1 /* 2 * Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "aot/aotLoader.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "code/codeCache.hpp" 31 #include "gc/parallel/gcTaskManager.hpp" 32 #include "gc/parallel/parallelScavengeHeap.inline.hpp" 33 #include "gc/parallel/parMarkBitMap.inline.hpp" 34 #include "gc/parallel/pcTasks.hpp" 35 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 36 #include "gc/parallel/psCompactionManager.inline.hpp" 37 #include "gc/parallel/psMarkSweep.hpp" 38 #include "gc/parallel/psMarkSweepDecorator.hpp" 39 #include "gc/parallel/psOldGen.hpp" 40 #include "gc/parallel/psParallelCompact.inline.hpp" 41 #include "gc/parallel/psPromotionManager.inline.hpp" 42 #include "gc/parallel/psScavenge.hpp" 43 #include "gc/parallel/psYoungGen.hpp" 44 #include "gc/shared/gcCause.hpp" 45 #include "gc/shared/gcHeapSummary.hpp" 46 #include "gc/shared/gcId.hpp" 47 #include "gc/shared/gcLocker.inline.hpp" 48 #include "gc/shared/gcTimer.hpp" 49 #include "gc/shared/gcTrace.hpp" 50 #include "gc/shared/gcTraceTime.inline.hpp" 51 #include "gc/shared/isGCActiveMark.hpp" 52 #include "gc/shared/referencePolicy.hpp" 53 #include "gc/shared/referenceProcessor.hpp" 54 #include "gc/shared/spaceDecorator.hpp" 55 #include "logging/log.hpp" 56 #include "memory/resourceArea.hpp" 57 #include "oops/instanceKlass.inline.hpp" 58 #include "oops/instanceMirrorKlass.inline.hpp" 59 #include "oops/methodData.hpp" 60 #include "oops/objArrayKlass.inline.hpp" 61 #include "oops/oop.inline.hpp" 62 #include "runtime/atomic.hpp" 63 #include "runtime/fprofiler.hpp" 64 #include "runtime/safepoint.hpp" 65 #include "runtime/vmThread.hpp" 66 #include "services/management.hpp" 67 #include "services/memTracker.hpp" 68 #include "services/memoryService.hpp" 69 #include "utilities/debug.hpp" 70 #include "utilities/events.hpp" 71 #include "utilities/formatBuffer.hpp" 72 #include "utilities/stack.inline.hpp" 73 74 #include <math.h> 75 76 // All sizes are in HeapWords. 77 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words 78 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize; 79 const size_t ParallelCompactData::RegionSizeBytes = 80 RegionSize << LogHeapWordSize; 81 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1; 82 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1; 83 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask; 84 85 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words 86 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize; 87 const size_t ParallelCompactData::BlockSizeBytes = 88 BlockSize << LogHeapWordSize; 89 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1; 90 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1; 91 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask; 92 93 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize; 94 const size_t ParallelCompactData::Log2BlocksPerRegion = 95 Log2RegionSize - Log2BlockSize; 96 97 const ParallelCompactData::RegionData::region_sz_t 98 ParallelCompactData::RegionData::dc_shift = 27; 99 100 const ParallelCompactData::RegionData::region_sz_t 101 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift; 102 103 const ParallelCompactData::RegionData::region_sz_t 104 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift; 105 106 const ParallelCompactData::RegionData::region_sz_t 107 ParallelCompactData::RegionData::los_mask = ~dc_mask; 108 109 const ParallelCompactData::RegionData::region_sz_t 110 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift; 111 112 const ParallelCompactData::RegionData::region_sz_t 113 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift; 114 115 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; 116 117 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; 118 119 double PSParallelCompact::_dwl_mean; 120 double PSParallelCompact::_dwl_std_dev; 121 double PSParallelCompact::_dwl_first_term; 122 double PSParallelCompact::_dwl_adjustment; 123 #ifdef ASSERT 124 bool PSParallelCompact::_dwl_initialized = false; 125 #endif // #ifdef ASSERT 126 127 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size, 128 HeapWord* destination) 129 { 130 assert(src_region_idx != 0, "invalid src_region_idx"); 131 assert(partial_obj_size != 0, "invalid partial_obj_size argument"); 132 assert(destination != NULL, "invalid destination argument"); 133 134 _src_region_idx = src_region_idx; 135 _partial_obj_size = partial_obj_size; 136 _destination = destination; 137 138 // These fields may not be updated below, so make sure they're clear. 139 assert(_dest_region_addr == NULL, "should have been cleared"); 140 assert(_first_src_addr == NULL, "should have been cleared"); 141 142 // Determine the number of destination regions for the partial object. 143 HeapWord* const last_word = destination + partial_obj_size - 1; 144 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 145 HeapWord* const beg_region_addr = sd.region_align_down(destination); 146 HeapWord* const end_region_addr = sd.region_align_down(last_word); 147 148 if (beg_region_addr == end_region_addr) { 149 // One destination region. 150 _destination_count = 1; 151 if (end_region_addr == destination) { 152 // The destination falls on a region boundary, thus the first word of the 153 // partial object will be the first word copied to the destination region. 154 _dest_region_addr = end_region_addr; 155 _first_src_addr = sd.region_to_addr(src_region_idx); 156 } 157 } else { 158 // Two destination regions. When copied, the partial object will cross a 159 // destination region boundary, so a word somewhere within the partial 160 // object will be the first word copied to the second destination region. 161 _destination_count = 2; 162 _dest_region_addr = end_region_addr; 163 const size_t ofs = pointer_delta(end_region_addr, destination); 164 assert(ofs < _partial_obj_size, "sanity"); 165 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs; 166 } 167 } 168 169 void SplitInfo::clear() 170 { 171 _src_region_idx = 0; 172 _partial_obj_size = 0; 173 _destination = NULL; 174 _destination_count = 0; 175 _dest_region_addr = NULL; 176 _first_src_addr = NULL; 177 assert(!is_valid(), "sanity"); 178 } 179 180 #ifdef ASSERT 181 void SplitInfo::verify_clear() 182 { 183 assert(_src_region_idx == 0, "not clear"); 184 assert(_partial_obj_size == 0, "not clear"); 185 assert(_destination == NULL, "not clear"); 186 assert(_destination_count == 0, "not clear"); 187 assert(_dest_region_addr == NULL, "not clear"); 188 assert(_first_src_addr == NULL, "not clear"); 189 } 190 #endif // #ifdef ASSERT 191 192 193 void PSParallelCompact::print_on_error(outputStream* st) { 194 _mark_bitmap.print_on_error(st); 195 } 196 197 #ifndef PRODUCT 198 const char* PSParallelCompact::space_names[] = { 199 "old ", "eden", "from", "to " 200 }; 201 202 void PSParallelCompact::print_region_ranges() { 203 if (!log_develop_is_enabled(Trace, gc, compaction)) { 204 return; 205 } 206 Log(gc, compaction) log; 207 ResourceMark rm; 208 Universe::print_on(log.trace_stream()); 209 log.trace("space bottom top end new_top"); 210 log.trace("------ ---------- ---------- ---------- ----------"); 211 212 for (unsigned int id = 0; id < last_space_id; ++id) { 213 const MutableSpace* space = _space_info[id].space(); 214 log.trace("%u %s " 215 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " 216 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", 217 id, space_names[id], 218 summary_data().addr_to_region_idx(space->bottom()), 219 summary_data().addr_to_region_idx(space->top()), 220 summary_data().addr_to_region_idx(space->end()), 221 summary_data().addr_to_region_idx(_space_info[id].new_top())); 222 } 223 } 224 225 void 226 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c) 227 { 228 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7) 229 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5) 230 231 ParallelCompactData& sd = PSParallelCompact::summary_data(); 232 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0; 233 log_develop_trace(gc, compaction)( 234 REGION_IDX_FORMAT " " PTR_FORMAT " " 235 REGION_IDX_FORMAT " " PTR_FORMAT " " 236 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " " 237 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d", 238 i, p2i(c->data_location()), dci, p2i(c->destination()), 239 c->partial_obj_size(), c->live_obj_size(), 240 c->data_size(), c->source_region(), c->destination_count()); 241 242 #undef REGION_IDX_FORMAT 243 #undef REGION_DATA_FORMAT 244 } 245 246 void 247 print_generic_summary_data(ParallelCompactData& summary_data, 248 HeapWord* const beg_addr, 249 HeapWord* const end_addr) 250 { 251 size_t total_words = 0; 252 size_t i = summary_data.addr_to_region_idx(beg_addr); 253 const size_t last = summary_data.addr_to_region_idx(end_addr); 254 HeapWord* pdest = 0; 255 256 while (i < last) { 257 ParallelCompactData::RegionData* c = summary_data.region(i); 258 if (c->data_size() != 0 || c->destination() != pdest) { 259 print_generic_summary_region(i, c); 260 total_words += c->data_size(); 261 pdest = c->destination(); 262 } 263 ++i; 264 } 265 266 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); 267 } 268 269 void 270 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data, 271 HeapWord* const beg_addr, 272 HeapWord* const end_addr) { 273 ::print_generic_summary_data(summary_data,beg_addr, end_addr); 274 } 275 276 void 277 print_generic_summary_data(ParallelCompactData& summary_data, 278 SpaceInfo* space_info) 279 { 280 if (!log_develop_is_enabled(Trace, gc, compaction)) { 281 return; 282 } 283 284 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { 285 const MutableSpace* space = space_info[id].space(); 286 print_generic_summary_data(summary_data, space->bottom(), 287 MAX2(space->top(), space_info[id].new_top())); 288 } 289 } 290 291 void 292 print_initial_summary_data(ParallelCompactData& summary_data, 293 const MutableSpace* space) { 294 if (space->top() == space->bottom()) { 295 return; 296 } 297 298 const size_t region_size = ParallelCompactData::RegionSize; 299 typedef ParallelCompactData::RegionData RegionData; 300 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top()); 301 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up); 302 const RegionData* c = summary_data.region(end_region - 1); 303 HeapWord* end_addr = c->destination() + c->data_size(); 304 const size_t live_in_space = pointer_delta(end_addr, space->bottom()); 305 306 // Print (and count) the full regions at the beginning of the space. 307 size_t full_region_count = 0; 308 size_t i = summary_data.addr_to_region_idx(space->bottom()); 309 while (i < end_region && summary_data.region(i)->data_size() == region_size) { 310 ParallelCompactData::RegionData* c = summary_data.region(i); 311 log_develop_trace(gc, compaction)( 312 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 313 i, p2i(c->destination()), 314 c->partial_obj_size(), c->live_obj_size(), 315 c->data_size(), c->source_region(), c->destination_count()); 316 ++full_region_count; 317 ++i; 318 } 319 320 size_t live_to_right = live_in_space - full_region_count * region_size; 321 322 double max_reclaimed_ratio = 0.0; 323 size_t max_reclaimed_ratio_region = 0; 324 size_t max_dead_to_right = 0; 325 size_t max_live_to_right = 0; 326 327 // Print the 'reclaimed ratio' for regions while there is something live in 328 // the region or to the right of it. The remaining regions are empty (and 329 // uninteresting), and computing the ratio will result in division by 0. 