1 /* 2 * Copyright (c) 2005, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "aot/aotLoader.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "code/codeCache.hpp" 31 #include "gc/parallel/gcTaskManager.hpp" 32 #include "gc/parallel/parallelScavengeHeap.inline.hpp" 33 #include "gc/parallel/pcTasks.hpp" 34 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 35 #include "gc/parallel/psCompactionManager.inline.hpp" 36 #include "gc/parallel/psMarkSweep.hpp" 37 #include "gc/parallel/psMarkSweepDecorator.hpp" 38 #include "gc/parallel/psOldGen.hpp" 39 #include "gc/parallel/psParallelCompact.inline.hpp" 40 #include "gc/parallel/psPromotionManager.inline.hpp" 41 #include "gc/parallel/psScavenge.hpp" 42 #include "gc/parallel/psYoungGen.hpp" 43 #include "gc/shared/gcCause.hpp" 44 #include "gc/shared/gcHeapSummary.hpp" 45 #include "gc/shared/gcId.hpp" 46 #include "gc/shared/gcLocker.inline.hpp" 47 #include "gc/shared/gcTimer.hpp" 48 #include "gc/shared/gcTrace.hpp" 49 #include "gc/shared/gcTraceTime.inline.hpp" 50 #include "gc/shared/isGCActiveMark.hpp" 51 #include "gc/shared/referencePolicy.hpp" 52 #include "gc/shared/referenceProcessor.hpp" 53 #include "gc/shared/spaceDecorator.hpp" 54 #include "logging/log.hpp" 55 #include "memory/resourceArea.hpp" 56 #include "oops/instanceKlass.inline.hpp" 57 #include "oops/instanceMirrorKlass.inline.hpp" 58 #include "oops/methodData.hpp" 59 #include "oops/objArrayKlass.inline.hpp" 60 #include "oops/oop.inline.hpp" 61 #include "runtime/atomic.hpp" 62 #include "runtime/fprofiler.hpp" 63 #include "runtime/safepoint.hpp" 64 #include "runtime/vmThread.hpp" 65 #include "services/management.hpp" 66 #include "services/memTracker.hpp" 67 #include "services/memoryService.hpp" 68 #include "utilities/events.hpp" 69 #include "utilities/stack.inline.hpp" 70 71 #include <math.h> 72 73 // All sizes are in HeapWords. 74 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words 75 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize; 76 const size_t ParallelCompactData::RegionSizeBytes = 77 RegionSize << LogHeapWordSize; 78 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1; 79 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1; 80 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask; 81 82 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words 83 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize; 84 const size_t ParallelCompactData::BlockSizeBytes = 85 BlockSize << LogHeapWordSize; 86 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1; 87 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1; 88 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask; 89 90 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize; 91 const size_t ParallelCompactData::Log2BlocksPerRegion = 92 Log2RegionSize - Log2BlockSize; 93 94 const ParallelCompactData::RegionData::region_sz_t 95 ParallelCompactData::RegionData::dc_shift = 27; 96 97 const ParallelCompactData::RegionData::region_sz_t 98 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift; 99 100 const ParallelCompactData::RegionData::region_sz_t 101 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift; 102 103 const ParallelCompactData::RegionData::region_sz_t 104 ParallelCompactData::RegionData::los_mask = ~dc_mask; 105 106 const ParallelCompactData::RegionData::region_sz_t 107 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift; 108 109 const ParallelCompactData::RegionData::region_sz_t 110 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift; 111 112 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; 113 114 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; 115 116 double PSParallelCompact::_dwl_mean; 117 double PSParallelCompact::_dwl_std_dev; 118 double PSParallelCompact::_dwl_first_term; 119 double PSParallelCompact::_dwl_adjustment; 120 #ifdef ASSERT 121 bool PSParallelCompact::_dwl_initialized = false; 122 #endif // #ifdef ASSERT 123 124 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size, 125 HeapWord* destination) 126 { 127 assert(src_region_idx != 0, "invalid src_region_idx"); 128 assert(partial_obj_size != 0, "invalid partial_obj_size argument"); 129 assert(destination != NULL, "invalid destination argument"); 130 131 _src_region_idx = src_region_idx; 132 _partial_obj_size = partial_obj_size; 133 _destination = destination; 134 135 // These fields may not be updated below, so make sure they're clear. 136 assert(_dest_region_addr == NULL, "should have been cleared"); 137 assert(_first_src_addr == NULL, "should have been cleared"); 138 139 // Determine the number of destination regions for the partial object. 140 HeapWord* const last_word = destination + partial_obj_size - 1; 141 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 142 HeapWord* const beg_region_addr = sd.region_align_down(destination); 143 HeapWord* const end_region_addr = sd.region_align_down(last_word); 144 145 if (beg_region_addr == end_region_addr) { 146 // One destination region. 147 _destination_count = 1; 148 if (end_region_addr == destination) { 149 // The destination falls on a region boundary, thus the first word of the 150 // partial object will be the first word copied to the destination region. 151 _dest_region_addr = end_region_addr; 152 _first_src_addr = sd.region_to_addr(src_region_idx); 153 } 154 } else { 155 // Two destination regions. When copied, the partial object will cross a 156 // destination region boundary, so a word somewhere within the partial 157 // object will be the first word copied to the second destination region. 158 _destination_count = 2; 159 _dest_region_addr = end_region_addr; 160 const size_t ofs = pointer_delta(end_region_addr, destination); 161 assert(ofs < _partial_obj_size, "sanity"); 162 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs; 163 } 164 } 165 166 void SplitInfo::clear() 167 { 168 _src_region_idx = 0; 169 _partial_obj_size = 0; 170 _destination = NULL; 171 _destination_count = 0; 172 _dest_region_addr = NULL; 173 _first_src_addr = NULL; 174 assert(!is_valid(), "sanity"); 175 } 176 177 #ifdef ASSERT 178 void SplitInfo::verify_clear() 179 { 180 assert(_src_region_idx == 0, "not clear"); 181 assert(_partial_obj_size == 0, "not clear"); 182 assert(_destination == NULL, "not clear"); 183 assert(_destination_count == 0, "not clear"); 184 assert(_dest_region_addr == NULL, "not clear"); 185 assert(_first_src_addr == NULL, "not clear"); 186 } 187 #endif // #ifdef ASSERT 188 189 190 void PSParallelCompact::print_on_error(outputStream* st) { 191 _mark_bitmap.print_on_error(st); 192 } 193 194 #ifndef PRODUCT 195 const char* PSParallelCompact::space_names[] = { 196 "old ", "eden", "from", "to " 197 }; 198 199 void PSParallelCompact::print_region_ranges() { 200 if (!log_develop_is_enabled(Trace, gc, compaction)) { 201 return; 202 } 203 Log(gc, compaction) log; 204 ResourceMark rm; 205 Universe::print_on(log.trace_stream()); 206 log.trace("space bottom top end new_top"); 207 log.trace("------ ---------- ---------- ---------- ----------"); 208 209 for (unsigned int id = 0; id < last_space_id; ++id) { 210 const MutableSpace* space = _space_info[id].space(); 211 log.trace("%u %s " 212 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " 213 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", 214 id, space_names[id], 215 summary_data().addr_to_region_idx(space->bottom()), 216 summary_data().addr_to_region_idx(space->top()), 217 summary_data().addr_to_region_idx(space->end()), 218 summary_data().addr_to_region_idx(_space_info[id].new_top())); 219 } 220 } 221 222 void 223 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c) 224 { 225 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7) 226 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5) 227 228 ParallelCompactData& sd = PSParallelCompact::summary_data(); 229 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0; 230 log_develop_trace(gc, compaction)( 231 REGION_IDX_FORMAT " " PTR_FORMAT " " 232 REGION_IDX_FORMAT " " PTR_FORMAT " " 233 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " " 234 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d", 235 i, p2i(c->data_location()), dci, p2i(c->destination()), 236 c->partial_obj_size(), c->live_obj_size(), 237 c->data_size(), c->source_region(), c->destination_count()); 238 239 #undef REGION_IDX_FORMAT 240 #undef REGION_DATA_FORMAT 241 } 242 243 void 244 print_generic_summary_data(ParallelCompactData& summary_data, 245 HeapWord* const beg_addr, 246 HeapWord* const end_addr) 247 { 248 size_t total_words = 0; 249 size_t i = summary_data.addr_to_region_idx(beg_addr); 250 const size_t last = summary_data.addr_to_region_idx(end_addr); 251 HeapWord* pdest = 0; 252 253 while (i < last) { 254 ParallelCompactData::RegionData* c = summary_data.region(i); 255 if (c->data_size() != 0 || c->destination() != pdest) { 256 print_generic_summary_region(i, c); 257 total_words += c->data_size(); 258 pdest = c->destination(); 259 } 260 ++i; 261 } 262 263 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); 264 } 265 266 void 267 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data, 268 HeapWord* const beg_addr, 269 HeapWord* const end_addr) { 270 ::print_generic_summary_data(summary_data,beg_addr, end_addr); 271 } 272 273 void 274 print_generic_summary_data(ParallelCompactData& summary_data, 275 SpaceInfo* space_info) 276 { 277 if (!log_develop_is_enabled(Trace, gc, compaction)) { 278 return; 279 } 280 281 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { 282 const MutableSpace* space = space_info[id].space(); 283 print_generic_summary_data(summary_data, space->bottom(), 284 MAX2(space->top(), space_info[id].new_top())); 285 } 286 } 287 288 void 289 print_initial_summary_data(ParallelCompactData& summary_data, 290 const MutableSpace* space) { 291 if (space->top() == space->bottom()) { 292 return; 293 } 294 295 const size_t region_size = ParallelCompactData::RegionSize; 296 typedef ParallelCompactData::RegionData RegionData; 297 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top()); 298 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up); 299 const RegionData* c = summary_data.region(end_region - 1); 300 HeapWord* end_addr = c->destination() + c->data_size(); 301 const size_t live_in_space = pointer_delta(end_addr, space->bottom()); 302 303 // Print (and count) the full regions at the beginning of the space. 304 size_t full_region_count = 0; 305 size_t i = summary_data.addr_to_region_idx(space->bottom()); 306 while (i < end_region && summary_data.region(i)->data_size() == region_size) { 307 ParallelCompactData::RegionData* c = summary_data.region(i); 308 log_develop_trace(gc, compaction)( 309 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 310 i, p2i(c->destination()), 311 c->partial_obj_size(), c->live_obj_size(), 312 c->data_size(), c->source_region(), c->destination_count()); 313 ++full_region_count; 314 ++i; 315 } 316 317 size_t live_to_right = live_in_space - full_region_count * region_size; 318 319 double max_reclaimed_ratio = 0.0; 320 size_t max_reclaimed_ratio_region = 0; 321 size_t max_dead_to_right = 0; 322 size_t max_live_to_right = 0; 323 324 // Print the 'reclaimed ratio' for regions while there is something live in 325 // the region or to the right of it. The remaining regions are empty (and 326 // uninteresting), and computing the ratio will result in division by 0. 327 while (i < end_region && live_to_right > 0) { 328 c = summary_data.region(i); 329 HeapWord* const region_addr = summary_data.region_to_addr(i); 330 const size_t used_to_right = pointer_delta(space->top(), region_addr); 331 const size_t dead_to_right = used_to_right - live_to_right; 332 const double reclaimed_ratio = double(dead_to_right) / live_to_right; 333 334 if (reclaimed_ratio > max_reclaimed_ratio) { 335 max_reclaimed_ratio = reclaimed_ratio; 336 max_reclaimed_ratio_region = i; 337 max_dead_to_right = dead_to_right; 338 max_live_to_right = live_to_right; 339 } 340 341 ParallelCompactData::RegionData* c = summary_data.region(i); 342 log_develop_trace(gc, compaction)( 343 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d" 344 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), 345 i, p2i(c->destination()), 346 c->partial_obj_size(), c->live_obj_size(), 347 c->data_size(), c->source_region(), c->destination_count(), 348 reclaimed_ratio, dead_to_right, live_to_right); 349 350 351 live_to_right -= c->data_size(); 352 ++i; 353 } 354 355 // Any remaining regions are empty. Print one more if there is one. 356 if (i < end_region) { 357 ParallelCompactData::RegionData* c = summary_data.region(i); 358 log_develop_trace(gc, compaction)( 359 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 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 } 364 365 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", 366 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio); 367 } 368 369 void 370 print_initial_summary_data(ParallelCompactData& summary_data, 371 SpaceInfo* space_info) { 372 if (!log_develop_is_enabled(Trace, gc, compaction)) { 373 return; 374 } 375 376 unsigned int id = PSParallelCompact::old_space_id; 377 const MutableSpace* space; 378 do { 379 space = space_info[id].space(); 380 print_initial_summary_data(summary_data, space); 381 } while (++id < PSParallelCompact::eden_space_id); 382 383 do { 384 space = space_info[id].space(); 385 print_generic_summary_data(summary_data, space->bottom(), space->top()); 386 } while (++id < PSParallelCompact::last_space_id); 387 } 388 #endif // #ifndef PRODUCT 389 390 #ifdef ASSERT 391 size_t add_obj_count; 392 size_t add_obj_size; 393 size_t mark_bitmap_count; 394 size_t mark_bitmap_size; 395 #endif // #ifdef ASSERT 396 397 ParallelCompactData::ParallelCompactData() 398 { 399 _region_start = 0; 400 401 _region_vspace = 0; 402 _reserved_byte_size = 0; 403 _region_data = 0; 404 _region_count = 0; 405 406 _block_vspace = 0; 407 _block_data = 0; 408 _block_count = 0; 409 } 410 411 bool ParallelCompactData::initialize(MemRegion covered_region) 412 { 413 _region_start = covered_region.start(); 414 const size_t region_size = covered_region.word_size(); 415 DEBUG_ONLY(_region_end = _region_start + region_size;) 416 417 assert(region_align_down(_region_start) == _region_start, 418 "region start not aligned"); 419 assert((region_size & RegionSizeOffsetMask) == 0, 420 "region size not a multiple of RegionSize"); 421 422 bool result = initialize_region_data(region_size) && initialize_block_data(); 423 return result; 424 } 425 426 PSVirtualSpace* 427 ParallelCompactData::create_vspace(size_t count, size_t element_size) 428 { 429 const size_t raw_bytes = count * element_size; 430 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10); 431 const size_t granularity = os::vm_allocation_granularity(); 432 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity)); 433 434 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : 435 MAX2(page_sz, granularity); 436 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0); 437 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(), 438 rs.size()); 439 440 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 441 442 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); 443 if (vspace != 0) { 444 if (vspace->expand_by(_reserved_byte_size)) { 445 return vspace; 446 } 447 delete vspace; 448 // Release memory reserved in the space. 