1 /* 2 * Copyright (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "aot/aotLoader.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "code/codeCache.hpp" 31 #include "gc/parallel/gcTaskManager.hpp" 32 #include "gc/parallel/parallelScavengeHeap.inline.hpp" 33 #include "gc/parallel/parMarkBitMap.inline.hpp" 34 #include "gc/parallel/pcTasks.hpp" 35 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 36 #include "gc/parallel/psCompactionManager.inline.hpp" 37 #include "gc/parallel/psMarkSweep.hpp" 38 #include "gc/parallel/psMarkSweepDecorator.hpp" 39 #include "gc/parallel/psOldGen.hpp" 40 #include "gc/parallel/psParallelCompact.inline.hpp" 41 #include "gc/parallel/psPromotionManager.inline.hpp" 42 #include "gc/parallel/psScavenge.hpp" 43 #include "gc/parallel/psYoungGen.hpp" 44 #include "gc/shared/gcCause.hpp" 45 #include "gc/shared/gcHeapSummary.hpp" 46 #include "gc/shared/gcId.hpp" 47 #include "gc/shared/gcLocker.hpp" 48 #include "gc/shared/gcTimer.hpp" 49 #include "gc/shared/gcTrace.hpp" 50 #include "gc/shared/gcTraceTime.inline.hpp" 51 #include "gc/shared/isGCActiveMark.hpp" 52 #include "gc/shared/referencePolicy.hpp" 53 #include "gc/shared/referenceProcessor.hpp" 54 #include "gc/shared/spaceDecorator.hpp" 55 #include "gc/shared/weakProcessor.hpp" 56 #include "logging/log.hpp" 57 #include "memory/resourceArea.hpp" 58 #include "oops/access.inline.hpp" 59 #include "oops/instanceKlass.inline.hpp" 60 #include "oops/instanceMirrorKlass.inline.hpp" 61 #include "oops/methodData.hpp" 62 #include "oops/objArrayKlass.inline.hpp" 63 #include "oops/oop.inline.hpp" 64 #include "runtime/atomic.hpp" 65 #include "runtime/handles.inline.hpp" 66 #include "runtime/safepoint.hpp" 67 #include "runtime/vmThread.hpp" 68 #include "services/management.hpp" 69 #include "services/memTracker.hpp" 70 #include "services/memoryService.hpp" 71 #include "utilities/align.hpp" 72 #include "utilities/debug.hpp" 73 #include "utilities/events.hpp" 74 #include "utilities/formatBuffer.hpp" 75 #include "utilities/stack.inline.hpp" 76 77 #include <math.h> 78 79 // All sizes are in HeapWords. 80 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words 81 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize; 82 const size_t ParallelCompactData::RegionSizeBytes = 83 RegionSize << LogHeapWordSize; 84 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1; 85 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1; 86 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask; 87 88 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words 89 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize; 90 const size_t ParallelCompactData::BlockSizeBytes = 91 BlockSize << LogHeapWordSize; 92 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1; 93 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1; 94 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask; 95 96 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize; 97 const size_t ParallelCompactData::Log2BlocksPerRegion = 98 Log2RegionSize - Log2BlockSize; 99 100 const ParallelCompactData::RegionData::region_sz_t 101 ParallelCompactData::RegionData::dc_shift = 27; 102 103 const ParallelCompactData::RegionData::region_sz_t 104 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift; 105 106 const ParallelCompactData::RegionData::region_sz_t 107 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift; 108 109 const ParallelCompactData::RegionData::region_sz_t 110 ParallelCompactData::RegionData::los_mask = ~dc_mask; 111 112 const ParallelCompactData::RegionData::region_sz_t 113 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift; 114 115 const ParallelCompactData::RegionData::region_sz_t 116 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift; 117 118 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; 119 120 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; 121 122 double PSParallelCompact::_dwl_mean; 123 double PSParallelCompact::_dwl_std_dev; 124 double PSParallelCompact::_dwl_first_term; 125 double PSParallelCompact::_dwl_adjustment; 126 #ifdef ASSERT 127 bool PSParallelCompact::_dwl_initialized = false; 128 #endif // #ifdef ASSERT 129 130 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size, 131 HeapWord* destination) 132 { 133 assert(src_region_idx != 0, "invalid src_region_idx"); 134 assert(partial_obj_size != 0, "invalid partial_obj_size argument"); 135 assert(destination != NULL, "invalid destination argument"); 136 137 _src_region_idx = src_region_idx; 138 _partial_obj_size = partial_obj_size; 139 _destination = destination; 140 141 // These fields may not be updated below, so make sure they're clear. 142 assert(_dest_region_addr == NULL, "should have been cleared"); 143 assert(_first_src_addr == NULL, "should have been cleared"); 144 145 // Determine the number of destination regions for the partial object. 146 HeapWord* const last_word = destination + partial_obj_size - 1; 147 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 148 HeapWord* const beg_region_addr = sd.region_align_down(destination); 149 HeapWord* const end_region_addr = sd.region_align_down(last_word); 150 151 if (beg_region_addr == end_region_addr) { 152 // One destination region. 153 _destination_count = 1; 154 if (end_region_addr == destination) { 155 // The destination falls on a region boundary, thus the first word of the 156 // partial object will be the first word copied to the destination region. 157 _dest_region_addr = end_region_addr; 158 _first_src_addr = sd.region_to_addr(src_region_idx); 159 } 160 } else { 161 // Two destination regions. When copied, the partial object will cross a 162 // destination region boundary, so a word somewhere within the partial 163 // object will be the first word copied to the second destination region. 164 _destination_count = 2; 165 _dest_region_addr = end_region_addr; 166 const size_t ofs = pointer_delta(end_region_addr, destination); 167 assert(ofs < _partial_obj_size, "sanity"); 168 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs; 169 } 170 } 171 172 void SplitInfo::clear() 173 { 174 _src_region_idx = 0; 175 _partial_obj_size = 0; 176 _destination = NULL; 177 _destination_count = 0; 178 _dest_region_addr = NULL; 179 _first_src_addr = NULL; 180 assert(!is_valid(), "sanity"); 181 } 182 183 #ifdef ASSERT 184 void SplitInfo::verify_clear() 185 { 186 assert(_src_region_idx == 0, "not clear"); 187 assert(_partial_obj_size == 0, "not clear"); 188 assert(_destination == NULL, "not clear"); 189 assert(_destination_count == 0, "not clear"); 190 assert(_dest_region_addr == NULL, "not clear"); 191 assert(_first_src_addr == NULL, "not clear"); 192 } 193 #endif // #ifdef ASSERT 194 195 196 void PSParallelCompact::print_on_error(outputStream* st) { 197 _mark_bitmap.print_on_error(st); 198 } 199 200 #ifndef PRODUCT 201 const char* PSParallelCompact::space_names[] = { 202 "old ", "eden", "from", "to " 203 }; 204 205 void PSParallelCompact::print_region_ranges() { 206 if (!log_develop_is_enabled(Trace, gc, compaction)) { 207 return; 208 } 209 Log(gc, compaction) log; 210 ResourceMark rm; 211 LogStream ls(log.trace()); 212 Universe::print_on(&ls); 213 log.trace("space bottom top end new_top"); 214 log.trace("------ ---------- ---------- ---------- ----------"); 215 216 for (unsigned int id = 0; id < last_space_id; ++id) { 217 const MutableSpace* space = _space_info[id].space(); 218 log.trace("%u %s " 219 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " 220 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", 221 id, space_names[id], 222 summary_data().addr_to_region_idx(space->bottom()), 223 summary_data().addr_to_region_idx(space->top()), 224 summary_data().addr_to_region_idx(space->end()), 225 summary_data().addr_to_region_idx(_space_info[id].new_top())); 226 } 227 } 228 229 void 230 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c) 231 { 232 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7) 233 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5) 234 235 ParallelCompactData& sd = PSParallelCompact::summary_data(); 236 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0; 237 log_develop_trace(gc, compaction)( 238 REGION_IDX_FORMAT " " PTR_FORMAT " " 239 REGION_IDX_FORMAT " " PTR_FORMAT " " 240 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " " 241 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d", 242 i, p2i(c->data_location()), dci, p2i(c->destination()), 243 c->partial_obj_size(), c->live_obj_size(), 244 c->data_size(), c->source_region(), c->destination_count()); 245 246 #undef REGION_IDX_FORMAT 247 #undef REGION_DATA_FORMAT 248 } 249 250 void 251 print_generic_summary_data(ParallelCompactData& summary_data, 252 HeapWord* const beg_addr, 253 HeapWord* const end_addr) 254 { 255 size_t total_words = 0; 256 size_t i = summary_data.addr_to_region_idx(beg_addr); 257 const size_t last = summary_data.addr_to_region_idx(end_addr); 258 HeapWord* pdest = 0; 259 260 while (i < last) { 261 ParallelCompactData::RegionData* c = summary_data.region(i); 262 if (c->data_size() != 0 || c->destination() != pdest) { 263 print_generic_summary_region(i, c); 264 total_words += c->data_size(); 265 pdest = c->destination(); 266 } 267 ++i; 268 } 269 270 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); 271 } 272 273 void 274 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data, 275 HeapWord* const beg_addr, 276 HeapWord* const end_addr) { 277 ::print_generic_summary_data(summary_data,beg_addr, end_addr); 278 } 279 280 void 281 print_generic_summary_data(ParallelCompactData& summary_data, 282 SpaceInfo* space_info) 283 { 284 if (!log_develop_is_enabled(Trace, gc, compaction)) { 285 return; 286 } 287 288 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { 289 const MutableSpace* space = space_info[id].space(); 290 print_generic_summary_data(summary_data, space->bottom(), 291 MAX2(space->top(), space_info[id].new_top())); 292 } 293 } 294 295 void 296 print_initial_summary_data(ParallelCompactData& summary_data, 297 const MutableSpace* space) { 298 if (space->top() == space->bottom()) { 299 return; 300 } 301 302 const size_t region_size = ParallelCompactData::RegionSize; 303 typedef ParallelCompactData::RegionData RegionData; 304 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top()); 305 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up); 306 const RegionData* c = summary_data.region(end_region - 1); 307 HeapWord* end_addr = c->destination() + c->data_size(); 308 const size_t live_in_space = pointer_delta(end_addr, space->bottom()); 309 310 // Print (and count) the full regions at the beginning of the space. 311 size_t full_region_count = 0; 312 size_t i = summary_data.addr_to_region_idx(space->bottom()); 313 while (i < end_region && summary_data.region(i)->data_size() == region_size) { 314 ParallelCompactData::RegionData* c = summary_data.region(i); 315 log_develop_trace(gc, compaction)( 316 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 317 i, p2i(c->destination()), 318 c->partial_obj_size(), c->live_obj_size(), 319 c->data_size(), c->source_region(), c->destination_count()); 320 ++full_region_count; 321 ++i; 322 } 323 324 size_t live_to_right = live_in_space - full_region_count * region_size; 325 326 double max_reclaimed_ratio = 0.0; 327 size_t max_reclaimed_ratio_region = 0; 328 size_t max_dead_to_right = 0; 329 size_t max_live_to_right = 0; 330 331 // Print the 'reclaimed ratio' for regions while there is something live in 332 // the region or to the right of it. The remaining regions are empty (and 333 // uninteresting), and computing the ratio will result in division by 0. 334 while (i < end_region && live_to_right > 0) { 335 c = summary_data.region(i); 336 HeapWord* const region_addr = summary_data.region_to_addr(i); 337 const size_t used_to_right = pointer_delta(space->top(), region_addr); 338 const size_t dead_to_right = used_to_right - live_to_right; 339 const double reclaimed_ratio = double(dead_to_right) / live_to_right; 340 341 if (reclaimed_ratio > max_reclaimed_ratio) { 342 max_reclaimed_ratio = reclaimed_ratio; 343 max_reclaimed_ratio_region = i; 344 max_dead_to_right = dead_to_right; 345 max_live_to_right = live_to_right; 346 } 347 348 ParallelCompactData::RegionData* c = summary_data.region(i); 349 log_develop_trace(gc, compaction)( 350 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d" 351 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), 352 i, p2i(c->destination()), 353 c->partial_obj_size(), c->live_obj_size(), 354 c->data_size(), c->source_region(), c->destination_count(), 355 reclaimed_ratio, dead_to_right, live_to_right); 356 357 358 live_to_right -= c->data_size(); 359 ++i; 360 } 361 362 // Any remaining regions are empty. Print one more if there is one. 363 if (i < end_region) { 364 ParallelCompactData::RegionData* c = summary_data.region(i); 365 log_develop_trace(gc, compaction)( 366 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 367 i, p2i(c->destination()), 368 c->partial_obj_size(), c->live_obj_size(), 369 c->data_size(), c->source_region(), c->destination_count()); 370 } 371 372 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", 373 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio); 374 } 375 376 void 377 print_initial_summary_data(ParallelCompactData& summary_data, 378 SpaceInfo* space_info) { 379 if (!log_develop_is_enabled(Trace, gc, compaction)) { 380 return; 381 } 382 383 unsigned int id = PSParallelCompact::old_space_id; 384 const MutableSpace* space; 385 do { 386 space = space_info[id].space(); 387 print_initial_summary_data(summary_data, space); 388 } while (++id < PSParallelCompact::eden_space_id); 389 390 do { 391 space = space_info[id].space(); 392 print_generic_summary_data(summary_data, space->bottom(), space->top()); 393 } while (++id < PSParallelCompact::last_space_id); 394 } 395 #endif // #ifndef PRODUCT 396 397 #ifdef ASSERT 398 size_t add_obj_count; 399 size_t add_obj_size; 400 size_t mark_bitmap_count; 401 size_t mark_bitmap_size; 402 #endif // #ifdef ASSERT 403 404 ParallelCompactData::ParallelCompactData() 405 { 406 _region_start = 0; 407 408 _region_vspace = 0; 409 _reserved_byte_size = 0; 410 _region_data = 0; 411 _region_count = 0; 412 413 _block_vspace = 0; 414 _block_data = 0; 415 _block_count = 0; 416 } 417 418 bool ParallelCompactData::initialize(MemRegion covered_region) 419 { 420 _region_start = covered_region.start(); 421 const size_t region_size = covered_region.word_size(); 422 DEBUG_ONLY(_region_end = _region_start + region_size;) 423 424 assert(region_align_down(_region_start) == _region_start, 425 "region start not aligned"); 426 assert((region_size & RegionSizeOffsetMask) == 0, 427 "region size not a multiple of RegionSize"); 428 429 bool result = initialize_region_data(region_size) && initialize_block_data(); 430 return result; 431 } 432 433 PSVirtualSpace* 434 ParallelCompactData::create_vspace(size_t count, size_t element_size) 435 { 436 const size_t raw_bytes = count * element_size; 437 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10); 438 const size_t granularity = os::vm_allocation_granularity(); 439 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity)); 440 441 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : 442 MAX2(page_sz, granularity); 443 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0); 444 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(), 445 rs.size()); 446 447 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 448 449 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); 450 if (vspace != 0) { 451 if (vspace->expand_by(_reserved_byte_size)) { 452 return vspace; 453 } 454 delete vspace; 455 // Release memory reserved in the space. 