330 while (i < end_region && live_to_right > 0) { 331 c = summary_data.region(i); 332 HeapWord* const region_addr = summary_data.region_to_addr(i); 333 const size_t used_to_right = pointer_delta(space->top(), region_addr); 334 const size_t dead_to_right = used_to_right - live_to_right; 335 const double reclaimed_ratio = double(dead_to_right) / live_to_right; 336 337 if (reclaimed_ratio > max_reclaimed_ratio) { 338 max_reclaimed_ratio = reclaimed_ratio; 339 max_reclaimed_ratio_region = i; 340 max_dead_to_right = dead_to_right; 341 max_live_to_right = live_to_right; 342 } 343 344 ParallelCompactData::RegionData* c = summary_data.region(i); 345 log_develop_trace(gc, compaction)( 346 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d" 347 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), 348 i, p2i(c->destination()), 349 c->partial_obj_size(), c->live_obj_size(), 350 c->data_size(), c->source_region(), c->destination_count(), 351 reclaimed_ratio, dead_to_right, live_to_right); 352 353 354 live_to_right -= c->data_size(); 355 ++i; 356 } 357 358 // Any remaining regions are empty. Print one more if there is one. 359 if (i < end_region) { 360 ParallelCompactData::RegionData* c = summary_data.region(i); 361 log_develop_trace(gc, compaction)( 362 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 363 i, p2i(c->destination()), 364 c->partial_obj_size(), c->live_obj_size(), 365 c->data_size(), c->source_region(), c->destination_count()); 366 } 367 368 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", 369 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio); 370 } 371 372 void 373 print_initial_summary_data(ParallelCompactData& summary_data, 374 SpaceInfo* space_info) { 375 if (!log_develop_is_enabled(Trace, gc, compaction)) { 376 return; 377 } 378 379 unsigned int id = PSParallelCompact::old_space_id; 380 const MutableSpace* space; 381 do { 382 space = space_info[id].space(); 383 print_initial_summary_data(summary_data, space); 384 } while (++id < PSParallelCompact::eden_space_id); 385 386 do { 387 space = space_info[id].space(); 388 print_generic_summary_data(summary_data, space->bottom(), space->top()); 389 } while (++id < PSParallelCompact::last_space_id); 390 } 391 #endif // #ifndef PRODUCT 392 393 #ifdef ASSERT 394 size_t add_obj_count; 395 size_t add_obj_size; 396 size_t mark_bitmap_count; 397 size_t mark_bitmap_size; 398 #endif // #ifdef ASSERT 399 400 ParallelCompactData::ParallelCompactData() 401 { 402 _region_start = 0; 403 404 _region_vspace = 0; 405 _reserved_byte_size = 0; 406 _region_data = 0; 407 _region_count = 0; 408 409 _block_vspace = 0; 410 _block_data = 0; 411 _block_count = 0; 412 } 413 414 bool ParallelCompactData::initialize(MemRegion covered_region) 415 { 416 _region_start = covered_region.start(); 417 const size_t region_size = covered_region.word_size(); 418 DEBUG_ONLY(_region_end = _region_start + region_size;) 419 420 assert(region_align_down(_region_start) == _region_start, 421 "region start not aligned"); 422 assert((region_size & RegionSizeOffsetMask) == 0, 423 "region size not a multiple of RegionSize"); 424 425 bool result = initialize_region_data(region_size) && initialize_block_data(); 426 return result; 427 } 428 429 PSVirtualSpace* 430 ParallelCompactData::create_vspace(size_t count, size_t element_size) 431 { 432 const size_t raw_bytes = count * element_size; 433 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10); 434 const size_t granularity = os::vm_allocation_granularity(); 435 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity)); 436 437 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : 438 MAX2(page_sz, granularity); 439 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0); 440 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(), 441 rs.size()); 442 443 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 444 445 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); 446 if (vspace != 0) { 447 if (vspace->expand_by(_reserved_byte_size)) { 448 return vspace; 449 } 450 delete vspace; 451 // Release memory reserved in the space. 452 rs.release(); 453 } 454 455 return 0; 456 } 457 458 bool ParallelCompactData::initialize_region_data(size_t region_size) 459 { 460 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize; 461 _region_vspace = create_vspace(count, sizeof(RegionData)); 462 if (_region_vspace != 0) { 463 _region_data = (RegionData*)_region_vspace->reserved_low_addr(); 464 _region_count = count; 465 return true; 466 } 467 return false; 468 } 469 470 bool ParallelCompactData::initialize_block_data() 471 { 472 assert(_region_count != 0, "region data must be initialized first"); 473 const size_t count = _region_count << Log2BlocksPerRegion; 474 _block_vspace = create_vspace(count, sizeof(BlockData)); 475 if (_block_vspace != 0) { 476 _block_data = (BlockData*)_block_vspace->reserved_low_addr(); 477 _block_count = count; 478 return true; 479 } 480 return false; 481 } 482 483 void ParallelCompactData::clear() 484 { 485 memset(_region_data, 0, _region_vspace->committed_size()); 486 memset(_block_data, 0, _block_vspace->committed_size()); 487 } 488 489 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) { 490 assert(beg_region <= _region_count, "beg_region out of range"); 491 assert(end_region <= _region_count, "end_region out of range"); 492 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize"); 493 494 const size_t region_cnt = end_region - beg_region; 495 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData)); 496 497 const size_t beg_block = beg_region * BlocksPerRegion; 498 const size_t block_cnt = region_cnt * BlocksPerRegion; 499 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData)); 500 } 501 502 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const 503 { 504 const RegionData* cur_cp = region(region_idx); 505 const RegionData* const end_cp = region(region_count() - 1); 506 507 HeapWord* result = region_to_addr(region_idx); 508 if (cur_cp < end_cp) { 509 do { 510 result += cur_cp->partial_obj_size(); 511 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp); 512 } 513 return result; 514 } 515 516 void ParallelCompactData::add_obj(HeapWord* addr, size_t len) 517 { 518 const size_t obj_ofs = pointer_delta(addr, _region_start); 519 const size_t beg_region = obj_ofs >> Log2RegionSize; 520 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize; 521 522 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);) 523 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);) 524 525 if (beg_region == end_region) { 526 // All in one region. 527 _region_data[beg_region].add_live_obj(len); 528 return; 529 } 530 531 // First region. 532 const size_t beg_ofs = region_offset(addr); 533 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs); 534 535 Klass* klass = ((oop)addr)->klass(); 536 // Middle regions--completely spanned by this object. 537 for (size_t region = beg_region + 1; region < end_region; ++region) { 538 _region_data[region].set_partial_obj_size(RegionSize); 539 _region_data[region].set_partial_obj_addr(addr); 540 } 541 542 // Last region. 543 const size_t end_ofs = region_offset(addr + len - 1); 544 _region_data[end_region].set_partial_obj_size(end_ofs + 1); 545 _region_data[end_region].set_partial_obj_addr(addr); 546 } 547 548 void 549 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) 550 { 551 assert(region_offset(beg) == 0, "not RegionSize aligned"); 552 assert(region_offset(end) == 0, "not RegionSize aligned"); 553 554 size_t cur_region = addr_to_region_idx(beg); 555 const size_t end_region = addr_to_region_idx(end); 556 HeapWord* addr = beg; 557 while (cur_region < end_region) { 558 _region_data[cur_region].set_destination(addr); 559 _region_data[cur_region].set_destination_count(0); 560 _region_data[cur_region].set_source_region(cur_region); 561 _region_data[cur_region].set_data_location(addr); 562 563 // Update live_obj_size so the region appears completely full. 564 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size(); 565 _region_data[cur_region].set_live_obj_size(live_size); 566 567 ++cur_region; 568 addr += RegionSize; 569 } 570 } 571 572 // Find the point at which a space can be split and, if necessary, record the 573 // split point. 574 // 575 // If the current src region (which overflowed the destination space) doesn't 576 // have a partial object, the split point is at the beginning of the current src 577 // region (an "easy" split, no extra bookkeeping required). 578 // 579 // If the current src region has a partial object, the split point is in the 580 // region where that partial object starts (call it the split_region). If 581 // split_region has a partial object, then the split point is just after that 582 // partial object (a "hard" split where we have to record the split data and 583 // zero the partial_obj_size field). With a "hard" split, we know that the 584 // partial_obj ends within split_region because the partial object that caused 585 // the overflow starts in split_region. If split_region doesn't have a partial 586 // obj, then the split is at the beginning of split_region (another "easy" 587 // split). 588 HeapWord* 589 ParallelCompactData::summarize_split_space(size_t src_region, 590 SplitInfo& split_info, 591 HeapWord* destination, 592 HeapWord* target_end, 593 HeapWord** target_next) 594 { 595 assert(destination <= target_end, "sanity"); 596 assert(destination + _region_data[src_region].data_size() > target_end, 597 "region should not fit into target space"); 598 assert(is_region_aligned(target_end), "sanity"); 599 600 size_t split_region = src_region; 601 HeapWord* split_destination = destination; 602 size_t partial_obj_size = _region_data[src_region].partial_obj_size(); 603 604 if (destination + partial_obj_size > target_end) { 605 // The split point is just after the partial object (if any) in the 606 // src_region that contains the start of the object that overflowed the 607 // destination space. 608 // 609 // Find the start of the "overflow" object and set split_region to the 610 // region containing it. 611 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr(); 612 split_region = addr_to_region_idx(overflow_obj); 613 614 // Clear the source_region field of all destination regions whose first word 615 // came from data after the split point (a non-null source_region field 616 // implies a region must be filled). 617 // 618 // An alternative to the simple loop below: clear during post_compact(), 619 // which uses memcpy instead of individual stores, and is easy to 620 // parallelize. (The downside is that it clears the entire RegionData 621 // object as opposed to just one field.) 622 // 623 // post_compact() would have to clear the summary data up to the highest 624 // address that was written during the summary phase, which would be 625 // 626 // max(top, max(new_top, clear_top)) 627 // 628 // where clear_top is a new field in SpaceInfo. Would have to set clear_top 629 // to target_end. 630 const RegionData* const sr = region(split_region); 631 const size_t beg_idx = 632 addr_to_region_idx(region_align_up(sr->destination() + 633 sr->partial_obj_size())); 634 const size_t end_idx = addr_to_region_idx(target_end); 635 636 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx); 637 for (size_t idx = beg_idx; idx < end_idx; ++idx) { 638 _region_data[idx].set_source_region(0); 639 } 640 641 // Set split_destination and partial_obj_size to reflect the split region. 642 split_destination = sr->destination(); 643 partial_obj_size = sr->partial_obj_size(); 644 } 645 646 // The split is recorded only if a partial object extends onto the region. 647 if (partial_obj_size != 0) { 648 _region_data[split_region].set_partial_obj_size(0); 649 split_info.record(split_region, partial_obj_size, split_destination); 650 } 651 652 // Setup the continuation addresses. 