449 rs.release(); 450 } 451 452 return 0; 453 } 454 455 bool ParallelCompactData::initialize_region_data(size_t region_size) 456 { 457 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize; 458 _region_vspace = create_vspace(count, sizeof(RegionData)); 459 if (_region_vspace != 0) { 460 _region_data = (RegionData*)_region_vspace->reserved_low_addr(); 461 _region_count = count; 462 return true; 463 } 464 return false; 465 } 466 467 bool ParallelCompactData::initialize_block_data() 468 { 469 assert(_region_count != 0, "region data must be initialized first"); 470 const size_t count = _region_count << Log2BlocksPerRegion; 471 _block_vspace = create_vspace(count, sizeof(BlockData)); 472 if (_block_vspace != 0) { 473 _block_data = (BlockData*)_block_vspace->reserved_low_addr(); 474 _block_count = count; 475 return true; 476 } 477 return false; 478 } 479 480 void ParallelCompactData::clear() 481 { 482 memset(_region_data, 0, _region_vspace->committed_size()); 483 memset(_block_data, 0, _block_vspace->committed_size()); 484 } 485 486 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) { 487 assert(beg_region <= _region_count, "beg_region out of range"); 488 assert(end_region <= _region_count, "end_region out of range"); 489 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize"); 490 491 const size_t region_cnt = end_region - beg_region; 492 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData)); 493 494 const size_t beg_block = beg_region * BlocksPerRegion; 495 const size_t block_cnt = region_cnt * BlocksPerRegion; 496 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData)); 497 } 498 499 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const 500 { 501 const RegionData* cur_cp = region(region_idx); 502 const RegionData* const end_cp = region(region_count() - 1); 503 504 HeapWord* result = region_to_addr(region_idx); 505 if (cur_cp < end_cp) { 506 do { 507 result += cur_cp->partial_obj_size(); 508 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp); 509 } 510 return result; 511 } 512 513 void ParallelCompactData::add_obj(HeapWord* addr, size_t len) 514 { 515 const size_t obj_ofs = pointer_delta(addr, _region_start); 516 const size_t beg_region = obj_ofs >> Log2RegionSize; 517 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize; 518 519 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);) 520 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);) 521 522 if (beg_region == end_region) { 523 // All in one region. 524 _region_data[beg_region].add_live_obj(len); 525 return; 526 } 527 528 // First region. 529 const size_t beg_ofs = region_offset(addr); 530 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs); 531 532 Klass* klass = ((oop)addr)->klass(); 533 // Middle regions--completely spanned by this object. 534 for (size_t region = beg_region + 1; region < end_region; ++region) { 535 _region_data[region].set_partial_obj_size(RegionSize); 536 _region_data[region].set_partial_obj_addr(addr); 537 } 538 539 // Last region. 540 const size_t end_ofs = region_offset(addr + len - 1); 541 _region_data[end_region].set_partial_obj_size(end_ofs + 1); 542 _region_data[end_region].set_partial_obj_addr(addr); 543 } 544 545 void 546 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) 547 { 548 assert(region_offset(beg) == 0, "not RegionSize aligned"); 549 assert(region_offset(end) == 0, "not RegionSize aligned"); 550 551 size_t cur_region = addr_to_region_idx(beg); 552 const size_t end_region = addr_to_region_idx(end); 553 HeapWord* addr = beg; 554 while (cur_region < end_region) { 555 _region_data[cur_region].set_destination(addr); 556 _region_data[cur_region].set_destination_count(0); 557 _region_data[cur_region].set_source_region(cur_region); 558 _region_data[cur_region].set_data_location(addr); 559 560 // Update live_obj_size so the region appears completely full. 561 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size(); 562 _region_data[cur_region].set_live_obj_size(live_size); 563 564 ++cur_region; 565 addr += RegionSize; 566 } 567 } 568 569 // Find the point at which a space can be split and, if necessary, record the 570 // split point. 571 // 572 // If the current src region (which overflowed the destination space) doesn't 573 // have a partial object, the split point is at the beginning of the current src 574 // region (an "easy" split, no extra bookkeeping required). 575 // 576 // If the current src region has a partial object, the split point is in the 577 // region where that partial object starts (call it the split_region). If 578 // split_region has a partial object, then the split point is just after that 579 // partial object (a "hard" split where we have to record the split data and 580 // zero the partial_obj_size field). With a "hard" split, we know that the 581 // partial_obj ends within split_region because the partial object that caused 582 // the overflow starts in split_region. If split_region doesn't have a partial 583 // obj, then the split is at the beginning of split_region (another "easy" 584 // split). 585 HeapWord* 586 ParallelCompactData::summarize_split_space(size_t src_region, 587 SplitInfo& split_info, 588 HeapWord* destination, 589 HeapWord* target_end, 590 HeapWord** target_next) 591 { 592 assert(destination <= target_end, "sanity"); 593 assert(destination + _region_data[src_region].data_size() > target_end, 594 "region should not fit into target space"); 595 assert(is_region_aligned(target_end), "sanity"); 596 597 size_t split_region = src_region; 598 HeapWord* split_destination = destination; 599 size_t partial_obj_size = _region_data[src_region].partial_obj_size(); 600 601 if (destination + partial_obj_size > target_end) { 602 // The split point is just after the partial object (if any) in the 603 // src_region that contains the start of the object that overflowed the 604 // destination space. 605 // 606 // Find the start of the "overflow" object and set split_region to the 607 // region containing it. 608 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr(); 609 split_region = addr_to_region_idx(overflow_obj); 610 611 // Clear the source_region field of all destination regions whose first word 612 // came from data after the split point (a non-null source_region field 613 // implies a region must be filled). 614 // 615 // An alternative to the simple loop below: clear during post_compact(), 616 // which uses memcpy instead of individual stores, and is easy to 617 // parallelize. (The downside is that it clears the entire RegionData 618 // object as opposed to just one field.) 619 // 620 // post_compact() would have to clear the summary data up to the highest 621 // address that was written during the summary phase, which would be 622 // 623 // max(top, max(new_top, clear_top)) 624 // 625 // where clear_top is a new field in SpaceInfo. Would have to set clear_top 626 // to target_end. 627 const RegionData* const sr = region(split_region); 628 const size_t beg_idx = 629 addr_to_region_idx(region_align_up(sr->destination() + 630 sr->partial_obj_size())); 631 const size_t end_idx = addr_to_region_idx(target_end); 632 633 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx); 634 for (size_t idx = beg_idx; idx < end_idx; ++idx) { 635 _region_data[idx].set_source_region(0); 636 } 637 638 // Set split_destination and partial_obj_size to reflect the split region. 639 split_destination = sr->destination(); 640 partial_obj_size = sr->partial_obj_size(); 641 } 642 643 // The split is recorded only if a partial object extends onto the region. 644 if (partial_obj_size != 0) { 645 _region_data[split_region].set_partial_obj_size(0); 646 split_info.record(split_region, partial_obj_size, split_destination); 647 } 648 649 // Setup the continuation addresses. 650 *target_next = split_destination + partial_obj_size; 651 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size; 652 653 if (log_develop_is_enabled(Trace, gc, compaction)) { 654 const char * split_type = partial_obj_size == 0 ? "easy" : "hard"; 655 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT, 656 split_type, p2i(source_next), split_region, partial_obj_size); 657 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT, 658 split_type, p2i(split_destination), 659 addr_to_region_idx(split_destination), 660 p2i(*target_next)); 661 662 if (partial_obj_size != 0) { 663 HeapWord* const po_beg = split_info.destination(); 664 HeapWord* const po_end = po_beg + split_info.partial_obj_size(); 665 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT, 666 split_type, 667 p2i(po_beg), addr_to_region_idx(po_beg), 668 p2i(po_end), addr_to_region_idx(po_end)); 669 } 670 } 671 672 return source_next; 673 } 674 675 bool ParallelCompactData::summarize(SplitInfo& split_info, 676 HeapWord* source_beg, HeapWord* source_end, 677 HeapWord** source_next, 678 HeapWord* target_beg, HeapWord* target_end, 679 HeapWord** target_next) 680 { 681 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next; 682 log_develop_trace(gc, compaction)( 683 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT 684 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT, 685 p2i(source_beg), p2i(source_end), p2i(source_next_val), 686 p2i(target_beg), p2i(target_end), p2i(*target_next)); 687 688 size_t cur_region = addr_to_region_idx(source_beg); 689 const size_t end_region = addr_to_region_idx(region_align_up(source_end)); 690 691 HeapWord *dest_addr = target_beg; 692 while (cur_region < end_region) { 693 // The destination must be set even if the region has no data. 694 _region_data[cur_region].set_destination(dest_addr); 695 696 size_t words = _region_data[cur_region].data_size(); 697 if (words > 0) { 698 // If cur_region does not fit entirely into the target space, find a point 699 // at which the source space can be 'split' so that part is copied to the 700 // target space and the rest is copied elsewhere. 701 if (dest_addr + words > target_end) { 702 assert(source_next != NULL, "source_next is NULL when splitting"); 703 *source_next = summarize_split_space(cur_region, split_info, dest_addr, 704 target_end, target_next); 705 return false; 706 } 707 708 // Compute the destination_count for cur_region, and if necessary, update 709 // source_region for a destination region. The source_region field is 710 // updated if cur_region is the first (left-most) region to be copied to a 711 // destination region. 712 // 713 // The destination_count calculation is a bit subtle. A region that has 714 // data that compacts into itself does not count itself as a destination. 715 // This maintains the invariant that a zero count means the region is 716 // available and can be claimed and then filled. 717 uint destination_count = 0; 718 if (split_info.is_split(cur_region)) { 719 // The current region has been split: the partial object will be copied 720 // to one destination space and the remaining data will be copied to 721 // another destination space. Adjust the initial destination_count and, 722 // if necessary, set the source_region field if the partial object will 723 // cross a destination region boundary. 724 destination_count = split_info.destination_count(); 725 if (destination_count == 2) { 726 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr()); 727 _region_data[dest_idx].set_source_region(cur_region); 728 } 729 } 730 731 HeapWord* const last_addr = dest_addr + words - 1; 732 const size_t dest_region_1 = addr_to_region_idx(dest_addr); 733 const size_t dest_region_2 = addr_to_region_idx(last_addr); 734 735 // Initially assume that the destination regions will be the same and 736 // adjust the value below if necessary. Under this assumption, if 737 // cur_region == dest_region_2, then cur_region will be compacted 738 // completely into itself. 739 destination_count += cur_region == dest_region_2 ? 0 : 1; 740 if (dest_region_1 != dest_region_2) { 741 // Destination regions differ; adjust destination_count. 742 destination_count += 1; 743 // Data from cur_region will be copied to the start of dest_region_2. 744 _region_data[dest_region_2].set_source_region(cur_region); 745 } else if (region_offset(dest_addr) == 0) { 746 // Data from cur_region will be copied to the start of the destination 747 // region. 748 _region_data[dest_region_1].set_source_region(cur_region); 749 } 750 751 _region_data[cur_region].set_destination_count(destination_count); 752 _region_data[cur_region].set_data_location(region_to_addr(cur_region)); 753 dest_addr += words; 754 } 755 756 ++cur_region; 757 } 758 759 *target_next = dest_addr; 760 return true; 761 } 762 763 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) { 764 assert(addr != NULL, "Should detect NULL oop earlier"); 765 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap"); 766 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked"); 767 768 // Region covering the object. 769 RegionData* const region_ptr = addr_to_region_ptr(addr); 770 HeapWord* result = region_ptr->destination(); 771 772 // If the entire Region is live, the new location is region->destination + the 773 // offset of the object within in the Region. 774 775 // Run some performance tests to determine if this special case pays off. It 776 // is worth it for pointers into the dense prefix. If the optimization to 777 // avoid pointer updates in regions that only point to the dense prefix is 778 // ever implemented, this should be revisited. 779 if (region_ptr->data_size() == RegionSize) { 780 result += region_offset(addr); 781 return result; 782 } 783 784 // Otherwise, the new location is region->destination + block offset + the 785 // number of live words in the Block that are (a) to the left of addr and (b) 786 // due to objects that start in the Block. 787 788 // Fill in the block table if necessary. This is unsynchronized, so multiple 789 // threads may fill the block table for a region (harmless, since it is 790 // idempotent). 