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