653 *target_next = split_destination + partial_obj_size; 654 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size; 655 656 if (log_develop_is_enabled(Trace, gc, compaction)) { 657 const char * split_type = partial_obj_size == 0 ? "easy" : "hard"; 658 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT, 659 split_type, p2i(source_next), split_region, partial_obj_size); 660 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT, 661 split_type, p2i(split_destination), 662 addr_to_region_idx(split_destination), 663 p2i(*target_next)); 664 665 if (partial_obj_size != 0) { 666 HeapWord* const po_beg = split_info.destination(); 667 HeapWord* const po_end = po_beg + split_info.partial_obj_size(); 668 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT, 669 split_type, 670 p2i(po_beg), addr_to_region_idx(po_beg), 671 p2i(po_end), addr_to_region_idx(po_end)); 672 } 673 } 674 675 return source_next; 676 } 677 678 bool ParallelCompactData::summarize(SplitInfo& split_info, 679 HeapWord* source_beg, HeapWord* source_end, 680 HeapWord** source_next, 681 HeapWord* target_beg, HeapWord* target_end, 682 HeapWord** target_next) 683 { 684 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next; 685 log_develop_trace(gc, compaction)( 686 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT 687 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT, 688 p2i(source_beg), p2i(source_end), p2i(source_next_val), 689 p2i(target_beg), p2i(target_end), p2i(*target_next)); 690 691 size_t cur_region = addr_to_region_idx(source_beg); 692 const size_t end_region = addr_to_region_idx(region_align_up(source_end)); 693 694 HeapWord *dest_addr = target_beg; 695 while (cur_region < end_region) { 696 // The destination must be set even if the region has no data. 697 _region_data[cur_region].set_destination(dest_addr); 698 699 size_t words = _region_data[cur_region].data_size(); 700 if (words > 0) { 701 // If cur_region does not fit entirely into the target space, find a point 702 // at which the source space can be 'split' so that part is copied to the 703 // target space and the rest is copied elsewhere. 704 if (dest_addr + words > target_end) { 705 assert(source_next != NULL, "source_next is NULL when splitting"); 706 *source_next = summarize_split_space(cur_region, split_info, dest_addr, 707 target_end, target_next); 708 return false; 709 } 710 711 // Compute the destination_count for cur_region, and if necessary, update 712 // source_region for a destination region. The source_region field is 713 // updated if cur_region is the first (left-most) region to be copied to a 714 // destination region. 715 // 716 // The destination_count calculation is a bit subtle. A region that has 717 // data that compacts into itself does not count itself as a destination. 718 // This maintains the invariant that a zero count means the region is 719 // available and can be claimed and then filled. 720 uint destination_count = 0; 721 if (split_info.is_split(cur_region)) { 722 // The current region has been split: the partial object will be copied 723 // to one destination space and the remaining data will be copied to 724 // another destination space. Adjust the initial destination_count and, 725 // if necessary, set the source_region field if the partial object will 726 // cross a destination region boundary. 727 destination_count = split_info.destination_count(); 728 if (destination_count == 2) { 729 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr()); 730 _region_data[dest_idx].set_source_region(cur_region); 731 } 732 } 733 734 HeapWord* const last_addr = dest_addr + words - 1; 735 const size_t dest_region_1 = addr_to_region_idx(dest_addr); 736 const size_t dest_region_2 = addr_to_region_idx(last_addr); 737 738 // Initially assume that the destination regions will be the same and 739 // adjust the value below if necessary. Under this assumption, if 740 // cur_region == dest_region_2, then cur_region will be compacted 741 // completely into itself. 742 destination_count += cur_region == dest_region_2 ? 0 : 1; 743 if (dest_region_1 != dest_region_2) { 744 // Destination regions differ; adjust destination_count. 745 destination_count += 1; 746 // Data from cur_region will be copied to the start of dest_region_2. 747 _region_data[dest_region_2].set_source_region(cur_region); 748 } else if (region_offset(dest_addr) == 0) { 749 // Data from cur_region will be copied to the start of the destination 750 // region. 751 _region_data[dest_region_1].set_source_region(cur_region); 752 } 753 754 _region_data[cur_region].set_destination_count(destination_count); 755 _region_data[cur_region].set_data_location(region_to_addr(cur_region)); 756 dest_addr += words; 757 } 758 759 ++cur_region; 760 } 761 762 *target_next = dest_addr; 763 return true; 764 } 765 766 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) { 767 assert(addr != NULL, "Should detect NULL oop earlier"); 768 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap"); 769 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked"); 770 771 // Region covering the object. 772 RegionData* const region_ptr = addr_to_region_ptr(addr); 773 HeapWord* result = region_ptr->destination(); 774 775 // If the entire Region is live, the new location is region->destination + the 776 // offset of the object within in the Region. 777 778 // Run some performance tests to determine if this special case pays off. It 779 // is worth it for pointers into the dense prefix. If the optimization to 780 // avoid pointer updates in regions that only point to the dense prefix is 781 // ever implemented, this should be revisited. 782 if (region_ptr->data_size() == RegionSize) { 783 result += region_offset(addr); 784 return result; 785 } 786 787 // Otherwise, the new location is region->destination + block offset + the 788 // number of live words in the Block that are (a) to the left of addr and (b) 789 // due to objects that start in the Block. 790 791 // Fill in the block table if necessary. This is unsynchronized, so multiple 792 // threads may fill the block table for a region (harmless, since it is 793 // idempotent). 794 if (!region_ptr->blocks_filled()) { 795 PSParallelCompact::fill_blocks(addr_to_region_idx(addr)); 796 region_ptr->set_blocks_filled(); 797 } 798 799 HeapWord* const search_start = block_align_down(addr); 800 const size_t block_offset = addr_to_block_ptr(addr)->offset(); 801 802 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); 803 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr)); 804 result += block_offset + live; 805 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result)); 806 return result; 807 } 808 809 #ifdef ASSERT 810 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) 811 { 812 const size_t* const beg = (const size_t*)vspace->committed_low_addr(); 813 const size_t* const end = (const size_t*)vspace->committed_high_addr(); 814 for (const size_t* p = beg; p < end; ++p) { 815 assert(*p == 0, "not zero"); 816 } 817 } 818 819 void ParallelCompactData::verify_clear() 820 { 821 verify_clear(_region_vspace); 822 verify_clear(_block_vspace); 823 } 824 #endif // #ifdef ASSERT 825 826 STWGCTimer PSParallelCompact::_gc_timer; 827 ParallelOldTracer PSParallelCompact::_gc_tracer; 828 elapsedTimer PSParallelCompact::_accumulated_time; 829 unsigned int PSParallelCompact::_total_invocations = 0; 830 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; 831 jlong PSParallelCompact::_time_of_last_gc = 0; 832 CollectorCounters* PSParallelCompact::_counters = NULL; 833 ParMarkBitMap PSParallelCompact::_mark_bitmap; 834 ParallelCompactData PSParallelCompact::_summary_data; 835 836 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; 837 838 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } 839 840 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) { 841 PSParallelCompact::AdjustPointerClosure closure(_cm); 842 klass->oops_do(&closure); 843 } 844 845 void PSParallelCompact::post_initialize() { 846 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 847 MemRegion mr = heap->reserved_region(); 848 _ref_processor = 849 new ReferenceProcessor(mr, // span 850 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 851 ParallelGCThreads, // mt processing degree 852 true, // mt discovery 853 ParallelGCThreads, // mt discovery degree 854 true, // atomic_discovery 855 &_is_alive_closure); // non-header is alive closure 856 _counters = new CollectorCounters("PSParallelCompact", 1); 857 858 // Initialize static fields in ParCompactionManager. 859 ParCompactionManager::initialize(mark_bitmap()); 860 } 861 862 bool PSParallelCompact::initialize() { 863 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 864 MemRegion mr = heap->reserved_region(); 865 866 // Was the old gen get allocated successfully? 867 if (!heap->old_gen()->is_allocated()) { 868 return false; 869 } 870 871 initialize_space_info(); 872 initialize_dead_wood_limiter(); 873 874 if (!_mark_bitmap.initialize(mr)) { 875 vm_shutdown_during_initialization( 876 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel " 877 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 878 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K)); 879 return false; 880 } 881 882 if (!_summary_data.initialize(mr)) { 883 vm_shutdown_during_initialization( 884 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel " 885 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 886 _summary_data.reserved_byte_size()/K, mr.byte_size()/K)); 887 return false; 888 } 889 890 return true; 891 } 892 893 void PSParallelCompact::initialize_space_info() 894 { 895 memset(&_space_info, 0, sizeof(_space_info)); 896 897 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 898 PSYoungGen* young_gen = heap->young_gen(); 899 900 _space_info[old_space_id].set_space(heap->old_gen()->object_space()); 901 _space_info[eden_space_id].set_space(young_gen->eden_space()); 902 _space_info[from_space_id].set_space(young_gen->from_space()); 903 _space_info[to_space_id].set_space(young_gen->to_space()); 904 905 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); 906 } 907 908 void PSParallelCompact::initialize_dead_wood_limiter() 909 { 910 const size_t max = 100; 911 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; 912 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; 913 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); 914 DEBUG_ONLY(_dwl_initialized = true;) 915 _dwl_adjustment = normal_distribution(1.0); 916 } 917 918 void 919 PSParallelCompact::clear_data_covering_space(SpaceId id) 920 { 921 // At this point, top is the value before GC, new_top() is the value that will 922 // be set at the end of GC. The marking bitmap is cleared to top; nothing 923 // should be marked above top. The summary data is cleared to the larger of 924 // top & new_top. 925 MutableSpace* const space = _space_info[id].space(); 926 HeapWord* const bot = space->bottom(); 927 HeapWord* const top = space->top(); 928 HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); 929 930 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); 931 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top)); 932 _mark_bitmap.clear_range(beg_bit, end_bit); 933 934 const size_t beg_region = _summary_data.addr_to_region_idx(bot); 935 const size_t end_region = 936 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top)); 937 _summary_data.clear_range(beg_region, end_region); 938 939 // Clear the data used to 'split' regions. 