_new_top(); 999 } 1000 1001 ParCompactionManager::flush_all_string_dedup_requests(); 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 1010 // Update heap occupancy information which is used as input to the soft ref 1011 // clearing policy at the next gc. 1012 Universe::heap()->update_capacity_and_used_at_gc(); 1013 1014 bool young_gen_empty = eden_empty && from_space->is_empty() && 1015 to_space->is_empty(); 1016 1017 PSCardTable* ct = heap->card_table(); 1018 MemRegion old_mr = heap->old_gen()->reserved(); 1019 if (young_gen_empty) { 1020 ct->clear(old_mr); 1021 } else { 1022 ct->invalidate(old_mr); 1023 } 1024 1025 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1026 ClassLoaderDataGraph::purge(/*at_safepoint*/true); 1027 DEBUG_ONLY(MetaspaceUtils::verify();) 1028 1029 heap->prune_scavengable_nmethods(); 1030 1031 #if COMPILER2_OR_JVMCI 1032 DerivedPointerTable::update_pointers(); 1033 #endif 1034 1035 if (ZapUnusedHeapArea) { 1036 heap->gen_mangle_unused_area(); 1037 } 1038 1039 // Signal that we have completed a visit to all live objects. 1040 Universe::heap()->record_whole_heap_examined_timestamp(); 1041 } 1042 1043 HeapWord* 1044 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, 1045 bool maximum_compaction) 1046 { 1047 const size_t region_size = ParallelCompactData::RegionSize; 1048 const ParallelCompactData& sd = summary_data(); 1049 1050 const MutableSpace* const space = _space_info[id].space(); 1051 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 1052 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom()); 1053 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up); 1054 1055 // Skip full regions at the beginning of the space--they are necessarily part 1056 // of the dense prefix. 1057 size_t full_count = 0; 1058 const RegionData* cp; 1059 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) { 1060 ++full_count; 1061 } 1062 1063 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1064 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1065 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; 1066 if (maximum_compaction || cp == end_cp || interval_ended) { 1067 _maximum_compaction_gc_num = total_invocations(); 1068 return sd.region_to_addr(cp); 1069 } 1070 1071 HeapWord* const new_top = _space_info[id].new_top(); 1072 const size_t space_live = pointer_delta(new_top, space->bottom()); 1073 const size_t space_used = space->used_in_words(); 1074 const size_t space_capacity = space->capacity_in_words(); 1075 1076 const double cur_density = double(space_live) / space_capacity; 1077 const double deadwood_density = 1078 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; 1079 const size_t deadwood_goal = size_t(space_capacity * deadwood_density); 1080 1081 log_develop_debug(gc, compaction)( 1082 "cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, 1083 cur_density, deadwood_density, deadwood_goal); 1084 log_develop_debug(gc, compaction)( 1085 "space_live=" SIZE_FORMAT " space_used=" SIZE_FORMAT " " 1086 "space_cap=" SIZE_FORMAT, 1087 space_live, space_used, 1088 space_capacity); 1089 1090 // XXX - Use binary search? 1091 HeapWord* dense_prefix = sd.region_to_addr(cp); 1092 const RegionData* full_cp = cp; 1093 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1); 1094 while (cp < end_cp) { 1095 HeapWord* region_destination = cp->destination(); 1096 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination); 1097 1098 log_develop_trace(gc, compaction)( 1099 "c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " 1100 "dp=" PTR_FORMAT " cdw=" SIZE_FORMAT_W(8), 1101 sd.region(cp), p2i(region_destination), 1102 p2i(dense_prefix), cur_deadwood); 1103 1104 if (cur_deadwood >= deadwood_goal) { 1105 // Found the region that has the correct amount of deadwood to the left. 1106 // This typically occurs after crossing a fairly sparse set of regions, so 1107 // iterate backwards over those sparse regions, looking for the region 1108 // that has the lowest density of live objects 'to the right.' 1109 size_t space_to_left = sd.region(cp) * region_size; 1110 size_t live_to_left = space_to_left - cur_deadwood; 1111 size_t space_to_right = space_capacity - space_to_left; 1112 size_t live_to_right = space_live - live_to_left; 1113 double density_to_right = double(live_to_right) / space_to_right; 1114 while (cp > full_cp) { 1115 --cp; 1116 const size_t prev_region_live_to_right = live_to_right - 1117 cp->data_size(); 1118 const size_t prev_region_space_to_right = space_to_right + region_size; 1119 double prev_region_density_to_right = 1120 double(prev_region_live_to_right) / prev_region_space_to_right; 1121 if (density_to_right <= prev_region_density_to_right) { 1122 return dense_prefix; 1123 } 1124 1125 log_develop_trace(gc, compaction)( 1126 "backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " 1127 "pc_d2r=%10.8f", 1128 sd.region(cp), density_to_right, 1129 prev_region_density_to_right); 1130 1131 dense_prefix -= region_size; 1132 live_to_right = prev_region_live_to_right; 1133 space_to_right = prev_region_space_to_right; 1134 density_to_right = prev_region_density_to_right; 1135 } 1136 return dense_prefix; 1137 } 1138 1139 dense_prefix += region_size; 1140 ++cp; 1141 } 1142 1143 return dense_prefix; 1144 } 1145 1146 #ifndef PRODUCT 1147 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, 1148 const SpaceId id, 1149 const bool maximum_compaction, 1150 HeapWord* const addr) 1151 { 1152 const size_t region_idx = summary_data().addr_to_region_idx(addr); 1153 RegionData* const cp = summary_data().region(region_idx); 1154 const MutableSpace* const space = _space_info[id].space(); 1155 HeapWord* const new_top = _space_info[id].new_top(); 1156 1157 const size_t space_live = pointer_delta(new_top, space->bottom()); 1158 const size_t dead_to_left = pointer_delta(addr, cp->destination()); 1159 const size_t space_cap = space->capacity_in_words(); 1160 const double dead_to_left_pct = double(dead_to_left) / space_cap; 1161 const size_t live_to_right = new_top - cp->destination(); 1162 const size_t dead_to_right = space->top() - addr - live_to_right; 1163 1164 log_develop_debug(gc, compaction)( 1165 "%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " 1166 "spl=" SIZE_FORMAT " " 1167 "d2l=" SIZE_FORMAT " d2l%%=%6.4f " 1168 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT " " 1169 "ratio=%10.8f", 1170 algorithm, p2i(addr), region_idx, 1171 space_live, 1172 dead_to_left, dead_to_left_pct, 1173 dead_to_right, live_to_right, 1174 double(dead_to_right) / live_to_right); 1175 } 1176 #endif // #ifndef PRODUCT 1177 1178 // Return a fraction indicating how much of the generation can be treated as 1179 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution 1180 // based on the density of live objects in the generation to determine a limit, 1181 // which is then adjusted so the return value is min_percent when the density is 1182 // 1. 1183 // 1184 // The following table shows some return values for a different values of the 1185 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and 1186 // min_percent is 1. 1187 // 1188 // fraction allowed as dead wood 1189 // ----------------------------------------------------------------- 1190 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 1191 // ------- ---------- ---------- ---------- ---------- ---------- ---------- 1192 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1193 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1194 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1195 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1196 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1197 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1198 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1199 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1200 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1201 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1202 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 1203 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1204 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1205 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1206 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1207 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1208 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1209 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1210 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1211 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1212 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1213 1214 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) 1215 { 1216 assert(_dwl_initialized, "uninitialized"); 1217 1218 // The raw limit is the value of the normal distribution at x = density. 1219 const double raw_limit = normal_distribution(density); 1220 1221 // Adjust the raw limit so it becomes the minimum when the density is 1. 1222 // 1223 // First subtract the adjustment value (which is simply the precomputed value 1224 // normal_distribution(1.0)); this yields a value of 0 when the density is 1. 1225 // Then add the minimum value, so the minimum is returned when the density is 1226 // 1. Finally, prevent negative values, which occur when the mean is not 0.5. 1227 const double min = double(min_percent) / 100.0; 1228 const double limit = raw_limit - _dwl_adjustment + min; 1229 return MAX2(limit, 0.0); 1230 } 1231 1232 ParallelCompactData::RegionData* 1233 PSParallelCompact::first_dead_space_region(const RegionData* beg, 1234 const RegionData* end) 1235 { 1236 const size_t region_size = ParallelCompactData::RegionSize; 1237 ParallelCompactData& sd = summary_data(); 1238 size_t left = sd.region(beg); 1239 size_t right = end > beg ? sd.region(end) - 1 : left; 1240 1241 // Binary search. 1242 while (left < right) { 1243 // Equivalent to (left + right) / 2, but does not overflow. 1244 const size_t middle = left + (right - left) / 2; 1245 RegionData* const middle_ptr = sd.region(middle); 1246 HeapWord* const dest = middle_ptr->destination(); 1247 HeapWord* const addr = sd.region_to_addr(middle); 1248 assert(dest != NULL, "sanity"); 1249 assert(dest <= addr, "must move left"); 1250 1251 if (middle > left && dest < addr) { 1252 right = middle - 1; 1253 } else if (middle < right && middle_ptr->data_size() == region_size) { 1254 left = middle + 1; 1255 } else { 1256 return middle_ptr; 1257 } 1258 } 1259 return sd.region(left); 1260 } 1261 1262 ParallelCompactData::RegionData* 1263 PSParallelCompact::dead_wood_limit_region(const RegionData* beg, 1264 const RegionData* end, 1265 size_t dead_words) 1266 { 1267 ParallelCompactData& sd = summary_data(); 1268 size_t left = sd.region(beg); 1269 size_t right = end > beg ? sd.region(end) - 1 : left; 1270 1271 // Binary search. 