791 if (!region_ptr->blocks_filled()) { 792 PSParallelCompact::fill_blocks(addr_to_region_idx(addr)); 793 region_ptr->set_blocks_filled(); 794 } 795 796 HeapWord* const search_start = block_align_down(addr); 797 const size_t block_offset = addr_to_block_ptr(addr)->offset(); 798 799 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); 800 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr)); 801 result += block_offset + live; 802 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result)); 803 return result; 804 } 805 806 #ifdef ASSERT 807 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) 808 { 809 const size_t* const beg = (const size_t*)vspace->committed_low_addr(); 810 const size_t* const end = (const size_t*)vspace->committed_high_addr(); 811 for (const size_t* p = beg; p < end; ++p) { 812 assert(*p == 0, "not zero"); 813 } 814 } 815 816 void ParallelCompactData::verify_clear() 817 { 818 verify_clear(_region_vspace); 819 verify_clear(_block_vspace); 820 } 821 #endif // #ifdef ASSERT 822 823 STWGCTimer PSParallelCompact::_gc_timer; 824 ParallelOldTracer PSParallelCompact::_gc_tracer; 825 elapsedTimer PSParallelCompact::_accumulated_time; 826 unsigned int PSParallelCompact::_total_invocations = 0; 827 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; 828 jlong PSParallelCompact::_time_of_last_gc = 0; 829 CollectorCounters* PSParallelCompact::_counters = NULL; 830 ParMarkBitMap PSParallelCompact::_mark_bitmap; 831 ParallelCompactData PSParallelCompact::_summary_data; 832 833 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; 834 835 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } 836 837 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) { 838 PSParallelCompact::AdjustPointerClosure closure(_cm); 839 klass->oops_do(&closure); 840 } 841 842 void PSParallelCompact::post_initialize() { 843 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 844 MemRegion mr = heap->reserved_region(); 845 _ref_processor = 846 new ReferenceProcessor(mr, // span 847 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 848 ParallelGCThreads, // mt processing degree 849 true, // mt discovery 850 ParallelGCThreads, // mt discovery degree 851 true, // atomic_discovery 852 &_is_alive_closure); // non-header is alive closure 853 _counters = new CollectorCounters("PSParallelCompact", 1); 854 855 // Initialize static fields in ParCompactionManager. 856 ParCompactionManager::initialize(mark_bitmap()); 857 } 858 859 bool PSParallelCompact::initialize() { 860 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 861 MemRegion mr = heap->reserved_region(); 862 863 // Was the old gen get allocated successfully? 864 if (!heap->old_gen()->is_allocated()) { 865 return false; 866 } 867 868 initialize_space_info(); 869 initialize_dead_wood_limiter(); 870 871 if (!_mark_bitmap.initialize(mr)) { 872 vm_shutdown_during_initialization( 873 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel " 874 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 875 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K)); 876 return false; 877 } 878 879 if (!_summary_data.initialize(mr)) { 880 vm_shutdown_during_initialization( 881 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel " 882 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 883 _summary_data.reserved_byte_size()/K, mr.byte_size()/K)); 884 return false; 885 } 886 887 return true; 888 } 889 890 void PSParallelCompact::initialize_space_info() 891 { 892 memset(&_space_info, 0, sizeof(_space_info)); 893 894 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 895 PSYoungGen* young_gen = heap->young_gen(); 896 897 _space_info[old_space_id].set_space(heap->old_gen()->object_space()); 898 _space_info[eden_space_id].set_space(young_gen->eden_space()); 899 _space_info[from_space_id].set_space(young_gen->from_space()); 900 _space_info[to_space_id].set_space(young_gen->to_space()); 901 902 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); 903 } 904 905 void PSParallelCompact::initialize_dead_wood_limiter() 906 { 907 const size_t max = 100; 908 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; 909 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; 910 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); 911 DEBUG_ONLY(_dwl_initialized = true;) 912 _dwl_adjustment = normal_distribution(1.0); 913 } 914 915 void 916 PSParallelCompact::clear_data_covering_space(SpaceId id) 917 { 918 // At this point, top is the value before GC, new_top() is the value that will 919 // be set at the end of GC. The marking bitmap is cleared to top; nothing 920 // should be marked above top. The summary data is cleared to the larger of 921 // top & new_top. 922 MutableSpace* const space = _space_info[id].space(); 923 HeapWord* const bot = space->bottom(); 924 HeapWord* const top = space->top(); 925 HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); 926 927 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); 928 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top)); 929 _mark_bitmap.clear_range(beg_bit, end_bit); 930 931 const size_t beg_region = _summary_data.addr_to_region_idx(bot); 932 const size_t end_region = 933 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top)); 934 _summary_data.clear_range(beg_region, end_region); 935 936 // Clear the data used to 'split' regions. 937 SplitInfo& split_info = _space_info[id].split_info(); 938 if (split_info.is_valid()) { 939 split_info.clear(); 940 } 941 DEBUG_ONLY(split_info.verify_clear();) 942 } 943 944 void PSParallelCompact::pre_compact() 945 { 946 // Update the from & to space pointers in space_info, since they are swapped 947 // at each young gen gc. Do the update unconditionally (even though a 948 // promotion failure does not swap spaces) because an unknown number of young 949 // collections will have swapped the spaces an unknown number of times. 950 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer); 951 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 952 _space_info[from_space_id].set_space(heap->young_gen()->from_space()); 953 _space_info[to_space_id].set_space(heap->young_gen()->to_space()); 954 955 DEBUG_ONLY(add_obj_count = add_obj_size = 0;) 956 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;) 957 958 // Increment the invocation count 959 heap->increment_total_collections(true); 960 961 // We need to track unique mark sweep invocations as well. 962 _total_invocations++; 963 964 heap->print_heap_before_gc(); 965 heap->trace_heap_before_gc(&_gc_tracer); 966 967 // Fill in TLABs 968 heap->accumulate_statistics_all_tlabs(); 969 heap->ensure_parsability(true); // retire TLABs 970 971 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 972 HandleMark hm; // Discard invalid handles created during verification 973 Universe::verify("Before GC"); 974 } 975 976 // Verify object start arrays 977 if (VerifyObjectStartArray && 978 VerifyBeforeGC) { 979 heap->old_gen()->verify_object_start_array(); 980 } 981 982 DEBUG_ONLY(mark_bitmap()->verify_clear();) 983 DEBUG_ONLY(summary_data().verify_clear();) 984 985 // Have worker threads release resources the next time they run a task. 986 gc_task_manager()->release_all_resources(); 987 988 ParCompactionManager::reset_all_bitmap_query_caches(); 989 } 990 991 void PSParallelCompact::post_compact() 992 { 993 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer); 994 995 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 996 // Clear the marking bitmap, summary data and split info. 997 clear_data_covering_space(SpaceId(id)); 998 // Update top(). Must be done after clearing the bitmap and summary data. 999 _space_info[id].publish_new_top(); 1000 } 1001 1002 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1003 MutableSpace* const from_space = _space_info[from_space_id].space(); 1004 MutableSpace* const to_space = _space_info[to_space_id].space(); 1005 1006 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1007 bool eden_empty = eden_space->is_empty(); 1008 if (!eden_empty) { 1009 eden_empty = absorb_live_data_from_eden(heap->size_policy(), 1010 heap->young_gen(), heap->old_gen()); 1011 } 1012 1013 // Update heap occupancy information which is used as input to the soft ref 1014 // clearing policy at the next gc. 1015 Universe::update_heap_info_at_gc(); 1016 1017 bool young_gen_empty = eden_empty && from_space->is_empty() && 1018 to_space->is_empty(); 1019 1020 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set()); 1021 MemRegion old_mr = heap->old_gen()->reserved(); 1022 if (young_gen_empty) { 1023 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 1024 } else { 1025 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 1026 } 1027 1028 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1029 ClassLoaderDataGraph::purge(); 1030 MetaspaceAux::verify_metrics(); 1031 1032 CodeCache::gc_epilogue(); 1033 JvmtiExport::gc_epilogue(); 1034 1035 #if defined(COMPILER2) || INCLUDE_JVMCI 1036 DerivedPointerTable::update_pointers(); 1037 #endif 1038 1039 ref_processor()->enqueue_discovered_references(NULL); 1040 1041 if (ZapUnusedHeapArea) { 1042 heap->gen_mangle_unused_area(); 1043 } 1044 1045 // Update time of last GC 1046 reset_millis_since_last_gc(); 1047 } 1048 1049 HeapWord* 1050 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, 1051 bool maximum_compaction) 1052 { 1053 const size_t region_size = ParallelCompactData::RegionSize; 1054 const ParallelCompactData& sd = summary_data(); 1055 1056 const MutableSpace* const space = _space_info[id].space(); 1057 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 1058 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom()); 1059 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up); 1060 1061 // Skip full regions at the beginning of the space--they are necessarily part 1062 // of the dense prefix. 1063 size_t full_count = 0; 1064 const RegionData* cp; 1065 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) { 1066 ++full_count; 1067 } 1068 1069 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1070 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1071 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; 1072 if (maximum_compaction || cp == end_cp || interval_ended) { 1073 _maximum_compaction_gc_num = total_invocations(); 1074 return sd.region_to_addr(cp); 1075 } 1076 1077 HeapWord* const new_top = _space_info[id].new_top(); 1078 const size_t space_live = pointer_delta(new_top, space->bottom()); 1079 const size_t space_used = space->used_in_words(); 1080 const size_t space_capacity = space->capacity_in_words(); 1081 1082 const double cur_density = double(space_live) / space_capacity; 1083 const double deadwood_density = 1084 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; 1085 const size_t deadwood_goal = size_t(space_capacity * deadwood_density); 1086 1087 if (TraceParallelOldGCDensePrefix) { 1088 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, 1089 cur_density, deadwood_density, deadwood_goal); 1090 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1091 "space_cap=" SIZE_FORMAT, 1092 space_live, space_used, 1093 space_capacity); 1094 } 1095 1096 // XXX - Use binary search? 1097 HeapWord* dense_prefix = sd.region_to_addr(cp); 1098 const RegionData* full_cp = cp; 1099 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1); 1100 while (cp < end_cp) { 1101 HeapWord* region_destination = cp->destination(); 1102 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination); 1103 if (TraceParallelOldGCDensePrefix && Verbose) { 1104 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " 1105 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8), 1106 sd.region(cp), p2i(region_destination), 1107 p2i(dense_prefix), cur_deadwood); 1108 } 1109 1110 if (cur_deadwood >= deadwood_goal) { 1111 // Found the region that has the correct amount of deadwood to the left. 1112 // This typically occurs after crossing a fairly sparse set of regions, so 1113 // iterate backwards over those sparse regions, looking for the region 1114 // that has the lowest density of live objects 'to the right.' 1115 size_t space_to_left = sd.region(cp) * region_size; 1116 size_t live_to_left = space_to_left - cur_deadwood; 1117 size_t space_to_right = space_capacity - space_to_left; 1118 size_t live_to_right = space_live - live_to_left; 1119 double density_to_right = double(live_to_right) / space_to_right; 1120 while (cp > full_cp) { 1121 --cp; 1122 const size_t prev_region_live_to_right = live_to_right - 1123 cp->data_size(); 1124 const size_t prev_region_space_to_right = space_to_right + region_size; 1125 double prev_region_density_to_right = 1126 double(prev_region_live_to_right) / prev_region_space_to_right; 1127 if (density_to_right <= prev_region_density_to_right) { 1128 return dense_prefix; 1129 } 1130 if (TraceParallelOldGCDensePrefix && Verbose) { 1131 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " 1132 "pc_d2r=%10.8f", sd.region(cp), density_to_right, 1133 prev_region_density_to_right); 1134 } 1135 dense_prefix -= region_size; 1136 live_to_right = prev_region_live_to_right; 1137 space_to_right = prev_region_space_to_right; 1138 density_to_right = prev_region_density_to_right; 1139 } 1140 return dense_prefix; 1141 } 1142 1143 dense_prefix += region_size; 1144 ++cp; 1145 } 1146 1147 return dense_prefix; 1148 } 1149 1150 #ifndef PRODUCT 1151 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, 1152 const SpaceId id, 1153 const bool maximum_compaction, 1154 HeapWord* const addr) 1155 { 1156 const size_t region_idx = summary_data().addr_to_region_idx(addr); 1157 RegionData* const cp = summary_data().region(region_idx); 1158 const MutableSpace* const space = _space_info[id].space(); 1159 HeapWord* const new_top = _space_info[id].new_top(); 1160 1161 const size_t space_live = pointer_delta(new_top, space->bottom()); 1162 const size_t dead_to_left = pointer_delta(addr, cp->destination()); 1163 const size_t space_cap = space->capacity_in_words(); 1164 const double dead_to_left_pct = double(dead_to_left) / space_cap; 1165 const size_t live_to_right = new_top - cp->destination(); 1166 const size_t dead_to_right = space->top() - addr - live_to_right; 1167 1168 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " 1169 "spl=" SIZE_FORMAT " " 1170 "d2l=" SIZE_FORMAT " d2l%%=%6.4f " 1171 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT 1172 " ratio=%10.8f", 1173 algorithm, p2i(addr), region_idx, 1174 space_live, 1175 dead_to_left, dead_to_left_pct, 1176 dead_to_right, live_to_right, 1177 double(dead_to_right) / live_to_right); 1178 } 1179 #endif // #ifndef PRODUCT 1180 1181 // Return a fraction indicating how much of the generation can be treated as 1182 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution 1183 // based on the density of live objects in the generation to determine a limit, 1184 // which is then adjusted so the return value is min_percent when the density is 1185 // 1. 1186 // 1187 // The following table shows some return values for a different values of the 1188 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and 1189 // min_percent is 1. 