456 rs.release(); 457 } 458 459 return 0; 460 } 461 462 bool ParallelCompactData::initialize_region_data(size_t region_size) 463 { 464 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize; 465 _region_vspace = create_vspace(count, sizeof(RegionData)); 466 if (_region_vspace != 0) { 467 _region_data = (RegionData*)_region_vspace->reserved_low_addr(); 468 _region_count = count; 469 return true; 470 } 471 return false; 472 } 473 474 bool ParallelCompactData::initialize_block_data() 475 { 476 assert(_region_count != 0, "region data must be initialized first"); 477 const size_t count = _region_count << Log2BlocksPerRegion; 478 _block_vspace = create_vspace(count, sizeof(BlockData)); 479 if (_block_vspace != 0) { 480 _block_data = (BlockData*)_block_vspace->reserved_low_addr(); 481 _block_count = count; 482 return true; 483 } 484 return false; 485 } 486 487 void ParallelCompactData::clear() 488 { 489 memset(_region_data, 0, _region_vspace->committed_size()); 490 memset(_block_data, 0, _block_vspace->committed_size()); 491 } 492 493 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) { 494 assert(beg_region <= _region_count, "beg_region out of range"); 495 assert(end_region <= _region_count, "end_region out of range"); 496 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize"); 497 498 const size_t region_cnt = end_region - beg_region; 499 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData)); 500 501 const size_t beg_block = beg_region * BlocksPerRegion; 502 const size_t block_cnt = region_cnt * BlocksPerRegion; 503 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData)); 504 } 505 506 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const 507 { 508 const RegionData* cur_cp = region(region_idx); 509 const RegionData* const end_cp = region(region_count() - 1); 510 511 HeapWord* result = region_to_addr(region_idx); 512 if (cur_cp < end_cp) { 513 do { 514 result += cur_cp->partial_obj_size(); 515 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp); 516 } 517 return result; 518 } 519 520 void ParallelCompactData::add_obj(HeapWord* addr, size_t len) 521 { 522 const size_t obj_ofs = pointer_delta(addr, _region_start); 523 const size_t beg_region = obj_ofs >> Log2RegionSize; 524 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize; 525 526 DEBUG_ONLY(Atomic::inc(&add_obj_count);) 527 DEBUG_ONLY(Atomic::add(len, &add_obj_size);) 528 529 if (beg_region == end_region) { 530 // All in one region. 531 _region_data[beg_region].add_live_obj(len); 532 return; 533 } 534 535 // First region. 536 const size_t beg_ofs = region_offset(addr); 537 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs); 538 539 Klass* klass = ((oop)addr)->klass(); 540 // Middle regions--completely spanned by this object. 541 for (size_t region = beg_region + 1; region < end_region; ++region) { 542 _region_data[region].set_partial_obj_size(RegionSize); 543 _region_data[region].set_partial_obj_addr(addr); 544 } 545 546 // Last region. 547 const size_t end_ofs = region_offset(addr + len - 1); 548 _region_data[end_region].set_partial_obj_size(end_ofs + 1); 549 _region_data[end_region].set_partial_obj_addr(addr); 550 } 551 552 void 553 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) 554 { 555 assert(region_offset(beg) == 0, "not RegionSize aligned"); 556 assert(region_offset(end) == 0, "not RegionSize aligned"); 557 558 size_t cur_region = addr_to_region_idx(beg); 559 const size_t end_region = addr_to_region_idx(end); 560 HeapWord* addr = beg; 561 while (cur_region < end_region) { 562 _region_data[cur_region].set_destination(addr); 563 _region_data[cur_region].set_destination_count(0); 564 _region_data[cur_region].set_source_region(cur_region); 565 _region_data[cur_region].set_data_location(addr); 566 567 // Update live_obj_size so the region appears completely full. 568 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size(); 569 _region_data[cur_region].set_live_obj_size(live_size); 570 571 ++cur_region; 572 addr += RegionSize; 573 } 574 } 575 576 // Find the point at which a space can be split and, if necessary, record the 577 // split point. 578 // 579 // If the current src region (which overflowed the destination space) doesn't 580 // have a partial object, the split point is at the beginning of the current src 581 // region (an "easy" split, no extra bookkeeping required). 582 // 583 // If the current src region has a partial object, the split point is in the 584 // region where that partial object starts (call it the split_region). If 585 // split_region has a partial object, then the split point is just after that 586 // partial object (a "hard" split where we have to record the split data and 587 // zero the partial_obj_size field). With a "hard" split, we know that the 588 // partial_obj ends within split_region because the partial object that caused 589 // the overflow starts in split_region. If split_region doesn't have a partial 590 // obj, then the split is at the beginning of split_region (another "easy" 591 // split). 592 HeapWord* 593 ParallelCompactData::summarize_split_space(size_t src_region, 594 SplitInfo& split_info, 595 HeapWord* destination, 596 HeapWord* target_end, 597 HeapWord** target_next) 598 { 599 assert(destination <= target_end, "sanity"); 600 assert(destination + _region_data[src_region].data_size() > target_end, 601 "region should not fit into target space"); 602 assert(is_region_aligned(target_end), "sanity"); 603 604 size_t split_region = src_region; 605 HeapWord* split_destination = destination; 606 size_t partial_obj_size = _region_data[src_region].partial_obj_size(); 607 608 if (destination + partial_obj_size > target_end) { 609 // The split point is just after the partial object (if any) in the 610 // src_region that contains the start of the object that overflowed the 611 // destination space. 612 // 613 // Find the start of the "overflow" object and set split_region to the 614 // region containing it. 615 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr(); 616 split_region = addr_to_region_idx(overflow_obj); 617 618 // Clear the source_region field of all destination regions whose first word 619 // came from data after the split point (a non-null source_region field 620 // implies a region must be filled). 621 // 622 // An alternative to the simple loop below: clear during post_compact(), 623 // which uses memcpy instead of individual stores, and is easy to 624 // parallelize. (The downside is that it clears the entire RegionData 625 // object as opposed to just one field.) 626 // 627 // post_compact() would have to clear the summary data up to the highest 628 // address that was written during the summary phase, which would be 629 // 630 // max(top, max(new_top, clear_top)) 631 // 632 // where clear_top is a new field in SpaceInfo. Would have to set clear_top 633 // to target_end. 634 const RegionData* const sr = region(split_region); 635 const size_t beg_idx = 636 addr_to_region_idx(region_align_up(sr->destination() + 637 sr->partial_obj_size())); 638 const size_t end_idx = addr_to_region_idx(target_end); 639 640 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx); 641 for (size_t idx = beg_idx; idx < end_idx; ++idx) { 642 _region_data[idx].set_source_region(0); 643 } 644 645 // Set split_destination and partial_obj_size to reflect the split region. 646 split_destination = sr->destination(); 647 partial_obj_size = sr->partial_obj_size(); 648 } 649 650 // The split is recorded only if a partial object extends onto the region. 651 if (partial_obj_size != 0) { 652 _region_data[split_region].set_partial_obj_size(0); 653 split_info.record(split_region, partial_obj_size, split_destination); 654 } 655 656 // Setup the continuation addresses. 657 *target_next = split_destination + partial_obj_size; 658 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size; 659 660 if (log_develop_is_enabled(Trace, gc, compaction)) { 661 const char * split_type = partial_obj_size == 0 ? "easy" : "hard"; 662 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT, 663 split_type, p2i(source_next), split_region, partial_obj_size); 664 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT, 665 split_type, p2i(split_destination), 666 addr_to_region_idx(split_destination), 667 p2i(*target_next)); 668 669 if (partial_obj_size != 0) { 670 HeapWord* const po_beg = split_info.destination(); 671 HeapWord* const po_end = po_beg + split_info.partial_obj_size(); 672 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT, 673 split_type, 674 p2i(po_beg), addr_to_region_idx(po_beg), 675 p2i(po_end), addr_to_region_idx(po_end)); 676 } 677 } 678 679 return source_next; 680 } 681 682 bool ParallelCompactData::summarize(SplitInfo& split_info, 683 HeapWord* source_beg, HeapWord* source_end, 684 HeapWord** source_next, 685 HeapWord* target_beg, HeapWord* target_end, 686 HeapWord** target_next) 687 { 688 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next; 689 log_develop_trace(gc, compaction)( 690 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT 691 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT, 692 p2i(source_beg), p2i(source_end), p2i(source_next_val), 693 p2i(target_beg), p2i(target_end), p2i(*target_next)); 694 695 size_t cur_region = addr_to_region_idx(source_beg); 696 const size_t end_region = addr_to_region_idx(region_align_up(source_end)); 697 698 HeapWord *dest_addr = target_beg; 699 while (cur_region < end_region) { 700 // The destination must be set even if the region has no data. 701 _region_data[cur_region].set_destination(dest_addr); 702 703 size_t words = _region_data[cur_region].data_size(); 704 if (words > 0) { 705 // If cur_region does not fit entirely into the target space, find a point 706 // at which the source space can be 'split' so that part is copied to the 707 // target space and the rest is copied elsewhere. 708 if (dest_addr + words > target_end) { 709 assert(source_next != NULL, "source_next is NULL when splitting"); 710 *source_next = summarize_split_space(cur_region, split_info, dest_addr, 711 target_end, target_next); 712 return false; 713 } 714 715 // Compute the destination_count for cur_region, and if necessary, update 716 // source_region for a destination region. The source_region field is 717 // updated if cur_region is the first (left-most) region to be copied to a 718 // destination region. 719 // 720 // The destination_count calculation is a bit subtle. A region that has 721 // data that compacts into itself does not count itself as a destination. 722 // This maintains the invariant that a zero count means the region is 723 // available and can be claimed and then filled. 724 uint destination_count = 0; 725 if (split_info.is_split(cur_region)) { 726 // The current region has been split: the partial object will be copied 727 // to one destination space and the remaining data will be copied to 728 // another destination space. Adjust the initial destination_count and, 729 // if necessary, set the source_region field if the partial object will 730 // cross a destination region boundary. 731 destination_count = split_info.destination_count(); 732 if (destination_count == 2) { 733 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr()); 734 _region_data[dest_idx].set_source_region(cur_region); 735 } 736 } 737 738 HeapWord* const last_addr = dest_addr + words - 1; 739 const size_t dest_region_1 = addr_to_region_idx(dest_addr); 740 const size_t dest_region_2 = addr_to_region_idx(last_addr); 741 742 // Initially assume that the destination regions will be the same and 743 // adjust the value below if necessary. Under this assumption, if 744 // cur_region == dest_region_2, then cur_region will be compacted 745 // completely into itself. 746 destination_count += cur_region == dest_region_2 ? 0 : 1; 747 if (dest_region_1 != dest_region_2) { 748 // Destination regions differ; adjust destination_count. 749 destination_count += 1; 750 // Data from cur_region will be copied to the start of dest_region_2. 751 _region_data[dest_region_2].set_source_region(cur_region); 752 } else if (region_offset(dest_addr) == 0) { 753 // Data from cur_region will be copied to the start of the destination 754 // region. 755 _region_data[dest_region_1].set_source_region(cur_region); 756 } 757 758 _region_data[cur_region].set_destination_count(destination_count); 759 _region_data[cur_region].set_data_location(region_to_addr(cur_region)); 760 dest_addr += words; 761 } 762 763 ++cur_region; 764 } 765 766 *target_next = dest_addr; 767 return true; 768 } 769 770 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) { 771 assert(addr != NULL, "Should detect NULL oop earlier"); 772 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap"); 773 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked"); 774 775 // Region covering the object. 776 RegionData* const region_ptr = addr_to_region_ptr(addr); 777 HeapWord* result = region_ptr->destination(); 778 779 // If the entire Region is live, the new location is region->destination + the 780 // offset of the object within in the Region. 781 782 // Run some performance tests to determine if this special case pays off. It 783 // is worth it for pointers into the dense prefix. If the optimization to 784 // avoid pointer updates in regions that only point to the dense prefix is 785 // ever implemented, this should be revisited. 786 if (region_ptr->data_size() == RegionSize) { 787 result += region_offset(addr); 788 return result; 789 } 790 791 // Otherwise, the new location is region->destination + block offset + the 792 // number of live words in the Block that are (a) to the left of addr and (b) 793 // due to objects that start in the Block. 794 795 // Fill in the block table if necessary. This is unsynchronized, so multiple 796 // threads may fill the block table for a region (harmless, since it is 797 // idempotent). 