1272 while (left < right) { 1273 // Equivalent to (left + right) / 2, but does not overflow. 1274 const size_t middle = left + (right - left) / 2; 1275 RegionData* const middle_ptr = sd.region(middle); 1276 HeapWord* const dest = middle_ptr->destination(); 1277 HeapWord* const addr = sd.region_to_addr(middle); 1278 assert(dest != NULL, "sanity"); 1279 assert(dest <= addr, "must move left"); 1280 1281 const size_t dead_to_left = pointer_delta(addr, dest); 1282 if (middle > left && dead_to_left > dead_words) { 1283 right = middle - 1; 1284 } else if (middle < right && dead_to_left < dead_words) { 1285 left = middle + 1; 1286 } else { 1287 return middle_ptr; 1288 } 1289 } 1290 return sd.region(left); 1291 } 1292 1293 // The result is valid during the summary phase, after the initial summarization 1294 // of each space into itself, and before final summarization. 1295 inline double 1296 PSParallelCompact::reclaimed_ratio(const RegionData* const cp, 1297 HeapWord* const bottom, 1298 HeapWord* const top, 1299 HeapWord* const new_top) 1300 { 1301 ParallelCompactData& sd = summary_data(); 1302 1303 assert(cp != NULL, "sanity"); 1304 assert(bottom != NULL, "sanity"); 1305 assert(top != NULL, "sanity"); 1306 assert(new_top != NULL, "sanity"); 1307 assert(top >= new_top, "summary data problem?"); 1308 assert(new_top > bottom, "space is empty; should not be here"); 1309 assert(new_top >= cp->destination(), "sanity"); 1310 assert(top >= sd.region_to_addr(cp), "sanity"); 1311 1312 HeapWord* const destination = cp->destination(); 1313 const size_t dense_prefix_live = pointer_delta(destination, bottom); 1314 const size_t compacted_region_live = pointer_delta(new_top, destination); 1315 const size_t compacted_region_used = pointer_delta(top, 1316 sd.region_to_addr(cp)); 1317 const size_t reclaimable = compacted_region_used - compacted_region_live; 1318 1319 const double divisor = dense_prefix_live + 1.25 * compacted_region_live; 1320 return double(reclaimable) / divisor; 1321 } 1322 1323 // Return the address of the end of the dense prefix, a.k.a. the start of the 1324 // compacted region. The address is always on a region boundary. 1325 // 1326 // Completely full regions at the left are skipped, since no compaction can 1327 // occur in those regions. Then the maximum amount of dead wood to allow is 1328 // computed, based on the density (amount live / capacity) of the generation; 1329 // the region with approximately that amount of dead space to the left is 1330 // identified as the limit region. Regions between the last completely full 1331 // region and the limit region are scanned and the one that has the best 1332 // (maximum) reclaimed_ratio() is selected. 1333 HeapWord* 1334 PSParallelCompact::compute_dense_prefix(const SpaceId id, 1335 bool maximum_compaction) 1336 { 1337 const size_t region_size = ParallelCompactData::RegionSize; 1338 const ParallelCompactData& sd = summary_data(); 1339 1340 const MutableSpace* const space = _space_info[id].space(); 1341 HeapWord* const top = space->top(); 1342 HeapWord* const top_aligned_up = sd.region_align_up(top); 1343 HeapWord* const new_top = _space_info[id].new_top(); 1344 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top); 1345 HeapWord* const bottom = space->bottom(); 1346 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom); 1347 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 1348 const RegionData* const new_top_cp = 1349 sd.addr_to_region_ptr(new_top_aligned_up); 1350 1351 // Skip full regions at the beginning of the space--they are necessarily part 1352 // of the dense prefix. 1353 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp); 1354 assert(full_cp->destination() == sd.region_to_addr(full_cp) || 1355 space->is_empty(), "no dead space allowed to the left"); 1356 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1, 1357 "region must have dead space"); 1358 1359 // The gc number is saved whenever a maximum compaction is done, and used to 1360 // determine when the maximum compaction interval has expired. This avoids 1361 // successive max compactions for different reasons. 1362 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1363 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1364 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || 1365 total_invocations() == HeapFirstMaximumCompactionCount; 1366 if (maximum_compaction || full_cp == top_cp || interval_ended) { 1367 _maximum_compaction_gc_num = total_invocations(); 1368 return sd.region_to_addr(full_cp); 1369 } 1370 1371 const size_t space_live = pointer_delta(new_top, bottom); 1372 const size_t space_used = space->used_in_words(); 1373 const size_t space_capacity = space->capacity_in_words(); 1374 1375 const double density = double(space_live) / double(space_capacity); 1376 const size_t min_percent_free = MarkSweepDeadRatio; 1377 const double limiter = dead_wood_limiter(density, min_percent_free); 1378 const size_t dead_wood_max = space_used - space_live; 1379 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), 1380 dead_wood_max); 1381 1382 log_develop_debug(gc, compaction)( 1383 "space_live=" SIZE_FORMAT " space_used=" SIZE_FORMAT " " 1384 "space_cap=" SIZE_FORMAT, 1385 space_live, space_used, 1386 space_capacity); 1387 log_develop_debug(gc, compaction)( 1388 "dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f " 1389 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, 1390 density, min_percent_free, limiter, 1391 dead_wood_max, dead_wood_limit); 1392 1393 // Locate the region with the desired amount of dead space to the left. 1394 const RegionData* const limit_cp = 1395 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit); 1396 1397 // Scan from the first region with dead space to the limit region and find the 1398 // one with the best (largest) reclaimed ratio. 1399 double best_ratio = 0.0; 1400 const RegionData* best_cp = full_cp; 1401 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) { 1402 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); 1403 if (tmp_ratio > best_ratio) { 1404 best_cp = cp; 1405 best_ratio = tmp_ratio; 1406 } 1407 } 1408 1409 return sd.region_to_addr(best_cp); 1410 } 1411 1412 void PSParallelCompact::summarize_spaces_quick() 1413 { 1414 for (unsigned int i = 0; i < last_space_id; ++i) { 1415 const MutableSpace* space = _space_info[i].space(); 1416 HeapWord** nta = _space_info[i].new_top_addr(); 1417 bool result = _summary_data.summarize(_space_info[i].split_info(), 1418 space->bottom(), space->top(), NULL, 1419 space->bottom(), space->end(), nta); 1420 assert(result, "space must fit into itself"); 1421 _space_info[i].set_dense_prefix(space->bottom()); 1422 } 1423 } 1424 1425 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) 1426 { 1427 HeapWord* const dense_prefix_end = dense_prefix(id); 1428 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end); 1429 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); 1430 if (dead_space_crosses_boundary(region, dense_prefix_bit)) { 1431 // Only enough dead space is filled so that any remaining dead space to the 1432 // left is larger than the minimum filler object. (The remainder is filled 1433 // during the copy/update phase.) 1434 // 1435 // The size of the dead space to the right of the boundary is not a 1436 // concern, since compaction will be able to use whatever space is 1437 // available. 1438 // 1439 // Here '||' is the boundary, 'x' represents a don't care bit and a box 1440 // surrounds the space to be filled with an object. 1441 // 1442 // In the 32-bit VM, each bit represents two 32-bit words: 1443 // +---+ 1444 // a) beg_bits: ... x x x | 0 | || 0 x x ... 1445 // end_bits: ... x x x | 0 | || 0 x x ... 1446 // +---+ 1447 // 1448 // In the 64-bit VM, each bit represents one 64-bit word: 1449 // +------------+ 1450 // b) beg_bits: ... x x x | 0 || 0 | x x ... 1451 // end_bits: ... x x 1 | 0 || 0 | x x ... 1452 // +------------+ 1453 // +-------+ 1454 // c) beg_bits: ... x x | 0 0 | || 0 x x ... 1455 // end_bits: ... x 1 | 0 0 | || 0 x x ... 1456 // +-------+ 1457 // +-----------+ 1458 // d) beg_bits: ... x | 0 0 0 | || 0 x x ... 1459 // end_bits: ... 1 | 0 0 0 | || 0 x x ... 1460 // +-----------+ 1461 // +-------+ 1462 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... 1463 // end_bits: ... 0 0 | 0 0 | || 0 x x ... 1464 // +-------+ 1465 1466 // Initially assume case a, c or e will apply. 1467 size_t obj_len = CollectedHeap::min_fill_size(); 1468 HeapWord* obj_beg = dense_prefix_end - obj_len; 1469 1470 #ifdef _LP64 1471 if (MinObjAlignment > 1) { // object alignment > heap word size 1472 // Cases a, c or e. 1473 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { 1474 // Case b above. 1475 obj_beg = dense_prefix_end - 1; 1476 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && 1477 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { 1478 // Case d above. 1479 obj_beg = dense_prefix_end - 3; 1480 obj_len = 3; 1481 } 1482 #endif // #ifdef _LP64 1483 1484 CollectedHeap::fill_with_object(obj_beg, obj_len); 1485 _mark_bitmap.mark_obj(obj_beg, obj_len); 1486 _summary_data.add_obj(obj_beg, obj_len); 1487 assert(start_array(id) != NULL, "sanity"); 1488 start_array(id)->allocate_block(obj_beg); 1489 } 1490 } 1491 1492 void 1493 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) 1494 { 1495 assert(id < last_space_id, "id out of range"); 1496 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(), 1497 "should have been reset in summarize_spaces_quick()"); 1498 1499 const MutableSpace* space = _space_info[id].space(); 1500 if (_space_info[id].new_top() != space->bottom()) { 1501 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); 1502 _space_info[id].set_dense_prefix(dense_prefix_end); 1503 1504 #ifndef PRODUCT 1505 if (log_is_enabled(Debug, gc, compaction)) { 1506 print_dense_prefix_stats("ratio", id, maximum_compaction, 1507 dense_prefix_end); 1508 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); 1509 print_dense_prefix_stats("density", id, maximum_compaction, addr); 1510 } 1511 #endif // #ifndef PRODUCT 1512 1513 // Recompute the summary data, taking into account the dense prefix. If 1514 // every last byte will be reclaimed, then the existing summary data which 1515 // compacts everything can be left in place. 