1190 // 1191 // fraction allowed as dead wood 1192 // ----------------------------------------------------------------- 1193 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 1194 // ------- ---------- ---------- ---------- ---------- ---------- ---------- 1195 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1196 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1197 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1198 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1199 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1200 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1201 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1202 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1203 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1204 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1205 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 1206 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1207 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1208 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1209 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1210 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1211 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1212 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1213 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1214 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1215 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1216 1217 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) 1218 { 1219 assert(_dwl_initialized, "uninitialized"); 1220 1221 // The raw limit is the value of the normal distribution at x = density. 1222 const double raw_limit = normal_distribution(density); 1223 1224 // Adjust the raw limit so it becomes the minimum when the density is 1. 1225 // 1226 // First subtract the adjustment value (which is simply the precomputed value 1227 // normal_distribution(1.0)); this yields a value of 0 when the density is 1. 1228 // Then add the minimum value, so the minimum is returned when the density is 1229 // 1. Finally, prevent negative values, which occur when the mean is not 0.5. 1230 const double min = double(min_percent) / 100.0; 1231 const double limit = raw_limit - _dwl_adjustment + min; 1232 return MAX2(limit, 0.0); 1233 } 1234 1235 ParallelCompactData::RegionData* 1236 PSParallelCompact::first_dead_space_region(const RegionData* beg, 1237 const RegionData* end) 1238 { 1239 const size_t region_size = ParallelCompactData::RegionSize; 1240 ParallelCompactData& sd = summary_data(); 1241 size_t left = sd.region(beg); 1242 size_t right = end > beg ? sd.region(end) - 1 : left; 1243 1244 // Binary search. 1245 while (left < right) { 1246 // Equivalent to (left + right) / 2, but does not overflow. 1247 const size_t middle = left + (right - left) / 2; 1248 RegionData* const middle_ptr = sd.region(middle); 1249 HeapWord* const dest = middle_ptr->destination(); 1250 HeapWord* const addr = sd.region_to_addr(middle); 1251 assert(dest != NULL, "sanity"); 1252 assert(dest <= addr, "must move left"); 1253 1254 if (middle > left && dest < addr) { 1255 right = middle - 1; 1256 } else if (middle < right && middle_ptr->data_size() == region_size) { 1257 left = middle + 1; 1258 } else { 1259 return middle_ptr; 1260 } 1261 } 1262 return sd.region(left); 1263 } 1264 1265 ParallelCompactData::RegionData* 1266 PSParallelCompact::dead_wood_limit_region(const RegionData* beg, 1267 const RegionData* end, 1268 size_t dead_words) 1269 { 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 const size_t dead_to_left = pointer_delta(addr, dest); 1285 if (middle > left && dead_to_left > dead_words) { 1286 right = middle - 1; 1287 } else if (middle < right && dead_to_left < dead_words) { 1288 left = middle + 1; 1289 } else { 1290 return middle_ptr; 1291 } 1292 } 1293 return sd.region(left); 1294 } 1295 1296 // The result is valid during the summary phase, after the initial summarization 1297 // of each space into itself, and before final summarization. 1298 inline double 1299 PSParallelCompact::reclaimed_ratio(const RegionData* const cp, 1300 HeapWord* const bottom, 1301 HeapWord* const top, 1302 HeapWord* const new_top) 1303 { 1304 ParallelCompactData& sd = summary_data(); 1305 1306 assert(cp != NULL, "sanity"); 1307 assert(bottom != NULL, "sanity"); 1308 assert(top != NULL, "sanity"); 1309 assert(new_top != NULL, "sanity"); 1310 assert(top >= new_top, "summary data problem?"); 1311 assert(new_top > bottom, "space is empty; should not be here"); 1312 assert(new_top >= cp->destination(), "sanity"); 1313 assert(top >= sd.region_to_addr(cp), "sanity"); 1314 1315 HeapWord* const destination = cp->destination(); 1316 const size_t dense_prefix_live = pointer_delta(destination, bottom); 1317 const size_t compacted_region_live = pointer_delta(new_top, destination); 1318 const size_t compacted_region_used = pointer_delta(top, 1319 sd.region_to_addr(cp)); 1320 const size_t reclaimable = compacted_region_used - compacted_region_live; 1321 1322 const double divisor = dense_prefix_live + 1.25 * compacted_region_live; 1323 return double(reclaimable) / divisor; 1324 } 1325 1326 // Return the address of the end of the dense prefix, a.k.a. the start of the 1327 // compacted region. The address is always on a region boundary. 1328 // 1329 // Completely full regions at the left are skipped, since no compaction can 1330 // occur in those regions. Then the maximum amount of dead wood to allow is 1331 // computed, based on the density (amount live / capacity) of the generation; 1332 // the region with approximately that amount of dead space to the left is 1333 // identified as the limit region. Regions between the last completely full 1334 // region and the limit region are scanned and the one that has the best 1335 // (maximum) reclaimed_ratio() is selected. 1336 HeapWord* 1337 PSParallelCompact::compute_dense_prefix(const SpaceId id, 1338 bool maximum_compaction) 1339 { 1340 const size_t region_size = ParallelCompactData::RegionSize; 1341 const ParallelCompactData& sd = summary_data(); 1342 1343 const MutableSpace* const space = _space_info[id].space(); 1344 HeapWord* const top = space->top(); 1345 HeapWord* const top_aligned_up = sd.region_align_up(top); 1346 HeapWord* const new_top = _space_info[id].new_top(); 1347 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top); 1348 HeapWord* const bottom = space->bottom(); 1349 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom); 1350 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 1351 const RegionData* const new_top_cp = 1352 sd.addr_to_region_ptr(new_top_aligned_up); 1353 1354 // Skip full regions at the beginning of the space--they are necessarily part 1355 // of the dense prefix. 1356 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp); 1357 assert(full_cp->destination() == sd.region_to_addr(full_cp) || 1358 space->is_empty(), "no dead space allowed to the left"); 1359 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1, 1360 "region must have dead space"); 1361 1362 // The gc number is saved whenever a maximum compaction is done, and used to 1363 // determine when the maximum compaction interval has expired. This avoids 1364 // successive max compactions for different reasons. 1365 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1366 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1367 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || 1368 total_invocations() == HeapFirstMaximumCompactionCount; 1369 if (maximum_compaction || full_cp == top_cp || interval_ended) { 1370 _maximum_compaction_gc_num = total_invocations(); 1371 return sd.region_to_addr(full_cp); 1372 } 1373 1374 const size_t space_live = pointer_delta(new_top, bottom); 1375 const size_t space_used = space->used_in_words(); 1376 const size_t space_capacity = space->capacity_in_words(); 1377 1378 const double density = double(space_live) / double(space_capacity); 1379 const size_t min_percent_free = MarkSweepDeadRatio; 1380 const double limiter = dead_wood_limiter(density, min_percent_free); 1381 const size_t dead_wood_max = space_used - space_live; 1382 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), 1383 dead_wood_max); 1384 1385 if (TraceParallelOldGCDensePrefix) { 1386 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1387 "space_cap=" SIZE_FORMAT, 1388 space_live, space_used, 1389 space_capacity); 1390 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f " 1391 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, 1392 density, min_percent_free, limiter, 1393 dead_wood_max, dead_wood_limit); 1394 } 1395 1396 // Locate the region with the desired amount of dead space to the left. 1397 const RegionData* const limit_cp = 1398 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit); 1399 1400 // Scan from the first region with dead space to the limit region and find the 1401 // one with the best (largest) reclaimed ratio. 1402 double best_ratio = 0.0; 1403 const RegionData* best_cp = full_cp; 1404 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) { 1405 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); 1406 if (tmp_ratio > best_ratio) { 1407 best_cp = cp; 1408 best_ratio = tmp_ratio; 1409 } 1410 } 1411 1412 return sd.region_to_addr(best_cp); 1413 } 1414 1415 void PSParallelCompact::summarize_spaces_quick() 1416 { 1417 for (unsigned int i = 0; i < last_space_id; ++i) { 1418 const MutableSpace* space = _space_info[i].space(); 1419 HeapWord** nta = _space_info[i].new_top_addr(); 1420 bool result = _summary_data.summarize(_space_info[i].split_info(), 1421 space->bottom(), space->top(), NULL, 1422 space->bottom(), space->end(), nta); 1423 assert(result, "space must fit into itself"); 1424 _space_info[i].set_dense_prefix(space->bottom()); 1425 } 1426 } 1427 1428 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) 1429 { 1430 HeapWord* const dense_prefix_end = dense_prefix(id); 1431 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end); 1432 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); 1433 if (dead_space_crosses_boundary(region, dense_prefix_bit)) { 1434 // Only enough dead space is filled so that any remaining dead space to the 1435 // left is larger than the minimum filler object. (The remainder is filled 1436 // during the copy/update phase.) 1437 // 1438 // The size of the dead space to the right of the boundary is not a 1439 // concern, since compaction will be able to use whatever space is 1440 // available. 1441 // 1442 // Here '||' is the boundary, 'x' represents a don't care bit and a box 1443 // surrounds the space to be filled with an object. 1444 // 1445 // In the 32-bit VM, each bit represents two 32-bit words: 1446 // +---+ 1447 // a) beg_bits: ... x x x | 0 | || 0 x x ... 1448 // end_bits: ... x x x | 0 | || 0 x x ... 1449 // +---+ 1450 // 1451 // In the 64-bit VM, each bit represents one 64-bit word: 1452 // +------------+ 1453 // b) beg_bits: ... x x x | 0 || 0 | x x ... 1454 // end_bits: ... x x 1 | 0 || 0 | x x ... 1455 // +------------+ 1456 // +-------+ 1457 // c) beg_bits: ... x x | 0 0 | || 0 x x ... 1458 // end_bits: ... x 1 | 0 0 | || 0 x x ... 1459 // +-------+ 1460 // +-----------+ 1461 // d) beg_bits: ... x | 0 0 0 | || 0 x x ... 1462 // end_bits: ... 1 | 0 0 0 | || 0 x x ... 1463 // +-----------+ 1464 // +-------+ 1465 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... 1466 // end_bits: ... 0 0 | 0 0 | || 0 x x ... 1467 // +-------+ 1468 1469 // Initially assume case a, c or e will apply. 1470 size_t obj_len = CollectedHeap::min_fill_size(); 1471 HeapWord* obj_beg = dense_prefix_end - obj_len; 1472 1473 #ifdef _LP64 1474 if (MinObjAlignment > 1) { // object alignment > heap word size 1475 // Cases a, c or e. 1476 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { 1477 // Case b above. 1478 obj_beg = dense_prefix_end - 1; 1479 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && 1480 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { 1481 // Case d above. 1482 obj_beg = dense_prefix_end - 3; 1483 obj_len = 3; 1484 } 1485 #endif // #ifdef _LP64 1486 1487 CollectedHeap::fill_with_object(obj_beg, obj_len); 1488 _mark_bitmap.mark_obj(obj_beg, obj_len); 1489 _summary_data.add_obj(obj_beg, obj_len); 1490 assert(start_array(id) != NULL, "sanity"); 1491 start_array(id)->allocate_block(obj_beg); 1492 } 1493 } 1494 1495 void 1496 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) 1497 { 1498 assert(id < last_space_id, "id out of range"); 1499 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(), 1500 "should have been reset in summarize_spaces_quick()"); 1501 1502 const MutableSpace* space = _space_info[id].space(); 1503 if (_space_info[id].new_top() != space->bottom()) { 1504 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); 1505 _space_info[id].set_dense_prefix(dense_prefix_end); 1506 1507 #ifndef PRODUCT 1508 if (TraceParallelOldGCDensePrefix) { 1509 print_dense_prefix_stats("ratio", id, maximum_compaction, 1510 dense_prefix_end); 1511 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); 1512 print_dense_prefix_stats("density", id, maximum_compaction, addr); 1513 } 1514 #endif // #ifndef PRODUCT 1515 1516 // Recompute the summary data, taking into account the dense prefix. If 1517 // every last byte will be reclaimed, then the existing summary data which 1518 // compacts everything can be left in place. 1519 if (!maximum_compaction && dense_prefix_end != space->bottom()) { 1520 // If dead space crosses the dense prefix boundary, it is (at least 1521 // partially) filled with a dummy object, marked live and added to the 1522 // summary data. This simplifies the copy/update phase and must be done 1523 // before the final locations of objects are determined, to prevent 1524 // leaving a fragment of dead space that is too small to fill. 1525 fill_dense_prefix_end(id); 1526 1527 // Compute the destination of each Region, and thus each object. 1528 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); 1529 _summary_data.summarize(_space_info[id].split_info(), 1530 dense_prefix_end, space->top(), NULL, 1531 dense_prefix_end, space->end(), 1532 _space_info[id].new_top_addr()); 1533 } 1534 } 1535 1536 if (log_develop_is_enabled(Trace, gc, compaction)) { 1537 const size_t region_size = ParallelCompactData::RegionSize; 1538 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); 1539 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end); 1540 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); 1541 HeapWord* const new_top = _space_info[id].new_top(); 1542 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top); 1543 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); 1544 log_develop_trace(gc, compaction)( 1545 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " 1546 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " 1547 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, 1548 id, space->capacity_in_words(), p2i(dense_prefix_end), 1549 dp_region, dp_words / region_size, 1550 cr_words / region_size, p2i(new_top)); 1551 } 1552 } 1553 1554 #ifndef PRODUCT 1555 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id, 1556 HeapWord* dst_beg, HeapWord* dst_end, 1557 SpaceId src_space_id, 1558 HeapWord* src_beg, HeapWord* src_end) 1559 { 1560 log_develop_trace(gc, compaction)( 1561 "Summarizing %d [%s] into %d [%s]: " 1562 "src=" PTR_FORMAT "-" PTR_FORMAT " " 1563 SIZE_FORMAT "-" SIZE_FORMAT " " 1564 "dst=" PTR_FORMAT "-" PTR_FORMAT " " 1565 SIZE_FORMAT "-" SIZE_FORMAT, 1566 src_space_id, space_names[src_space_id], 1567 dst_space_id, space_names[dst_space_id], 1568 p2i(src_beg), p2i(src_end), 1569 _summary_data.addr_to_region_idx(src_beg), 1570 _summary_data.addr_to_region_idx(src_end), 1571 p2i(dst_beg), p2i(dst_end), 1572 _summary_data.addr_to_region_idx(dst_beg), 1573 _summary_data.addr_to_region_idx(dst_end)); 1574 } 1575 #endif // #ifndef PRODUCT 1576 1577 void PSParallelCompact::summary_phase(ParCompactionManager* cm, 1578 bool maximum_compaction) 1579 { 1580 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer); 1581 1582 #ifdef ASSERT 1583 if (TraceParallelOldGCMarkingPhase) { 1584 tty->print_cr("add_obj_count=" SIZE_FORMAT " " 1585 "add_obj_bytes=" SIZE_FORMAT, 1586 add_obj_count, add_obj_size * HeapWordSize); 1587 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " " 1588 "mark_bitmap_bytes=" SIZE_FORMAT, 1589 mark_bitmap_count, mark_bitmap_size * HeapWordSize); 1590 } 1591 #endif // #ifdef ASSERT 1592 1593 // Quick summarization of each space into itself, to see how much is live. 1594 summarize_spaces_quick(); 1595 1596 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self"); 1597 NOT_PRODUCT(print_region_ranges()); 1598 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1599 1600 // The amount of live data that will end up in old space (assuming it fits). 