798 if (!region_ptr->blocks_filled()) { 799 PSParallelCompact::fill_blocks(addr_to_region_idx(addr)); 800 region_ptr->set_blocks_filled(); 801 } 802 803 HeapWord* const search_start = block_align_down(addr); 804 const size_t block_offset = addr_to_block_ptr(addr)->offset(); 805 806 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); 807 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr)); 808 result += block_offset + live; 809 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result)); 810 return result; 811 } 812 813 #ifdef ASSERT 814 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) 815 { 816 const size_t* const beg = (const size_t*)vspace->committed_low_addr(); 817 const size_t* const end = (const size_t*)vspace->committed_high_addr(); 818 for (const size_t* p = beg; p < end; ++p) { 819 assert(*p == 0, "not zero"); 820 } 821 } 822 823 void ParallelCompactData::verify_clear() 824 { 825 verify_clear(_region_vspace); 826 verify_clear(_block_vspace); 827 } 828 #endif // #ifdef ASSERT 829 830 STWGCTimer PSParallelCompact::_gc_timer; 831 ParallelOldTracer PSParallelCompact::_gc_tracer; 832 elapsedTimer PSParallelCompact::_accumulated_time; 833 unsigned int PSParallelCompact::_total_invocations = 0; 834 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; 835 jlong PSParallelCompact::_time_of_last_gc = 0; 836 CollectorCounters* PSParallelCompact::_counters = NULL; 837 ParMarkBitMap PSParallelCompact::_mark_bitmap; 838 ParallelCompactData PSParallelCompact::_summary_data; 839 840 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; 841 842 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } 843 844 void PSParallelCompact::post_initialize() { 845 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 846 MemRegion mr = heap->reserved_region(); 847 _ref_processor = 848 new SpanReferenceProcessor(mr, // span 849 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 850 ParallelGCThreads, // mt processing degree 851 true, // mt discovery 852 ParallelGCThreads, // mt discovery degree 853 true, // atomic_discovery 854 &_is_alive_closure); // non-header is alive closure 855 _counters = new CollectorCounters("PSParallelCompact", 1); 856 857 // Initialize static fields in ParCompactionManager. 858 ParCompactionManager::initialize(mark_bitmap()); 859 } 860 861 bool PSParallelCompact::initialize() { 862 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 863 MemRegion mr = heap->reserved_region(); 864 865 // Was the old gen get allocated successfully? 866 if (!heap->old_gen()->is_allocated()) { 867 return false; 868 } 869 870 initialize_space_info(); 871 initialize_dead_wood_limiter(); 872 873 if (!_mark_bitmap.initialize(mr)) { 874 vm_shutdown_during_initialization( 875 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel " 876 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 877 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K)); 878 return false; 879 } 880 881 if (!_summary_data.initialize(mr)) { 882 vm_shutdown_during_initialization( 883 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel " 884 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 885 _summary_data.reserved_byte_size()/K, mr.byte_size()/K)); 886 return false; 887 } 888 889 return true; 890 } 891 892 void PSParallelCompact::initialize_space_info() 893 { 894 memset(&_space_info, 0, sizeof(_space_info)); 895 896 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 897 PSYoungGen* young_gen = heap->young_gen(); 898 899 _space_info[old_space_id].set_space(heap->old_gen()->object_space()); 900 _space_info[eden_space_id].set_space(young_gen->eden_space()); 901 _space_info[from_space_id].set_space(young_gen->from_space()); 902 _space_info[to_space_id].set_space(young_gen->to_space()); 903 904 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); 905 } 906 907 void PSParallelCompact::initialize_dead_wood_limiter() 908 { 909 const size_t max = 100; 910 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; 911 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; 912 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); 913 DEBUG_ONLY(_dwl_initialized = true;) 914 _dwl_adjustment = normal_distribution(1.0); 915 } 916 917 void 918 PSParallelCompact::clear_data_covering_space(SpaceId id) 919 { 920 // At this point, top is the value before GC, new_top() is the value that will 921 // be set at the end of GC. The marking bitmap is cleared to top; nothing 922 // should be marked above top. The summary data is cleared to the larger of 923 // top & new_top. 924 MutableSpace* const space = _space_info[id].space(); 925 HeapWord* const bot = space->bottom(); 926 HeapWord* const top = space->top(); 927 HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); 928 929 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); 930 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top)); 931 _mark_bitmap.clear_range(beg_bit, end_bit); 932 933 const size_t beg_region = _summary_data.addr_to_region_idx(bot); 934 const size_t end_region = 935 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top)); 936 _summary_data.clear_range(beg_region, end_region); 937 938 // Clear the data used to 'split' regions. 939 SplitInfo& split_info = _space_info[id].split_info(); 940 if (split_info.is_valid()) { 941 split_info.clear(); 942 } 943 DEBUG_ONLY(split_info.verify_clear();) 944 } 945 946 void PSParallelCompact::pre_compact() 947 { 948 // Update the from & to space pointers in space_info, since they are swapped 949 // at each young gen gc. Do the update unconditionally (even though a 950 // promotion failure does not swap spaces) because an unknown number of young 951 // collections will have swapped the spaces an unknown number of times. 952 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer); 953 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 954 _space_info[from_space_id].set_space(heap->young_gen()->from_space()); 955 _space_info[to_space_id].set_space(heap->young_gen()->to_space()); 956 957 DEBUG_ONLY(add_obj_count = add_obj_size = 0;) 958 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;) 959 960 // Increment the invocation count 961 heap->increment_total_collections(true); 962 963 // We need to track unique mark sweep invocations as well. 964 _total_invocations++; 965 966 heap->print_heap_before_gc(); 967 heap->trace_heap_before_gc(&_gc_tracer); 968 969 // Fill in TLABs 970 heap->accumulate_statistics_all_tlabs(); 971 heap->ensure_parsability(true); // retire TLABs 972 973 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 974 HandleMark hm; // Discard invalid handles created during verification 975 Universe::verify("Before GC"); 976 } 977 978 // Verify object start arrays 979 if (VerifyObjectStartArray && 980 VerifyBeforeGC) { 981 heap->old_gen()->verify_object_start_array(); 982 } 983 984 DEBUG_ONLY(mark_bitmap()->verify_clear();) 985 DEBUG_ONLY(summary_data().verify_clear();) 986 987 // Have worker threads release resources the next time they run a task. 988 gc_task_manager()->release_all_resources(); 989 990 ParCompactionManager::reset_all_bitmap_query_caches(); 991 } 992 993 void PSParallelCompact::post_compact() 994 { 995 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer); 996 997 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 998 // Clear the marking bitmap, summary data and split info. 999 clear_data_covering_space(SpaceId(id)); 1000 // Update top(). Must be done after clearing the bitmap and summary data. 1001 _space_info[id].publish_new_top(); 1002 } 1003 1004 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1005 MutableSpace* const from_space = _space_info[from_space_id].space(); 1006 MutableSpace* const to_space = _space_info[to_space_id].space(); 1007 1008 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1009 bool eden_empty = eden_space->is_empty(); 1010 if (!eden_empty) { 1011 eden_empty = absorb_live_data_from_eden(heap->size_policy(), 1012 heap->young_gen(), heap->old_gen()); 1013 } 1014 1015 // Update heap occupancy information which is used as input to the soft ref 1016 // clearing policy at the next gc. 1017 Universe::update_heap_info_at_gc(); 1018 1019 bool young_gen_empty = eden_empty && from_space->is_empty() && 1020 to_space->is_empty(); 1021 1022 PSCardTable* ct = heap->card_table(); 1023 MemRegion old_mr = heap->old_gen()->reserved(); 1024 if (young_gen_empty) { 1025 ct->clear(MemRegion(old_mr.start(), old_mr.end())); 1026 } else { 1027 ct->invalidate(MemRegion(old_mr.start(), old_mr.end())); 1028 } 1029 1030 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1031 ClassLoaderDataGraph::purge(); 1032 MetaspaceUtils::verify_metrics(); 1033 1034 CodeCache::gc_epilogue(); 1035 JvmtiExport::gc_epilogue(); 1036 1037 #if COMPILER2_OR_JVMCI 1038 DerivedPointerTable::update_pointers(); 1039 #endif 1040 1041 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->num_queues()); 1042 1043 ref_processor()->enqueue_discovered_references(NULL, &pt); 1044 1045 pt.print_enqueue_phase(); 1046 1047 if (ZapUnusedHeapArea) { 1048 heap->gen_mangle_unused_area(); 1049 } 1050 1051 // Update time of last GC 1052 reset_millis_since_last_gc(); 1053 } 1054 1055 HeapWord* 1056 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, 1057 bool maximum_compaction) 1058 { 1059 const size_t region_size = ParallelCompactData::RegionSize; 1060 const ParallelCompactData& sd = summary_data(); 1061 1062 const MutableSpace* const space = _space_info[id].space(); 1063 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 1064 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom()); 1065 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up); 1066 1067 // Skip full regions at the beginning of the space--they are necessarily part 1068 // of the dense prefix. 1069 size_t full_count = 0; 1070 const RegionData* cp; 1071 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) { 1072 ++full_count; 1073 } 1074 1075 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1076 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1077 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; 1078 if (maximum_compaction || cp == end_cp || interval_ended) { 1079 _maximum_compaction_gc_num = total_invocations(); 1080 return sd.region_to_addr(cp); 1081 } 1082 1083 HeapWord* const new_top = _space_info[id].new_top(); 1084 const size_t space_live = pointer_delta(new_top, space->bottom()); 1085 const size_t space_used = space->used_in_words(); 1086 const size_t space_capacity = space->capacity_in_words(); 1087 1088 const double cur_density = double(space_live) / space_capacity; 1089 const double deadwood_density = 1090 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; 1091 const size_t deadwood_goal = size_t(space_capacity * deadwood_density); 1092 1093 if (TraceParallelOldGCDensePrefix) { 1094 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, 1095 cur_density, deadwood_density, deadwood_goal); 1096 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1097 "space_cap=" SIZE_FORMAT, 1098 space_live, space_used, 1099 space_capacity); 1100 } 1101 1102 // XXX - Use binary search? 1103 HeapWord* dense_prefix = sd.region_to_addr(cp); 1104 const RegionData* full_cp = cp; 1105 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1); 1106 while (cp < end_cp) { 1107 HeapWord* region_destination = cp->destination(); 1108 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination); 1109 if (TraceParallelOldGCDensePrefix && Verbose) { 1110 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " 1111 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8), 1112 sd.region(cp), p2i(region_destination), 1113 p2i(dense_prefix), cur_deadwood); 1114 } 1115 1116 if (cur_deadwood >= deadwood_goal) { 1117 // Found the region that has the correct amount of deadwood to the left. 1118 // This typically occurs after crossing a fairly sparse set of regions, so 1119 // iterate backwards over those sparse regions, looking for the region 1120 // that has the lowest density of live objects 'to the right.' 1121 size_t space_to_left = sd.region(cp) * region_size; 1122 size_t live_to_left = space_to_left - cur_deadwood; 1123 size_t space_to_right = space_capacity - space_to_left; 1124 size_t live_to_right = space_live - live_to_left; 1125 double density_to_right = double(live_to_right) / space_to_right; 1126 while (cp > full_cp) { 1127 --cp; 1128 const size_t prev_region_live_to_right = live_to_right - 1129 cp->data_size(); 1130 const size_t prev_region_space_to_right = space_to_right + region_size; 1131 double prev_region_density_to_right = 1132 double(prev_region_live_to_right) / prev_region_space_to_right; 1133 if (density_to_right <= prev_region_density_to_right) { 1134 return dense_prefix; 1135 } 1136 if (TraceParallelOldGCDensePrefix && Verbose) { 1137 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " 1138 "pc_d2r=%10.8f", sd.region(cp), density_to_right, 1139 prev_region_density_to_right); 1140 } 1141 dense_prefix -= region_size; 1142 live_to_right = prev_region_live_to_right; 1143 space_to_right = prev_region_space_to_right; 1144 density_to_right = prev_region_density_to_right; 1145 } 1146 return dense_prefix; 1147 } 1148 1149 dense_prefix += region_size; 1150 ++cp; 1151 } 1152 1153 return dense_prefix; 1154 } 1155 1156 #ifndef PRODUCT 1157 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, 1158 const SpaceId id, 1159 const bool maximum_compaction, 1160 HeapWord* const addr) 1161 { 1162 const size_t region_idx = summary_data().addr_to_region_idx(addr); 1163 RegionData* const cp = summary_data().region(region_idx); 1164 const MutableSpace* const space = _space_info[id].space(); 1165 HeapWord* const new_top = _space_info[id].new_top(); 1166 1167 const size_t space_live = pointer_delta(new_top, space->bottom()); 1168 const size_t dead_to_left = pointer_delta(addr, cp->destination()); 1169 const size_t space_cap = space->capacity_in_words(); 1170 const double dead_to_left_pct = double(dead_to_left) / space_cap; 1171 const size_t live_to_right = new_top - cp->destination(); 1172 const size_t dead_to_right = space->top() - addr - live_to_right; 1173 1174 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " 1175 "spl=" SIZE_FORMAT " " 1176 "d2l=" SIZE_FORMAT " d2l%%=%6.4f " 1177 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT 1178 " ratio=%10.8f", 1179 algorithm, p2i(addr), region_idx, 1180 space_live, 1181 dead_to_left, dead_to_left_pct, 1182 dead_to_right, live_to_right, 1183 double(dead_to_right) / live_to_right); 1184 } 1185 #endif // #ifndef PRODUCT 1186 1187 // Return a fraction indicating how much of the generation can be treated as 1188 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution 1189 // based on the density of live objects in the generation to determine a limit, 1190 // which is then adjusted so the return value is min_percent when the density is 1191 // 1. 1192 // 1193 // The following table shows some return values for a different values of the 1194 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and 1195 // min_percent is 1. 1196 // 1197 // fraction allowed as dead wood 1198 // ----------------------------------------------------------------- 1199 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 1200 // ------- ---------- ---------- ---------- ---------- ---------- ---------- 1201 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1202 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1203 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1204 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1205 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1206 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1207 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1208 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1209 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1210 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1211 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 1212 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1213 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1214 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1215 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1216 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1217 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1218 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1219 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1220 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1221 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1222 1223 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) 1224 { 1225 assert(_dwl_initialized, "uninitialized"); 1226 1227 // The raw limit is the value of the normal distribution at x = density. 