1516 if (!maximum_compaction && dense_prefix_end != space->bottom()) { 1517 // If dead space crosses the dense prefix boundary, it is (at least 1518 // partially) filled with a dummy object, marked live and added to the 1519 // summary data. This simplifies the copy/update phase and must be done 1520 // before the final locations of objects are determined, to prevent 1521 // leaving a fragment of dead space that is too small to fill. 1522 fill_dense_prefix_end(id); 1523 1524 // Compute the destination of each Region, and thus each object. 1525 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); 1526 _summary_data.summarize(_space_info[id].split_info(), 1527 dense_prefix_end, space->top(), NULL, 1528 dense_prefix_end, space->end(), 1529 _space_info[id].new_top_addr()); 1530 } 1531 } 1532 1533 if (log_develop_is_enabled(Trace, gc, compaction)) { 1534 const size_t region_size = ParallelCompactData::RegionSize; 1535 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); 1536 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end); 1537 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); 1538 HeapWord* const new_top = _space_info[id].new_top(); 1539 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top); 1540 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); 1541 log_develop_trace(gc, compaction)( 1542 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " 1543 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " 1544 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, 1545 id, space->capacity_in_words(), p2i(dense_prefix_end), 1546 dp_region, dp_words / region_size, 1547 cr_words / region_size, p2i(new_top)); 1548 } 1549 } 1550 1551 #ifndef PRODUCT 1552 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id, 1553 HeapWord* dst_beg, HeapWord* dst_end, 1554 SpaceId src_space_id, 1555 HeapWord* src_beg, HeapWord* src_end) 1556 { 1557 log_develop_trace(gc, compaction)( 1558 "Summarizing %d [%s] into %d [%s]: " 1559 "src=" PTR_FORMAT "-" PTR_FORMAT " " 1560 SIZE_FORMAT "-" SIZE_FORMAT " " 1561 "dst=" PTR_FORMAT "-" PTR_FORMAT " " 1562 SIZE_FORMAT "-" SIZE_FORMAT, 1563 src_space_id, space_names[src_space_id], 1564 dst_space_id, space_names[dst_space_id], 1565 p2i(src_beg), p2i(src_end), 1566 _summary_data.addr_to_region_idx(src_beg), 1567 _summary_data.addr_to_region_idx(src_end), 1568 p2i(dst_beg), p2i(dst_end), 1569 _summary_data.addr_to_region_idx(dst_beg), 1570 _summary_data.addr_to_region_idx(dst_end)); 1571 } 1572 #endif // #ifndef PRODUCT 1573 1574 void PSParallelCompact::summary_phase(bool maximum_compaction) 1575 { 1576 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer); 1577 1578 // Quick summarization of each space into itself, to see how much is live. 1579 summarize_spaces_quick(); 1580 1581 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self"); 1582 NOT_PRODUCT(print_region_ranges()); 1583 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1584 1585 // The amount of live data that will end up in old space (assuming it fits). 1586 size_t old_space_total_live = 0; 1587 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1588 old_space_total_live += pointer_delta(_space_info[id].new_top(), 1589 _space_info[id].space()->bottom()); 1590 } 1591 1592 MutableSpace* const old_space = _space_info[old_space_id].space(); 1593 const size_t old_capacity = old_space->capacity_in_words(); 1594 if (old_space_total_live > old_capacity) { 1595 // XXX - should also try to expand 1596 maximum_compaction = true; 1597 } 1598 1599 // Old generations. 1600 summarize_space(old_space_id, maximum_compaction); 1601 1602 // Summarize the remaining spaces in the young gen. The initial target space 1603 // is the old gen. If a space does not fit entirely into the target, then the 1604 // remainder is compacted into the space itself and that space becomes the new 1605 // target. 1606 SpaceId dst_space_id = old_space_id; 1607 HeapWord* dst_space_end = old_space->end(); 1608 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr(); 1609 for (unsigned int id = eden_space_id; id < last_space_id; ++id) { 1610 const MutableSpace* space = _space_info[id].space(); 1611 const size_t live = pointer_delta(_space_info[id].new_top(), 1612 space->bottom()); 1613 const size_t available = pointer_delta(dst_space_end, *new_top_addr); 1614 1615 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end, 1616 SpaceId(id), space->bottom(), space->top());) 1617 if (live > 0 && live <= available) { 1618 // All the live data will fit. 1619 bool done = _summary_data.summarize(_space_info[id].split_info(), 1620 space->bottom(), space->top(), 1621 NULL, 1622 *new_top_addr, dst_space_end, 1623 new_top_addr); 1624 assert(done, "space must fit into old gen"); 1625 1626 // Reset the new_top value for the space. 1627 _space_info[id].set_new_top(space->bottom()); 1628 } else if (live > 0) { 1629 // Attempt to fit part of the source space into the target space. 1630 HeapWord* next_src_addr = NULL; 1631 bool done = _summary_data.summarize(_space_info[id].split_info(), 1632 space->bottom(), space->top(), 1633 &next_src_addr, 1634 *new_top_addr, dst_space_end, 1635 new_top_addr); 1636 assert(!done, "space should not fit into old gen"); 1637 assert(next_src_addr != NULL, "sanity"); 1638 1639 // The source space becomes the new target, so the remainder is compacted 1640 // within the space itself. 1641 dst_space_id = SpaceId(id); 1642 dst_space_end = space->end(); 1643 new_top_addr = _space_info[id].new_top_addr(); 1644 NOT_PRODUCT(summary_phase_msg(dst_space_id, 1645 space->bottom(), dst_space_end, 1646 SpaceId(id), next_src_addr, space->top());) 1647 done = _summary_data.summarize(_space_info[id].split_info(), 1648 next_src_addr, space->top(), 1649 NULL, 1650 space->bottom(), dst_space_end, 1651 new_top_addr); 1652 assert(done, "space must fit when compacted into itself"); 1653 assert(*new_top_addr <= space->top(), "usage should not grow"); 1654 } 1655 } 1656 1657 log_develop_trace(gc, compaction)("Summary_phase: after final summarization"); 1658 NOT_PRODUCT(print_region_ranges()); 1659 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1660 } 1661 1662 // This method should contain all heap-specific policy for invoking a full 1663 // collection. invoke_no_policy() will only attempt to compact the heap; it 1664 // will do nothing further. If we need to bail out for policy reasons, scavenge 1665 // before full gc, or any other specialized behavior, it needs to be added here. 1666 // 1667 // Note that this method should only be called from the vm_thread while at a 1668 // safepoint. 1669 // 1670 // Note that the all_soft_refs_clear flag in the soft ref policy 1671 // may be true because this method can be called without intervening 1672 // activity. For example when the heap space is tight and full measure 1673 // are being taken to free space. 1674 void PSParallelCompact::invoke(bool maximum_heap_compaction) { 1675 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 1676 assert(Thread::current() == (Thread*)VMThread::vm_thread(), 1677 "should be in vm thread"); 1678 1679 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1680 GCCause::Cause gc_cause = heap->gc_cause(); 1681 assert(!heap->is_gc_active(), "not reentrant"); 1682 1683 PSAdaptiveSizePolicy* policy = heap->size_policy(); 1684 IsGCActiveMark mark; 1685 1686 if (ScavengeBeforeFullGC) { 1687 PSScavenge::invoke_no_policy(); 1688 } 1689 1690 const bool clear_all_soft_refs = 1691 heap->soft_ref_policy()->should_clear_all_soft_refs(); 1692 1693 PSParallelCompact::invoke_no_policy(clear_all_soft_refs || 1694 maximum_heap_compaction); 1695 } 1696 1697 // This method contains no policy. You should probably 1698 // be calling invoke() instead. 1699 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { 1700 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 1701 assert(ref_processor() != NULL, "Sanity"); 1702 1703 if (GCLocker::check_active_before_gc()) { 1704 return false; 1705 } 1706 1707 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1708 1709 GCIdMark gc_id_mark; 1710 _gc_timer.register_gc_start(); 1711 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 1712 1713 GCCause::Cause gc_cause = heap->gc_cause(); 1714 PSYoungGen* young_gen = heap->young_gen(); 1715 PSOldGen* old_gen = heap->old_gen(); 1716 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 1717 1718 // The scope of casr should end after code that can change 1719 // SoftRefPolicy::_should_clear_all_soft_refs. 1720 ClearedAllSoftRefs casr(maximum_heap_compaction, 1721 heap->soft_ref_policy()); 1722 1723 if (ZapUnusedHeapArea) { 1724 // Save information needed to minimize mangling 1725 heap->record_gen_tops_before_GC(); 1726 } 1727 1728 // Make sure data structures are sane, make the heap parsable, and do other 1729 // miscellaneous bookkeeping. 1730 pre_compact(); 1731 1732 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values(); 1733 1734 { 1735 const uint active_workers = 1736 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().max_workers(), 1737 ParallelScavengeHeap::heap()->workers().active_workers(), 1738 Threads::number_of_non_daemon_threads()); 1739 ParallelScavengeHeap::heap()->workers().set_active_workers(active_workers); 1740 1741 GCTraceCPUTime tcpu; 1742 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true); 1743 1744 heap->pre_full_gc_dump(&_gc_timer); 1745 1746 TraceCollectorStats tcs(counters()); 1747 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause); 1748 1749 if (log_is_enabled(Debug, gc, heap, exit)) { 1750 accumulated_time()->start(); 1751 } 1752 1753 // Let the size policy know we're starting 1754 size_policy->major_collection_begin(); 1755 1756 #if COMPILER2_OR_JVMCI 1757 DerivedPointerTable::clear(); 1758 #endif 1759 1760 ref_processor()->start_discovery(maximum_heap_compaction); 1761 1762 marking_phase(&_gc_tracer); 1763 1764 bool max_on_system_gc = UseMaximumCompactionOnSystemGC 1765 && GCCause::is_user_requested_gc(gc_cause); 1766 summary_phase(maximum_heap_compaction || max_on_system_gc); 1767 1768 #if COMPILER2_OR_JVMCI 1769 assert(DerivedPointerTable::is_active(), "Sanity"); 1770 DerivedPointerTable::set_active(false); 1771 #endif 1772 1773 // adjust_roots() updates Universe::_intArrayKlassObj which is 1774 // needed by the compaction for filling holes in the dense prefix. 