940 SplitInfo& split_info = _space_info[id].split_info(); 941 if (split_info.is_valid()) { 942 split_info.clear(); 943 } 944 DEBUG_ONLY(split_info.verify_clear();) 945 } 946 947 void PSParallelCompact::pre_compact() 948 { 949 // Update the from & to space pointers in space_info, since they are swapped 950 // at each young gen gc. Do the update unconditionally (even though a 951 // promotion failure does not swap spaces) because an unknown number of young 952 // collections will have swapped the spaces an unknown number of times. 953 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer); 954 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 955 _space_info[from_space_id].set_space(heap->young_gen()->from_space()); 956 _space_info[to_space_id].set_space(heap->young_gen()->to_space()); 957 958 DEBUG_ONLY(add_obj_count = add_obj_size = 0;) 959 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;) 960 961 // Increment the invocation count 962 heap->increment_total_collections(true); 963 964 // We need to track unique mark sweep invocations as well. 965 _total_invocations++; 966 967 heap->print_heap_before_gc(); 968 heap->trace_heap_before_gc(&_gc_tracer); 969 970 // Fill in TLABs 971 heap->accumulate_statistics_all_tlabs(); 972 heap->ensure_parsability(true); // retire TLABs 973 974 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 975 HandleMark hm; // Discard invalid handles created during verification 976 Universe::verify("Before GC"); 977 } 978 979 // Verify object start arrays 980 if (VerifyObjectStartArray && 981 VerifyBeforeGC) { 982 heap->old_gen()->verify_object_start_array(); 983 } 984 985 DEBUG_ONLY(mark_bitmap()->verify_clear();) 986 DEBUG_ONLY(summary_data().verify_clear();) 987 988 // Have worker threads release resources the next time they run a task. 989 gc_task_manager()->release_all_resources(); 990 991 ParCompactionManager::reset_all_bitmap_query_caches(); 992 } 993 994 void PSParallelCompact::post_compact() 995 { 996 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer); 997 998 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 999 // Clear the marking bitmap, summary data and split info. 1000 clear_data_covering_space(SpaceId(id)); 1001 // Update top(). Must be done after clearing the bitmap and summary data. 1002 _space_info[id].publish_new_top(); 1003 } 1004 1005 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1006 MutableSpace* const from_space = _space_info[from_space_id].space(); 1007 MutableSpace* const to_space = _space_info[to_space_id].space(); 1008 1009 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1010 bool eden_empty = eden_space->is_empty(); 1011 if (!eden_empty) { 1012 eden_empty = absorb_live_data_from_eden(heap->size_policy(), 1013 heap->young_gen(), heap->old_gen()); 1014 } 1015 1016 // Update heap occupancy information which is used as input to the soft ref 1017 // clearing policy at the next gc. 1018 Universe::update_heap_info_at_gc(); 1019 1020 bool young_gen_empty = eden_empty && from_space->is_empty() && 1021 to_space->is_empty(); 1022 1023 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set()); 1024 MemRegion old_mr = heap->old_gen()->reserved(); 1025 if (young_gen_empty) { 1026 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 1027 } else { 1028 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 1029 } 1030 1031 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1032 ClassLoaderDataGraph::purge(); 1033 MetaspaceAux::verify_metrics(); 1034 1035 CodeCache::gc_epilogue(); 1036 JvmtiExport::gc_epilogue(); 1037 1038 #if defined(COMPILER2) || INCLUDE_JVMCI 1039 DerivedPointerTable::update_pointers(); 1040 #endif 1041 1042 ref_processor()->enqueue_discovered_references(NULL); 1043 1044 if (ZapUnusedHeapArea) { 1045 heap->gen_mangle_unused_area(); 1046 } 1047 1048 // Update time of last GC 1049 reset_millis_since_last_gc(); 1050 } 1051 1052 HeapWord* 1053 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, 1054 bool maximum_compaction) 1055 { 1056 const size_t region_size = ParallelCompactData::RegionSize; 1057 const ParallelCompactData& sd = summary_data(); 1058 1059 const MutableSpace* const space = _space_info[id].space(); 1060 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 1061 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom()); 1062 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up); 1063 1064 // Skip full regions at the beginning of the space--they are necessarily part 1065 // of the dense prefix. 1066 size_t full_count = 0; 1067 const RegionData* cp; 1068 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) { 1069 ++full_count; 1070 } 1071 1072 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1073 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1074 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; 1075 if (maximum_compaction || cp == end_cp || interval_ended) { 1076 _maximum_compaction_gc_num = total_invocations(); 1077 return sd.region_to_addr(cp); 1078 } 1079 1080 HeapWord* const new_top = _space_info[id].new_top(); 1081 const size_t space_live = pointer_delta(new_top, space->bottom()); 1082 const size_t space_used = space->used_in_words(); 1083 const size_t space_capacity = space->capacity_in_words(); 1084 1085 const double cur_density = double(space_live) / space_capacity; 1086 const double deadwood_density = 1087 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; 1088 const size_t deadwood_goal = size_t(space_capacity * deadwood_density); 1089 1090 if (TraceParallelOldGCDensePrefix) { 1091 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, 1092 cur_density, deadwood_density, deadwood_goal); 1093 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1094 "space_cap=" SIZE_FORMAT, 1095 space_live, space_used, 1096 space_capacity); 1097 } 1098 1099 // XXX - Use binary search? 1100 HeapWord* dense_prefix = sd.region_to_addr(cp); 1101 const RegionData* full_cp = cp; 1102 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1); 1103 while (cp < end_cp) { 1104 HeapWord* region_destination = cp->destination(); 1105 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination); 1106 if (TraceParallelOldGCDensePrefix && Verbose) { 1107 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " 1108 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8), 1109 sd.region(cp), p2i(region_destination), 1110 p2i(dense_prefix), cur_deadwood); 1111 } 1112 1113 if (cur_deadwood >= deadwood_goal) { 1114 // Found the region that has the correct amount of deadwood to the left. 1115 // This typically occurs after crossing a fairly sparse set of regions, so 1116 // iterate backwards over those sparse regions, looking for the region 1117 // that has the lowest density of live objects 'to the right.' 1118 size_t space_to_left = sd.region(cp) * region_size; 1119 size_t live_to_left = space_to_left - cur_deadwood; 1120 size_t space_to_right = space_capacity - space_to_left; 1121 size_t live_to_right = space_live - live_to_left; 1122 double density_to_right = double(live_to_right) / space_to_right; 1123 while (cp > full_cp) { 1124 --cp; 1125 const size_t prev_region_live_to_right = live_to_right - 1126 cp->data_size(); 1127 const size_t prev_region_space_to_right = space_to_right + region_size; 1128 double prev_region_density_to_right = 1129 double(prev_region_live_to_right) / prev_region_space_to_right; 1130 if (density_to_right <= prev_region_density_to_right) { 1131 return dense_prefix; 1132 } 1133 if (TraceParallelOldGCDensePrefix && Verbose) { 1134 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " 1135 "pc_d2r=%10.8f", sd.region(cp), density_to_right, 1136 prev_region_density_to_right); 1137 } 1138 dense_prefix -= region_size; 1139 live_to_right = prev_region_live_to_right; 1140 space_to_right = prev_region_space_to_right; 1141 density_to_right = prev_region_density_to_right; 1142 } 1143 return dense_prefix; 1144 } 1145 1146 dense_prefix += region_size; 1147 ++cp; 1148 } 1149 1150 return dense_prefix; 1151 } 1152 1153 #ifndef PRODUCT 1154 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, 1155 const SpaceId id, 1156 const bool maximum_compaction, 1157 HeapWord* const addr) 1158 { 1159 const size_t region_idx = summary_data().addr_to_region_idx(addr); 1160 RegionData* const cp = summary_data().region(region_idx); 1161 const MutableSpace* const space = _space_info[id].space(); 1162 HeapWord* const new_top = _space_info[id].new_top(); 1163 1164 const size_t space_live = pointer_delta(new_top, space->bottom()); 1165 const size_t dead_to_left = pointer_delta(addr, cp->destination()); 1166 const size_t space_cap = space->capacity_in_words(); 1167 const double dead_to_left_pct = double(dead_to_left) / space_cap; 1168 const size_t live_to_right = new_top - cp->destination(); 1169 const size_t dead_to_right = space->top() - addr - live_to_right; 1170 1171 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " 1172 "spl=" SIZE_FORMAT " " 1173 "d2l=" SIZE_FORMAT " d2l%%=%6.4f " 1174 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT 1175 " ratio=%10.8f", 1176 algorithm, p2i(addr), region_idx, 1177 space_live, 1178 dead_to_left, dead_to_left_pct, 1179 dead_to_right, live_to_right, 1180 double(dead_to_right) / live_to_right); 1181 } 1182 #endif // #ifndef PRODUCT 1183 1184 // Return a fraction indicating how much of the generation can be treated as 1185 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution 1186 // based on the density of live objects in the generation to determine a limit, 1187 // which is then adjusted so the return value is min_percent when the density is 1188 // 1. 1189 // 1190 // The following table shows some return values for a different values of the 1191 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and 1192 // min_percent is 1. 1193 // 1194 // fraction allowed as dead wood 1195 // ----------------------------------------------------------------- 1196 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 1197 // ------- ---------- ---------- ---------- ---------- ---------- ---------- 1198 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1199 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1200 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1201 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1202 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1203 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1204 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1205 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1206 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1207 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1208 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 1209 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1210 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1211 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1212 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1213 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1214 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1215 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1216 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1217 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1218 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1219 1220 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) 1221 { 1222 assert(_dwl_initialized, "uninitialized"); 1223 1224 // The raw limit is the value of the normal distribution at x = density. 1225 const double raw_limit = normal_distribution(density); 1226 1227 // Adjust the raw limit so it becomes the minimum when the density is 1. 1228 // 1229 // First subtract the adjustment value (which is simply the precomputed value 1230 // normal_distribution(1.0)); this yields a value of 0 when the density is 1. 