1228 const double raw_limit = normal_distribution(density); 1229 1230 // Adjust the raw limit so it becomes the minimum when the density is 1. 1231 // 1232 // First subtract the adjustment value (which is simply the precomputed value 1233 // normal_distribution(1.0)); this yields a value of 0 when the density is 1. 1234 // Then add the minimum value, so the minimum is returned when the density is 1235 // 1. Finally, prevent negative values, which occur when the mean is not 0.5. 1236 const double min = double(min_percent) / 100.0; 1237 const double limit = raw_limit - _dwl_adjustment + min; 1238 return MAX2(limit, 0.0); 1239 } 1240 1241 ParallelCompactData::RegionData* 1242 PSParallelCompact::first_dead_space_region(const RegionData* beg, 1243 const RegionData* end) 1244 { 1245 const size_t region_size = ParallelCompactData::RegionSize; 1246 ParallelCompactData& sd = summary_data(); 1247 size_t left = sd.region(beg); 1248 size_t right = end > beg ? sd.region(end) - 1 : left; 1249 1250 // Binary search. 1251 while (left < right) { 1252 // Equivalent to (left + right) / 2, but does not overflow. 1253 const size_t middle = left + (right - left) / 2; 1254 RegionData* const middle_ptr = sd.region(middle); 1255 HeapWord* const dest = middle_ptr->destination(); 1256 HeapWord* const addr = sd.region_to_addr(middle); 1257 assert(dest != NULL, "sanity"); 1258 assert(dest <= addr, "must move left"); 1259 1260 if (middle > left && dest < addr) { 1261 right = middle - 1; 1262 } else if (middle < right && middle_ptr->data_size() == region_size) { 1263 left = middle + 1; 1264 } else { 1265 return middle_ptr; 1266 } 1267 } 1268 return sd.region(left); 1269 } 1270 1271 ParallelCompactData::RegionData* 1272 PSParallelCompact::dead_wood_limit_region(const RegionData* beg, 1273 const RegionData* end, 1274 size_t dead_words) 1275 { 1276 ParallelCompactData& sd = summary_data(); 1277 size_t left = sd.region(beg); 1278 size_t right = end > beg ? sd.region(end) - 1 : left; 1279 1280 // Binary search. 1281 while (left < right) { 1282 // Equivalent to (left + right) / 2, but does not overflow. 1283 const size_t middle = left + (right - left) / 2; 1284 RegionData* const middle_ptr = sd.region(middle); 1285 HeapWord* const dest = middle_ptr->destination(); 1286 HeapWord* const addr = sd.region_to_addr(middle); 1287 assert(dest != NULL, "sanity"); 1288 assert(dest <= addr, "must move left"); 1289 1290 const size_t dead_to_left = pointer_delta(addr, dest); 1291 if (middle > left && dead_to_left > dead_words) { 1292 right = middle - 1; 1293 } else if (middle < right && dead_to_left < dead_words) { 1294 left = middle + 1; 1295 } else { 1296 return middle_ptr; 1297 } 1298 } 1299 return sd.region(left); 1300 } 1301 1302 // The result is valid during the summary phase, after the initial summarization 1303 // of each space into itself, and before final summarization. 1304 inline double 1305 PSParallelCompact::reclaimed_ratio(const RegionData* const cp, 1306 HeapWord* const bottom, 1307 HeapWord* const top, 1308 HeapWord* const new_top) 1309 { 1310 ParallelCompactData& sd = summary_data(); 1311 1312 assert(cp != NULL, "sanity"); 1313 assert(bottom != NULL, "sanity"); 1314 assert(top != NULL, "sanity"); 1315 assert(new_top != NULL, "sanity"); 1316 assert(top >= new_top, "summary data problem?"); 1317 assert(new_top > bottom, "space is empty; should not be here"); 1318 assert(new_top >= cp->destination(), "sanity"); 1319 assert(top >= sd.region_to_addr(cp), "sanity"); 1320 1321 HeapWord* const destination = cp->destination(); 1322 const size_t dense_prefix_live = pointer_delta(destination, bottom); 1323 const size_t compacted_region_live = pointer_delta(new_top, destination); 1324 const size_t compacted_region_used = pointer_delta(top, 1325 sd.region_to_addr(cp)); 1326 const size_t reclaimable = compacted_region_used - compacted_region_live; 1327 1328 const double divisor = dense_prefix_live + 1.25 * compacted_region_live; 1329 return double(reclaimable) / divisor; 1330 } 1331 1332 // Return the address of the end of the dense prefix, a.k.a. the start of the 1333 // compacted region. The address is always on a region boundary. 1334 // 1335 // Completely full regions at the left are skipped, since no compaction can 1336 // occur in those regions. Then the maximum amount of dead wood to allow is 1337 // computed, based on the density (amount live / capacity) of the generation; 1338 // the region with approximately that amount of dead space to the left is 1339 // identified as the limit region. Regions between the last completely full 1340 // region and the limit region are scanned and the one that has the best 1341 // (maximum) reclaimed_ratio() is selected. 1342 HeapWord* 1343 PSParallelCompact::compute_dense_prefix(const SpaceId id, 1344 bool maximum_compaction) 1345 { 1346 const size_t region_size = ParallelCompactData::RegionSize; 1347 const ParallelCompactData& sd = summary_data(); 1348 1349 const MutableSpace* const space = _space_info[id].space(); 1350 HeapWord* const top = space->top(); 1351 HeapWord* const top_aligned_up = sd.region_align_up(top); 1352 HeapWord* const new_top = _space_info[id].new_top(); 1353 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top); 1354 HeapWord* const bottom = space->bottom(); 1355 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom); 1356 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 1357 const RegionData* const new_top_cp = 1358 sd.addr_to_region_ptr(new_top_aligned_up); 1359 1360 // Skip full regions at the beginning of the space--they are necessarily part 1361 // of the dense prefix. 1362 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp); 1363 assert(full_cp->destination() == sd.region_to_addr(full_cp) || 1364 space->is_empty(), "no dead space allowed to the left"); 1365 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1, 1366 "region must have dead space"); 1367 1368 // The gc number is saved whenever a maximum compaction is done, and used to 1369 // determine when the maximum compaction interval has expired. This avoids 1370 // successive max compactions for different reasons. 1371 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1372 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1373 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || 1374 total_invocations() == HeapFirstMaximumCompactionCount; 1375 if (maximum_compaction || full_cp == top_cp || interval_ended) { 1376 _maximum_compaction_gc_num = total_invocations(); 1377 return sd.region_to_addr(full_cp); 1378 } 1379 1380 const size_t space_live = pointer_delta(new_top, bottom); 1381 const size_t space_used = space->used_in_words(); 1382 const size_t space_capacity = space->capacity_in_words(); 1383 1384 const double density = double(space_live) / double(space_capacity); 1385 const size_t min_percent_free = MarkSweepDeadRatio; 1386 const double limiter = dead_wood_limiter(density, min_percent_free); 1387 const size_t dead_wood_max = space_used - space_live; 1388 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), 1389 dead_wood_max); 1390 1391 if (TraceParallelOldGCDensePrefix) { 1392 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1393 "space_cap=" SIZE_FORMAT, 1394 space_live, space_used, 1395 space_capacity); 1396 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f " 1397 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, 1398 density, min_percent_free, limiter, 1399 dead_wood_max, dead_wood_limit); 1400 } 1401 1402 // Locate the region with the desired amount of dead space to the left. 1403 const RegionData* const limit_cp = 1404 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit); 1405 1406 // Scan from the first region with dead space to the limit region and find the 1407 // one with the best (largest) reclaimed ratio. 1408 double best_ratio = 0.0; 1409 const RegionData* best_cp = full_cp; 1410 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) { 1411 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); 1412 if (tmp_ratio > best_ratio) { 1413 best_cp = cp; 1414 best_ratio = tmp_ratio; 1415 } 1416 } 1417 1418 return sd.region_to_addr(best_cp); 1419 } 1420 1421 void PSParallelCompact::summarize_spaces_quick() 1422 { 1423 for (unsigned int i = 0; i < last_space_id; ++i) { 1424 const MutableSpace* space = _space_info[i].space(); 1425 HeapWord** nta = _space_info[i].new_top_addr(); 1426 bool result = _summary_data.summarize(_space_info[i].split_info(), 1427 space->bottom(), space->top(), NULL, 1428 space->bottom(), space->end(), nta); 1429 assert(result, "space must fit into itself"); 1430 _space_info[i].set_dense_prefix(space->bottom()); 1431 } 1432 } 1433 1434 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) 1435 { 1436 HeapWord* const dense_prefix_end = dense_prefix(id); 1437 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end); 1438 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); 1439 if (dead_space_crosses_boundary(region, dense_prefix_bit)) { 1440 // Only enough dead space is filled so that any remaining dead space to the 1441 // left is larger than the minimum filler object. (The remainder is filled 1442 // during the copy/update phase.) 1443 // 1444 // The size of the dead space to the right of the boundary is not a 1445 // concern, since compaction will be able to use whatever space is 1446 // available. 1447 // 1448 // Here '||' is the boundary, 'x' represents a don't care bit and a box 1449 // surrounds the space to be filled with an object. 1450 // 1451 // In the 32-bit VM, each bit represents two 32-bit words: 1452 // +---+ 1453 // a) beg_bits: ... x x x | 0 | || 0 x x ... 1454 // end_bits: ... x x x | 0 | || 0 x x ... 1455 // +---+ 1456 // 1457 // In the 64-bit VM, each bit represents one 64-bit word: 1458 // +------------+ 1459 // b) beg_bits: ... x x x | 0 || 0 | x x ... 1460 // end_bits: ... x x 1 | 0 || 0 | x x ... 1461 // +------------+ 1462 // +-------+ 1463 // c) beg_bits: ... x x | 0 0 | || 0 x x ... 1464 // end_bits: ... x 1 | 0 0 | || 0 x x ... 1465 // +-------+ 1466 // +-----------+ 1467 // d) beg_bits: ... x | 0 0 0 | || 0 x x ... 1468 // end_bits: ... 1 | 0 0 0 | || 0 x x ... 1469 // +-----------+ 1470 // +-------+ 1471 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... 1472 // end_bits: ... 0 0 | 0 0 | || 0 x x ... 1473 // +-------+ 1474 1475 // Initially assume case a, c or e will apply. 1476 size_t obj_len = CollectedHeap::min_fill_size(); 1477 HeapWord* obj_beg = dense_prefix_end - obj_len; 1478 1479 #ifdef _LP64 1480 if (MinObjAlignment > 1) { // object alignment > heap word size 1481 // Cases a, c or e. 1482 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { 1483 // Case b above. 1484 obj_beg = dense_prefix_end - 1; 1485 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && 1486 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { 1487 // Case d above. 1488 obj_beg = dense_prefix_end - 3; 1489 obj_len = 3; 1490 } 1491 #endif // #ifdef _LP64 1492 1493 CollectedHeap::fill_with_object(obj_beg, obj_len); 1494 _mark_bitmap.mark_obj(obj_beg, obj_len); 1495 _summary_data.add_obj(obj_beg, obj_len); 1496 assert(start_array(id) != NULL, "sanity"); 1497 start_array(id)->allocate_block(obj_beg); 1498 } 1499 } 1500 1501 void 1502 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) 1503 { 1504 assert(id < last_space_id, "id out of range"); 1505 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(), 1506 "should have been reset in summarize_spaces_quick()"); 1507 1508 const MutableSpace* space = _space_info[id].space(); 1509 if (_space_info[id].new_top() != space->bottom()) { 1510 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); 1511 _space_info[id].set_dense_prefix(dense_prefix_end); 1512 1513 #ifndef PRODUCT 1514 if (TraceParallelOldGCDensePrefix) { 1515 print_dense_prefix_stats("ratio", id, maximum_compaction, 1516 dense_prefix_end); 1517 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); 1518 print_dense_prefix_stats("density", id, maximum_compaction, addr); 1519 } 1520 #endif // #ifndef PRODUCT 1521 1522 // Recompute the summary data, taking into account the dense prefix. If 1523 // every last byte will be reclaimed, then the existing summary data which 1524 // compacts everything can be left in place. 1525 if (!maximum_compaction && dense_prefix_end != space->bottom()) { 1526 // If dead space crosses the dense prefix boundary, it is (at least 1527 // partially) filled with a dummy object, marked live and added to the 1528 // summary data. This simplifies the copy/update phase and must be done 1529 // before the final locations of objects are determined, to prevent 1530 // leaving a fragment of dead space that is too small to fill. 1531 fill_dense_prefix_end(id); 1532 1533 // Compute the destination of each Region, and thus each object. 1534 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); 1535 _summary_data.summarize(_space_info[id].split_info(), 1536 dense_prefix_end, space->top(), NULL, 1537 dense_prefix_end, space->end(), 1538 _space_info[id].new_top_addr()); 1539 } 1540 } 1541 1542 if (log_develop_is_enabled(Trace, gc, compaction)) { 1543 const size_t region_size = ParallelCompactData::RegionSize; 1544 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); 1545 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end); 1546 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); 1547 HeapWord* const new_top = _space_info[id].new_top(); 1548 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top); 1549 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); 1550 log_develop_trace(gc, compaction)( 1551 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " 1552 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " 1553 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, 1554 id, space->capacity_in_words(), p2i(dense_prefix_end), 1555 dp_region, dp_words / region_size, 1556 cr_words / region_size, p2i(new_top)); 1557 } 1558 } 1559 1560 #ifndef PRODUCT 1561 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id, 1562 HeapWord* dst_beg, HeapWord* dst_end, 1563 SpaceId src_space_id, 1564 HeapWord* src_beg, HeapWord* src_end) 1565 { 1566 log_develop_trace(gc, compaction)( 1567 "Summarizing %d [%s] into %d [%s]: " 1568 "src=" PTR_FORMAT "-" PTR_FORMAT " " 1569 SIZE_FORMAT "-" SIZE_FORMAT " " 1570 "dst=" PTR_FORMAT "-" PTR_FORMAT " " 1571 SIZE_FORMAT "-" SIZE_FORMAT, 1572 src_space_id, space_names[src_space_id], 1573 dst_space_id, space_names[dst_space_id], 1574 p2i(src_beg), p2i(src_end), 1575 _summary_data.addr_to_region_idx(src_beg), 1576 _summary_data.addr_to_region_idx(src_end), 1577 p2i(dst_beg), p2i(dst_end), 1578 _summary_data.addr_to_region_idx(dst_beg), 1579 _summary_data.addr_to_region_idx(dst_end)); 1580 } 1581 #endif // #ifndef PRODUCT 1582 1583 void PSParallelCompact::summary_phase(ParCompactionManager* cm, 1584 bool maximum_compaction) 1585 { 1586 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer); 1587 1588 #ifdef ASSERT 1589 if (TraceParallelOldGCMarkingPhase) { 1590 tty->print_cr("add_obj_count=" SIZE_FORMAT " " 1591 "add_obj_bytes=" SIZE_FORMAT, 1592 add_obj_count, add_obj_size * HeapWordSize); 1593 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " " 1594 "mark_bitmap_bytes=" SIZE_FORMAT, 1595 mark_bitmap_count, mark_bitmap_size * HeapWordSize); 1596 } 1597 #endif // #ifdef ASSERT 1598 1599 // Quick summarization of each space into itself, to see how much is live. 1600 summarize_spaces_quick(); 1601 1602 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self"); 1603 NOT_PRODUCT(print_region_ranges()); 1604 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1605 1606 // The amount of live data that will end up in old space (assuming it fits). 