1601 size_t old_space_total_live = 0; 1602 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1603 old_space_total_live += pointer_delta(_space_info[id].new_top(), 1604 _space_info[id].space()->bottom()); 1605 } 1606 1607 MutableSpace* const old_space = _space_info[old_space_id].space(); 1608 const size_t old_capacity = old_space->capacity_in_words(); 1609 if (old_space_total_live > old_capacity) { 1610 // XXX - should also try to expand 1611 maximum_compaction = true; 1612 } 1613 1614 // Old generations. 1615 summarize_space(old_space_id, maximum_compaction); 1616 1617 // Summarize the remaining spaces in the young gen. The initial target space 1618 // is the old gen. If a space does not fit entirely into the target, then the 1619 // remainder is compacted into the space itself and that space becomes the new 1620 // target. 1621 SpaceId dst_space_id = old_space_id; 1622 HeapWord* dst_space_end = old_space->end(); 1623 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr(); 1624 for (unsigned int id = eden_space_id; id < last_space_id; ++id) { 1625 const MutableSpace* space = _space_info[id].space(); 1626 const size_t live = pointer_delta(_space_info[id].new_top(), 1627 space->bottom()); 1628 const size_t available = pointer_delta(dst_space_end, *new_top_addr); 1629 1630 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end, 1631 SpaceId(id), space->bottom(), space->top());) 1632 if (live > 0 && live <= available) { 1633 // All the live data will fit. 1634 bool done = _summary_data.summarize(_space_info[id].split_info(), 1635 space->bottom(), space->top(), 1636 NULL, 1637 *new_top_addr, dst_space_end, 1638 new_top_addr); 1639 assert(done, "space must fit into old gen"); 1640 1641 // Reset the new_top value for the space. 1642 _space_info[id].set_new_top(space->bottom()); 1643 } else if (live > 0) { 1644 // Attempt to fit part of the source space into the target space. 1645 HeapWord* next_src_addr = NULL; 1646 bool done = _summary_data.summarize(_space_info[id].split_info(), 1647 space->bottom(), space->top(), 1648 &next_src_addr, 1649 *new_top_addr, dst_space_end, 1650 new_top_addr); 1651 assert(!done, "space should not fit into old gen"); 1652 assert(next_src_addr != NULL, "sanity"); 1653 1654 // The source space becomes the new target, so the remainder is compacted 1655 // within the space itself. 1656 dst_space_id = SpaceId(id); 1657 dst_space_end = space->end(); 1658 new_top_addr = _space_info[id].new_top_addr(); 1659 NOT_PRODUCT(summary_phase_msg(dst_space_id, 1660 space->bottom(), dst_space_end, 1661 SpaceId(id), next_src_addr, space->top());) 1662 done = _summary_data.summarize(_space_info[id].split_info(), 1663 next_src_addr, space->top(), 1664 NULL, 1665 space->bottom(), dst_space_end, 1666 new_top_addr); 1667 assert(done, "space must fit when compacted into itself"); 1668 assert(*new_top_addr <= space->top(), "usage should not grow"); 1669 } 1670 } 1671 1672 log_develop_trace(gc, compaction)("Summary_phase: after final summarization"); 1673 NOT_PRODUCT(print_region_ranges()); 1674 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1675 } 1676 1677 // This method should contain all heap-specific policy for invoking a full 1678 // collection. invoke_no_policy() will only attempt to compact the heap; it 1679 // will do nothing further. If we need to bail out for policy reasons, scavenge 1680 // before full gc, or any other specialized behavior, it needs to be added here. 1681 // 1682 // Note that this method should only be called from the vm_thread while at a 1683 // safepoint. 1684 // 1685 // Note that the all_soft_refs_clear flag in the collector policy 1686 // may be true because this method can be called without intervening 1687 // activity. For example when the heap space is tight and full measure 1688 // are being taken to free space. 1689 void PSParallelCompact::invoke(bool maximum_heap_compaction) { 1690 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 1691 assert(Thread::current() == (Thread*)VMThread::vm_thread(), 1692 "should be in vm thread"); 1693 1694 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1695 GCCause::Cause gc_cause = heap->gc_cause(); 1696 assert(!heap->is_gc_active(), "not reentrant"); 1697 1698 PSAdaptiveSizePolicy* policy = heap->size_policy(); 1699 IsGCActiveMark mark; 1700 1701 if (ScavengeBeforeFullGC) { 1702 PSScavenge::invoke_no_policy(); 1703 } 1704 1705 const bool clear_all_soft_refs = 1706 heap->collector_policy()->should_clear_all_soft_refs(); 1707 1708 PSParallelCompact::invoke_no_policy(clear_all_soft_refs || 1709 maximum_heap_compaction); 1710 } 1711 1712 // This method contains no policy. You should probably 1713 // be calling invoke() instead. 1714 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { 1715 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 1716 assert(ref_processor() != NULL, "Sanity"); 1717 1718 if (GCLocker::check_active_before_gc()) { 1719 return false; 1720 } 1721 1722 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1723 1724 GCIdMark gc_id_mark; 1725 _gc_timer.register_gc_start(); 1726 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 1727 1728 TimeStamp marking_start; 1729 TimeStamp compaction_start; 1730 TimeStamp collection_exit; 1731 1732 GCCause::Cause gc_cause = heap->gc_cause(); 1733 PSYoungGen* young_gen = heap->young_gen(); 1734 PSOldGen* old_gen = heap->old_gen(); 1735 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 1736 1737 // The scope of casr should end after code that can change 1738 // CollectorPolicy::_should_clear_all_soft_refs. 1739 ClearedAllSoftRefs casr(maximum_heap_compaction, 1740 heap->collector_policy()); 1741 1742 if (ZapUnusedHeapArea) { 1743 // Save information needed to minimize mangling 1744 heap->record_gen_tops_before_GC(); 1745 } 1746 1747 // Make sure data structures are sane, make the heap parsable, and do other 1748 // miscellaneous bookkeeping. 1749 pre_compact(); 1750 1751 PreGCValues pre_gc_values(heap); 1752 1753 // Get the compaction manager reserved for the VM thread. 1754 ParCompactionManager* const vmthread_cm = 1755 ParCompactionManager::manager_array(gc_task_manager()->workers()); 1756 1757 { 1758 ResourceMark rm; 1759 HandleMark hm; 1760 1761 // Set the number of GC threads to be used in this collection 1762 gc_task_manager()->set_active_gang(); 1763 gc_task_manager()->task_idle_workers(); 1764 1765 GCTraceCPUTime tcpu; 1766 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true); 1767 1768 heap->pre_full_gc_dump(&_gc_timer); 1769 1770 TraceCollectorStats tcs(counters()); 1771 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 1772 1773 if (TraceOldGenTime) accumulated_time()->start(); 1774 1775 // Let the size policy know we're starting 1776 size_policy->major_collection_begin(); 1777 1778 CodeCache::gc_prologue(); 1779 1780 #if defined(COMPILER2) || INCLUDE_JVMCI 1781 DerivedPointerTable::clear(); 1782 #endif 1783 1784 ref_processor()->enable_discovery(); 1785 ref_processor()->setup_policy(maximum_heap_compaction); 1786 1787 bool marked_for_unloading = false; 1788 1789 marking_start.update(); 1790 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer); 1791 1792 bool max_on_system_gc = UseMaximumCompactionOnSystemGC 1793 && GCCause::is_user_requested_gc(gc_cause); 1794 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc); 1795 1796 #if defined(COMPILER2) || INCLUDE_JVMCI 1797 assert(DerivedPointerTable::is_active(), "Sanity"); 1798 DerivedPointerTable::set_active(false); 1799 #endif 1800 1801 // adjust_roots() updates Universe::_intArrayKlassObj which is 1802 // needed by the compaction for filling holes in the dense prefix. 1803 adjust_roots(vmthread_cm); 1804 1805 compaction_start.update(); 1806 compact(); 1807 1808 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be 1809 // done before resizing. 1810 post_compact(); 1811 1812 // Let the size policy know we're done 1813 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 1814 1815 if (UseAdaptiveSizePolicy) { 1816 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 1817 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 1818 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 1819 1820 // Don't check if the size_policy is ready here. Let 1821 // the size_policy check that internally. 1822 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 1823 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 1824 // Swap the survivor spaces if from_space is empty. The 1825 // resize_young_gen() called below is normally used after 1826 // a successful young GC and swapping of survivor spaces; 1827 // otherwise, it will fail to resize the young gen with 1828 // the current implementation. 1829 if (young_gen->from_space()->is_empty()) { 1830 young_gen->from_space()->clear(SpaceDecorator::Mangle); 1831 young_gen->swap_spaces(); 1832 } 1833 1834 // Calculate optimal free space amounts 1835 assert(young_gen->max_size() > 1836 young_gen->from_space()->capacity_in_bytes() + 1837 young_gen->to_space()->capacity_in_bytes(), 1838 "Sizes of space in young gen are out-of-bounds"); 1839 1840 size_t young_live = young_gen->used_in_bytes(); 1841 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 1842 size_t old_live = old_gen->used_in_bytes(); 1843 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 1844 size_t max_old_gen_size = old_gen->max_gen_size(); 1845 size_t max_eden_size = young_gen->max_size() - 1846 young_gen->from_space()->capacity_in_bytes() - 1847 young_gen->to_space()->capacity_in_bytes(); 1848 1849 // Used for diagnostics 1850 size_policy->clear_generation_free_space_flags(); 1851 1852 size_policy->compute_generations_free_space(young_live, 1853 eden_live, 1854 old_live, 1855 cur_eden, 1856 max_old_gen_size, 1857 max_eden_size, 1858 true /* full gc*/); 1859 1860 size_policy->check_gc_overhead_limit(young_live, 1861 eden_live, 1862 max_old_gen_size, 1863 max_eden_size, 1864 true /* full gc*/, 1865 gc_cause, 1866 heap->collector_policy()); 1867 1868 size_policy->decay_supplemental_growth(true /* full gc*/); 1869 1870 heap->resize_old_gen( 1871 size_policy->calculated_old_free_size_in_bytes()); 1872 1873 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 1874 size_policy->calculated_survivor_size_in_bytes()); 1875 } 1876 1877 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 1878 } 1879 1880 if (UsePerfData) { 1881 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 1882 counters->update_counters(); 1883 counters->update_old_capacity(old_gen->capacity_in_bytes()); 1884 counters->update_young_capacity(young_gen->capacity_in_bytes()); 1885 } 1886 1887 heap->resize_all_tlabs(); 1888 1889 // Resize the metaspace capacity after a collection 1890 MetaspaceGC::compute_new_size(); 1891 1892 if (TraceOldGenTime) { 1893 accumulated_time()->stop(); 1894 } 1895 1896 young_gen->print_used_change(pre_gc_values.young_gen_used()); 1897 old_gen->print_used_change(pre_gc_values.old_gen_used()); 1898 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used()); 1899 1900 // Track memory usage and detect low memory 1901 MemoryService::track_memory_usage(); 1902 heap->update_counters(); 1903 gc_task_manager()->release_idle_workers(); 1904 1905 heap->post_full_gc_dump(&_gc_timer); 1906 } 1907 1908 #ifdef ASSERT 1909 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) { 1910 ParCompactionManager* const cm = 1911 ParCompactionManager::manager_array(int(i)); 1912 assert(cm->marking_stack()->is_empty(), "should be empty"); 1913 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i); 1914 } 1915 #endif // ASSERT 1916 1917 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 1918 HandleMark hm; // Discard invalid handles created during verification 1919 Universe::verify("After GC"); 1920 } 1921 1922 // Re-verify object start arrays 1923 if (VerifyObjectStartArray && 1924 VerifyAfterGC) { 1925 old_gen->verify_object_start_array(); 1926 } 1927 1928 if (ZapUnusedHeapArea) { 1929 old_gen->object_space()->check_mangled_unused_area_complete(); 1930 } 1931 1932 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 1933 1934 collection_exit.update(); 1935 1936 heap->print_heap_after_gc(); 1937 heap->trace_heap_after_gc(&_gc_tracer); 1938 1939 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 1940 marking_start.ticks(), compaction_start.ticks(), 1941 collection_exit.ticks()); 1942 gc_task_manager()->print_task_time_stamps(); 1943 1944 #ifdef TRACESPINNING 1945 ParallelTaskTerminator::print_termination_counts(); 1946 #endif 1947 1948 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 1949 1950 _gc_timer.register_gc_end(); 1951 1952 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id)); 1953 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 1954 1955 return true; 1956 } 1957 1958 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 1959 PSYoungGen* young_gen, 1960 PSOldGen* old_gen) { 1961 MutableSpace* const eden_space = young_gen->eden_space(); 1962 assert(!eden_space->is_empty(), "eden must be non-empty"); 1963 assert(young_gen->virtual_space()->alignment() == 1964 old_gen->virtual_space()->alignment(), "alignments do not match"); 1965 1966 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 1967 return false; 1968 } 1969 1970 // Both generations must be completely committed. 