1775 adjust_roots(); 1776 1777 compact(); 1778 1779 ParCompactionManager::verify_all_region_stack_empty(); 1780 1781 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be 1782 // done before resizing. 1783 post_compact(); 1784 1785 // Let the size policy know we're done 1786 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 1787 1788 if (UseAdaptiveSizePolicy) { 1789 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 1790 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 1791 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 1792 1793 // Don't check if the size_policy is ready here. Let 1794 // the size_policy check that internally. 1795 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 1796 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 1797 // Swap the survivor spaces if from_space is empty. The 1798 // resize_young_gen() called below is normally used after 1799 // a successful young GC and swapping of survivor spaces; 1800 // otherwise, it will fail to resize the young gen with 1801 // the current implementation. 1802 if (young_gen->from_space()->is_empty()) { 1803 young_gen->from_space()->clear(SpaceDecorator::Mangle); 1804 young_gen->swap_spaces(); 1805 } 1806 1807 // Calculate optimal free space amounts 1808 assert(young_gen->max_gen_size() > 1809 young_gen->from_space()->capacity_in_bytes() + 1810 young_gen->to_space()->capacity_in_bytes(), 1811 "Sizes of space in young gen are out-of-bounds"); 1812 1813 size_t young_live = young_gen->used_in_bytes(); 1814 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 1815 size_t old_live = old_gen->used_in_bytes(); 1816 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 1817 size_t max_old_gen_size = old_gen->max_gen_size(); 1818 size_t max_eden_size = young_gen->max_gen_size() - 1819 young_gen->from_space()->capacity_in_bytes() - 1820 young_gen->to_space()->capacity_in_bytes(); 1821 1822 // Used for diagnostics 1823 size_policy->clear_generation_free_space_flags(); 1824 1825 size_policy->compute_generations_free_space(young_live, 1826 eden_live, 1827 old_live, 1828 cur_eden, 1829 max_old_gen_size, 1830 max_eden_size, 1831 true /* full gc*/); 1832 1833 size_policy->check_gc_overhead_limit(eden_live, 1834 max_old_gen_size, 1835 max_eden_size, 1836 true /* full gc*/, 1837 gc_cause, 1838 heap->soft_ref_policy()); 1839 1840 size_policy->decay_supplemental_growth(true /* full gc*/); 1841 1842 heap->resize_old_gen( 1843 size_policy->calculated_old_free_size_in_bytes()); 1844 1845 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 1846 size_policy->calculated_survivor_size_in_bytes()); 1847 } 1848 1849 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 1850 } 1851 1852 if (UsePerfData) { 1853 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 1854 counters->update_counters(); 1855 counters->update_old_capacity(old_gen->capacity_in_bytes()); 1856 counters->update_young_capacity(young_gen->capacity_in_bytes()); 1857 } 1858 1859 heap->resize_all_tlabs(); 1860 1861 // Resize the metaspace capacity after a collection 1862 MetaspaceGC::compute_new_size(); 1863 1864 if (log_is_enabled(Debug, gc, heap, exit)) { 1865 accumulated_time()->stop(); 1866 } 1867 1868 heap->print_heap_change(pre_gc_values); 1869 1870 // Track memory usage and detect low memory 1871 MemoryService::track_memory_usage(); 1872 heap->update_counters(); 1873 1874 heap->post_full_gc_dump(&_gc_timer); 1875 } 1876 1877 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 1878 Universe::verify("After GC"); 1879 } 1880 1881 // Re-verify object start arrays 1882 if (VerifyObjectStartArray && 1883 VerifyAfterGC) { 1884 old_gen->verify_object_start_array(); 1885 } 1886 1887 if (ZapUnusedHeapArea) { 1888 old_gen->object_space()->check_mangled_unused_area_complete(); 1889 } 1890 1891 heap->print_heap_after_gc(); 1892 heap->trace_heap_after_gc(&_gc_tracer); 1893 1894 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 1895 1896 _gc_timer.register_gc_end(); 1897 1898 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id)); 1899 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 1900 1901 return true; 1902 } 1903 1904 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure { 1905 private: 1906 uint _worker_id; 1907 1908 public: 1909 PCAddThreadRootsMarkingTaskClosure(uint worker_id) : _worker_id(worker_id) { } 1910 void do_thread(Thread* thread) { 1911 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc"); 1912 1913 ResourceMark rm; 1914 1915 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(_worker_id); 1916 1917 PCMarkAndPushClosure mark_and_push_closure(cm); 1918 MarkingCodeBlobClosure mark_and_push_in_blobs(&mark_and_push_closure, !CodeBlobToOopClosure::FixRelocations); 1919 1920 thread->oops_do(&mark_and_push_closure, &mark_and_push_in_blobs); 1921 1922 // Do the real work 1923 cm->follow_marking_stacks(); 1924 } 1925 }; 1926 1927 void steal_marking_work(TaskTerminator& terminator, uint worker_id) { 1928 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc"); 1929 1930 ParCompactionManager* cm = 1931 ParCompactionManager::gc_thread_compaction_manager(worker_id); 1932 1933 do { 1934 oop obj = NULL; 1935 ObjArrayTask task; 1936 if (ParCompactionManager::steal_objarray(worker_id, task)) { 1937 cm->follow_array((objArrayOop)task.obj(), task.index()); 1938 } else if (ParCompactionManager::steal(worker_id, obj)) { 1939 cm->follow_contents(obj); 1940 } 1941 cm->follow_marking_stacks(); 1942 } while (!terminator.offer_termination()); 1943 } 1944 1945 class MarkFromRootsTask : public WorkerTask { 1946 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do 1947 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state; 1948 TaskTerminator _terminator; 1949 uint _active_workers; 1950 1951 public: 1952 MarkFromRootsTask(uint active_workers) : 1953 WorkerTask("MarkFromRootsTask"), 1954 _strong_roots_scope(active_workers), 1955 _terminator(active_workers, ParCompactionManager::oop_task_queues()), 1956 _active_workers(active_workers) {} 1957 1958 virtual void work(uint worker_id) { 1959 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id); 1960 PCMarkAndPushClosure mark_and_push_closure(cm); 1961 1962 { 1963 CLDToOopClosure cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_strong); 1964 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure); 1965 1966 // Do the real work 1967 cm->follow_marking_stacks(); 1968 } 1969 1970 PCAddThreadRootsMarkingTaskClosure closure(worker_id); 1971 Threads::possibly_parallel_threads_do(true /*parallel */, &closure); 1972 1973 // Mark from OopStorages 1974 { 1975 _oop_storage_set_par_state.oops_do(&mark_and_push_closure); 1976 // Do the real work 1977 cm->follow_marking_stacks(); 1978 } 1979 1980 if (_active_workers > 1) { 1981 steal_marking_work(_terminator, worker_id); 1982 } 1983 } 1984 }; 1985 1986 class ParallelCompactRefProcProxyTask : public RefProcProxyTask { 1987 TaskTerminator _terminator; 1988 1989 public: 1990 ParallelCompactRefProcProxyTask(uint max_workers) 1991 : RefProcProxyTask("ParallelCompactRefProcProxyTask", max_workers), 1992 _terminator(_max_workers, ParCompactionManager::oop_task_queues()) {} 1993 1994 void work(uint worker_id) override { 1995 assert(worker_id < _max_workers, "sanity"); 1996 ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id); 1997 PCMarkAndPushClosure keep_alive(cm); 1998 BarrierEnqueueDiscoveredFieldClosure enqueue; 1999 ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id); 2000 _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &keep_alive, &enqueue, &complete_gc); 2001 } 2002 2003 void prepare_run_task_hook() override { 2004 _terminator.reset_for_reuse(_queue_count); 2005 } 2006 }; 2007 2008 void PSParallelCompact::marking_phase(ParallelOldTracer *gc_tracer) { 2009 // Recursively traverse all live objects and mark them 2010 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer); 2011 2012 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers(); 2013 2014 // Need new claim bits before marking starts. 2015 ClassLoaderDataGraph::clear_claimed_marks(); 2016 2017 { 2018 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer); 2019 2020 MarkFromRootsTask task(active_gc_threads); 2021 ParallelScavengeHeap::heap()->workers().run_task(&task); 2022 } 2023 2024 // Process reference objects found during marking 2025 { 2026 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 2027 2028 ReferenceProcessorStats stats; 2029 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues()); 2030 2031 ref_processor()->set_active_mt_degree(active_gc_threads); 2032 ParallelCompactRefProcProxyTask task(ref_processor()->max_num_queues()); 2033 stats = ref_processor()->process_discovered_references(task, pt); 2034 2035 gc_tracer->report_gc_reference_stats(stats); 2036 pt.print_all_references(); 2037 } 2038 2039 // This is the point where the entire marking should have completed. 2040 ParCompactionManager::verify_all_marking_stack_empty(); 2041 2042 { 2043 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer); 2044 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(), 2045 is_alive_closure(), 2046 &do_nothing_cl, 2047 1); 2048 } 2049 2050 { 2051 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer); 2052 2053 // Follow system dictionary roots and unload classes. 2054 bool purged_class = SystemDictionary::do_unloading(&_gc_timer); 2055 2056 // Unload nmethods. 2057 CodeCache::do_unloading(is_alive_closure(), purged_class); 2058 2059 // Prune dead klasses from subklass/sibling/implementor lists. 2060 Klass::clean_weak_klass_links(purged_class); 2061 2062 // Clean JVMCI metadata handles. 2063 JVMCI_ONLY(JVMCI::do_unloading(purged_class)); 2064 } 2065 2066 _gc_tracer.report_object_count_after_gc(is_alive_closure()); 2067 #if TASKQUEUE_STATS 2068 ParCompactionManager::oop_task_queues()->print_and_reset_taskqueue_stats("Oop Queue"); 2069 ParCompactionManager::_objarray_task_queues->print_and_reset_taskqueue_stats("ObjArrayOop Queue"); 2070 #endif 2071 } 2072 2073 class PSAdjustTask final : public WorkerTask { 2074 SubTasksDone _sub_tasks; 2075 WeakProcessor::Task _weak_proc_task; 2076 OopStorageSetStrongParState<false, false> _oop_storage_iter; 2077 uint _nworkers; 2078 2079 enum PSAdjustSubTask { 2080 PSAdjustSubTask_code_cache, 2081 2082 PSAdjustSubTask_num_elements 2083 }; 2084 2085 public: 2086 PSAdjustTask(uint nworkers) : 2087 WorkerTask("PSAdjust task"), 2088 _sub_tasks(PSAdjustSubTask_num_elements), 2089 _weak_proc_task(nworkers), 2090 _nworkers(nworkers) { 2091 // Need new claim bits when tracing through and adjusting pointers. 