1607 size_t old_space_total_live = 0; 1608 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1609 old_space_total_live += pointer_delta(_space_info[id].new_top(), 1610 _space_info[id].space()->bottom()); 1611 } 1612 1613 MutableSpace* const old_space = _space_info[old_space_id].space(); 1614 const size_t old_capacity = old_space->capacity_in_words(); 1615 if (old_space_total_live > old_capacity) { 1616 // XXX - should also try to expand 1617 maximum_compaction = true; 1618 } 1619 1620 // Old generations. 1621 summarize_space(old_space_id, maximum_compaction); 1622 1623 // Summarize the remaining spaces in the young gen. The initial target space 1624 // is the old gen. If a space does not fit entirely into the target, then the 1625 // remainder is compacted into the space itself and that space becomes the new 1626 // target. 1627 SpaceId dst_space_id = old_space_id; 1628 HeapWord* dst_space_end = old_space->end(); 1629 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr(); 1630 for (unsigned int id = eden_space_id; id < last_space_id; ++id) { 1631 const MutableSpace* space = _space_info[id].space(); 1632 const size_t live = pointer_delta(_space_info[id].new_top(), 1633 space->bottom()); 1634 const size_t available = pointer_delta(dst_space_end, *new_top_addr); 1635 1636 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end, 1637 SpaceId(id), space->bottom(), space->top());) 1638 if (live > 0 && live <= available) { 1639 // All the live data will fit. 1640 bool done = _summary_data.summarize(_space_info[id].split_info(), 1641 space->bottom(), space->top(), 1642 NULL, 1643 *new_top_addr, dst_space_end, 1644 new_top_addr); 1645 assert(done, "space must fit into old gen"); 1646 1647 // Reset the new_top value for the space. 1648 _space_info[id].set_new_top(space->bottom()); 1649 } else if (live > 0) { 1650 // Attempt to fit part of the source space into the target space. 1651 HeapWord* next_src_addr = NULL; 1652 bool done = _summary_data.summarize(_space_info[id].split_info(), 1653 space->bottom(), space->top(), 1654 &next_src_addr, 1655 *new_top_addr, dst_space_end, 1656 new_top_addr); 1657 assert(!done, "space should not fit into old gen"); 1658 assert(next_src_addr != NULL, "sanity"); 1659 1660 // The source space becomes the new target, so the remainder is compacted 1661 // within the space itself. 1662 dst_space_id = SpaceId(id); 1663 dst_space_end = space->end(); 1664 new_top_addr = _space_info[id].new_top_addr(); 1665 NOT_PRODUCT(summary_phase_msg(dst_space_id, 1666 space->bottom(), dst_space_end, 1667 SpaceId(id), next_src_addr, space->top());) 1668 done = _summary_data.summarize(_space_info[id].split_info(), 1669 next_src_addr, space->top(), 1670 NULL, 1671 space->bottom(), dst_space_end, 1672 new_top_addr); 1673 assert(done, "space must fit when compacted into itself"); 1674 assert(*new_top_addr <= space->top(), "usage should not grow"); 1675 } 1676 } 1677 1678 log_develop_trace(gc, compaction)("Summary_phase: after final summarization"); 1679 NOT_PRODUCT(print_region_ranges()); 1680 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1681 } 1682 1683 // This method should contain all heap-specific policy for invoking a full 1684 // collection. invoke_no_policy() will only attempt to compact the heap; it 1685 // will do nothing further. If we need to bail out for policy reasons, scavenge 1686 // before full gc, or any other specialized behavior, it needs to be added here. 1687 // 1688 // Note that this method should only be called from the vm_thread while at a 1689 // safepoint. 1690 // 1691 // Note that the all_soft_refs_clear flag in the collector policy 1692 // may be true because this method can be called without intervening 1693 // activity. For example when the heap space is tight and full measure 1694 // are being taken to free space. 1695 void PSParallelCompact::invoke(bool maximum_heap_compaction) { 1696 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 1697 assert(Thread::current() == (Thread*)VMThread::vm_thread(), 1698 "should be in vm thread"); 1699 1700 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1701 GCCause::Cause gc_cause = heap->gc_cause(); 1702 assert(!heap->is_gc_active(), "not reentrant"); 1703 1704 PSAdaptiveSizePolicy* policy = heap->size_policy(); 1705 IsGCActiveMark mark; 1706 1707 if (ScavengeBeforeFullGC) { 1708 PSScavenge::invoke_no_policy(); 1709 } 1710 1711 const bool clear_all_soft_refs = 1712 heap->soft_ref_policy()->should_clear_all_soft_refs(); 1713 1714 PSParallelCompact::invoke_no_policy(clear_all_soft_refs || 1715 maximum_heap_compaction); 1716 } 1717 1718 // This method contains no policy. You should probably 1719 // be calling invoke() instead. 1720 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { 1721 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 1722 assert(ref_processor() != NULL, "Sanity"); 1723 1724 if (GCLocker::check_active_before_gc()) { 1725 return false; 1726 } 1727 1728 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1729 1730 GCIdMark gc_id_mark; 1731 _gc_timer.register_gc_start(); 1732 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 1733 1734 TimeStamp marking_start; 1735 TimeStamp compaction_start; 1736 TimeStamp collection_exit; 1737 1738 GCCause::Cause gc_cause = heap->gc_cause(); 1739 PSYoungGen* young_gen = heap->young_gen(); 1740 PSOldGen* old_gen = heap->old_gen(); 1741 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 1742 1743 // The scope of casr should end after code that can change 1744 // CollectorPolicy::_should_clear_all_soft_refs. 1745 ClearedAllSoftRefs casr(maximum_heap_compaction, 1746 heap->soft_ref_policy()); 1747 1748 if (ZapUnusedHeapArea) { 1749 // Save information needed to minimize mangling 1750 heap->record_gen_tops_before_GC(); 1751 } 1752 1753 // Make sure data structures are sane, make the heap parsable, and do other 1754 // miscellaneous bookkeeping. 1755 pre_compact(); 1756 1757 PreGCValues pre_gc_values(heap); 1758 1759 // Get the compaction manager reserved for the VM thread. 1760 ParCompactionManager* const vmthread_cm = 1761 ParCompactionManager::manager_array(gc_task_manager()->workers()); 1762 1763 { 1764 ResourceMark rm; 1765 HandleMark hm; 1766 1767 // Set the number of GC threads to be used in this collection 1768 gc_task_manager()->set_active_gang(); 1769 gc_task_manager()->task_idle_workers(); 1770 1771 GCTraceCPUTime tcpu; 1772 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true); 1773 1774 heap->pre_full_gc_dump(&_gc_timer); 1775 1776 TraceCollectorStats tcs(counters()); 1777 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause); 1778 1779 if (log_is_enabled(Debug, gc, heap, exit)) { 1780 accumulated_time()->start(); 1781 } 1782 1783 // Let the size policy know we're starting 1784 size_policy->major_collection_begin(); 1785 1786 CodeCache::gc_prologue(); 1787 1788 #if COMPILER2_OR_JVMCI 1789 DerivedPointerTable::clear(); 1790 #endif 1791 1792 ref_processor()->enable_discovery(); 1793 ref_processor()->setup_policy(maximum_heap_compaction); 1794 1795 bool marked_for_unloading = false; 1796 1797 marking_start.update(); 1798 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer); 1799 1800 bool max_on_system_gc = UseMaximumCompactionOnSystemGC 1801 && GCCause::is_user_requested_gc(gc_cause); 1802 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc); 1803 1804 #if COMPILER2_OR_JVMCI 1805 assert(DerivedPointerTable::is_active(), "Sanity"); 1806 DerivedPointerTable::set_active(false); 1807 #endif 1808 1809 // adjust_roots() updates Universe::_intArrayKlassObj which is 1810 // needed by the compaction for filling holes in the dense prefix. 1811 adjust_roots(vmthread_cm); 1812 1813 compaction_start.update(); 1814 compact(); 1815 1816 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be 1817 // done before resizing. 1818 post_compact(); 1819 1820 // Let the size policy know we're done 1821 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 1822 1823 if (UseAdaptiveSizePolicy) { 1824 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 1825 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 1826 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 1827 1828 // Don't check if the size_policy is ready here. Let 1829 // the size_policy check that internally. 1830 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 1831 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 1832 // Swap the survivor spaces if from_space is empty. The 1833 // resize_young_gen() called below is normally used after 1834 // a successful young GC and swapping of survivor spaces; 1835 // otherwise, it will fail to resize the young gen with 1836 // the current implementation. 1837 if (young_gen->from_space()->is_empty()) { 1838 young_gen->from_space()->clear(SpaceDecorator::Mangle); 1839 young_gen->swap_spaces(); 1840 } 1841 1842 // Calculate optimal free space amounts 1843 assert(young_gen->max_size() > 1844 young_gen->from_space()->capacity_in_bytes() + 1845 young_gen->to_space()->capacity_in_bytes(), 1846 "Sizes of space in young gen are out-of-bounds"); 1847 1848 size_t young_live = young_gen->used_in_bytes(); 1849 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 1850 size_t old_live = old_gen->used_in_bytes(); 1851 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 1852 size_t max_old_gen_size = old_gen->max_gen_size(); 1853 size_t max_eden_size = young_gen->max_size() - 1854 young_gen->from_space()->capacity_in_bytes() - 1855 young_gen->to_space()->capacity_in_bytes(); 1856 1857 // Used for diagnostics 1858 size_policy->clear_generation_free_space_flags(); 1859 1860 size_policy->compute_generations_free_space(young_live, 1861 eden_live, 1862 old_live, 1863 cur_eden, 1864 max_old_gen_size, 1865 max_eden_size, 1866 true /* full gc*/); 1867 1868 size_policy->check_gc_overhead_limit(young_live, 1869 eden_live, 1870 max_old_gen_size, 1871 max_eden_size, 1872 true /* full gc*/, 1873 gc_cause, 1874 heap->soft_ref_policy()); 1875 1876 size_policy->decay_supplemental_growth(true /* full gc*/); 1877 1878 heap->resize_old_gen( 1879 size_policy->calculated_old_free_size_in_bytes()); 1880 1881 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 1882 size_policy->calculated_survivor_size_in_bytes()); 1883 } 1884 1885 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 1886 } 1887 1888 if (UsePerfData) { 1889 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 1890 counters->update_counters(); 1891 counters->update_old_capacity(old_gen->capacity_in_bytes()); 1892 counters->update_young_capacity(young_gen->capacity_in_bytes()); 1893 } 1894 1895 heap->resize_all_tlabs(); 1896 1897 // Resize the metaspace capacity after a collection 1898 MetaspaceGC::compute_new_size(); 1899 1900 if (log_is_enabled(Debug, gc, heap, exit)) { 1901 accumulated_time()->stop(); 1902 } 1903 1904 young_gen->print_used_change(pre_gc_values.young_gen_used()); 1905 old_gen->print_used_change(pre_gc_values.old_gen_used()); 1906 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used()); 1907 1908 // Track memory usage and detect low memory 1909 MemoryService::track_memory_usage(); 1910 heap->update_counters(); 1911 gc_task_manager()->release_idle_workers(); 1912 1913 heap->post_full_gc_dump(&_gc_timer); 1914 } 1915 1916 #ifdef ASSERT 1917 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) { 1918 ParCompactionManager* const cm = 1919 ParCompactionManager::manager_array(int(i)); 1920 assert(cm->marking_stack()->is_empty(), "should be empty"); 1921 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i); 1922 } 1923 #endif // ASSERT 1924 1925 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 1926 HandleMark hm; // Discard invalid handles created during verification 1927 Universe::verify("After GC"); 1928 } 1929 1930 // Re-verify object start arrays 1931 if (VerifyObjectStartArray && 1932 VerifyAfterGC) { 1933 old_gen->verify_object_start_array(); 1934 } 1935 1936 if (ZapUnusedHeapArea) { 1937 old_gen->object_space()->check_mangled_unused_area_complete(); 1938 } 1939 1940 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 1941 1942 collection_exit.update(); 1943 1944 heap->print_heap_after_gc(); 1945 heap->trace_heap_after_gc(&_gc_tracer); 1946 1947 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 1948 marking_start.ticks(), compaction_start.ticks(), 1949 collection_exit.ticks()); 1950 gc_task_manager()->print_task_time_stamps(); 1951 1952 #ifdef TRACESPINNING 1953 ParallelTaskTerminator::print_termination_counts(); 1954 #endif 1955 1956 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 1957 1958 _gc_timer.register_gc_end(); 1959 1960 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id)); 1961 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 1962 1963 return true; 1964 } 1965 1966 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 1967 PSYoungGen* young_gen, 1968 PSOldGen* old_gen) { 1969 MutableSpace* const eden_space = young_gen->eden_space(); 1970 assert(!eden_space->is_empty(), "eden must be non-empty"); 1971 assert(young_gen->virtual_space()->alignment() == 1972 old_gen->virtual_space()->alignment(), "alignments do not match"); 1973 1974 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 1975 return false; 1976 } 1977 1978 // Both generations must be completely committed. 