1231 // Then add the minimum value, so the minimum is returned when the density is 1232 // 1. Finally, prevent negative values, which occur when the mean is not 0.5. 1233 const double min = double(min_percent) / 100.0; 1234 const double limit = raw_limit - _dwl_adjustment + min; 1235 return MAX2(limit, 0.0); 1236 } 1237 1238 ParallelCompactData::RegionData* 1239 PSParallelCompact::first_dead_space_region(const RegionData* beg, 1240 const RegionData* end) 1241 { 1242 const size_t region_size = ParallelCompactData::RegionSize; 1243 ParallelCompactData& sd = summary_data(); 1244 size_t left = sd.region(beg); 1245 size_t right = end > beg ? sd.region(end) - 1 : left; 1246 1247 // Binary search. 1248 while (left < right) { 1249 // Equivalent to (left + right) / 2, but does not overflow. 1250 const size_t middle = left + (right - left) / 2; 1251 RegionData* const middle_ptr = sd.region(middle); 1252 HeapWord* const dest = middle_ptr->destination(); 1253 HeapWord* const addr = sd.region_to_addr(middle); 1254 assert(dest != NULL, "sanity"); 1255 assert(dest <= addr, "must move left"); 1256 1257 if (middle > left && dest < addr) { 1258 right = middle - 1; 1259 } else if (middle < right && middle_ptr->data_size() == region_size) { 1260 left = middle + 1; 1261 } else { 1262 return middle_ptr; 1263 } 1264 } 1265 return sd.region(left); 1266 } 1267 1268 ParallelCompactData::RegionData* 1269 PSParallelCompact::dead_wood_limit_region(const RegionData* beg, 1270 const RegionData* end, 1271 size_t dead_words) 1272 { 1273 ParallelCompactData& sd = summary_data(); 1274 size_t left = sd.region(beg); 1275 size_t right = end > beg ? sd.region(end) - 1 : left; 1276 1277 // Binary search. 1278 while (left < right) { 1279 // Equivalent to (left + right) / 2, but does not overflow. 1280 const size_t middle = left + (right - left) / 2; 1281 RegionData* const middle_ptr = sd.region(middle); 1282 HeapWord* const dest = middle_ptr->destination(); 1283 HeapWord* const addr = sd.region_to_addr(middle); 1284 assert(dest != NULL, "sanity"); 1285 assert(dest <= addr, "must move left"); 1286 1287 const size_t dead_to_left = pointer_delta(addr, dest); 1288 if (middle > left && dead_to_left > dead_words) { 1289 right = middle - 1; 1290 } else if (middle < right && dead_to_left < dead_words) { 1291 left = middle + 1; 1292 } else { 1293 return middle_ptr; 1294 } 1295 } 1296 return sd.region(left); 1297 } 1298 1299 // The result is valid during the summary phase, after the initial summarization 1300 // of each space into itself, and before final summarization. 1301 inline double 1302 PSParallelCompact::reclaimed_ratio(const RegionData* const cp, 1303 HeapWord* const bottom, 1304 HeapWord* const top, 1305 HeapWord* const new_top) 1306 { 1307 ParallelCompactData& sd = summary_data(); 1308 1309 assert(cp != NULL, "sanity"); 1310 assert(bottom != NULL, "sanity"); 1311 assert(top != NULL, "sanity"); 1312 assert(new_top != NULL, "sanity"); 1313 assert(top >= new_top, "summary data problem?"); 1314 assert(new_top > bottom, "space is empty; should not be here"); 1315 assert(new_top >= cp->destination(), "sanity"); 1316 assert(top >= sd.region_to_addr(cp), "sanity"); 1317 1318 HeapWord* const destination = cp->destination(); 1319 const size_t dense_prefix_live = pointer_delta(destination, bottom); 1320 const size_t compacted_region_live = pointer_delta(new_top, destination); 1321 const size_t compacted_region_used = pointer_delta(top, 1322 sd.region_to_addr(cp)); 1323 const size_t reclaimable = compacted_region_used - compacted_region_live; 1324 1325 const double divisor = dense_prefix_live + 1.25 * compacted_region_live; 1326 return double(reclaimable) / divisor; 1327 } 1328 1329 // Return the address of the end of the dense prefix, a.k.a. the start of the 1330 // compacted region. The address is always on a region boundary. 1331 // 1332 // Completely full regions at the left are skipped, since no compaction can 1333 // occur in those regions. Then the maximum amount of dead wood to allow is 1334 // computed, based on the density (amount live / capacity) of the generation; 1335 // the region with approximately that amount of dead space to the left is 1336 // identified as the limit region. Regions between the last completely full 1337 // region and the limit region are scanned and the one that has the best 1338 // (maximum) reclaimed_ratio() is selected. 1339 HeapWord* 1340 PSParallelCompact::compute_dense_prefix(const SpaceId id, 1341 bool maximum_compaction) 1342 { 1343 const size_t region_size = ParallelCompactData::RegionSize; 1344 const ParallelCompactData& sd = summary_data(); 1345 1346 const MutableSpace* const space = _space_info[id].space(); 1347 HeapWord* const top = space->top(); 1348 HeapWord* const top_aligned_up = sd.region_align_up(top); 1349 HeapWord* const new_top = _space_info[id].new_top(); 1350 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top); 1351 HeapWord* const bottom = space->bottom(); 1352 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom); 1353 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 1354 const RegionData* const new_top_cp = 1355 sd.addr_to_region_ptr(new_top_aligned_up); 1356 1357 // Skip full regions at the beginning of the space--they are necessarily part 1358 // of the dense prefix. 1359 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp); 1360 assert(full_cp->destination() == sd.region_to_addr(full_cp) || 1361 space->is_empty(), "no dead space allowed to the left"); 1362 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1, 1363 "region must have dead space"); 1364 1365 // The gc number is saved whenever a maximum compaction is done, and used to 1366 // determine when the maximum compaction interval has expired. This avoids 1367 // successive max compactions for different reasons. 1368 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1369 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1370 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || 1371 total_invocations() == HeapFirstMaximumCompactionCount; 1372 if (maximum_compaction || full_cp == top_cp || interval_ended) { 1373 _maximum_compaction_gc_num = total_invocations(); 1374 return sd.region_to_addr(full_cp); 1375 } 1376 1377 const size_t space_live = pointer_delta(new_top, bottom); 1378 const size_t space_used = space->used_in_words(); 1379 const size_t space_capacity = space->capacity_in_words(); 1380 1381 const double density = double(space_live) / double(space_capacity); 1382 const size_t min_percent_free = MarkSweepDeadRatio; 1383 const double limiter = dead_wood_limiter(density, min_percent_free); 1384 const size_t dead_wood_max = space_used - space_live; 1385 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), 1386 dead_wood_max); 1387 1388 if (TraceParallelOldGCDensePrefix) { 1389 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1390 "space_cap=" SIZE_FORMAT, 1391 space_live, space_used, 1392 space_capacity); 1393 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f " 1394 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, 1395 density, min_percent_free, limiter, 1396 dead_wood_max, dead_wood_limit); 1397 } 1398 1399 // Locate the region with the desired amount of dead space to the left. 1400 const RegionData* const limit_cp = 1401 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit); 1402 1403 // Scan from the first region with dead space to the limit region and find the 1404 // one with the best (largest) reclaimed ratio. 1405 double best_ratio = 0.0; 1406 const RegionData* best_cp = full_cp; 1407 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) { 1408 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); 1409 if (tmp_ratio > best_ratio) { 1410 best_cp = cp; 1411 best_ratio = tmp_ratio; 1412 } 1413 } 1414 1415 return sd.region_to_addr(best_cp); 1416 } 1417 1418 void PSParallelCompact::summarize_spaces_quick() 1419 { 1420 for (unsigned int i = 0; i < last_space_id; ++i) { 1421 const MutableSpace* space = _space_info[i].space(); 1422 HeapWord** nta = _space_info[i].new_top_addr(); 1423 bool result = _summary_data.summarize(_space_info[i].split_info(), 1424 space->bottom(), space->top(), NULL, 1425 space->bottom(), space->end(), nta); 1426 assert(result, "space must fit into itself"); 1427 _space_info[i].set_dense_prefix(space->bottom()); 1428 } 1429 } 1430 1431 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) 1432 { 1433 HeapWord* const dense_prefix_end = dense_prefix(id); 1434 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end); 1435 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); 1436 if (dead_space_crosses_boundary(region, dense_prefix_bit)) { 1437 // Only enough dead space is filled so that any remaining dead space to the 1438 // left is larger than the minimum filler object. (The remainder is filled 1439 // during the copy/update phase.) 1440 // 1441 // The size of the dead space to the right of the boundary is not a 1442 // concern, since compaction will be able to use whatever space is 1443 // available. 1444 // 1445 // Here '||' is the boundary, 'x' represents a don't care bit and a box 1446 // surrounds the space to be filled with an object. 1447 // 1448 // In the 32-bit VM, each bit represents two 32-bit words: 1449 // +---+ 1450 // a) beg_bits: ... x x x | 0 | || 0 x x ... 1451 // end_bits: ... x x x | 0 | || 0 x x ... 1452 // +---+ 1453 // 1454 // In the 64-bit VM, each bit represents one 64-bit word: 1455 // +------------+ 1456 // b) beg_bits: ... x x x | 0 || 0 | x x ... 1457 // end_bits: ... x x 1 | 0 || 0 | x x ... 1458 // +------------+ 1459 // +-------+ 1460 // c) beg_bits: ... x x | 0 0 | || 0 x x ... 1461 // end_bits: ... x 1 | 0 0 | || 0 x x ... 1462 // +-------+ 1463 // +-----------+ 1464 // d) beg_bits: ... x | 0 0 0 | || 0 x x ... 1465 // end_bits: ... 1 | 0 0 0 | || 0 x x ... 1466 // +-----------+ 1467 // +-------+ 1468 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... 1469 // end_bits: ... 0 0 | 0 0 | || 0 x x ... 1470 // +-------+ 1471 1472 // Initially assume case a, c or e will apply. 1473 size_t obj_len = CollectedHeap::min_fill_size(); 1474 HeapWord* obj_beg = dense_prefix_end - obj_len; 1475 1476 #ifdef _LP64 1477 if (MinObjAlignment > 1) { // object alignment > heap word size 1478 // Cases a, c or e. 1479 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { 1480 // Case b above. 1481 obj_beg = dense_prefix_end - 1; 1482 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && 1483 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { 1484 // Case d above. 1485 obj_beg = dense_prefix_end - 3; 1486 obj_len = 3; 1487 } 1488 #endif // #ifdef _LP64 1489 1490 CollectedHeap::fill_with_object(obj_beg, obj_len); 1491 _mark_bitmap.mark_obj(obj_beg, obj_len); 1492 _summary_data.add_obj(obj_beg, obj_len); 1493 assert(start_array(id) != NULL, "sanity"); 1494 start_array(id)->allocate_block(obj_beg); 1495 } 1496 } 1497 1498 void 1499 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) 1500 { 1501 assert(id < last_space_id, "id out of range"); 1502 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(), 1503 "should have been reset in summarize_spaces_quick()"); 1504 1505 const MutableSpace* space = _space_info[id].space(); 1506 if (_space_info[id].new_top() != space->bottom()) { 1507 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); 1508 _space_info[id].set_dense_prefix(dense_prefix_end); 1509 1510 #ifndef PRODUCT 1511 if (TraceParallelOldGCDensePrefix) { 1512 print_dense_prefix_stats("ratio", id, maximum_compaction, 1513 dense_prefix_end); 1514 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); 1515 print_dense_prefix_stats("density", id, maximum_compaction, addr); 1516 } 1517 #endif // #ifndef PRODUCT 1518 1519 // Recompute the summary data, taking into account the dense prefix. If 1520 // every last byte will be reclaimed, then the existing summary data which 1521 // compacts everything can be left in place. 