2092 ClassLoaderDataGraph::clear_claimed_marks(); 2093 if (nworkers > 1) { 2094 Threads::change_thread_claim_token(); 2095 } 2096 } 2097 2098 ~PSAdjustTask() { 2099 Threads::assert_all_threads_claimed(); 2100 } 2101 2102 void work(uint worker_id) { 2103 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id); 2104 PCAdjustPointerClosure adjust(cm); 2105 { 2106 ResourceMark rm; 2107 Threads::possibly_parallel_oops_do(_nworkers > 1, &adjust, nullptr); 2108 } 2109 _oop_storage_iter.oops_do(&adjust); 2110 { 2111 CLDToOopClosure cld_closure(&adjust, ClassLoaderData::_claim_strong); 2112 ClassLoaderDataGraph::cld_do(&cld_closure); 2113 } 2114 { 2115 AlwaysTrueClosure always_alive; 2116 _weak_proc_task.work(worker_id, &always_alive, &adjust); 2117 } 2118 if (_sub_tasks.try_claim_task(PSAdjustSubTask_code_cache)) { 2119 CodeBlobToOopClosure adjust_code(&adjust, CodeBlobToOopClosure::FixRelocations); 2120 CodeCache::blobs_do(&adjust_code); 2121 } 2122 _sub_tasks.all_tasks_claimed(); 2123 } 2124 }; 2125 2126 void PSParallelCompact::adjust_roots() { 2127 // Adjust the pointers to reflect the new locations 2128 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer); 2129 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers(); 2130 PSAdjustTask task(nworkers); 2131 ParallelScavengeHeap::heap()->workers().run_task(&task); 2132 } 2133 2134 // Helper class to print 8 region numbers per line and then print the total at the end. 2135 class FillableRegionLogger : public StackObj { 2136 private: 2137 Log(gc, compaction) log; 2138 static const int LineLength = 8; 2139 size_t _regions[LineLength]; 2140 int _next_index; 2141 bool _enabled; 2142 size_t _total_regions; 2143 public: 2144 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { } 2145 ~FillableRegionLogger() { 2146 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions); 2147 } 2148 2149 void print_line() { 2150 if (!_enabled || _next_index == 0) { 2151 return; 2152 } 2153 FormatBuffer<> line("Fillable: "); 2154 for (int i = 0; i < _next_index; i++) { 2155 line.append(" " SIZE_FORMAT_W(7), _regions[i]); 2156 } 2157 log.trace("%s", line.buffer()); 2158 _next_index = 0; 2159 } 2160 2161 void handle(size_t region) { 2162 if (!_enabled) { 2163 return; 2164 } 2165 _regions[_next_index++] = region; 2166 if (_next_index == LineLength) { 2167 print_line(); 2168 } 2169 _total_regions++; 2170 } 2171 }; 2172 2173 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads) 2174 { 2175 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer); 2176 2177 // Find the threads that are active 2178 uint worker_id = 0; 2179 2180 // Find all regions that are available (can be filled immediately) and 2181 // distribute them to the thread stacks. The iteration is done in reverse 2182 // order (high to low) so the regions will be removed in ascending order. 2183 2184 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 2185 2186 // id + 1 is used to test termination so unsigned can 2187 // be used with an old_space_id == 0. 2188 FillableRegionLogger region_logger; 2189 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) { 2190 SpaceInfo* const space_info = _space_info + id; 2191 HeapWord* const new_top = space_info->new_top(); 2192 2193 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix()); 2194 const size_t end_region = 2195 sd.addr_to_region_idx(sd.region_align_up(new_top)); 2196 2197 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) { 2198 if (sd.region(cur)->claim_unsafe()) { 2199 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id); 2200 bool result = sd.region(cur)->mark_normal(); 2201 assert(result, "Must succeed at this point."); 2202 cm->region_stack()->push(cur); 2203 region_logger.handle(cur); 2204 // Assign regions to tasks in round-robin fashion. 2205 if (++worker_id == parallel_gc_threads) { 2206 worker_id = 0; 2207 } 2208 } 2209 } 2210 region_logger.print_line(); 2211 } 2212 } 2213 2214 class TaskQueue : StackObj { 2215 volatile uint _counter; 2216 uint _size; 2217 uint _insert_index; 2218 PSParallelCompact::UpdateDensePrefixTask* _backing_array; 2219 public: 2220 explicit TaskQueue(uint size) : _counter(0), _size(size), _insert_index(0), _backing_array(NULL) { 2221 _backing_array = NEW_C_HEAP_ARRAY(PSParallelCompact::UpdateDensePrefixTask, _size, mtGC); 2222 } 2223 ~TaskQueue() { 2224 assert(_counter >= _insert_index, "not all queue elements were claimed"); 2225 FREE_C_HEAP_ARRAY(T, _backing_array); 2226 } 2227 2228 void push(const PSParallelCompact::UpdateDensePrefixTask& value) { 2229 assert(_insert_index < _size, "too small backing array"); 2230 _backing_array[_insert_index++] = value; 2231 } 2232 2233 bool try_claim(PSParallelCompact::UpdateDensePrefixTask& reference) { 2234 uint claimed = Atomic::fetch_and_add(&_counter, 1u); 2235 if (claimed < _insert_index) { 2236 reference = _backing_array[claimed]; 2237 return true; 2238 } else { 2239 return false; 2240 } 2241 } 2242 }; 2243 2244 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 2245 2246 void PSParallelCompact::enqueue_dense_prefix_tasks(TaskQueue& task_queue, 2247 uint parallel_gc_threads) { 2248 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer); 2249 2250 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2251 2252 // Iterate over all the spaces adding tasks for updating 2253 // regions in the dense prefix. Assume that 1 gc thread 2254 // will work on opening the gaps and the remaining gc threads 2255 // will work on the dense prefix. 2256 unsigned int space_id; 2257 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) { 2258 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); 2259 const MutableSpace* const space = _space_info[space_id].space(); 2260 2261 if (dense_prefix_end == space->bottom()) { 2262 // There is no dense prefix for this space. 2263 continue; 2264 } 2265 2266 // The dense prefix is before this region. 2267 size_t region_index_end_dense_prefix = 2268 sd.addr_to_region_idx(dense_prefix_end); 2269 RegionData* const dense_prefix_cp = 2270 sd.region(region_index_end_dense_prefix); 2271 assert(dense_prefix_end == space->end() || 2272 dense_prefix_cp->available() || 2273 dense_prefix_cp->claimed(), 2274 "The region after the dense prefix should always be ready to fill"); 2275 2276 size_t region_index_start = sd.addr_to_region_idx(space->bottom()); 2277 2278 // Is there dense prefix work? 2279 size_t total_dense_prefix_regions = 2280 region_index_end_dense_prefix - region_index_start; 2281 // How many regions of the dense prefix should be given to 2282 // each thread? 2283 if (total_dense_prefix_regions > 0) { 2284 uint tasks_for_dense_prefix = 1; 2285 if (total_dense_prefix_regions <= 2286 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { 2287 // Don't over partition. This assumes that 2288 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value 2289 // so there are not many regions to process. 2290 tasks_for_dense_prefix = parallel_gc_threads; 2291 } else { 2292 // Over partition 2293 tasks_for_dense_prefix = parallel_gc_threads * 2294 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; 2295 } 2296 size_t regions_per_thread = total_dense_prefix_regions / 2297 tasks_for_dense_prefix; 2298 // Give each thread at least 1 region. 2299 if (regions_per_thread == 0) { 2300 regions_per_thread = 1; 2301 } 2302 2303 for (uint k = 0; k < tasks_for_dense_prefix; k++) { 2304 if (region_index_start >= region_index_end_dense_prefix) { 2305 break; 2306 } 2307 // region_index_end is not processed 2308 size_t region_index_end = MIN2(region_index_start + regions_per_thread, 2309 region_index_end_dense_prefix); 2310 task_queue.push(UpdateDensePrefixTask(SpaceId(space_id), 2311 region_index_start, 2312 region_index_end)); 2313 region_index_start = region_index_end; 2314 } 2315 } 2316 // This gets any part of the dense prefix that did not 2317 // fit evenly. 2318 if (region_index_start < region_index_end_dense_prefix) { 2319 task_queue.push(UpdateDensePrefixTask(SpaceId(space_id), 2320 region_index_start, 2321 region_index_end_dense_prefix)); 2322 } 2323 } 2324 } 2325 2326 #ifdef ASSERT 2327 // Write a histogram of the number of times the block table was filled for a 2328 // region. 2329 void PSParallelCompact::write_block_fill_histogram() 2330 { 2331 if (!log_develop_is_enabled(Trace, gc, compaction)) { 2332 return; 2333 } 2334 2335 Log(gc, compaction) log; 2336 ResourceMark rm; 2337 LogStream ls(log.trace()); 2338 outputStream* out = &ls; 2339 2340 typedef ParallelCompactData::RegionData rd_t; 2341 ParallelCompactData& sd = summary_data(); 2342 2343 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2344 MutableSpace* const spc = _space_info[id].space(); 2345 if (spc->bottom() != spc->top()) { 2346 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom()); 2347 HeapWord* const top_aligned_up = sd.region_align_up(spc->top()); 2348 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up); 2349 2350 size_t histo[5] = { 0, 0, 0, 0, 0 }; 2351 const size_t histo_len = sizeof(histo) / sizeof(size_t); 2352 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t)); 2353 2354 for (const rd_t* cur = beg; cur < end; ++cur) { 2355 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)]; 2356 } 2357 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt); 2358 for (size_t i = 0; i < histo_len; ++i) { 2359 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%", 2360 histo[i], 100.0 * histo[i] / region_cnt); 2361 } 2362 out->cr(); 2363 } 2364 } 2365 } 2366 #endif // #ifdef ASSERT 2367 2368 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) { 2369 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc"); 2370 2371 ParCompactionManager* cm = 2372 ParCompactionManager::gc_thread_compaction_manager(worker_id); 2373 2374 // Drain the stacks that have been preloaded with regions 2375 // that are ready to fill. 2376 2377 cm->drain_region_stacks(); 2378 2379 guarantee(cm->region_stack()->is_empty(), "Not empty"); 2380 2381 size_t region_index = 0; 2382 2383 while (true) { 2384 if (ParCompactionManager::steal(worker_id, region_index)) { 2385 PSParallelCompact::fill_and_update_region(cm, region_index); 2386 cm->drain_region_stacks(); 2387 } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) { 2388 // Fill and update an unavailable region with the help of a shadow region 2389 PSParallelCompact::fill_and_update_shadow_region(cm, region_index); 2390 cm->drain_region_stacks(); 2391 } else { 2392 if (terminator->offer_termination()) { 2393 break; 2394 } 2395 // Go around again. 