1979 if (young_gen->virtual_space()->uncommitted_size() != 0) { 1980 return false; 1981 } 1982 if (old_gen->virtual_space()->uncommitted_size() != 0) { 1983 return false; 1984 } 1985 1986 // Figure out how much to take from eden. Include the average amount promoted 1987 // in the total; otherwise the next young gen GC will simply bail out to a 1988 // full GC. 1989 const size_t alignment = old_gen->virtual_space()->alignment(); 1990 const size_t eden_used = eden_space->used_in_bytes(); 1991 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 1992 const size_t absorb_size = align_up(eden_used + promoted, alignment); 1993 const size_t eden_capacity = eden_space->capacity_in_bytes(); 1994 1995 if (absorb_size >= eden_capacity) { 1996 return false; // Must leave some space in eden. 1997 } 1998 1999 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 2000 if (new_young_size < young_gen->min_gen_size()) { 2001 return false; // Respect young gen minimum size. 2002 } 2003 2004 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 2005 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 2006 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 2007 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 2008 absorb_size / K, 2009 eden_capacity / K, (eden_capacity - absorb_size) / K, 2010 young_gen->from_space()->used_in_bytes() / K, 2011 young_gen->to_space()->used_in_bytes() / K, 2012 young_gen->capacity_in_bytes() / K, new_young_size / K); 2013 2014 // Fill the unused part of the old gen. 2015 MutableSpace* const old_space = old_gen->object_space(); 2016 HeapWord* const unused_start = old_space->top(); 2017 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 2018 2019 if (unused_words > 0) { 2020 if (unused_words < CollectedHeap::min_fill_size()) { 2021 return false; // If the old gen cannot be filled, must give up. 2022 } 2023 CollectedHeap::fill_with_objects(unused_start, unused_words); 2024 } 2025 2026 // Take the live data from eden and set both top and end in the old gen to 2027 // eden top. (Need to set end because reset_after_change() mangles the region 2028 // from end to virtual_space->high() in debug builds). 2029 HeapWord* const new_top = eden_space->top(); 2030 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 2031 absorb_size); 2032 young_gen->reset_after_change(); 2033 old_space->set_top(new_top); 2034 old_space->set_end(new_top); 2035 old_gen->reset_after_change(); 2036 2037 // Update the object start array for the filler object and the data from eden. 2038 ObjectStartArray* const start_array = old_gen->start_array(); 2039 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 2040 start_array->allocate_block(p); 2041 } 2042 2043 // Could update the promoted average here, but it is not typically updated at 2044 // full GCs and the value to use is unclear. Something like 2045 // 2046 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 2047 2048 size_policy->set_bytes_absorbed_from_eden(absorb_size); 2049 return true; 2050 } 2051 2052 GCTaskManager* const PSParallelCompact::gc_task_manager() { 2053 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 2054 "shouldn't return NULL"); 2055 return ParallelScavengeHeap::gc_task_manager(); 2056 } 2057 2058 void PSParallelCompact::marking_phase(ParCompactionManager* cm, 2059 bool maximum_heap_compaction, 2060 ParallelOldTracer *gc_tracer) { 2061 // Recursively traverse all live objects and mark them 2062 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer); 2063 2064 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2065 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2066 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2067 TaskQueueSetSuper* qset = ParCompactionManager::stack_array(); 2068 ParallelTaskTerminator terminator(active_gc_threads, qset); 2069 2070 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm); 2071 ParCompactionManager::FollowStackClosure follow_stack_closure(cm); 2072 2073 // Need new claim bits before marking starts. 2074 ClassLoaderDataGraph::clear_claimed_marks(); 2075 2076 { 2077 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer); 2078 2079 ParallelScavengeHeap::ParStrongRootsScope psrs; 2080 2081 GCTaskQueue* q = GCTaskQueue::create(); 2082 2083 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe)); 2084 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles)); 2085 // We scan the thread roots in parallel 2086 Threads::create_thread_roots_marking_tasks(q); 2087 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer)); 2088 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management)); 2089 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary)); 2090 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data)); 2091 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti)); 2092 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache)); 2093 2094 if (active_gc_threads > 1) { 2095 for (uint j = 0; j < active_gc_threads; j++) { 2096 q->enqueue(new StealMarkingTask(&terminator)); 2097 } 2098 } 2099 2100 gc_task_manager()->execute_and_wait(q); 2101 } 2102 2103 // Process reference objects found during marking 2104 { 2105 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 2106 2107 ReferenceProcessorStats stats; 2108 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->num_queues()); 2109 if (ref_processor()->processing_is_mt()) { 2110 RefProcTaskExecutor task_executor; 2111 stats = ref_processor()->process_discovered_references( 2112 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, 2113 &task_executor, &pt); 2114 } else { 2115 stats = ref_processor()->process_discovered_references( 2116 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL, 2117 &pt); 2118 } 2119 2120 gc_tracer->report_gc_reference_stats(stats); 2121 pt.print_all_references(); 2122 } 2123 2124 // This is the point where the entire marking should have completed. 2125 assert(cm->marking_stacks_empty(), "Marking should have completed"); 2126 2127 { 2128 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer); 2129 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl); 2130 } 2131 2132 { 2133 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer); 2134 2135 // Follow system dictionary roots and unload classes. 2136 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), &_gc_timer); 2137 2138 // Unload nmethods. 2139 CodeCache::do_unloading(is_alive_closure(), purged_class); 2140 2141 // Prune dead klasses from subklass/sibling/implementor lists. 2142 Klass::clean_weak_klass_links(); 2143 } 2144 2145 { 2146 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer); 2147 // Delete entries for dead interned strings. 2148 StringTable::unlink(is_alive_closure()); 2149 } 2150 2151 { 2152 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer); 2153 // Clean up unreferenced symbols in symbol table. 2154 SymbolTable::unlink(); 2155 } 2156 2157 _gc_tracer.report_object_count_after_gc(is_alive_closure()); 2158 } 2159 2160 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) { 2161 // Adjust the pointers to reflect the new locations 2162 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer); 2163 2164 // Need new claim bits when tracing through and adjusting pointers. 2165 ClassLoaderDataGraph::clear_claimed_marks(); 2166 2167 PSParallelCompact::AdjustPointerClosure oop_closure(cm); 2168 2169 // General strong roots. 2170 Universe::oops_do(&oop_closure); 2171 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles 2172 Threads::oops_do(&oop_closure, NULL); 2173 ObjectSynchronizer::oops_do(&oop_closure); 2174 Management::oops_do(&oop_closure); 2175 JvmtiExport::oops_do(&oop_closure); 2176 SystemDictionary::oops_do(&oop_closure); 2177 ClassLoaderDataGraph::oops_do(&oop_closure, true); 2178 2179 // Now adjust pointers in remaining weak roots. (All of which should 2180 // have been cleared if they pointed to non-surviving objects.) 2181 WeakProcessor::oops_do(&oop_closure); 2182 2183 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations); 2184 CodeCache::blobs_do(&adjust_from_blobs); 2185 AOTLoader::oops_do(&oop_closure); 2186 StringTable::oops_do(&oop_closure); 2187 ref_processor()->weak_oops_do(&oop_closure); 2188 // Roots were visited so references into the young gen in roots 2189 // may have been scanned. Process them also. 2190 // Should the reference processor have a span that excludes 2191 // young gen objects? 2192 PSScavenge::reference_processor()->weak_oops_do(&oop_closure); 2193 } 2194 2195 // Helper class to print 8 region numbers per line and then print the total at the end. 2196 class FillableRegionLogger : public StackObj { 2197 private: 2198 Log(gc, compaction) log; 2199 static const int LineLength = 8; 2200 size_t _regions[LineLength]; 2201 int _next_index; 2202 bool _enabled; 2203 size_t _total_regions; 2204 public: 2205 FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { } 2206 ~FillableRegionLogger() { 2207 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions); 2208 } 2209 2210 void print_line() { 2211 if (!_enabled || _next_index == 0) { 2212 return; 2213 } 2214 FormatBuffer<> line("Fillable: "); 2215 for (int i = 0; i < _next_index; i++) { 2216 line.append(" " SIZE_FORMAT_W(7), _regions[i]); 2217 } 2218 log.trace("%s", line.buffer()); 2219 _next_index = 0; 2220 } 2221 2222 void handle(size_t region) { 2223 if (!_enabled) { 2224 return; 2225 } 2226 _regions[_next_index++] = region; 2227 if (_next_index == LineLength) { 2228 print_line(); 2229 } 2230 _total_regions++; 2231 } 2232 }; 2233 2234 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q, 2235 uint parallel_gc_threads) 2236 { 2237 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer); 2238 2239 // Find the threads that are active 2240 unsigned int which = 0; 2241 2242 // Find all regions that are available (can be filled immediately) and 2243 // distribute them to the thread stacks. The iteration is done in reverse 2244 // order (high to low) so the regions will be removed in ascending order. 2245 2246 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 2247 2248 which = 0; 2249 // id + 1 is used to test termination so unsigned can 2250 // be used with an old_space_id == 0. 2251 FillableRegionLogger region_logger; 2252 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) { 2253 SpaceInfo* const space_info = _space_info + id; 2254 MutableSpace* const space = space_info->space(); 2255 HeapWord* const new_top = space_info->new_top(); 2256 2257 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix()); 2258 const size_t end_region = 2259 sd.addr_to_region_idx(sd.region_align_up(new_top)); 2260 2261 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) { 2262 if (sd.region(cur)->claim_unsafe()) { 2263 ParCompactionManager* cm = ParCompactionManager::manager_array(which); 2264 cm->region_stack()->push(cur); 2265 region_logger.handle(cur); 2266 // Assign regions to tasks in round-robin fashion. 2267 if (++which == parallel_gc_threads) { 2268 which = 0; 2269 } 2270 } 2271 } 2272 region_logger.print_line(); 2273 } 2274 } 2275 2276 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 2277 2278 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q, 2279 uint parallel_gc_threads) { 2280 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer); 2281 2282 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2283 2284 // Iterate over all the spaces adding tasks for updating 2285 // regions in the dense prefix. Assume that 1 gc thread 2286 // will work on opening the gaps and the remaining gc threads 2287 // will work on the dense prefix. 2288 unsigned int space_id; 2289 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) { 2290 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); 2291 const MutableSpace* const space = _space_info[space_id].space(); 2292 2293 if (dense_prefix_end == space->bottom()) { 2294 // There is no dense prefix for this space. 2295 continue; 2296 } 2297 2298 // The dense prefix is before this region. 2299 size_t region_index_end_dense_prefix = 2300 sd.addr_to_region_idx(dense_prefix_end); 2301 RegionData* const dense_prefix_cp = 2302 sd.region(region_index_end_dense_prefix); 2303 assert(dense_prefix_end == space->end() || 2304 dense_prefix_cp->available() || 2305 dense_prefix_cp->claimed(), 2306 "The region after the dense prefix should always be ready to fill"); 2307 2308 size_t region_index_start = sd.addr_to_region_idx(space->bottom()); 2309 2310 // Is there dense prefix work? 2311 size_t total_dense_prefix_regions = 2312 region_index_end_dense_prefix - region_index_start; 2313 // How many regions of the dense prefix should be given to 2314 // each thread? 2315 if (total_dense_prefix_regions > 0) { 2316 uint tasks_for_dense_prefix = 1; 2317 if (total_dense_prefix_regions <= 2318 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { 2319 // Don't over partition. This assumes that 2320 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value 2321 // so there are not many regions to process. 2322 tasks_for_dense_prefix = parallel_gc_threads; 2323 } else { 2324 // Over partition 2325 tasks_for_dense_prefix = parallel_gc_threads * 2326 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; 2327 } 2328 size_t regions_per_thread = total_dense_prefix_regions / 2329 tasks_for_dense_prefix; 2330 // Give each thread at least 1 region. 2331 if (regions_per_thread == 0) { 2332 regions_per_thread = 1; 2333 } 2334 2335 for (uint k = 0; k < tasks_for_dense_prefix; k++) { 2336 if (region_index_start >= region_index_end_dense_prefix) { 2337 break; 2338 } 2339 // region_index_end is not processed 2340 size_t region_index_end = MIN2(region_index_start + regions_per_thread, 2341 region_index_end_dense_prefix); 2342 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2343 region_index_start, 2344 region_index_end)); 2345 region_index_start = region_index_end; 2346 } 2347 } 2348 // This gets any part of the dense prefix that did not 2349 // fit evenly. 2350 if (region_index_start < region_index_end_dense_prefix) { 2351 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2352 region_index_start, 2353 region_index_end_dense_prefix)); 2354 } 2355 } 2356 } 2357 2358 void PSParallelCompact::enqueue_region_stealing_tasks( 2359 GCTaskQueue* q, 2360 ParallelTaskTerminator* terminator_ptr, 2361 uint parallel_gc_threads) { 2362 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer); 2363 2364 // Once a thread has drained it's stack, it should try to steal regions from 2365 // other threads. 2366 for (uint j = 0; j < parallel_gc_threads; j++) { 2367 q->enqueue(new CompactionWithStealingTask(terminator_ptr)); 2368 } 2369 } 2370 2371 #ifdef ASSERT 2372 // Write a histogram of the number of times the block table was filled for a 2373 // region. 