1522 if (!maximum_compaction && dense_prefix_end != space->bottom()) { 1523 // If dead space crosses the dense prefix boundary, it is (at least 1524 // partially) filled with a dummy object, marked live and added to the 1525 // summary data. This simplifies the copy/update phase and must be done 1526 // before the final locations of objects are determined, to prevent 1527 // leaving a fragment of dead space that is too small to fill. 1528 fill_dense_prefix_end(id); 1529 1530 // Compute the destination of each Region, and thus each object. 1531 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); 1532 _summary_data.summarize(_space_info[id].split_info(), 1533 dense_prefix_end, space->top(), NULL, 1534 dense_prefix_end, space->end(), 1535 _space_info[id].new_top_addr()); 1536 } 1537 } 1538 1539 if (log_develop_is_enabled(Trace, gc, compaction)) { 1540 const size_t region_size = ParallelCompactData::RegionSize; 1541 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); 1542 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end); 1543 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); 1544 HeapWord* const new_top = _space_info[id].new_top(); 1545 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top); 1546 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); 1547 log_develop_trace(gc, compaction)( 1548 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " 1549 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " 1550 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, 1551 id, space->capacity_in_words(), p2i(dense_prefix_end), 1552 dp_region, dp_words / region_size, 1553 cr_words / region_size, p2i(new_top)); 1554 } 1555 } 1556 1557 #ifndef PRODUCT 1558 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id, 1559 HeapWord* dst_beg, HeapWord* dst_end, 1560 SpaceId src_space_id, 1561 HeapWord* src_beg, HeapWord* src_end) 1562 { 1563 log_develop_trace(gc, compaction)( 1564 "Summarizing %d [%s] into %d [%s]: " 1565 "src=" PTR_FORMAT "-" PTR_FORMAT " " 1566 SIZE_FORMAT "-" SIZE_FORMAT " " 1567 "dst=" PTR_FORMAT "-" PTR_FORMAT " " 1568 SIZE_FORMAT "-" SIZE_FORMAT, 1569 src_space_id, space_names[src_space_id], 1570 dst_space_id, space_names[dst_space_id], 1571 p2i(src_beg), p2i(src_end), 1572 _summary_data.addr_to_region_idx(src_beg), 1573 _summary_data.addr_to_region_idx(src_end), 1574 p2i(dst_beg), p2i(dst_end), 1575 _summary_data.addr_to_region_idx(dst_beg), 1576 _summary_data.addr_to_region_idx(dst_end)); 1577 } 1578 #endif // #ifndef PRODUCT 1579 1580 void PSParallelCompact::summary_phase(ParCompactionManager* cm, 1581 bool maximum_compaction) 1582 { 1583 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer); 1584 1585 #ifdef ASSERT 1586 if (TraceParallelOldGCMarkingPhase) { 1587 tty->print_cr("add_obj_count=" SIZE_FORMAT " " 1588 "add_obj_bytes=" SIZE_FORMAT, 1589 add_obj_count, add_obj_size * HeapWordSize); 1590 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " " 1591 "mark_bitmap_bytes=" SIZE_FORMAT, 1592 mark_bitmap_count, mark_bitmap_size * HeapWordSize); 1593 } 1594 #endif // #ifdef ASSERT 1595 1596 // Quick summarization of each space into itself, to see how much is live. 1597 summarize_spaces_quick(); 1598 1599 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self"); 1600 NOT_PRODUCT(print_region_ranges()); 1601 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1602 1603 // The amount of live data that will end up in old space (assuming it fits). 1604 size_t old_space_total_live = 0; 1605 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1606 old_space_total_live += pointer_delta(_space_info[id].new_top(), 1607 _space_info[id].space()->bottom()); 1608 } 1609 1610 MutableSpace* const old_space = _space_info[old_space_id].space(); 1611 const size_t old_capacity = old_space->capacity_in_words(); 1612 if (old_space_total_live > old_capacity) { 1613 // XXX - should also try to expand 1614 maximum_compaction = true; 1615 } 1616 1617 // Old generations. 1618 summarize_space(old_space_id, maximum_compaction); 1619 1620 // Summarize the remaining spaces in the young gen. The initial target space 1621 // is the old gen. If a space does not fit entirely into the target, then the 1622 // remainder is compacted into the space itself and that space becomes the new 1623 // target. 1624 SpaceId dst_space_id = old_space_id; 1625 HeapWord* dst_space_end = old_space->end(); 1626 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr(); 1627 for (unsigned int id = eden_space_id; id < last_space_id; ++id) { 1628 const MutableSpace* space = _space_info[id].space(); 1629 const size_t live = pointer_delta(_space_info[id].new_top(), 1630 space->bottom()); 1631 const size_t available = pointer_delta(dst_space_end, *new_top_addr); 1632 1633 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end, 1634 SpaceId(id), space->bottom(), space->top());) 1635 if (live > 0 && live <= available) { 1636 // All the live data will fit. 1637 bool done = _summary_data.summarize(_space_info[id].split_info(), 1638 space->bottom(), space->top(), 1639 NULL, 1640 *new_top_addr, dst_space_end, 1641 new_top_addr); 1642 assert(done, "space must fit into old gen"); 1643 1644 // Reset the new_top value for the space. 1645 _space_info[id].set_new_top(space->bottom()); 1646 } else if (live > 0) { 1647 // Attempt to fit part of the source space into the target space. 1648 HeapWord* next_src_addr = NULL; 1649 bool done = _summary_data.summarize(_space_info[id].split_info(), 1650 space->bottom(), space->top(), 1651 &next_src_addr, 1652 *new_top_addr, dst_space_end, 1653 new_top_addr); 1654 assert(!done, "space should not fit into old gen"); 1655 assert(next_src_addr != NULL, "sanity"); 1656 1657 // The source space becomes the new target, so the remainder is compacted 1658 // within the space itself. 1659 dst_space_id = SpaceId(id); 1660 dst_space_end = space->end(); 1661 new_top_addr = _space_info[id].new_top_addr(); 1662 NOT_PRODUCT(summary_phase_msg(dst_space_id, 1663 space->bottom(), dst_space_end, 1664 SpaceId(id), next_src_addr, space->top());) 1665 done = _summary_data.summarize(_space_info[id].split_info(), 1666 next_src_addr, space->top(), 1667 NULL, 1668 space->bottom(), dst_space_end, 1669 new_top_addr); 1670 assert(done, "space must fit when compacted into itself"); 1671 assert(*new_top_addr <= space->top(), "usage should not grow"); 1672 } 1673 } 1674 1675 log_develop_trace(gc, compaction)("Summary_phase: after final summarization"); 1676 NOT_PRODUCT(print_region_ranges()); 1677 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1678 } 1679 1680 // This method should contain all heap-specific policy for invoking a full 1681 // collection. invoke_no_policy() will only attempt to compact the heap; it 1682 // will do nothing further. If we need to bail out for policy reasons, scavenge 1683 // before full gc, or any other specialized behavior, it needs to be added here. 1684 // 1685 // Note that this method should only be called from the vm_thread while at a 1686 // safepoint. 1687 // 1688 // Note that the all_soft_refs_clear flag in the collector policy 1689 // may be true because this method can be called without intervening 1690 // activity. For example when the heap space is tight and full measure 1691 // are being taken to free space. 1692 void PSParallelCompact::invoke(bool maximum_heap_compaction) { 1693 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 1694 assert(Thread::current() == (Thread*)VMThread::vm_thread(), 1695 "should be in vm thread"); 1696 1697 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1698 GCCause::Cause gc_cause = heap->gc_cause(); 1699 assert(!heap->is_gc_active(), "not reentrant"); 1700 1701 PSAdaptiveSizePolicy* policy = heap->size_policy(); 1702 IsGCActiveMark mark; 1703 1704 if (ScavengeBeforeFullGC) { 1705 PSScavenge::invoke_no_policy(); 1706 } 1707 1708 const bool clear_all_soft_refs = 1709 heap->collector_policy()->should_clear_all_soft_refs(); 1710 1711 PSParallelCompact::invoke_no_policy(clear_all_soft_refs || 1712 maximum_heap_compaction); 1713 } 1714 1715 // This method contains no policy. You should probably 1716 // be calling invoke() instead. 1717 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { 1718 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 1719 assert(ref_processor() != NULL, "Sanity"); 1720 1721 if (GCLocker::check_active_before_gc()) { 1722 return false; 1723 } 1724 1725 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 1726 1727 GCIdMark gc_id_mark; 1728 _gc_timer.register_gc_start(); 1729 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 1730 1731 TimeStamp marking_start; 1732 TimeStamp compaction_start; 1733 TimeStamp collection_exit; 1734 1735 GCCause::Cause gc_cause = heap->gc_cause(); 1736 PSYoungGen* young_gen = heap->young_gen(); 1737 PSOldGen* old_gen = heap->old_gen(); 1738 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 1739 1740 // The scope of casr should end after code that can change 1741 // CollectorPolicy::_should_clear_all_soft_refs. 1742 ClearedAllSoftRefs casr(maximum_heap_compaction, 1743 heap->collector_policy()); 1744 1745 if (ZapUnusedHeapArea) { 1746 // Save information needed to minimize mangling 1747 heap->record_gen_tops_before_GC(); 1748 } 1749 1750 // Make sure data structures are sane, make the heap parsable, and do other 1751 // miscellaneous bookkeeping. 1752 pre_compact(); 1753 1754 PreGCValues pre_gc_values(heap); 1755 1756 // Get the compaction manager reserved for the VM thread. 1757 ParCompactionManager* const vmthread_cm = 1758 ParCompactionManager::manager_array(gc_task_manager()->workers()); 1759 1760 { 1761 ResourceMark rm; 1762 HandleMark hm; 1763 1764 // Set the number of GC threads to be used in this collection 1765 gc_task_manager()->set_active_gang(); 1766 gc_task_manager()->task_idle_workers(); 1767 1768 GCTraceCPUTime tcpu; 1769 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true); 1770 1771 heap->pre_full_gc_dump(&_gc_timer); 1772 1773 TraceCollectorStats tcs(counters()); 1774 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 1775 1776 if (TraceOldGenTime) accumulated_time()->start(); 1777 1778 // Let the size policy know we're starting 1779 size_policy->major_collection_begin(); 1780 1781 CodeCache::gc_prologue(); 1782 1783 #if defined(COMPILER2) || INCLUDE_JVMCI 1784 DerivedPointerTable::clear(); 1785 #endif 1786 1787 ref_processor()->enable_discovery(); 1788 ref_processor()->setup_policy(maximum_heap_compaction); 1789 1790 bool marked_for_unloading = false; 1791 1792 marking_start.update(); 1793 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer); 1794 1795 bool max_on_system_gc = UseMaximumCompactionOnSystemGC 1796 && GCCause::is_user_requested_gc(gc_cause); 1797 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc); 1798 1799 #if defined(COMPILER2) || INCLUDE_JVMCI 1800 assert(DerivedPointerTable::is_active(), "Sanity"); 1801 DerivedPointerTable::set_active(false); 1802 #endif 1803 1804 // adjust_roots() updates Universe::_intArrayKlassObj which is 1805 // needed by the compaction for filling holes in the dense prefix. 1806 adjust_roots(vmthread_cm); 1807 1808 compaction_start.update(); 1809 compact(); 1810 1811 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be 1812 // done before resizing. 