1971 if (young_gen->virtual_space()->uncommitted_size() != 0) { 1972 return false; 1973 } 1974 if (old_gen->virtual_space()->uncommitted_size() != 0) { 1975 return false; 1976 } 1977 1978 // Figure out how much to take from eden. Include the average amount promoted 1979 // in the total; otherwise the next young gen GC will simply bail out to a 1980 // full GC. 1981 const size_t alignment = old_gen->virtual_space()->alignment(); 1982 const size_t eden_used = eden_space->used_in_bytes(); 1983 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 1984 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 1985 const size_t eden_capacity = eden_space->capacity_in_bytes(); 1986 1987 if (absorb_size >= eden_capacity) { 1988 return false; // Must leave some space in eden. 1989 } 1990 1991 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 1992 if (new_young_size < young_gen->min_gen_size()) { 1993 return false; // Respect young gen minimum size. 1994 } 1995 1996 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 1997 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 1998 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 1999 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 2000 absorb_size / K, 2001 eden_capacity / K, (eden_capacity - absorb_size) / K, 2002 young_gen->from_space()->used_in_bytes() / K, 2003 young_gen->to_space()->used_in_bytes() / K, 2004 young_gen->capacity_in_bytes() / K, new_young_size / K); 2005 2006 // Fill the unused part of the old gen. 2007 MutableSpace* const old_space = old_gen->object_space(); 2008 HeapWord* const unused_start = old_space->top(); 2009 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 2010 2011 if (unused_words > 0) { 2012 if (unused_words < CollectedHeap::min_fill_size()) { 2013 return false; // If the old gen cannot be filled, must give up. 2014 } 2015 CollectedHeap::fill_with_objects(unused_start, unused_words); 2016 } 2017 2018 // Take the live data from eden and set both top and end in the old gen to 2019 // eden top. (Need to set end because reset_after_change() mangles the region 2020 // from end to virtual_space->high() in debug builds). 2021 HeapWord* const new_top = eden_space->top(); 2022 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 2023 absorb_size); 2024 young_gen->reset_after_change(); 2025 old_space->set_top(new_top); 2026 old_space->set_end(new_top); 2027 old_gen->reset_after_change(); 2028 2029 // Update the object start array for the filler object and the data from eden. 2030 ObjectStartArray* const start_array = old_gen->start_array(); 2031 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 2032 start_array->allocate_block(p); 2033 } 2034 2035 // Could update the promoted average here, but it is not typically updated at 2036 // full GCs and the value to use is unclear. Something like 2037 // 2038 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 2039 2040 size_policy->set_bytes_absorbed_from_eden(absorb_size); 2041 return true; 2042 } 2043 2044 GCTaskManager* const PSParallelCompact::gc_task_manager() { 2045 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 2046 "shouldn't return NULL"); 2047 return ParallelScavengeHeap::gc_task_manager(); 2048 } 2049 2050 void PSParallelCompact::marking_phase(ParCompactionManager* cm, 2051 bool maximum_heap_compaction, 2052 ParallelOldTracer *gc_tracer) { 2053 // Recursively traverse all live objects and mark them 2054 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer); 2055 2056 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2057 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2058 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2059 TaskQueueSetSuper* qset = ParCompactionManager::stack_array(); 2060 ParallelTaskTerminator terminator(active_gc_threads, qset); 2061 2062 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm); 2063 ParCompactionManager::FollowStackClosure follow_stack_closure(cm); 2064 2065 // Need new claim bits before marking starts. 2066 ClassLoaderDataGraph::clear_claimed_marks(); 2067 2068 { 2069 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer); 2070 2071 ParallelScavengeHeap::ParStrongRootsScope psrs; 2072 2073 GCTaskQueue* q = GCTaskQueue::create(); 2074 2075 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe)); 2076 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles)); 2077 // We scan the thread roots in parallel 2078 Threads::create_thread_roots_marking_tasks(q); 2079 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer)); 2080 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler)); 2081 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management)); 2082 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary)); 2083 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data)); 2084 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti)); 2085 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache)); 2086 2087 if (active_gc_threads > 1) { 2088 for (uint j = 0; j < active_gc_threads; j++) { 2089 q->enqueue(new StealMarkingTask(&terminator)); 2090 } 2091 } 2092 2093 gc_task_manager()->execute_and_wait(q); 2094 } 2095 2096 // Process reference objects found during marking 2097 { 2098 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 2099 2100 ReferenceProcessorStats stats; 2101 if (ref_processor()->processing_is_mt()) { 2102 RefProcTaskExecutor task_executor; 2103 stats = ref_processor()->process_discovered_references( 2104 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, 2105 &task_executor, &_gc_timer); 2106 } else { 2107 stats = ref_processor()->process_discovered_references( 2108 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL, 2109 &_gc_timer); 2110 } 2111 2112 gc_tracer->report_gc_reference_stats(stats); 2113 } 2114 2115 // This is the point where the entire marking should have completed. 2116 assert(cm->marking_stacks_empty(), "Marking should have completed"); 2117 2118 { 2119 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer); 2120 2121 // Follow system dictionary roots and unload classes. 2122 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 2123 2124 // Unload nmethods. 2125 CodeCache::do_unloading(is_alive_closure(), purged_class); 2126 2127 // Prune dead klasses from subklass/sibling/implementor lists. 2128 Klass::clean_weak_klass_links(is_alive_closure()); 2129 } 2130 2131 { 2132 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer); 2133 // Delete entries for dead interned strings. 2134 StringTable::unlink(is_alive_closure()); 2135 } 2136 2137 { 2138 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer); 2139 // Clean up unreferenced symbols in symbol table. 2140 SymbolTable::unlink(); 2141 } 2142 2143 _gc_tracer.report_object_count_after_gc(is_alive_closure()); 2144 } 2145 2146 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) { 2147 // Adjust the pointers to reflect the new locations 2148 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer); 2149 2150 // Need new claim bits when tracing through and adjusting pointers. 2151 ClassLoaderDataGraph::clear_claimed_marks(); 2152 2153 PSParallelCompact::AdjustPointerClosure oop_closure(cm); 2154 PSParallelCompact::AdjustKlassClosure klass_closure(cm); 2155 2156 // General strong roots. 2157 Universe::oops_do(&oop_closure); 2158 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles 2159 Threads::oops_do(&oop_closure, NULL); 2160 ObjectSynchronizer::oops_do(&oop_closure); 2161 FlatProfiler::oops_do(&oop_closure); 2162 Management::oops_do(&oop_closure); 2163 JvmtiExport::oops_do(&oop_closure); 2164 SystemDictionary::oops_do(&oop_closure); 2165 ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true); 2166 2167 // Now adjust pointers in remaining weak roots. (All of which should 2168 // have been cleared if they pointed to non-surviving objects.) 2169 // Global (weak) JNI handles 2170 JNIHandles::weak_oops_do(&oop_closure); 2171 2172 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations); 2173 CodeCache::blobs_do(&adjust_from_blobs); 2174 AOTLoader::oops_do(&oop_closure); 2175 StringTable::oops_do(&oop_closure); 2176 ref_processor()->weak_oops_do(&oop_closure); 2177 // Roots were visited so references into the young gen in roots 2178 // may have been scanned. Process them also. 2179 // Should the reference processor have a span that excludes 2180 // young gen objects? 2181 PSScavenge::reference_processor()->weak_oops_do(&oop_closure); 2182 } 2183 2184 // Helper class to print 8 region numbers per line and then print the total at the end. 2185 class FillableRegionLogger : public StackObj { 2186 private: 2187 Log(gc, compaction) log; 2188 static const int LineLength = 8; 2189 size_t _regions[LineLength]; 2190 int _next_index; 2191 bool _enabled; 2192 size_t _total_regions; 2193 public: 2194 FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { } 2195 ~FillableRegionLogger() { 2196 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions); 2197 } 2198 2199 void print_line() { 2200 if (!_enabled || _next_index == 0) { 2201 return; 2202 } 2203 FormatBuffer<> line("Fillable: "); 2204 for (int i = 0; i < _next_index; i++) { 2205 line.append(" " SIZE_FORMAT_W(7), _regions[i]); 2206 } 2207 log.trace("%s", line.buffer()); 2208 _next_index = 0; 2209 } 2210 2211 void handle(size_t region) { 2212 if (!_enabled) { 2213 return; 2214 } 2215 _regions[_next_index++] = region; 2216 if (_next_index == LineLength) { 2217 print_line(); 2218 } 2219 _total_regions++; 2220 } 2221 }; 2222 2223 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q, 2224 uint parallel_gc_threads) 2225 { 2226 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer); 2227 2228 // Find the threads that are active 2229 unsigned int which = 0; 2230 2231 // Find all regions that are available (can be filled immediately) and 2232 // distribute them to the thread stacks. The iteration is done in reverse 2233 // order (high to low) so the regions will be removed in ascending order. 2234 2235 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 2236 2237 which = 0; 2238 // id + 1 is used to test termination so unsigned can 2239 // be used with an old_space_id == 0. 2240 FillableRegionLogger region_logger; 2241 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) { 2242 SpaceInfo* const space_info = _space_info + id; 2243 MutableSpace* const space = space_info->space(); 2244 HeapWord* const new_top = space_info->new_top(); 2245 2246 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix()); 2247 const size_t end_region = 2248 sd.addr_to_region_idx(sd.region_align_up(new_top)); 2249 2250 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) { 2251 if (sd.region(cur)->claim_unsafe()) { 2252 ParCompactionManager* cm = ParCompactionManager::manager_array(which); 2253 cm->region_stack()->push(cur); 2254 region_logger.handle(cur); 2255 // Assign regions to tasks in round-robin fashion. 2256 if (++which == parallel_gc_threads) { 2257 which = 0; 2258 } 2259 } 2260 } 2261 region_logger.print_line(); 2262 } 2263 } 2264 2265 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 2266 2267 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q, 2268 uint parallel_gc_threads) { 2269 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer); 2270 2271 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2272 2273 // Iterate over all the spaces adding tasks for updating 2274 // regions in the dense prefix. Assume that 1 gc thread 2275 // will work on opening the gaps and the remaining gc threads 2276 // will work on the dense prefix. 2277 unsigned int space_id; 2278 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) { 2279 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); 2280 const MutableSpace* const space = _space_info[space_id].space(); 2281 2282 if (dense_prefix_end == space->bottom()) { 2283 // There is no dense prefix for this space. 2284 continue; 2285 } 2286 2287 // The dense prefix is before this region. 2288 size_t region_index_end_dense_prefix = 2289 sd.addr_to_region_idx(dense_prefix_end); 2290 RegionData* const dense_prefix_cp = 2291 sd.region(region_index_end_dense_prefix); 2292 assert(dense_prefix_end == space->end() || 2293 dense_prefix_cp->available() || 2294 dense_prefix_cp->claimed(), 2295 "The region after the dense prefix should always be ready to fill"); 2296 2297 size_t region_index_start = sd.addr_to_region_idx(space->bottom()); 2298 2299 // Is there dense prefix work? 2300 size_t total_dense_prefix_regions = 2301 region_index_end_dense_prefix - region_index_start; 2302 // How many regions of the dense prefix should be given to 2303 // each thread? 2304 if (total_dense_prefix_regions > 0) { 2305 uint tasks_for_dense_prefix = 1; 2306 if (total_dense_prefix_regions <= 2307 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { 2308 // Don't over partition. This assumes that 2309 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value 2310 // so there are not many regions to process. 2311 tasks_for_dense_prefix = parallel_gc_threads; 2312 } else { 2313 // Over partition 2314 tasks_for_dense_prefix = parallel_gc_threads * 2315 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; 2316 } 2317 size_t regions_per_thread = total_dense_prefix_regions / 2318 tasks_for_dense_prefix; 2319 // Give each thread at least 1 region. 2320 if (regions_per_thread == 0) { 2321 regions_per_thread = 1; 2322 } 2323 2324 for (uint k = 0; k < tasks_for_dense_prefix; k++) { 2325 if (region_index_start >= region_index_end_dense_prefix) { 2326 break; 2327 } 2328 // region_index_end is not processed 2329 size_t region_index_end = MIN2(region_index_start + regions_per_thread, 2330 region_index_end_dense_prefix); 2331 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2332 region_index_start, 2333 region_index_end)); 2334 region_index_start = region_index_end; 2335 } 2336 } 2337 // This gets any part of the dense prefix that did not 2338 // fit evenly. 2339 if (region_index_start < region_index_end_dense_prefix) { 2340 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2341 region_index_start, 2342 region_index_end_dense_prefix)); 2343 } 2344 } 2345 } 2346 2347 void PSParallelCompact::enqueue_region_stealing_tasks( 2348 GCTaskQueue* q, 2349 ParallelTaskTerminator* terminator_ptr, 2350 uint parallel_gc_threads) { 2351 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer); 2352 2353 // Once a thread has drained it's stack, it should try to steal regions from 2354 // other threads. 2355 for (uint j = 0; j < parallel_gc_threads; j++) { 2356 q->enqueue(new CompactionWithStealingTask(terminator_ptr)); 2357 } 2358 } 2359 2360 #ifdef ASSERT 2361 // Write a histogram of the number of times the block table was filled for a 2362 // region. 