2396 } 2397 } 2398 } 2399 2400 class UpdateDensePrefixAndCompactionTask: public WorkerTask { 2401 TaskQueue& _tq; 2402 TaskTerminator _terminator; 2403 uint _active_workers; 2404 2405 public: 2406 UpdateDensePrefixAndCompactionTask(TaskQueue& tq, uint active_workers) : 2407 WorkerTask("UpdateDensePrefixAndCompactionTask"), 2408 _tq(tq), 2409 _terminator(active_workers, ParCompactionManager::region_task_queues()), 2410 _active_workers(active_workers) { 2411 } 2412 virtual void work(uint worker_id) { 2413 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id); 2414 2415 for (PSParallelCompact::UpdateDensePrefixTask task; _tq.try_claim(task); /* empty */) { 2416 PSParallelCompact::update_and_deadwood_in_dense_prefix(cm, 2417 task._space_id, 2418 task._region_index_start, 2419 task._region_index_end); 2420 } 2421 2422 // Once a thread has drained it's stack, it should try to steal regions from 2423 // other threads. 2424 compaction_with_stealing_work(&_terminator, worker_id); 2425 } 2426 }; 2427 2428 void PSParallelCompact::compact() { 2429 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer); 2430 2431 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2432 PSOldGen* old_gen = heap->old_gen(); 2433 old_gen->start_array()->reset(); 2434 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers(); 2435 2436 // for [0..last_space_id) 2437 // for [0..active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING) 2438 // push 2439 // push 2440 // 2441 // max push count is thus: last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1) 2442 TaskQueue task_queue(last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1)); 2443 initialize_shadow_regions(active_gc_threads); 2444 prepare_region_draining_tasks(active_gc_threads); 2445 enqueue_dense_prefix_tasks(task_queue, active_gc_threads); 2446 2447 { 2448 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer); 2449 2450 UpdateDensePrefixAndCompactionTask task(task_queue, active_gc_threads); 2451 ParallelScavengeHeap::heap()->workers().run_task(&task); 2452 2453 #ifdef ASSERT 2454 // Verify that all regions have been processed before the deferred updates. 2455 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2456 verify_complete(SpaceId(id)); 2457 } 2458 #endif 2459 } 2460 2461 { 2462 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer); 2463 // Update the deferred objects, if any. 2464 ParCompactionManager* cm = ParCompactionManager::get_vmthread_cm(); 2465 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2466 update_deferred_objects(cm, SpaceId(id)); 2467 } 2468 } 2469 2470 DEBUG_ONLY(write_block_fill_histogram()); 2471 } 2472 2473 #ifdef ASSERT 2474 void PSParallelCompact::verify_complete(SpaceId space_id) { 2475 // All Regions between space bottom() to new_top() should be marked as filled 2476 // and all Regions between new_top() and top() should be available (i.e., 2477 // should have been emptied). 2478 ParallelCompactData& sd = summary_data(); 2479 SpaceInfo si = _space_info[space_id]; 2480 HeapWord* new_top_addr = sd.region_align_up(si.new_top()); 2481 HeapWord* old_top_addr = sd.region_align_up(si.space()->top()); 2482 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom()); 2483 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr); 2484 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr); 2485 2486 bool issued_a_warning = false; 2487 2488 size_t cur_region; 2489 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) { 2490 const RegionData* const c = sd.region(cur_region); 2491 if (!c->completed()) { 2492 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u", 2493 cur_region, c->destination_count()); 2494 issued_a_warning = true; 2495 } 2496 } 2497 2498 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) { 2499 const RegionData* const c = sd.region(cur_region); 2500 if (!c->available()) { 2501 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u", 2502 cur_region, c->destination_count()); 2503 issued_a_warning = true; 2504 } 2505 } 2506 2507 if (issued_a_warning) { 2508 print_region_ranges(); 2509 } 2510 } 2511 #endif // #ifdef ASSERT 2512 2513 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) { 2514 _start_array->allocate_block(addr); 2515 compaction_manager()->update_contents(cast_to_oop(addr)); 2516 } 2517 2518 // Update interior oops in the ranges of regions [beg_region, end_region). 2519 void 2520 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 2521 SpaceId space_id, 2522 size_t beg_region, 2523 size_t end_region) { 2524 ParallelCompactData& sd = summary_data(); 2525 ParMarkBitMap* const mbm = mark_bitmap(); 2526 2527 HeapWord* beg_addr = sd.region_to_addr(beg_region); 2528 HeapWord* const end_addr = sd.region_to_addr(end_region); 2529 assert(beg_region <= end_region, "bad region range"); 2530 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); 2531 2532 #ifdef ASSERT 2533 // Claim the regions to avoid triggering an assert when they are marked as 2534 // filled. 2535 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) { 2536 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed"); 2537 } 2538 #endif // #ifdef ASSERT 2539 2540 if (beg_addr != space(space_id)->bottom()) { 2541 // Find the first live object or block of dead space that *starts* in this 2542 // range of regions. If a partial object crosses onto the region, skip it; 2543 // it will be marked for 'deferred update' when the object head is 2544 // processed. If dead space crosses onto the region, it is also skipped; it 2545 // will be filled when the prior region is processed. If neither of those 2546 // apply, the first word in the region is the start of a live object or dead 2547 // space. 2548 assert(beg_addr > space(space_id)->bottom(), "sanity"); 2549 const RegionData* const cp = sd.region(beg_region); 2550 if (cp->partial_obj_size() != 0) { 2551 beg_addr = sd.partial_obj_end(beg_region); 2552 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) { 2553 beg_addr = mbm->find_obj_beg(beg_addr, end_addr); 2554 } 2555 } 2556 2557 if (beg_addr < end_addr) { 2558 // A live object or block of dead space starts in this range of Regions. 2559 HeapWord* const dense_prefix_end = dense_prefix(space_id); 2560 2561 // Create closures and iterate. 2562 UpdateOnlyClosure update_closure(mbm, cm, space_id); 2563 FillClosure fill_closure(cm, space_id); 2564 ParMarkBitMap::IterationStatus status; 2565 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, 2566 dense_prefix_end); 2567 if (status == ParMarkBitMap::incomplete) { 2568 update_closure.do_addr(update_closure.source()); 2569 } 2570 } 2571 2572 // Mark the regions as filled. 2573 RegionData* const beg_cp = sd.region(beg_region); 2574 RegionData* const end_cp = sd.region(end_region); 2575 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) { 2576 cp->set_completed(); 2577 } 2578 } 2579 2580 // Return the SpaceId for the space containing addr. If addr is not in the 2581 // heap, last_space_id is returned. In debug mode it expects the address to be 2582 // in the heap and asserts such. 2583 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) { 2584 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap"); 2585 2586 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2587 if (_space_info[id].space()->contains(addr)) { 2588 return SpaceId(id); 2589 } 2590 } 2591 2592 assert(false, "no space contains the addr"); 2593 return last_space_id; 2594 } 2595 2596 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm, 2597 SpaceId id) { 2598 assert(id < last_space_id, "bad space id"); 2599 2600 ParallelCompactData& sd = summary_data(); 2601 const SpaceInfo* const space_info = _space_info + id; 2602 ObjectStartArray* const start_array = space_info->start_array(); 2603 2604 const MutableSpace* const space = space_info->space(); 2605 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set"); 2606 HeapWord* const beg_addr = space_info->dense_prefix(); 2607 HeapWord* const end_addr = sd.region_align_up(space_info->new_top()); 2608 2609 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr); 2610 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr); 2611 const RegionData* cur_region; 2612 for (cur_region = beg_region; cur_region < end_region; ++cur_region) { 2613 HeapWord* const addr = cur_region->deferred_obj_addr(); 2614 if (addr != NULL) { 2615 if (start_array != NULL) { 2616 start_array->allocate_block(addr); 2617 } 2618 cm->update_contents(cast_to_oop(addr)); 2619 assert(oopDesc::is_oop_or_null(cast_to_oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(cast_to_oop(addr))); 2620 } 2621 } 2622 } 2623 2624 // Skip over count live words starting from beg, and return the address of the 2625 // next live word. Unless marked, the word corresponding to beg is assumed to 2626 // be dead. Callers must either ensure beg does not correspond to the middle of 2627 // an object, or account for those live words in some other way. Callers must 2628 // also ensure that there are enough live words in the range [beg, end) to skip. 2629 HeapWord* 2630 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count) 2631 { 2632 assert(count > 0, "sanity"); 2633 2634 ParMarkBitMap* m = mark_bitmap(); 2635 idx_t bits_to_skip = m->words_to_bits(count); 2636 idx_t cur_beg = m->addr_to_bit(beg); 2637 const idx_t search_end = m->align_range_end(m->addr_to_bit(end)); 2638 2639 do { 2640 cur_beg = m->find_obj_beg(cur_beg, search_end); 2641 idx_t cur_end = m->find_obj_end(cur_beg, search_end); 2642 const size_t obj_bits = cur_end - cur_beg + 1; 2643 if (obj_bits > bits_to_skip) { 2644 return m->bit_to_addr(cur_beg + bits_to_skip); 2645 } 2646 bits_to_skip -= obj_bits; 2647 cur_beg = cur_end + 1; 2648 } while (bits_to_skip > 0); 2649 2650 // Skipping the desired number of words landed just past the end of an object. 2651 // Find the start of the next object. 