1813 post_compact(); 1814 1815 // Let the size policy know we're done 1816 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 1817 1818 if (UseAdaptiveSizePolicy) { 1819 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 1820 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 1821 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 1822 1823 // Don't check if the size_policy is ready here. Let 1824 // the size_policy check that internally. 1825 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 1826 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) { 1827 // Swap the survivor spaces if from_space is empty. The 1828 // resize_young_gen() called below is normally used after 1829 // a successful young GC and swapping of survivor spaces; 1830 // otherwise, it will fail to resize the young gen with 1831 // the current implementation. 1832 if (young_gen->from_space()->is_empty()) { 1833 young_gen->from_space()->clear(SpaceDecorator::Mangle); 1834 young_gen->swap_spaces(); 1835 } 1836 1837 // Calculate optimal free space amounts 1838 assert(young_gen->max_size() > 1839 young_gen->from_space()->capacity_in_bytes() + 1840 young_gen->to_space()->capacity_in_bytes(), 1841 "Sizes of space in young gen are out-of-bounds"); 1842 1843 size_t young_live = young_gen->used_in_bytes(); 1844 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 1845 size_t old_live = old_gen->used_in_bytes(); 1846 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 1847 size_t max_old_gen_size = old_gen->max_gen_size(); 1848 size_t max_eden_size = young_gen->max_size() - 1849 young_gen->from_space()->capacity_in_bytes() - 1850 young_gen->to_space()->capacity_in_bytes(); 1851 1852 // Used for diagnostics 1853 size_policy->clear_generation_free_space_flags(); 1854 1855 size_policy->compute_generations_free_space(young_live, 1856 eden_live, 1857 old_live, 1858 cur_eden, 1859 max_old_gen_size, 1860 max_eden_size, 1861 true /* full gc*/); 1862 1863 size_policy->check_gc_overhead_limit(young_live, 1864 eden_live, 1865 max_old_gen_size, 1866 max_eden_size, 1867 true /* full gc*/, 1868 gc_cause, 1869 heap->collector_policy()); 1870 1871 size_policy->decay_supplemental_growth(true /* full gc*/); 1872 1873 heap->resize_old_gen( 1874 size_policy->calculated_old_free_size_in_bytes()); 1875 1876 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 1877 size_policy->calculated_survivor_size_in_bytes()); 1878 } 1879 1880 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 1881 } 1882 1883 if (UsePerfData) { 1884 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 1885 counters->update_counters(); 1886 counters->update_old_capacity(old_gen->capacity_in_bytes()); 1887 counters->update_young_capacity(young_gen->capacity_in_bytes()); 1888 } 1889 1890 heap->resize_all_tlabs(); 1891 1892 // Resize the metaspace capacity after a collection 1893 MetaspaceGC::compute_new_size(); 1894 1895 if (TraceOldGenTime) { 1896 accumulated_time()->stop(); 1897 } 1898 1899 young_gen->print_used_change(pre_gc_values.young_gen_used()); 1900 old_gen->print_used_change(pre_gc_values.old_gen_used()); 1901 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used()); 1902 1903 // Track memory usage and detect low memory 1904 MemoryService::track_memory_usage(); 1905 heap->update_counters(); 1906 gc_task_manager()->release_idle_workers(); 1907 1908 heap->post_full_gc_dump(&_gc_timer); 1909 } 1910 1911 #ifdef ASSERT 1912 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) { 1913 ParCompactionManager* const cm = 1914 ParCompactionManager::manager_array(int(i)); 1915 assert(cm->marking_stack()->is_empty(), "should be empty"); 1916 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i); 1917 } 1918 #endif // ASSERT 1919 1920 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 1921 HandleMark hm; // Discard invalid handles created during verification 1922 Universe::verify("After GC"); 1923 } 1924 1925 // Re-verify object start arrays 1926 if (VerifyObjectStartArray && 1927 VerifyAfterGC) { 1928 old_gen->verify_object_start_array(); 1929 } 1930 1931 if (ZapUnusedHeapArea) { 1932 old_gen->object_space()->check_mangled_unused_area_complete(); 1933 } 1934 1935 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 1936 1937 collection_exit.update(); 1938 1939 heap->print_heap_after_gc(); 1940 heap->trace_heap_after_gc(&_gc_tracer); 1941 1942 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 1943 marking_start.ticks(), compaction_start.ticks(), 1944 collection_exit.ticks()); 1945 gc_task_manager()->print_task_time_stamps(); 1946 1947 #ifdef TRACESPINNING 1948 ParallelTaskTerminator::print_termination_counts(); 1949 #endif 1950 1951 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 1952 1953 _gc_timer.register_gc_end(); 1954 1955 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id)); 1956 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 1957 1958 return true; 1959 } 1960 1961 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 1962 PSYoungGen* young_gen, 1963 PSOldGen* old_gen) { 1964 MutableSpace* const eden_space = young_gen->eden_space(); 1965 assert(!eden_space->is_empty(), "eden must be non-empty"); 1966 assert(young_gen->virtual_space()->alignment() == 1967 old_gen->virtual_space()->alignment(), "alignments do not match"); 1968 1969 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 1970 return false; 1971 } 1972 1973 // Both generations must be completely committed. 1974 if (young_gen->virtual_space()->uncommitted_size() != 0) { 1975 return false; 1976 } 1977 if (old_gen->virtual_space()->uncommitted_size() != 0) { 1978 return false; 1979 } 1980 1981 // Figure out how much to take from eden. Include the average amount promoted 1982 // in the total; otherwise the next young gen GC will simply bail out to a 1983 // full GC. 1984 const size_t alignment = old_gen->virtual_space()->alignment(); 1985 const size_t eden_used = eden_space->used_in_bytes(); 1986 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 1987 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 1988 const size_t eden_capacity = eden_space->capacity_in_bytes(); 1989 1990 if (absorb_size >= eden_capacity) { 1991 return false; // Must leave some space in eden. 1992 } 1993 1994 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 1995 if (new_young_size < young_gen->min_gen_size()) { 1996 return false; // Respect young gen minimum size. 1997 } 1998 1999 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: " 2000 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 2001 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 2002 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 2003 absorb_size / K, 2004 eden_capacity / K, (eden_capacity - absorb_size) / K, 2005 young_gen->from_space()->used_in_bytes() / K, 2006 young_gen->to_space()->used_in_bytes() / K, 2007 young_gen->capacity_in_bytes() / K, new_young_size / K); 2008 2009 // Fill the unused part of the old gen. 2010 MutableSpace* const old_space = old_gen->object_space(); 2011 HeapWord* const unused_start = old_space->top(); 2012 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 2013 2014 if (unused_words > 0) { 2015 if (unused_words < CollectedHeap::min_fill_size()) { 2016 return false; // If the old gen cannot be filled, must give up. 2017 } 2018 CollectedHeap::fill_with_objects(unused_start, unused_words); 2019 } 2020 2021 // Take the live data from eden and set both top and end in the old gen to 2022 // eden top. (Need to set end because reset_after_change() mangles the region 2023 // from end to virtual_space->high() in debug builds). 2024 HeapWord* const new_top = eden_space->top(); 2025 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 2026 absorb_size); 2027 young_gen->reset_after_change(); 2028 old_space->set_top(new_top); 2029 old_space->set_end(new_top); 2030 old_gen->reset_after_change(); 2031 2032 // Update the object start array for the filler object and the data from eden. 2033 ObjectStartArray* const start_array = old_gen->start_array(); 2034 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 2035 start_array->allocate_block(p); 2036 } 2037 2038 // Could update the promoted average here, but it is not typically updated at 2039 // full GCs and the value to use is unclear. Something like 2040 // 2041 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 2042 2043 size_policy->set_bytes_absorbed_from_eden(absorb_size); 2044 return true; 2045 } 2046 2047 GCTaskManager* const PSParallelCompact::gc_task_manager() { 2048 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 2049 "shouldn't return NULL"); 2050 return ParallelScavengeHeap::gc_task_manager(); 2051 } 2052 2053 void PSParallelCompact::marking_phase(ParCompactionManager* cm, 2054 bool maximum_heap_compaction, 2055 ParallelOldTracer *gc_tracer) { 2056 // Recursively traverse all live objects and mark them 2057 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer); 2058 2059 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2060 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2061 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2062 TaskQueueSetSuper* qset = ParCompactionManager::stack_array(); 2063 ParallelTaskTerminator terminator(active_gc_threads, qset); 2064 2065 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm); 2066 ParCompactionManager::FollowStackClosure follow_stack_closure(cm); 2067 2068 // Need new claim bits before marking starts. 2069 ClassLoaderDataGraph::clear_claimed_marks(); 2070 2071 { 2072 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer); 2073 2074 ParallelScavengeHeap::ParStrongRootsScope psrs; 2075 2076 GCTaskQueue* q = GCTaskQueue::create(); 2077 2078 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe)); 2079 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles)); 2080 // We scan the thread roots in parallel 2081 Threads::create_thread_roots_marking_tasks(q); 2082 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer)); 2083 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler)); 2084 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management)); 2085 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary)); 2086 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data)); 2087 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti)); 2088 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache)); 2089 2090 if (active_gc_threads > 1) { 2091 for (uint j = 0; j < active_gc_threads; j++) { 2092 q->enqueue(new StealMarkingTask(&terminator)); 2093 } 2094 } 2095 2096 gc_task_manager()->execute_and_wait(q); 2097 } 2098 2099 // Process reference objects found during marking 2100 { 2101 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 2102 2103 ReferenceProcessorStats stats; 2104 if (ref_processor()->processing_is_mt()) { 2105 RefProcTaskExecutor task_executor; 2106 stats = ref_processor()->process_discovered_references( 2107 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, 2108 &task_executor, &_gc_timer); 2109 } else { 2110 stats = ref_processor()->process_discovered_references( 2111 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL, 2112 &_gc_timer); 2113 } 2114 2115 gc_tracer->report_gc_reference_stats(stats); 2116 } 2117 2118 // This is the point where the entire marking should have completed. 2119 assert(cm->marking_stacks_empty(), "Marking should have completed"); 2120 2121 { 2122 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer); 2123 2124 // Follow system dictionary roots and unload classes. 2125 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), &_gc_timer); 2126 2127 // Unload nmethods. 