2374 void PSParallelCompact::write_block_fill_histogram() 2375 { 2376 if (!log_develop_is_enabled(Trace, gc, compaction)) { 2377 return; 2378 } 2379 2380 Log(gc, compaction) log; 2381 ResourceMark rm; 2382 LogStream ls(log.trace()); 2383 outputStream* out = &ls; 2384 2385 typedef ParallelCompactData::RegionData rd_t; 2386 ParallelCompactData& sd = summary_data(); 2387 2388 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2389 MutableSpace* const spc = _space_info[id].space(); 2390 if (spc->bottom() != spc->top()) { 2391 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom()); 2392 HeapWord* const top_aligned_up = sd.region_align_up(spc->top()); 2393 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up); 2394 2395 size_t histo[5] = { 0, 0, 0, 0, 0 }; 2396 const size_t histo_len = sizeof(histo) / sizeof(size_t); 2397 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t)); 2398 2399 for (const rd_t* cur = beg; cur < end; ++cur) { 2400 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)]; 2401 } 2402 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt); 2403 for (size_t i = 0; i < histo_len; ++i) { 2404 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%", 2405 histo[i], 100.0 * histo[i] / region_cnt); 2406 } 2407 out->cr(); 2408 } 2409 } 2410 } 2411 #endif // #ifdef ASSERT 2412 2413 void PSParallelCompact::compact() { 2414 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer); 2415 2416 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2417 PSOldGen* old_gen = heap->old_gen(); 2418 old_gen->start_array()->reset(); 2419 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2420 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2421 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2422 ParallelTaskTerminator terminator(active_gc_threads, qset); 2423 2424 GCTaskQueue* q = GCTaskQueue::create(); 2425 prepare_region_draining_tasks(q, active_gc_threads); 2426 enqueue_dense_prefix_tasks(q, active_gc_threads); 2427 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads); 2428 2429 { 2430 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer); 2431 2432 gc_task_manager()->execute_and_wait(q); 2433 2434 #ifdef ASSERT 2435 // Verify that all regions have been processed before the deferred updates. 2436 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2437 verify_complete(SpaceId(id)); 2438 } 2439 #endif 2440 } 2441 2442 { 2443 // Update the deferred objects, if any. Any compaction manager can be used. 2444 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer); 2445 ParCompactionManager* cm = ParCompactionManager::manager_array(0); 2446 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2447 update_deferred_objects(cm, SpaceId(id)); 2448 } 2449 } 2450 2451 DEBUG_ONLY(write_block_fill_histogram()); 2452 } 2453 2454 #ifdef ASSERT 2455 void PSParallelCompact::verify_complete(SpaceId space_id) { 2456 // All Regions between space bottom() to new_top() should be marked as filled 2457 // and all Regions between new_top() and top() should be available (i.e., 2458 // should have been emptied). 2459 ParallelCompactData& sd = summary_data(); 2460 SpaceInfo si = _space_info[space_id]; 2461 HeapWord* new_top_addr = sd.region_align_up(si.new_top()); 2462 HeapWord* old_top_addr = sd.region_align_up(si.space()->top()); 2463 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom()); 2464 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr); 2465 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr); 2466 2467 bool issued_a_warning = false; 2468 2469 size_t cur_region; 2470 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) { 2471 const RegionData* const c = sd.region(cur_region); 2472 if (!c->completed()) { 2473 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u", 2474 cur_region, c->destination_count()); 2475 issued_a_warning = true; 2476 } 2477 } 2478 2479 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) { 2480 const RegionData* const c = sd.region(cur_region); 2481 if (!c->available()) { 2482 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u", 2483 cur_region, c->destination_count()); 2484 issued_a_warning = true; 2485 } 2486 } 2487 2488 if (issued_a_warning) { 2489 print_region_ranges(); 2490 } 2491 } 2492 #endif // #ifdef ASSERT 2493 2494 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) { 2495 _start_array->allocate_block(addr); 2496 compaction_manager()->update_contents(oop(addr)); 2497 } 2498 2499 // Update interior oops in the ranges of regions [beg_region, end_region). 2500 void 2501 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 2502 SpaceId space_id, 2503 size_t beg_region, 2504 size_t end_region) { 2505 ParallelCompactData& sd = summary_data(); 2506 ParMarkBitMap* const mbm = mark_bitmap(); 2507 2508 HeapWord* beg_addr = sd.region_to_addr(beg_region); 2509 HeapWord* const end_addr = sd.region_to_addr(end_region); 2510 assert(beg_region <= end_region, "bad region range"); 2511 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); 2512 2513 #ifdef ASSERT 2514 // Claim the regions to avoid triggering an assert when they are marked as 2515 // filled. 2516 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) { 2517 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed"); 2518 } 2519 #endif // #ifdef ASSERT 2520 2521 if (beg_addr != space(space_id)->bottom()) { 2522 // Find the first live object or block of dead space that *starts* in this 2523 // range of regions. If a partial object crosses onto the region, skip it; 2524 // it will be marked for 'deferred update' when the object head is 2525 // processed. If dead space crosses onto the region, it is also skipped; it 2526 // will be filled when the prior region is processed. If neither of those 2527 // apply, the first word in the region is the start of a live object or dead 2528 // space. 2529 assert(beg_addr > space(space_id)->bottom(), "sanity"); 2530 const RegionData* const cp = sd.region(beg_region); 2531 if (cp->partial_obj_size() != 0) { 2532 beg_addr = sd.partial_obj_end(beg_region); 2533 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) { 2534 beg_addr = mbm->find_obj_beg(beg_addr, end_addr); 2535 } 2536 } 2537 2538 if (beg_addr < end_addr) { 2539 // A live object or block of dead space starts in this range of Regions. 2540 HeapWord* const dense_prefix_end = dense_prefix(space_id); 2541 2542 // Create closures and iterate. 2543 UpdateOnlyClosure update_closure(mbm, cm, space_id); 2544 FillClosure fill_closure(cm, space_id); 2545 ParMarkBitMap::IterationStatus status; 2546 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, 2547 dense_prefix_end); 2548 if (status == ParMarkBitMap::incomplete) { 2549 update_closure.do_addr(update_closure.source()); 2550 } 2551 } 2552 2553 // Mark the regions as filled. 2554 RegionData* const beg_cp = sd.region(beg_region); 2555 RegionData* const end_cp = sd.region(end_region); 2556 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) { 2557 cp->set_completed(); 2558 } 2559 } 2560 2561 // Return the SpaceId for the space containing addr. If addr is not in the 2562 // heap, last_space_id is returned. In debug mode it expects the address to be 2563 // in the heap and asserts such. 2564 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) { 2565 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap"); 2566 2567 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2568 if (_space_info[id].space()->contains(addr)) { 2569 return SpaceId(id); 2570 } 2571 } 2572 2573 assert(false, "no space contains the addr"); 2574 return last_space_id; 2575 } 2576 2577 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm, 2578 SpaceId id) { 2579 assert(id < last_space_id, "bad space id"); 2580 2581 ParallelCompactData& sd = summary_data(); 2582 const SpaceInfo* const space_info = _space_info + id; 2583 ObjectStartArray* const start_array = space_info->start_array(); 2584 2585 const MutableSpace* const space = space_info->space(); 2586 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set"); 2587 HeapWord* const beg_addr = space_info->dense_prefix(); 2588 HeapWord* const end_addr = sd.region_align_up(space_info->new_top()); 2589 2590 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr); 2591 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr); 2592 const RegionData* cur_region; 2593 for (cur_region = beg_region; cur_region < end_region; ++cur_region) { 2594 HeapWord* const addr = cur_region->deferred_obj_addr(); 2595 if (addr != NULL) { 2596 if (start_array != NULL) { 2597 start_array->allocate_block(addr); 2598 } 2599 cm->update_contents(oop(addr)); 2600 assert(oopDesc::is_oop_or_null(oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr))); 2601 } 2602 } 2603 } 2604 2605 // Skip over count live words starting from beg, and return the address of the 2606 // next live word. Unless marked, the word corresponding to beg is assumed to 2607 // be dead. Callers must either ensure beg does not correspond to the middle of 2608 // an object, or account for those live words in some other way. Callers must 2609 // also ensure that there are enough live words in the range [beg, end) to skip. 2610 HeapWord* 2611 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count) 2612 { 2613 assert(count > 0, "sanity"); 2614 2615 ParMarkBitMap* m = mark_bitmap(); 2616 idx_t bits_to_skip = m->words_to_bits(count); 2617 idx_t cur_beg = m->addr_to_bit(beg); 2618 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end)); 2619 2620 do { 2621 cur_beg = m->find_obj_beg(cur_beg, search_end); 2622 idx_t cur_end = m->find_obj_end(cur_beg, search_end); 2623 const size_t obj_bits = cur_end - cur_beg + 1; 2624 if (obj_bits > bits_to_skip) { 2625 return m->bit_to_addr(cur_beg + bits_to_skip); 2626 } 2627 bits_to_skip -= obj_bits; 2628 cur_beg = cur_end + 1; 2629 } while (bits_to_skip > 0); 2630 2631 // Skipping the desired number of words landed just past the end of an object. 2632 // Find the start of the next object. 2633 cur_beg = m->find_obj_beg(cur_beg, search_end); 2634 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip"); 2635 return m->bit_to_addr(cur_beg); 2636 } 2637 2638 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr, 2639 SpaceId src_space_id, 2640 size_t src_region_idx) 2641 { 2642 assert(summary_data().is_region_aligned(dest_addr), "not aligned"); 2643 2644 const SplitInfo& split_info = _space_info[src_space_id].split_info(); 2645 if (split_info.dest_region_addr() == dest_addr) { 2646 // The partial object ending at the split point contains the first word to 2647 // be copied to dest_addr. 2648 return split_info.first_src_addr(); 2649 } 2650 2651 const ParallelCompactData& sd = summary_data(); 2652 ParMarkBitMap* const bitmap = mark_bitmap(); 2653 const size_t RegionSize = ParallelCompactData::RegionSize; 2654 2655 assert(sd.is_region_aligned(dest_addr), "not aligned"); 2656 const RegionData* const src_region_ptr = sd.region(src_region_idx); 2657 const size_t partial_obj_size = src_region_ptr->partial_obj_size(); 2658 HeapWord* const src_region_destination = src_region_ptr->destination(); 2659 2660 assert(dest_addr >= src_region_destination, "wrong src region"); 2661 assert(src_region_ptr->data_size() > 0, "src region cannot be empty"); 2662 2663 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx); 2664 HeapWord* const src_region_end = src_region_beg + RegionSize; 2665 2666 HeapWord* addr = src_region_beg; 2667 if (dest_addr == src_region_destination) { 2668 // Return the first live word in the source region. 2669 if (partial_obj_size == 0) { 2670 addr = bitmap->find_obj_beg(addr, src_region_end); 2671 assert(addr < src_region_end, "no objects start in src region"); 2672 } 2673 return addr; 2674 } 2675 2676 // Must skip some live data. 2677 size_t words_to_skip = dest_addr - src_region_destination; 2678 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region"); 2679 2680 if (partial_obj_size >= words_to_skip) { 2681 // All the live words to skip are part of the partial object. 2682 addr += words_to_skip; 2683 if (partial_obj_size == words_to_skip) { 2684 // Find the first live word past the partial object. 2685 addr = bitmap->find_obj_beg(addr, src_region_end); 2686 assert(addr < src_region_end, "wrong src region"); 2687 } 2688 return addr; 2689 } 2690 2691 // Skip over the partial object (if any). 2692 if (partial_obj_size != 0) { 2693 words_to_skip -= partial_obj_size; 2694 addr += partial_obj_size; 2695 } 2696 2697 // Skip over live words due to objects that start in the region. 2698 addr = skip_live_words(addr, src_region_end, words_to_skip); 2699 assert(addr < src_region_end, "wrong src region"); 2700 return addr; 2701 } 2702 2703 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, 2704 SpaceId src_space_id, 2705 size_t beg_region, 2706 HeapWord* end_addr) 2707 { 2708 ParallelCompactData& sd = summary_data(); 2709 2710 #ifdef ASSERT 2711 MutableSpace* const src_space = _space_info[src_space_id].space(); 2712 HeapWord* const beg_addr = sd.region_to_addr(beg_region); 2713 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(), 2714 "src_space_id does not match beg_addr"); 2715 assert(src_space->contains(end_addr) || end_addr == src_space->end(), 2716 "src_space_id does not match end_addr"); 2717 #endif // #ifdef ASSERT 2718 2719 RegionData* const beg = sd.region(beg_region); 2720 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr)); 2721 2722 // Regions up to new_top() are enqueued if they become available. 2723 HeapWord* const new_top = _space_info[src_space_id].new_top(); 2724 RegionData* const enqueue_end = 2725 sd.addr_to_region_ptr(sd.region_align_up(new_top)); 2726 2727 for (RegionData* cur = beg; cur < end; ++cur) { 2728 assert(cur->data_size() > 0, "region must have live data"); 2729 cur->decrement_destination_count(); 2730 if (cur < enqueue_end && cur->available() && cur->claim()) { 2731 cm->push_region(sd.region(cur)); 2732 } 2733 } 2734 } 2735 2736 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure, 2737 SpaceId& src_space_id, 2738 HeapWord*& src_space_top, 2739 HeapWord* end_addr) 2740 { 2741 typedef ParallelCompactData::RegionData RegionData; 2742 2743 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2744 const size_t region_size = ParallelCompactData::RegionSize; 2745 2746 size_t src_region_idx = 0; 2747 2748 // Skip empty regions (if any) up to the top of the space. 2749 HeapWord* const src_aligned_up = sd.region_align_up(end_addr); 2750 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up); 2751 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top); 2752 const RegionData* const top_region_ptr = 2753 sd.addr_to_region_ptr(top_aligned_up); 2754 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) { 2755 ++src_region_ptr; 2756 } 2757 2758 if (src_region_ptr < top_region_ptr) { 2759 // The next source region is in the current space. Update src_region_idx 2760 // and the source address to match src_region_ptr. 2761 src_region_idx = sd.region(src_region_ptr); 2762 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx); 2763 if (src_region_addr > closure.source()) { 2764 closure.set_source(src_region_addr); 2765 } 2766 return src_region_idx; 2767 } 2768 2769 // Switch to a new source space and find the first non-empty region. 2770 unsigned int space_id = src_space_id + 1; 2771 assert(space_id < last_space_id, "not enough spaces"); 2772 2773 HeapWord* const destination = closure.destination(); 2774 2775 do { 2776 MutableSpace* space = _space_info[space_id].space(); 2777 HeapWord* const bottom = space->bottom(); 2778 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom); 2779 2780 // Iterate over the spaces that do not compact into themselves. 