2652 cur_beg = m->find_obj_beg(cur_beg, search_end); 2653 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip"); 2654 return m->bit_to_addr(cur_beg); 2655 } 2656 2657 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr, 2658 SpaceId src_space_id, 2659 size_t src_region_idx) 2660 { 2661 assert(summary_data().is_region_aligned(dest_addr), "not aligned"); 2662 2663 const SplitInfo& split_info = _space_info[src_space_id].split_info(); 2664 if (split_info.dest_region_addr() == dest_addr) { 2665 // The partial object ending at the split point contains the first word to 2666 // be copied to dest_addr. 2667 return split_info.first_src_addr(); 2668 } 2669 2670 const ParallelCompactData& sd = summary_data(); 2671 ParMarkBitMap* const bitmap = mark_bitmap(); 2672 const size_t RegionSize = ParallelCompactData::RegionSize; 2673 2674 assert(sd.is_region_aligned(dest_addr), "not aligned"); 2675 const RegionData* const src_region_ptr = sd.region(src_region_idx); 2676 const size_t partial_obj_size = src_region_ptr->partial_obj_size(); 2677 HeapWord* const src_region_destination = src_region_ptr->destination(); 2678 2679 assert(dest_addr >= src_region_destination, "wrong src region"); 2680 assert(src_region_ptr->data_size() > 0, "src region cannot be empty"); 2681 2682 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx); 2683 HeapWord* const src_region_end = src_region_beg + RegionSize; 2684 2685 HeapWord* addr = src_region_beg; 2686 if (dest_addr == src_region_destination) { 2687 // Return the first live word in the source region. 2688 if (partial_obj_size == 0) { 2689 addr = bitmap->find_obj_beg(addr, src_region_end); 2690 assert(addr < src_region_end, "no objects start in src region"); 2691 } 2692 return addr; 2693 } 2694 2695 // Must skip some live data. 2696 size_t words_to_skip = dest_addr - src_region_destination; 2697 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region"); 2698 2699 if (partial_obj_size >= words_to_skip) { 2700 // All the live words to skip are part of the partial object. 2701 addr += words_to_skip; 2702 if (partial_obj_size == words_to_skip) { 2703 // Find the first live word past the partial object. 2704 addr = bitmap->find_obj_beg(addr, src_region_end); 2705 assert(addr < src_region_end, "wrong src region"); 2706 } 2707 return addr; 2708 } 2709 2710 // Skip over the partial object (if any). 2711 if (partial_obj_size != 0) { 2712 words_to_skip -= partial_obj_size; 2713 addr += partial_obj_size; 2714 } 2715 2716 // Skip over live words due to objects that start in the region. 2717 addr = skip_live_words(addr, src_region_end, words_to_skip); 2718 assert(addr < src_region_end, "wrong src region"); 2719 return addr; 2720 } 2721 2722 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, 2723 SpaceId src_space_id, 2724 size_t beg_region, 2725 HeapWord* end_addr) 2726 { 2727 ParallelCompactData& sd = summary_data(); 2728 2729 #ifdef ASSERT 2730 MutableSpace* const src_space = _space_info[src_space_id].space(); 2731 HeapWord* const beg_addr = sd.region_to_addr(beg_region); 2732 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(), 2733 "src_space_id does not match beg_addr"); 2734 assert(src_space->contains(end_addr) || end_addr == src_space->end(), 2735 "src_space_id does not match end_addr"); 2736 #endif // #ifdef ASSERT 2737 2738 RegionData* const beg = sd.region(beg_region); 2739 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr)); 2740 2741 // Regions up to new_top() are enqueued if they become available. 2742 HeapWord* const new_top = _space_info[src_space_id].new_top(); 2743 RegionData* const enqueue_end = 2744 sd.addr_to_region_ptr(sd.region_align_up(new_top)); 2745 2746 for (RegionData* cur = beg; cur < end; ++cur) { 2747 assert(cur->data_size() > 0, "region must have live data"); 2748 cur->decrement_destination_count(); 2749 if (cur < enqueue_end && cur->available() && cur->claim()) { 2750 if (cur->mark_normal()) { 2751 cm->push_region(sd.region(cur)); 2752 } else if (cur->mark_copied()) { 2753 // Try to copy the content of the shadow region back to its corresponding 2754 // heap region if the shadow region is filled. Otherwise, the GC thread 2755 // fills the shadow region will copy the data back (see 2756 // MoveAndUpdateShadowClosure::complete_region). 2757 copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur)); 2758 ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region()); 2759 cur->set_completed(); 2760 } 2761 } 2762 } 2763 } 2764 2765 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure, 2766 SpaceId& src_space_id, 2767 HeapWord*& src_space_top, 2768 HeapWord* end_addr) 2769 { 2770 typedef ParallelCompactData::RegionData RegionData; 2771 2772 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2773 const size_t region_size = ParallelCompactData::RegionSize; 2774 2775 size_t src_region_idx = 0; 2776 2777 // Skip empty regions (if any) up to the top of the space. 2778 HeapWord* const src_aligned_up = sd.region_align_up(end_addr); 2779 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up); 2780 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top); 2781 const RegionData* const top_region_ptr = 2782 sd.addr_to_region_ptr(top_aligned_up); 2783 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) { 2784 ++src_region_ptr; 2785 } 2786 2787 if (src_region_ptr < top_region_ptr) { 2788 // The next source region is in the current space. Update src_region_idx 2789 // and the source address to match src_region_ptr. 2790 src_region_idx = sd.region(src_region_ptr); 2791 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx); 2792 if (src_region_addr > closure.source()) { 2793 closure.set_source(src_region_addr); 2794 } 2795 return src_region_idx; 2796 } 2797 2798 // Switch to a new source space and find the first non-empty region. 2799 unsigned int space_id = src_space_id + 1; 2800 assert(space_id < last_space_id, "not enough spaces"); 2801 2802 HeapWord* const destination = closure.destination(); 2803 2804 do { 2805 MutableSpace* space = _space_info[space_id].space(); 2806 HeapWord* const bottom = space->bottom(); 2807 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom); 2808 2809 // Iterate over the spaces that do not compact into themselves. 2810 if (bottom_cp->destination() != bottom) { 2811 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 2812 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 2813 2814 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) { 2815 if (src_cp->live_obj_size() > 0) { 2816 // Found it. 2817 assert(src_cp->destination() == destination, 2818 "first live obj in the space must match the destination"); 2819 assert(src_cp->partial_obj_size() == 0, 2820 "a space cannot begin with a partial obj"); 2821 2822 src_space_id = SpaceId(space_id); 2823 src_space_top = space->top(); 2824 const size_t src_region_idx = sd.region(src_cp); 2825 closure.set_source(sd.region_to_addr(src_region_idx)); 2826 return src_region_idx; 2827 } else { 2828 assert(src_cp->data_size() == 0, "sanity"); 2829 } 2830 } 2831 } 2832 } while (++space_id < last_space_id); 2833 2834 assert(false, "no source region was found"); 2835 return 0; 2836 } 2837 2838 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx) 2839 { 2840 typedef ParMarkBitMap::IterationStatus IterationStatus; 2841 ParMarkBitMap* const bitmap = mark_bitmap(); 2842 ParallelCompactData& sd = summary_data(); 2843 RegionData* const region_ptr = sd.region(region_idx); 2844 2845 // Get the source region and related info. 2846 size_t src_region_idx = region_ptr->source_region(); 2847 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx)); 2848 HeapWord* src_space_top = _space_info[src_space_id].space()->top(); 2849 HeapWord* dest_addr = sd.region_to_addr(region_idx); 2850 2851 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx)); 2852 2853 // Adjust src_region_idx to prepare for decrementing destination counts (the 2854 // destination count is not decremented when a region is copied to itself). 2855 if (src_region_idx == region_idx) { 2856 src_region_idx += 1; 2857 } 2858 2859 if (bitmap->is_unmarked(closure.source())) { 2860 // The first source word is in the middle of an object; copy the remainder 2861 // of the object or as much as will fit. The fact that pointer updates were 2862 // deferred will be noted when the object header is processed. 2863 HeapWord* const old_src_addr = closure.source(); 2864 closure.copy_partial_obj(); 2865 if (closure.is_full()) { 2866 decrement_destination_counts(cm, src_space_id, src_region_idx, 2867 closure.source()); 2868 region_ptr->set_deferred_obj_addr(NULL); 2869 closure.complete_region(cm, dest_addr, region_ptr); 2870 return; 2871 } 2872 2873 HeapWord* const end_addr = sd.region_align_down(closure.source()); 2874 if (sd.region_align_down(old_src_addr) != end_addr) { 2875 // The partial object was copied from more than one source region. 2876 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2877 2878 // Move to the next source region, possibly switching spaces as well. All 2879 // args except end_addr may be modified. 2880 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2881 end_addr); 2882 } 2883 } 2884 2885 do { 2886 HeapWord* const cur_addr = closure.source(); 2887 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1), 2888 src_space_top); 2889 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr); 2890 2891 if (status == ParMarkBitMap::incomplete) { 2892 // The last obj that starts in the source region does not end in the 2893 // region. 2894 assert(closure.source() < end_addr, "sanity"); 2895 HeapWord* const obj_beg = closure.source(); 2896 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(), 2897 src_space_top); 2898 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end); 2899 if (obj_end < range_end) { 2900 // The end was found; the entire object will fit. 2901 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end)); 2902 assert(status != ParMarkBitMap::would_overflow, "sanity"); 2903 } else { 2904 // The end was not found; the object will not fit. 2905 assert(range_end < src_space_top, "obj cannot cross space boundary"); 2906 status = ParMarkBitMap::would_overflow; 2907 } 2908 } 2909 2910 if (status == ParMarkBitMap::would_overflow) { 2911 // The last object did not fit. Note that interior oop updates were 2912 // deferred, then copy enough of the object to fill the region. 2913 region_ptr->set_deferred_obj_addr(closure.destination()); 2914 status = closure.copy_until_full(); // copies from closure.source() 2915 2916 decrement_destination_counts(cm, src_space_id, src_region_idx, 2917 closure.source()); 2918 closure.complete_region(cm, dest_addr, region_ptr); 2919 return; 2920 } 2921 2922 if (status == ParMarkBitMap::full) { 2923 decrement_destination_counts(cm, src_space_id, src_region_idx, 2924 closure.source()); 2925 region_ptr->set_deferred_obj_addr(NULL); 2926 closure.complete_region(cm, dest_addr, region_ptr); 2927 return; 2928 } 2929 2930 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2931 2932 // Move to the next source region, possibly switching spaces as well. All 2933 // args except end_addr may be modified. 