2363 void PSParallelCompact::write_block_fill_histogram() 2364 { 2365 if (!log_develop_is_enabled(Trace, gc, compaction)) { 2366 return; 2367 } 2368 2369 Log(gc, compaction) log; 2370 ResourceMark rm; 2371 outputStream* out = log.trace_stream(); 2372 2373 typedef ParallelCompactData::RegionData rd_t; 2374 ParallelCompactData& sd = summary_data(); 2375 2376 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2377 MutableSpace* const spc = _space_info[id].space(); 2378 if (spc->bottom() != spc->top()) { 2379 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom()); 2380 HeapWord* const top_aligned_up = sd.region_align_up(spc->top()); 2381 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up); 2382 2383 size_t histo[5] = { 0, 0, 0, 0, 0 }; 2384 const size_t histo_len = sizeof(histo) / sizeof(size_t); 2385 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t)); 2386 2387 for (const rd_t* cur = beg; cur < end; ++cur) { 2388 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)]; 2389 } 2390 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt); 2391 for (size_t i = 0; i < histo_len; ++i) { 2392 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%", 2393 histo[i], 100.0 * histo[i] / region_cnt); 2394 } 2395 out->cr(); 2396 } 2397 } 2398 } 2399 #endif // #ifdef ASSERT 2400 2401 void PSParallelCompact::compact() { 2402 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer); 2403 2404 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2405 PSOldGen* old_gen = heap->old_gen(); 2406 old_gen->start_array()->reset(); 2407 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2408 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2409 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2410 ParallelTaskTerminator terminator(active_gc_threads, qset); 2411 2412 GCTaskQueue* q = GCTaskQueue::create(); 2413 prepare_region_draining_tasks(q, active_gc_threads); 2414 enqueue_dense_prefix_tasks(q, active_gc_threads); 2415 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads); 2416 2417 { 2418 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer); 2419 2420 gc_task_manager()->execute_and_wait(q); 2421 2422 #ifdef ASSERT 2423 // Verify that all regions have been processed before the deferred updates. 2424 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2425 verify_complete(SpaceId(id)); 2426 } 2427 #endif 2428 } 2429 2430 { 2431 // Update the deferred objects, if any. Any compaction manager can be used. 2432 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer); 2433 ParCompactionManager* cm = ParCompactionManager::manager_array(0); 2434 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2435 update_deferred_objects(cm, SpaceId(id)); 2436 } 2437 } 2438 2439 DEBUG_ONLY(write_block_fill_histogram()); 2440 } 2441 2442 #ifdef ASSERT 2443 void PSParallelCompact::verify_complete(SpaceId space_id) { 2444 // All Regions between space bottom() to new_top() should be marked as filled 2445 // and all Regions between new_top() and top() should be available (i.e., 2446 // should have been emptied). 2447 ParallelCompactData& sd = summary_data(); 2448 SpaceInfo si = _space_info[space_id]; 2449 HeapWord* new_top_addr = sd.region_align_up(si.new_top()); 2450 HeapWord* old_top_addr = sd.region_align_up(si.space()->top()); 2451 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom()); 2452 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr); 2453 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr); 2454 2455 bool issued_a_warning = false; 2456 2457 size_t cur_region; 2458 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) { 2459 const RegionData* const c = sd.region(cur_region); 2460 if (!c->completed()) { 2461 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u", 2462 cur_region, c->destination_count()); 2463 issued_a_warning = true; 2464 } 2465 } 2466 2467 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) { 2468 const RegionData* const c = sd.region(cur_region); 2469 if (!c->available()) { 2470 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u", 2471 cur_region, c->destination_count()); 2472 issued_a_warning = true; 2473 } 2474 } 2475 2476 if (issued_a_warning) { 2477 print_region_ranges(); 2478 } 2479 } 2480 #endif // #ifdef ASSERT 2481 2482 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) { 2483 _start_array->allocate_block(addr); 2484 compaction_manager()->update_contents(oop(addr)); 2485 } 2486 2487 // Update interior oops in the ranges of regions [beg_region, end_region). 2488 void 2489 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 2490 SpaceId space_id, 2491 size_t beg_region, 2492 size_t end_region) { 2493 ParallelCompactData& sd = summary_data(); 2494 ParMarkBitMap* const mbm = mark_bitmap(); 2495 2496 HeapWord* beg_addr = sd.region_to_addr(beg_region); 2497 HeapWord* const end_addr = sd.region_to_addr(end_region); 2498 assert(beg_region <= end_region, "bad region range"); 2499 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); 2500 2501 #ifdef ASSERT 2502 // Claim the regions to avoid triggering an assert when they are marked as 2503 // filled. 2504 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) { 2505 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed"); 2506 } 2507 #endif // #ifdef ASSERT 2508 2509 if (beg_addr != space(space_id)->bottom()) { 2510 // Find the first live object or block of dead space that *starts* in this 2511 // range of regions. If a partial object crosses onto the region, skip it; 2512 // it will be marked for 'deferred update' when the object head is 2513 // processed. If dead space crosses onto the region, it is also skipped; it 2514 // will be filled when the prior region is processed. If neither of those 2515 // apply, the first word in the region is the start of a live object or dead 2516 // space. 2517 assert(beg_addr > space(space_id)->bottom(), "sanity"); 2518 const RegionData* const cp = sd.region(beg_region); 2519 if (cp->partial_obj_size() != 0) { 2520 beg_addr = sd.partial_obj_end(beg_region); 2521 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) { 2522 beg_addr = mbm->find_obj_beg(beg_addr, end_addr); 2523 } 2524 } 2525 2526 if (beg_addr < end_addr) { 2527 // A live object or block of dead space starts in this range of Regions. 2528 HeapWord* const dense_prefix_end = dense_prefix(space_id); 2529 2530 // Create closures and iterate. 2531 UpdateOnlyClosure update_closure(mbm, cm, space_id); 2532 FillClosure fill_closure(cm, space_id); 2533 ParMarkBitMap::IterationStatus status; 2534 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, 2535 dense_prefix_end); 2536 if (status == ParMarkBitMap::incomplete) { 2537 update_closure.do_addr(update_closure.source()); 2538 } 2539 } 2540 2541 // Mark the regions as filled. 2542 RegionData* const beg_cp = sd.region(beg_region); 2543 RegionData* const end_cp = sd.region(end_region); 2544 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) { 2545 cp->set_completed(); 2546 } 2547 } 2548 2549 // Return the SpaceId for the space containing addr. If addr is not in the 2550 // heap, last_space_id is returned. In debug mode it expects the address to be 2551 // in the heap and asserts such. 2552 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) { 2553 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap"); 2554 2555 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2556 if (_space_info[id].space()->contains(addr)) { 2557 return SpaceId(id); 2558 } 2559 } 2560 2561 assert(false, "no space contains the addr"); 2562 return last_space_id; 2563 } 2564 2565 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm, 2566 SpaceId id) { 2567 assert(id < last_space_id, "bad space id"); 2568 2569 ParallelCompactData& sd = summary_data(); 2570 const SpaceInfo* const space_info = _space_info + id; 2571 ObjectStartArray* const start_array = space_info->start_array(); 2572 2573 const MutableSpace* const space = space_info->space(); 2574 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set"); 2575 HeapWord* const beg_addr = space_info->dense_prefix(); 2576 HeapWord* const end_addr = sd.region_align_up(space_info->new_top()); 2577 2578 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr); 2579 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr); 2580 const RegionData* cur_region; 2581 for (cur_region = beg_region; cur_region < end_region; ++cur_region) { 2582 HeapWord* const addr = cur_region->deferred_obj_addr(); 2583 if (addr != NULL) { 2584 if (start_array != NULL) { 2585 start_array->allocate_block(addr); 2586 } 2587 cm->update_contents(oop(addr)); 2588 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr))); 2589 } 2590 } 2591 } 2592 2593 // Skip over count live words starting from beg, and return the address of the 2594 // next live word. Unless marked, the word corresponding to beg is assumed to 2595 // be dead. Callers must either ensure beg does not correspond to the middle of 2596 // an object, or account for those live words in some other way. Callers must 2597 // also ensure that there are enough live words in the range [beg, end) to skip. 2598 HeapWord* 2599 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count) 2600 { 2601 assert(count > 0, "sanity"); 2602 2603 ParMarkBitMap* m = mark_bitmap(); 2604 idx_t bits_to_skip = m->words_to_bits(count); 2605 idx_t cur_beg = m->addr_to_bit(beg); 2606 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end)); 2607 2608 do { 2609 cur_beg = m->find_obj_beg(cur_beg, search_end); 2610 idx_t cur_end = m->find_obj_end(cur_beg, search_end); 2611 const size_t obj_bits = cur_end - cur_beg + 1; 2612 if (obj_bits > bits_to_skip) { 2613 return m->bit_to_addr(cur_beg + bits_to_skip); 2614 } 2615 bits_to_skip -= obj_bits; 2616 cur_beg = cur_end + 1; 2617 } while (bits_to_skip > 0); 2618 2619 // Skipping the desired number of words landed just past the end of an object. 2620 // Find the start of the next object. 2621 cur_beg = m->find_obj_beg(cur_beg, search_end); 2622 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip"); 2623 return m->bit_to_addr(cur_beg); 2624 } 2625 2626 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr, 2627 SpaceId src_space_id, 2628 size_t src_region_idx) 2629 { 2630 assert(summary_data().is_region_aligned(dest_addr), "not aligned"); 2631 2632 const SplitInfo& split_info = _space_info[src_space_id].split_info(); 2633 if (split_info.dest_region_addr() == dest_addr) { 2634 // The partial object ending at the split point contains the first word to 2635 // be copied to dest_addr. 2636 return split_info.first_src_addr(); 2637 } 2638 2639 const ParallelCompactData& sd = summary_data(); 2640 ParMarkBitMap* const bitmap = mark_bitmap(); 2641 const size_t RegionSize = ParallelCompactData::RegionSize; 2642 2643 assert(sd.is_region_aligned(dest_addr), "not aligned"); 2644 const RegionData* const src_region_ptr = sd.region(src_region_idx); 2645 const size_t partial_obj_size = src_region_ptr->partial_obj_size(); 2646 HeapWord* const src_region_destination = src_region_ptr->destination(); 2647 2648 assert(dest_addr >= src_region_destination, "wrong src region"); 2649 assert(src_region_ptr->data_size() > 0, "src region cannot be empty"); 2650 2651 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx); 2652 HeapWord* const src_region_end = src_region_beg + RegionSize; 2653 2654 HeapWord* addr = src_region_beg; 2655 if (dest_addr == src_region_destination) { 2656 // Return the first live word in the source region. 2657 if (partial_obj_size == 0) { 2658 addr = bitmap->find_obj_beg(addr, src_region_end); 2659 assert(addr < src_region_end, "no objects start in src region"); 2660 } 2661 return addr; 2662 } 2663 2664 // Must skip some live data. 2665 size_t words_to_skip = dest_addr - src_region_destination; 2666 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region"); 2667 2668 if (partial_obj_size >= words_to_skip) { 2669 // All the live words to skip are part of the partial object. 2670 addr += words_to_skip; 2671 if (partial_obj_size == words_to_skip) { 2672 // Find the first live word past the partial object. 2673 addr = bitmap->find_obj_beg(addr, src_region_end); 2674 assert(addr < src_region_end, "wrong src region"); 2675 } 2676 return addr; 2677 } 2678 2679 // Skip over the partial object (if any). 2680 if (partial_obj_size != 0) { 2681 words_to_skip -= partial_obj_size; 2682 addr += partial_obj_size; 2683 } 2684 2685 // Skip over live words due to objects that start in the region. 2686 addr = skip_live_words(addr, src_region_end, words_to_skip); 2687 assert(addr < src_region_end, "wrong src region"); 2688 return addr; 2689 } 2690 2691 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, 2692 SpaceId src_space_id, 2693 size_t beg_region, 2694 HeapWord* end_addr) 2695 { 2696 ParallelCompactData& sd = summary_data(); 2697 2698 #ifdef ASSERT 2699 MutableSpace* const src_space = _space_info[src_space_id].space(); 2700 HeapWord* const beg_addr = sd.region_to_addr(beg_region); 2701 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(), 2702 "src_space_id does not match beg_addr"); 2703 assert(src_space->contains(end_addr) || end_addr == src_space->end(), 2704 "src_space_id does not match end_addr"); 2705 #endif // #ifdef ASSERT 2706 2707 RegionData* const beg = sd.region(beg_region); 2708 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr)); 2709 2710 // Regions up to new_top() are enqueued if they become available. 2711 HeapWord* const new_top = _space_info[src_space_id].new_top(); 2712 RegionData* const enqueue_end = 2713 sd.addr_to_region_ptr(sd.region_align_up(new_top)); 2714 2715 for (RegionData* cur = beg; cur < end; ++cur) { 2716 assert(cur->data_size() > 0, "region must have live data"); 2717 cur->decrement_destination_count(); 2718 if (cur < enqueue_end && cur->available() && cur->claim()) { 2719 cm->push_region(sd.region(cur)); 2720 } 2721 } 2722 } 2723 2724 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure, 2725 SpaceId& src_space_id, 2726 HeapWord*& src_space_top, 2727 HeapWord* end_addr) 2728 { 2729 typedef ParallelCompactData::RegionData RegionData; 2730 2731 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2732 const size_t region_size = ParallelCompactData::RegionSize; 2733 2734 size_t src_region_idx = 0; 2735 2736 // Skip empty regions (if any) up to the top of the space. 2737 HeapWord* const src_aligned_up = sd.region_align_up(end_addr); 2738 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up); 2739 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top); 2740 const RegionData* const top_region_ptr = 2741 sd.addr_to_region_ptr(top_aligned_up); 2742 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) { 2743 ++src_region_ptr; 2744 } 2745 2746 if (src_region_ptr < top_region_ptr) { 2747 // The next source region is in the current space. Update src_region_idx 2748 // and the source address to match src_region_ptr. 2749 src_region_idx = sd.region(src_region_ptr); 2750 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx); 2751 if (src_region_addr > closure.source()) { 2752 closure.set_source(src_region_addr); 2753 } 2754 return src_region_idx; 2755 } 2756 2757 // Switch to a new source space and find the first non-empty region. 2758 unsigned int space_id = src_space_id + 1; 2759 assert(space_id < last_space_id, "not enough spaces"); 2760 2761 HeapWord* const destination = closure.destination(); 2762 2763 do { 2764 MutableSpace* space = _space_info[space_id].space(); 2765 HeapWord* const bottom = space->bottom(); 2766 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom); 2767 2768 // Iterate over the spaces that do not compact into themselves. 