2781 if (bottom_cp->destination() != bottom) { 2782 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 2783 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 2784 2785 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) { 2786 if (src_cp->live_obj_size() > 0) { 2787 // Found it. 2788 assert(src_cp->destination() == destination, 2789 "first live obj in the space must match the destination"); 2790 assert(src_cp->partial_obj_size() == 0, 2791 "a space cannot begin with a partial obj"); 2792 2793 src_space_id = SpaceId(space_id); 2794 src_space_top = space->top(); 2795 const size_t src_region_idx = sd.region(src_cp); 2796 closure.set_source(sd.region_to_addr(src_region_idx)); 2797 return src_region_idx; 2798 } else { 2799 assert(src_cp->data_size() == 0, "sanity"); 2800 } 2801 } 2802 } 2803 } while (++space_id < last_space_id); 2804 2805 assert(false, "no source region was found"); 2806 return 0; 2807 } 2808 2809 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx) 2810 { 2811 typedef ParMarkBitMap::IterationStatus IterationStatus; 2812 const size_t RegionSize = ParallelCompactData::RegionSize; 2813 ParMarkBitMap* const bitmap = mark_bitmap(); 2814 ParallelCompactData& sd = summary_data(); 2815 RegionData* const region_ptr = sd.region(region_idx); 2816 2817 // Get the items needed to construct the closure. 2818 HeapWord* dest_addr = sd.region_to_addr(region_idx); 2819 SpaceId dest_space_id = space_id(dest_addr); 2820 ObjectStartArray* start_array = _space_info[dest_space_id].start_array(); 2821 HeapWord* new_top = _space_info[dest_space_id].new_top(); 2822 assert(dest_addr < new_top, "sanity"); 2823 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize); 2824 2825 // Get the source region and related info. 2826 size_t src_region_idx = region_ptr->source_region(); 2827 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx)); 2828 HeapWord* src_space_top = _space_info[src_space_id].space()->top(); 2829 2830 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 2831 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx)); 2832 2833 // Adjust src_region_idx to prepare for decrementing destination counts (the 2834 // destination count is not decremented when a region is copied to itself). 2835 if (src_region_idx == region_idx) { 2836 src_region_idx += 1; 2837 } 2838 2839 if (bitmap->is_unmarked(closure.source())) { 2840 // The first source word is in the middle of an object; copy the remainder 2841 // of the object or as much as will fit. The fact that pointer updates were 2842 // deferred will be noted when the object header is processed. 2843 HeapWord* const old_src_addr = closure.source(); 2844 closure.copy_partial_obj(); 2845 if (closure.is_full()) { 2846 decrement_destination_counts(cm, src_space_id, src_region_idx, 2847 closure.source()); 2848 region_ptr->set_deferred_obj_addr(NULL); 2849 region_ptr->set_completed(); 2850 return; 2851 } 2852 2853 HeapWord* const end_addr = sd.region_align_down(closure.source()); 2854 if (sd.region_align_down(old_src_addr) != end_addr) { 2855 // The partial object was copied from more than one source region. 2856 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2857 2858 // Move to the next source region, possibly switching spaces as well. All 2859 // args except end_addr may be modified. 2860 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2861 end_addr); 2862 } 2863 } 2864 2865 do { 2866 HeapWord* const cur_addr = closure.source(); 2867 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1), 2868 src_space_top); 2869 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr); 2870 2871 if (status == ParMarkBitMap::incomplete) { 2872 // The last obj that starts in the source region does not end in the 2873 // region. 2874 assert(closure.source() < end_addr, "sanity"); 2875 HeapWord* const obj_beg = closure.source(); 2876 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(), 2877 src_space_top); 2878 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end); 2879 if (obj_end < range_end) { 2880 // The end was found; the entire object will fit. 2881 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end)); 2882 assert(status != ParMarkBitMap::would_overflow, "sanity"); 2883 } else { 2884 // The end was not found; the object will not fit. 2885 assert(range_end < src_space_top, "obj cannot cross space boundary"); 2886 status = ParMarkBitMap::would_overflow; 2887 } 2888 } 2889 2890 if (status == ParMarkBitMap::would_overflow) { 2891 // The last object did not fit. Note that interior oop updates were 2892 // deferred, then copy enough of the object to fill the region. 2893 region_ptr->set_deferred_obj_addr(closure.destination()); 2894 status = closure.copy_until_full(); // copies from closure.source() 2895 2896 decrement_destination_counts(cm, src_space_id, src_region_idx, 2897 closure.source()); 2898 region_ptr->set_completed(); 2899 return; 2900 } 2901 2902 if (status == ParMarkBitMap::full) { 2903 decrement_destination_counts(cm, src_space_id, src_region_idx, 2904 closure.source()); 2905 region_ptr->set_deferred_obj_addr(NULL); 2906 region_ptr->set_completed(); 2907 return; 2908 } 2909 2910 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2911 2912 // Move to the next source region, possibly switching spaces as well. All 2913 // args except end_addr may be modified. 2914 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2915 end_addr); 2916 } while (true); 2917 } 2918 2919 void PSParallelCompact::fill_blocks(size_t region_idx) 2920 { 2921 // Fill in the block table elements for the specified region. Each block 2922 // table element holds the number of live words in the region that are to the 2923 // left of the first object that starts in the block. Thus only blocks in 2924 // which an object starts need to be filled. 2925 // 2926 // The algorithm scans the section of the bitmap that corresponds to the 2927 // region, keeping a running total of the live words. When an object start is 2928 // found, if it's the first to start in the block that contains it, the 2929 // current total is written to the block table element. 2930 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize; 2931 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize; 2932 const size_t RegionSize = ParallelCompactData::RegionSize; 2933 2934 ParallelCompactData& sd = summary_data(); 2935 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size(); 2936 if (partial_obj_size >= RegionSize) { 2937 return; // No objects start in this region. 2938 } 2939 2940 // Ensure the first loop iteration decides that the block has changed. 2941 size_t cur_block = sd.block_count(); 2942 2943 const ParMarkBitMap* const bitmap = mark_bitmap(); 2944 2945 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment; 2946 assert((size_t)1 << Log2BitsPerBlock == 2947 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity"); 2948 2949 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize); 2950 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize); 2951 size_t live_bits = bitmap->words_to_bits(partial_obj_size); 2952 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end); 2953 while (beg_bit < range_end) { 2954 const size_t new_block = beg_bit >> Log2BitsPerBlock; 2955 if (new_block != cur_block) { 2956 cur_block = new_block; 2957 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits)); 2958 } 2959 2960 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end); 2961 if (end_bit < range_end - 1) { 2962 live_bits += end_bit - beg_bit + 1; 2963 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end); 2964 } else { 2965 return; 2966 } 2967 } 2968 } 2969 2970 void 2971 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) { 2972 const MutableSpace* sp = space(space_id); 2973 if (sp->is_empty()) { 2974 return; 2975 } 2976 2977 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2978 ParMarkBitMap* const bitmap = mark_bitmap(); 2979 HeapWord* const dp_addr = dense_prefix(space_id); 2980 HeapWord* beg_addr = sp->bottom(); 2981 HeapWord* end_addr = sp->top(); 2982 2983 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix"); 2984 2985 const size_t beg_region = sd.addr_to_region_idx(beg_addr); 2986 const size_t dp_region = sd.addr_to_region_idx(dp_addr); 2987 if (beg_region < dp_region) { 2988 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region); 2989 } 2990 2991 // The destination of the first live object that starts in the region is one 2992 // past the end of the partial object entering the region (if any). 2993 HeapWord* const dest_addr = sd.partial_obj_end(dp_region); 2994 HeapWord* const new_top = _space_info[space_id].new_top(); 2995 assert(new_top >= dest_addr, "bad new_top value"); 2996 const size_t words = pointer_delta(new_top, dest_addr); 2997 2998 if (words > 0) { 2999 ObjectStartArray* start_array = _space_info[space_id].start_array(); 3000 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 3001 3002 ParMarkBitMap::IterationStatus status; 3003 status = bitmap->iterate(&closure, dest_addr, end_addr); 3004 assert(status == ParMarkBitMap::full, "iteration not complete"); 3005 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr, 3006 "live objects skipped because closure is full"); 3007 } 3008 } 3009 3010 jlong PSParallelCompact::millis_since_last_gc() { 3011 // We need a monotonically non-decreasing time in ms but 3012 // os::javaTimeMillis() does not guarantee monotonicity. 3013 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3014 jlong ret_val = now - _time_of_last_gc; 3015 // XXX See note in genCollectedHeap::millis_since_last_gc(). 3016 if (ret_val < 0) { 3017 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 3018 return 0; 3019 } 3020 return ret_val; 3021 } 3022 3023 void PSParallelCompact::reset_millis_since_last_gc() { 3024 // We need a monotonically non-decreasing time in ms but 3025 // os::javaTimeMillis() does not guarantee monotonicity. 3026 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3027 } 3028 3029 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() 3030 { 3031 if (source() != destination()) { 3032 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3033 Copy::aligned_conjoint_words(source(), destination(), words_remaining()); 3034 } 3035 update_state(words_remaining()); 3036 assert(is_full(), "sanity"); 3037 return ParMarkBitMap::full; 3038 } 3039 3040 void MoveAndUpdateClosure::copy_partial_obj() 3041 { 3042 size_t words = words_remaining(); 3043 3044 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end()); 3045 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end); 3046 if (end_addr < range_end) { 3047 words = bitmap()->obj_size(source(), end_addr); 3048 } 3049 3050 // This test is necessary; if omitted, the pointer updates to a partial object 3051 // that crosses the dense prefix boundary could be overwritten. 3052 if (source() != destination()) { 3053 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3054 Copy::aligned_conjoint_words(source(), destination(), words); 3055 } 3056 update_state(words); 3057 } 3058 3059 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3060 PSParallelCompact::AdjustPointerClosure closure(cm); 3061 oop_oop_iterate_oop_maps<true>(obj, &closure); 3062 } 3063 3064 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3065 InstanceKlass::oop_pc_update_pointers(obj, cm); 3066 3067 PSParallelCompact::AdjustPointerClosure closure(cm); 3068 oop_oop_iterate_statics<true>(obj, &closure); 3069 } 3070 3071 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3072 InstanceKlass::oop_pc_update_pointers(obj, cm); 3073 } 3074 3075 #ifdef ASSERT 3076 template <class T> static void trace_reference_gc(const char *s, oop obj, 3077 T* referent_addr, 3078 T* next_addr, 3079 T* discovered_addr) { 3080 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj)); 3081 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3082 p2i(referent_addr), referent_addr ? p2i((oop)RawAccess<>::oop_load(referent_addr)) : NULL); 3083 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3084 p2i(next_addr), next_addr ? p2i((oop)RawAccess<>::oop_load(next_addr)) : NULL); 3085 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3086 p2i(discovered_addr), discovered_addr ? p2i((oop)RawAccess<>::oop_load(discovered_addr)) : NULL); 3087 } 3088 #endif 3089 3090 template <class T> 3091 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) { 3092 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr_raw(obj); 3093 PSParallelCompact::adjust_pointer(referent_addr, cm); 3094 T* next_addr = (T*)java_lang_ref_Reference::next_addr_raw(obj); 3095 PSParallelCompact::adjust_pointer(next_addr, cm); 3096 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr_raw(obj); 3097 PSParallelCompact::adjust_pointer(discovered_addr, cm); 3098 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj, 3099 referent_addr, next_addr, discovered_addr);) 3100 } 3101 3102 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3103 InstanceKlass::oop_pc_update_pointers(obj, cm); 3104 3105 if (UseCompressedOops) { 3106 oop_pc_update_pointers_specialized<narrowOop>(obj, cm); 3107 } else { 3108 oop_pc_update_pointers_specialized<oop>(obj, cm); 3109 } 3110 } 3111 3112 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3113 assert(obj->is_objArray(), "obj must be obj array"); 3114 PSParallelCompact::AdjustPointerClosure closure(cm); 3115 oop_oop_iterate_elements<true>(objArrayOop(obj), &closure); 3116 } 3117 3118 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3119 assert(obj->is_typeArray(),"must be a type array"); 3120 } 3121 3122 ParMarkBitMapClosure::IterationStatus 3123 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) { 3124 assert(destination() != NULL, "sanity"); 3125 assert(bitmap()->obj_size(addr) == words, "bad size"); 3126 3127 _source = addr; 3128 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) == 3129 destination(), "wrong destination"); 3130 3131 if (words > words_remaining()) { 3132 return ParMarkBitMap::would_overflow; 3133 } 3134 3135 // The start_array must be updated even if the object is not moving. 3136 if (_start_array != NULL) { 3137 _start_array->allocate_block(destination()); 3138 } 3139 3140 if (destination() != source()) { 3141 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3142 Copy::aligned_conjoint_words(source(), destination(), words); 3143 } 3144 3145 oop moved_oop = (oop) destination(); 3146 compaction_manager()->update_contents(moved_oop); 3147 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop)); 3148 3149 update_state(words); 3150 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity"); 3151 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete; 3152 } 3153 3154 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm, 3155 ParCompactionManager* cm, 3156 PSParallelCompact::SpaceId space_id) : 3157 ParMarkBitMapClosure(mbm, cm), 3158 _space_id(space_id), 3159 _start_array(PSParallelCompact::start_array(space_id)) 3160 { 3161 } 3162 3163 // Updates the references in the object to their new values. 3164 ParMarkBitMapClosure::IterationStatus 3165 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) { 3166 do_addr(addr); 3167 return ParMarkBitMap::incomplete; 3168 } 3169 3170 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : 3171 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), 3172 _start_array(PSParallelCompact::start_array(space_id)) 3173 { 3174 assert(space_id == PSParallelCompact::old_space_id, 3175 "cannot use FillClosure in the young gen"); 3176 } 3177 3178 ParMarkBitMapClosure::IterationStatus 3179 FillClosure::do_addr(HeapWord* addr, size_t size) { 3180 CollectedHeap::fill_with_objects(addr, size); 3181 HeapWord* const end = addr + size; 3182 do { 3183 _start_array->allocate_block(addr); 3184 addr += oop(addr)->size(); 3185 } while (addr < end); 3186 return ParMarkBitMap::incomplete; 3187 }