2934 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2935 end_addr); 2936 } while (true); 2937 } 2938 2939 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx) 2940 { 2941 MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx); 2942 fill_region(cm, cl, region_idx); 2943 } 2944 2945 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx) 2946 { 2947 // Get a shadow region first 2948 ParallelCompactData& sd = summary_data(); 2949 RegionData* const region_ptr = sd.region(region_idx); 2950 size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr); 2951 // The InvalidShadow return value indicates the corresponding heap region is available, 2952 // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use 2953 // MoveAndUpdateShadowClosure to fill the acquired shadow region. 2954 if (shadow_region == ParCompactionManager::InvalidShadow) { 2955 MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx); 2956 region_ptr->shadow_to_normal(); 2957 return fill_region(cm, cl, region_idx); 2958 } else { 2959 MoveAndUpdateShadowClosure cl(mark_bitmap(), cm, region_idx, shadow_region); 2960 return fill_region(cm, cl, region_idx); 2961 } 2962 } 2963 2964 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr) 2965 { 2966 Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize); 2967 } 2968 2969 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t ®ion_idx) 2970 { 2971 size_t next = cm->next_shadow_region(); 2972 ParallelCompactData& sd = summary_data(); 2973 size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top()); 2974 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers(); 2975 2976 while (next < old_new_top) { 2977 if (sd.region(next)->mark_shadow()) { 2978 region_idx = next; 2979 return true; 2980 } 2981 next = cm->move_next_shadow_region_by(active_gc_threads); 2982 } 2983 2984 return false; 2985 } 2986 2987 // The shadow region is an optimization to address region dependencies in full GC. The basic 2988 // idea is making more regions available by temporally storing their live objects in empty 2989 // shadow regions to resolve dependencies between them and the destination regions. Therefore, 2990 // GC threads need not wait destination regions to be available before processing sources. 2991 // 2992 // A typical workflow would be: 2993 // After draining its own stack and failing to steal from others, a GC worker would pick an 2994 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills 2995 // the shadow region by copying live objects from source regions of the unavailable one. Once 2996 // the unavailable region becomes available, the data in the shadow region will be copied back. 2997 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces. 2998 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads) 2999 { 3000 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 3001 3002 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 3003 SpaceInfo* const space_info = _space_info + id; 3004 MutableSpace* const space = space_info->space(); 3005 3006 const size_t beg_region = 3007 sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top()))); 3008 const size_t end_region = 3009 sd.addr_to_region_idx(sd.region_align_down(space->end())); 3010 3011 for (size_t cur = beg_region; cur < end_region; ++cur) { 3012 ParCompactionManager::push_shadow_region(cur); 3013 } 3014 } 3015 3016 size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix()); 3017 for (uint i = 0; i < parallel_gc_threads; i++) { 3018 ParCompactionManager *cm = ParCompactionManager::gc_thread_compaction_manager(i); 3019 cm->set_next_shadow_region(beg_region + i); 3020 } 3021 } 3022 3023 void PSParallelCompact::fill_blocks(size_t region_idx) 3024 { 3025 // Fill in the block table elements for the specified region. Each block 3026 // table element holds the number of live words in the region that are to the 3027 // left of the first object that starts in the block. Thus only blocks in 3028 // which an object starts need to be filled. 3029 // 3030 // The algorithm scans the section of the bitmap that corresponds to the 3031 // region, keeping a running total of the live words. When an object start is 3032 // found, if it's the first to start in the block that contains it, the 3033 // current total is written to the block table element. 3034 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize; 3035 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize; 3036 const size_t RegionSize = ParallelCompactData::RegionSize; 3037 3038 ParallelCompactData& sd = summary_data(); 3039 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size(); 3040 if (partial_obj_size >= RegionSize) { 3041 return; // No objects start in this region. 3042 } 3043 3044 // Ensure the first loop iteration decides that the block has changed. 3045 size_t cur_block = sd.block_count(); 3046 3047 const ParMarkBitMap* const bitmap = mark_bitmap(); 3048 3049 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment; 3050 assert((size_t)1 << Log2BitsPerBlock == 3051 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity"); 3052 3053 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize); 3054 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize); 3055 size_t live_bits = bitmap->words_to_bits(partial_obj_size); 3056 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end); 3057 while (beg_bit < range_end) { 3058 const size_t new_block = beg_bit >> Log2BitsPerBlock; 3059 if (new_block != cur_block) { 3060 cur_block = new_block; 3061 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits)); 3062 } 3063 3064 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end); 3065 if (end_bit < range_end - 1) { 3066 live_bits += end_bit - beg_bit + 1; 3067 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end); 3068 } else { 3069 return; 3070 } 3071 } 3072 } 3073 3074 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() 3075 { 3076 if (source() != copy_destination()) { 3077 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3078 Copy::aligned_conjoint_words(source(), copy_destination(), words_remaining()); 3079 } 3080 update_state(words_remaining()); 3081 assert(is_full(), "sanity"); 3082 return ParMarkBitMap::full; 3083 } 3084 3085 void MoveAndUpdateClosure::copy_partial_obj() 3086 { 3087 size_t words = words_remaining(); 3088 3089 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end()); 3090 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end); 3091 if (end_addr < range_end) { 3092 words = bitmap()->obj_size(source(), end_addr); 3093 } 3094 3095 // This test is necessary; if omitted, the pointer updates to a partial object 3096 // that crosses the dense prefix boundary could be overwritten. 3097 if (source() != copy_destination()) { 3098 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3099 Copy::aligned_conjoint_words(source(), copy_destination(), words); 3100 } 3101 update_state(words); 3102 } 3103 3104 void MoveAndUpdateClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr, 3105 PSParallelCompact::RegionData *region_ptr) { 3106 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished"); 3107 region_ptr->set_completed(); 3108 } 3109 3110 ParMarkBitMapClosure::IterationStatus 3111 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) { 3112 assert(destination() != NULL, "sanity"); 3113 assert(bitmap()->obj_size(addr) == words, "bad size"); 3114 3115 _source = addr; 3116 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) == 3117 destination(), "wrong destination"); 3118 3119 if (words > words_remaining()) { 3120 return ParMarkBitMap::would_overflow; 3121 } 3122 3123 // The start_array must be updated even if the object is not moving. 3124 if (_start_array != NULL) { 3125 _start_array->allocate_block(destination()); 3126 } 3127 3128 if (copy_destination() != source()) { 3129 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3130 Copy::aligned_conjoint_words(source(), copy_destination(), words); 3131 } 3132 3133 oop moved_oop = cast_to_oop(copy_destination()); 3134 compaction_manager()->update_contents(moved_oop); 3135 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop)); 3136 3137 update_state(words); 3138 assert(copy_destination() == cast_from_oop<HeapWord*>(moved_oop) + moved_oop->size(), "sanity"); 3139 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete; 3140 } 3141 3142 void MoveAndUpdateShadowClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr, 3143 PSParallelCompact::RegionData *region_ptr) { 3144 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow"); 3145 // Record the shadow region index 3146 region_ptr->set_shadow_region(_shadow); 3147 // Mark the shadow region as filled to indicate the data is ready to be 3148 // copied back 3149 region_ptr->mark_filled(); 3150 // Try to copy the content of the shadow region back to its corresponding 3151 // heap region if available; the GC thread that decreases the destination 3152 // count to zero will do the copying otherwise (see 3153 // PSParallelCompact::decrement_destination_counts). 3154 if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) { 3155 region_ptr->set_completed(); 3156 PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr); 3157 ParCompactionManager::push_shadow_region_mt_safe(_shadow); 3158 } 3159 } 3160 3161 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm, 3162 ParCompactionManager* cm, 3163 PSParallelCompact::SpaceId space_id) : 3164 ParMarkBitMapClosure(mbm, cm), 3165 _space_id(space_id), 3166 _start_array(PSParallelCompact::start_array(space_id)) 3167 { 3168 } 3169 3170 // Updates the references in the object to their new values. 3171 ParMarkBitMapClosure::IterationStatus 3172 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) { 3173 do_addr(addr); 3174 return ParMarkBitMap::incomplete; 3175 } 3176 3177 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : 3178 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), 3179 _start_array(PSParallelCompact::start_array(space_id)) 3180 { 3181 assert(space_id == PSParallelCompact::old_space_id, 3182 "cannot use FillClosure in the young gen"); 3183 } 3184 3185 ParMarkBitMapClosure::IterationStatus 3186 FillClosure::do_addr(HeapWord* addr, size_t size) { 3187 CollectedHeap::fill_with_objects(addr, size); 3188 HeapWord* const end = addr + size; 3189 do { 3190 _start_array->allocate_block(addr); 3191 addr += cast_to_oop(addr)->size(); 3192 } while (addr < end); 3193 return ParMarkBitMap::incomplete; 3194 }