2769 if (bottom_cp->destination() != bottom) { 2770 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 2771 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 2772 2773 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) { 2774 if (src_cp->live_obj_size() > 0) { 2775 // Found it. 2776 assert(src_cp->destination() == destination, 2777 "first live obj in the space must match the destination"); 2778 assert(src_cp->partial_obj_size() == 0, 2779 "a space cannot begin with a partial obj"); 2780 2781 src_space_id = SpaceId(space_id); 2782 src_space_top = space->top(); 2783 const size_t src_region_idx = sd.region(src_cp); 2784 closure.set_source(sd.region_to_addr(src_region_idx)); 2785 return src_region_idx; 2786 } else { 2787 assert(src_cp->data_size() == 0, "sanity"); 2788 } 2789 } 2790 } 2791 } while (++space_id < last_space_id); 2792 2793 assert(false, "no source region was found"); 2794 return 0; 2795 } 2796 2797 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx) 2798 { 2799 typedef ParMarkBitMap::IterationStatus IterationStatus; 2800 const size_t RegionSize = ParallelCompactData::RegionSize; 2801 ParMarkBitMap* const bitmap = mark_bitmap(); 2802 ParallelCompactData& sd = summary_data(); 2803 RegionData* const region_ptr = sd.region(region_idx); 2804 2805 // Get the items needed to construct the closure. 2806 HeapWord* dest_addr = sd.region_to_addr(region_idx); 2807 SpaceId dest_space_id = space_id(dest_addr); 2808 ObjectStartArray* start_array = _space_info[dest_space_id].start_array(); 2809 HeapWord* new_top = _space_info[dest_space_id].new_top(); 2810 assert(dest_addr < new_top, "sanity"); 2811 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize); 2812 2813 // Get the source region and related info. 2814 size_t src_region_idx = region_ptr->source_region(); 2815 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx)); 2816 HeapWord* src_space_top = _space_info[src_space_id].space()->top(); 2817 2818 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 2819 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx)); 2820 2821 // Adjust src_region_idx to prepare for decrementing destination counts (the 2822 // destination count is not decremented when a region is copied to itself). 2823 if (src_region_idx == region_idx) { 2824 src_region_idx += 1; 2825 } 2826 2827 if (bitmap->is_unmarked(closure.source())) { 2828 // The first source word is in the middle of an object; copy the remainder 2829 // of the object or as much as will fit. The fact that pointer updates were 2830 // deferred will be noted when the object header is processed. 2831 HeapWord* const old_src_addr = closure.source(); 2832 closure.copy_partial_obj(); 2833 if (closure.is_full()) { 2834 decrement_destination_counts(cm, src_space_id, src_region_idx, 2835 closure.source()); 2836 region_ptr->set_deferred_obj_addr(NULL); 2837 region_ptr->set_completed(); 2838 return; 2839 } 2840 2841 HeapWord* const end_addr = sd.region_align_down(closure.source()); 2842 if (sd.region_align_down(old_src_addr) != end_addr) { 2843 // The partial object was copied from more than one source region. 2844 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2845 2846 // Move to the next source region, possibly switching spaces as well. All 2847 // args except end_addr may be modified. 2848 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2849 end_addr); 2850 } 2851 } 2852 2853 do { 2854 HeapWord* const cur_addr = closure.source(); 2855 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1), 2856 src_space_top); 2857 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr); 2858 2859 if (status == ParMarkBitMap::incomplete) { 2860 // The last obj that starts in the source region does not end in the 2861 // region. 2862 assert(closure.source() < end_addr, "sanity"); 2863 HeapWord* const obj_beg = closure.source(); 2864 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(), 2865 src_space_top); 2866 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end); 2867 if (obj_end < range_end) { 2868 // The end was found; the entire object will fit. 2869 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end)); 2870 assert(status != ParMarkBitMap::would_overflow, "sanity"); 2871 } else { 2872 // The end was not found; the object will not fit. 2873 assert(range_end < src_space_top, "obj cannot cross space boundary"); 2874 status = ParMarkBitMap::would_overflow; 2875 } 2876 } 2877 2878 if (status == ParMarkBitMap::would_overflow) { 2879 // The last object did not fit. Note that interior oop updates were 2880 // deferred, then copy enough of the object to fill the region. 2881 region_ptr->set_deferred_obj_addr(closure.destination()); 2882 status = closure.copy_until_full(); // copies from closure.source() 2883 2884 decrement_destination_counts(cm, src_space_id, src_region_idx, 2885 closure.source()); 2886 region_ptr->set_completed(); 2887 return; 2888 } 2889 2890 if (status == ParMarkBitMap::full) { 2891 decrement_destination_counts(cm, src_space_id, src_region_idx, 2892 closure.source()); 2893 region_ptr->set_deferred_obj_addr(NULL); 2894 region_ptr->set_completed(); 2895 return; 2896 } 2897 2898 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2899 2900 // Move to the next source region, possibly switching spaces as well. All 2901 // args except end_addr may be modified. 2902 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2903 end_addr); 2904 } while (true); 2905 } 2906 2907 void PSParallelCompact::fill_blocks(size_t region_idx) 2908 { 2909 // Fill in the block table elements for the specified region. Each block 2910 // table element holds the number of live words in the region that are to the 2911 // left of the first object that starts in the block. Thus only blocks in 2912 // which an object starts need to be filled. 2913 // 2914 // The algorithm scans the section of the bitmap that corresponds to the 2915 // region, keeping a running total of the live words. When an object start is 2916 // found, if it's the first to start in the block that contains it, the 2917 // current total is written to the block table element. 2918 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize; 2919 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize; 2920 const size_t RegionSize = ParallelCompactData::RegionSize; 2921 2922 ParallelCompactData& sd = summary_data(); 2923 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size(); 2924 if (partial_obj_size >= RegionSize) { 2925 return; // No objects start in this region. 2926 } 2927 2928 // Ensure the first loop iteration decides that the block has changed. 2929 size_t cur_block = sd.block_count(); 2930 2931 const ParMarkBitMap* const bitmap = mark_bitmap(); 2932 2933 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment; 2934 assert((size_t)1 << Log2BitsPerBlock == 2935 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity"); 2936 2937 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize); 2938 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize); 2939 size_t live_bits = bitmap->words_to_bits(partial_obj_size); 2940 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end); 2941 while (beg_bit < range_end) { 2942 const size_t new_block = beg_bit >> Log2BitsPerBlock; 2943 if (new_block != cur_block) { 2944 cur_block = new_block; 2945 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits)); 2946 } 2947 2948 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end); 2949 if (end_bit < range_end - 1) { 2950 live_bits += end_bit - beg_bit + 1; 2951 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end); 2952 } else { 2953 return; 2954 } 2955 } 2956 } 2957 2958 void 2959 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) { 2960 const MutableSpace* sp = space(space_id); 2961 if (sp->is_empty()) { 2962 return; 2963 } 2964 2965 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2966 ParMarkBitMap* const bitmap = mark_bitmap(); 2967 HeapWord* const dp_addr = dense_prefix(space_id); 2968 HeapWord* beg_addr = sp->bottom(); 2969 HeapWord* end_addr = sp->top(); 2970 2971 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix"); 2972 2973 const size_t beg_region = sd.addr_to_region_idx(beg_addr); 2974 const size_t dp_region = sd.addr_to_region_idx(dp_addr); 2975 if (beg_region < dp_region) { 2976 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region); 2977 } 2978 2979 // The destination of the first live object that starts in the region is one 2980 // past the end of the partial object entering the region (if any). 2981 HeapWord* const dest_addr = sd.partial_obj_end(dp_region); 2982 HeapWord* const new_top = _space_info[space_id].new_top(); 2983 assert(new_top >= dest_addr, "bad new_top value"); 2984 const size_t words = pointer_delta(new_top, dest_addr); 2985 2986 if (words > 0) { 2987 ObjectStartArray* start_array = _space_info[space_id].start_array(); 2988 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 2989 2990 ParMarkBitMap::IterationStatus status; 2991 status = bitmap->iterate(&closure, dest_addr, end_addr); 2992 assert(status == ParMarkBitMap::full, "iteration not complete"); 2993 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr, 2994 "live objects skipped because closure is full"); 2995 } 2996 } 2997 2998 jlong PSParallelCompact::millis_since_last_gc() { 2999 // We need a monotonically non-decreasing time in ms but 3000 // os::javaTimeMillis() does not guarantee monotonicity. 3001 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3002 jlong ret_val = now - _time_of_last_gc; 3003 // XXX See note in genCollectedHeap::millis_since_last_gc(). 3004 if (ret_val < 0) { 3005 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 3006 return 0; 3007 } 3008 return ret_val; 3009 } 3010 3011 void PSParallelCompact::reset_millis_since_last_gc() { 3012 // We need a monotonically non-decreasing time in ms but 3013 // os::javaTimeMillis() does not guarantee monotonicity. 3014 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3015 } 3016 3017 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() 3018 { 3019 if (source() != destination()) { 3020 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3021 Copy::aligned_conjoint_words(source(), destination(), words_remaining()); 3022 } 3023 update_state(words_remaining()); 3024 assert(is_full(), "sanity"); 3025 return ParMarkBitMap::full; 3026 } 3027 3028 void MoveAndUpdateClosure::copy_partial_obj() 3029 { 3030 size_t words = words_remaining(); 3031 3032 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end()); 3033 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end); 3034 if (end_addr < range_end) { 3035 words = bitmap()->obj_size(source(), end_addr); 3036 } 3037 3038 // This test is necessary; if omitted, the pointer updates to a partial object 3039 // that crosses the dense prefix boundary could be overwritten. 3040 if (source() != destination()) { 3041 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3042 Copy::aligned_conjoint_words(source(), destination(), words); 3043 } 3044 update_state(words); 3045 } 3046 3047 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3048 PSParallelCompact::AdjustPointerClosure closure(cm); 3049 oop_oop_iterate_oop_maps<true>(obj, &closure); 3050 } 3051 3052 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3053 InstanceKlass::oop_pc_update_pointers(obj, cm); 3054 3055 PSParallelCompact::AdjustPointerClosure closure(cm); 3056 oop_oop_iterate_statics<true>(obj, &closure); 3057 } 3058 3059 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3060 InstanceKlass::oop_pc_update_pointers(obj, cm); 3061 } 3062 3063 #ifdef ASSERT 3064 template <class T> static void trace_reference_gc(const char *s, oop obj, 3065 T* referent_addr, 3066 T* next_addr, 3067 T* discovered_addr) { 3068 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj)); 3069 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3070 p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL); 3071 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3072 p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL); 3073 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3074 p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL); 3075 } 3076 #endif 3077 3078 template <class T> 3079 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) { 3080 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj); 3081 PSParallelCompact::adjust_pointer(referent_addr, cm); 3082 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj); 3083 PSParallelCompact::adjust_pointer(next_addr, cm); 3084 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj); 3085 PSParallelCompact::adjust_pointer(discovered_addr, cm); 3086 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj, 3087 referent_addr, next_addr, discovered_addr);) 3088 } 3089 3090 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3091 InstanceKlass::oop_pc_update_pointers(obj, cm); 3092 3093 if (UseCompressedOops) { 3094 oop_pc_update_pointers_specialized<narrowOop>(obj, cm); 3095 } else { 3096 oop_pc_update_pointers_specialized<oop>(obj, cm); 3097 } 3098 } 3099 3100 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3101 assert(obj->is_objArray(), "obj must be obj array"); 3102 PSParallelCompact::AdjustPointerClosure closure(cm); 3103 oop_oop_iterate_elements<true>(objArrayOop(obj), &closure); 3104 } 3105 3106 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3107 assert(obj->is_typeArray(),"must be a type array"); 3108 } 3109 3110 ParMarkBitMapClosure::IterationStatus 3111 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) { 3112 assert(destination() != NULL, "sanity"); 3113 assert(bitmap()->obj_size(addr) == words, "bad size"); 3114 3115 _source = addr; 3116 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) == 3117 destination(), "wrong destination"); 3118 3119 if (words > words_remaining()) { 3120 return ParMarkBitMap::would_overflow; 3121 } 3122 3123 // The start_array must be updated even if the object is not moving. 3124 if (_start_array != NULL) { 3125 _start_array->allocate_block(destination()); 3126 } 3127 3128 if (destination() != source()) { 3129 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3130 Copy::aligned_conjoint_words(source(), destination(), words); 3131 } 3132 3133 oop moved_oop = (oop) destination(); 3134 compaction_manager()->update_contents(moved_oop); 3135 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop)); 3136 3137 update_state(words); 3138 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity"); 3139 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete; 3140 } 3141 3142 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm, 3143 ParCompactionManager* cm, 3144 PSParallelCompact::SpaceId space_id) : 3145 ParMarkBitMapClosure(mbm, cm), 3146 _space_id(space_id), 3147 _start_array(PSParallelCompact::start_array(space_id)) 3148 { 3149 } 3150 3151 // Updates the references in the object to their new values. 3152 ParMarkBitMapClosure::IterationStatus 3153 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) { 3154 do_addr(addr); 3155 return ParMarkBitMap::incomplete; 3156 } 3157 3158 ParMarkBitMapClosure::IterationStatus 3159 FillClosure::do_addr(HeapWord* addr, size_t size) { 3160 CollectedHeap::fill_with_objects(addr, size); 3161 HeapWord* const end = addr + size; 3162 do { 3163 _start_array->allocate_block(addr); 3164 addr += oop(addr)->size(); 3165 } while (addr < end); 3166 return ParMarkBitMap::incomplete; 3167 }