2128 CodeCache::do_unloading(is_alive_closure(), purged_class); 2129 2130 // Prune dead klasses from subklass/sibling/implementor lists. 2131 Klass::clean_weak_klass_links(is_alive_closure()); 2132 } 2133 2134 { 2135 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer); 2136 // Delete entries for dead interned strings. 2137 StringTable::unlink(is_alive_closure()); 2138 } 2139 2140 { 2141 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer); 2142 // Clean up unreferenced symbols in symbol table. 2143 SymbolTable::unlink(); 2144 } 2145 2146 _gc_tracer.report_object_count_after_gc(is_alive_closure()); 2147 } 2148 2149 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) { 2150 // Adjust the pointers to reflect the new locations 2151 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer); 2152 2153 // Need new claim bits when tracing through and adjusting pointers. 2154 ClassLoaderDataGraph::clear_claimed_marks(); 2155 2156 PSParallelCompact::AdjustPointerClosure oop_closure(cm); 2157 PSParallelCompact::AdjustKlassClosure klass_closure(cm); 2158 2159 // General strong roots. 2160 Universe::oops_do(&oop_closure); 2161 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles 2162 Threads::oops_do(&oop_closure, NULL); 2163 ObjectSynchronizer::oops_do(&oop_closure); 2164 FlatProfiler::oops_do(&oop_closure); 2165 Management::oops_do(&oop_closure); 2166 JvmtiExport::oops_do(&oop_closure); 2167 SystemDictionary::oops_do(&oop_closure); 2168 ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true); 2169 2170 // Now adjust pointers in remaining weak roots. (All of which should 2171 // have been cleared if they pointed to non-surviving objects.) 2172 // Global (weak) JNI handles 2173 JNIHandles::weak_oops_do(&oop_closure); 2174 2175 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations); 2176 CodeCache::blobs_do(&adjust_from_blobs); 2177 AOTLoader::oops_do(&oop_closure); 2178 StringTable::oops_do(&oop_closure); 2179 ref_processor()->weak_oops_do(&oop_closure); 2180 // Roots were visited so references into the young gen in roots 2181 // may have been scanned. Process them also. 2182 // Should the reference processor have a span that excludes 2183 // young gen objects? 2184 PSScavenge::reference_processor()->weak_oops_do(&oop_closure); 2185 } 2186 2187 // Helper class to print 8 region numbers per line and then print the total at the end. 2188 class FillableRegionLogger : public StackObj { 2189 private: 2190 Log(gc, compaction) log; 2191 static const int LineLength = 8; 2192 size_t _regions[LineLength]; 2193 int _next_index; 2194 bool _enabled; 2195 size_t _total_regions; 2196 public: 2197 FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { } 2198 ~FillableRegionLogger() { 2199 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions); 2200 } 2201 2202 void print_line() { 2203 if (!_enabled || _next_index == 0) { 2204 return; 2205 } 2206 FormatBuffer<> line("Fillable: "); 2207 for (int i = 0; i < _next_index; i++) { 2208 line.append(" " SIZE_FORMAT_W(7), _regions[i]); 2209 } 2210 log.trace("%s", line.buffer()); 2211 _next_index = 0; 2212 } 2213 2214 void handle(size_t region) { 2215 if (!_enabled) { 2216 return; 2217 } 2218 _regions[_next_index++] = region; 2219 if (_next_index == LineLength) { 2220 print_line(); 2221 } 2222 _total_regions++; 2223 } 2224 }; 2225 2226 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q, 2227 uint parallel_gc_threads) 2228 { 2229 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer); 2230 2231 // Find the threads that are active 2232 unsigned int which = 0; 2233 2234 // Find all regions that are available (can be filled immediately) and 2235 // distribute them to the thread stacks. The iteration is done in reverse 2236 // order (high to low) so the regions will be removed in ascending order. 2237 2238 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 2239 2240 which = 0; 2241 // id + 1 is used to test termination so unsigned can 2242 // be used with an old_space_id == 0. 2243 FillableRegionLogger region_logger; 2244 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) { 2245 SpaceInfo* const space_info = _space_info + id; 2246 MutableSpace* const space = space_info->space(); 2247 HeapWord* const new_top = space_info->new_top(); 2248 2249 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix()); 2250 const size_t end_region = 2251 sd.addr_to_region_idx(sd.region_align_up(new_top)); 2252 2253 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) { 2254 if (sd.region(cur)->claim_unsafe()) { 2255 ParCompactionManager* cm = ParCompactionManager::manager_array(which); 2256 cm->region_stack()->push(cur); 2257 region_logger.handle(cur); 2258 // Assign regions to tasks in round-robin fashion. 2259 if (++which == parallel_gc_threads) { 2260 which = 0; 2261 } 2262 } 2263 } 2264 region_logger.print_line(); 2265 } 2266 } 2267 2268 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 2269 2270 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q, 2271 uint parallel_gc_threads) { 2272 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer); 2273 2274 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2275 2276 // Iterate over all the spaces adding tasks for updating 2277 // regions in the dense prefix. Assume that 1 gc thread 2278 // will work on opening the gaps and the remaining gc threads 2279 // will work on the dense prefix. 2280 unsigned int space_id; 2281 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) { 2282 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); 2283 const MutableSpace* const space = _space_info[space_id].space(); 2284 2285 if (dense_prefix_end == space->bottom()) { 2286 // There is no dense prefix for this space. 2287 continue; 2288 } 2289 2290 // The dense prefix is before this region. 2291 size_t region_index_end_dense_prefix = 2292 sd.addr_to_region_idx(dense_prefix_end); 2293 RegionData* const dense_prefix_cp = 2294 sd.region(region_index_end_dense_prefix); 2295 assert(dense_prefix_end == space->end() || 2296 dense_prefix_cp->available() || 2297 dense_prefix_cp->claimed(), 2298 "The region after the dense prefix should always be ready to fill"); 2299 2300 size_t region_index_start = sd.addr_to_region_idx(space->bottom()); 2301 2302 // Is there dense prefix work? 2303 size_t total_dense_prefix_regions = 2304 region_index_end_dense_prefix - region_index_start; 2305 // How many regions of the dense prefix should be given to 2306 // each thread? 2307 if (total_dense_prefix_regions > 0) { 2308 uint tasks_for_dense_prefix = 1; 2309 if (total_dense_prefix_regions <= 2310 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { 2311 // Don't over partition. This assumes that 2312 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value 2313 // so there are not many regions to process. 2314 tasks_for_dense_prefix = parallel_gc_threads; 2315 } else { 2316 // Over partition 2317 tasks_for_dense_prefix = parallel_gc_threads * 2318 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; 2319 } 2320 size_t regions_per_thread = total_dense_prefix_regions / 2321 tasks_for_dense_prefix; 2322 // Give each thread at least 1 region. 2323 if (regions_per_thread == 0) { 2324 regions_per_thread = 1; 2325 } 2326 2327 for (uint k = 0; k < tasks_for_dense_prefix; k++) { 2328 if (region_index_start >= region_index_end_dense_prefix) { 2329 break; 2330 } 2331 // region_index_end is not processed 2332 size_t region_index_end = MIN2(region_index_start + regions_per_thread, 2333 region_index_end_dense_prefix); 2334 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2335 region_index_start, 2336 region_index_end)); 2337 region_index_start = region_index_end; 2338 } 2339 } 2340 // This gets any part of the dense prefix that did not 2341 // fit evenly. 2342 if (region_index_start < region_index_end_dense_prefix) { 2343 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2344 region_index_start, 2345 region_index_end_dense_prefix)); 2346 } 2347 } 2348 } 2349 2350 void PSParallelCompact::enqueue_region_stealing_tasks( 2351 GCTaskQueue* q, 2352 ParallelTaskTerminator* terminator_ptr, 2353 uint parallel_gc_threads) { 2354 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer); 2355 2356 // Once a thread has drained it's stack, it should try to steal regions from 2357 // other threads. 2358 for (uint j = 0; j < parallel_gc_threads; j++) { 2359 q->enqueue(new CompactionWithStealingTask(terminator_ptr)); 2360 } 2361 } 2362 2363 #ifdef ASSERT 2364 // Write a histogram of the number of times the block table was filled for a 2365 // region. 2366 void PSParallelCompact::write_block_fill_histogram() 2367 { 2368 if (!log_develop_is_enabled(Trace, gc, compaction)) { 2369 return; 2370 } 2371 2372 Log(gc, compaction) log; 2373 ResourceMark rm; 2374 outputStream* out = log.trace_stream(); 2375 2376 typedef ParallelCompactData::RegionData rd_t; 2377 ParallelCompactData& sd = summary_data(); 2378 2379 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2380 MutableSpace* const spc = _space_info[id].space(); 2381 if (spc->bottom() != spc->top()) { 2382 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom()); 2383 HeapWord* const top_aligned_up = sd.region_align_up(spc->top()); 2384 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up); 2385 2386 size_t histo[5] = { 0, 0, 0, 0, 0 }; 2387 const size_t histo_len = sizeof(histo) / sizeof(size_t); 2388 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t)); 2389 2390 for (const rd_t* cur = beg; cur < end; ++cur) { 2391 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)]; 2392 } 2393 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt); 2394 for (size_t i = 0; i < histo_len; ++i) { 2395 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%", 2396 histo[i], 100.0 * histo[i] / region_cnt); 2397 } 2398 out->cr(); 2399 } 2400 } 2401 } 2402 #endif // #ifdef ASSERT 2403 2404 void PSParallelCompact::compact() { 2405 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer); 2406 2407 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 2408 PSOldGen* old_gen = heap->old_gen(); 2409 old_gen->start_array()->reset(); 2410 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2411 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2412 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2413 ParallelTaskTerminator terminator(active_gc_threads, qset); 2414 2415 GCTaskQueue* q = GCTaskQueue::create(); 2416 prepare_region_draining_tasks(q, active_gc_threads); 2417 enqueue_dense_prefix_tasks(q, active_gc_threads); 2418 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads); 2419 2420 { 2421 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer); 2422 2423 gc_task_manager()->execute_and_wait(q); 2424 2425 #ifdef ASSERT 2426 // Verify that all regions have been processed before the deferred updates. 2427 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2428 verify_complete(SpaceId(id)); 2429 } 2430 #endif 2431 } 2432 2433 { 2434 // Update the deferred objects, if any. Any compaction manager can be used. 2435 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer); 2436 ParCompactionManager* cm = ParCompactionManager::manager_array(0); 2437 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2438 update_deferred_objects(cm, SpaceId(id)); 2439 } 2440 } 2441 2442 DEBUG_ONLY(write_block_fill_histogram()); 2443 } 2444 2445 #ifdef ASSERT 2446 void PSParallelCompact::verify_complete(SpaceId space_id) { 2447 // All Regions between space bottom() to new_top() should be marked as filled 2448 // and all Regions between new_top() and top() should be available (i.e., 2449 // should have been emptied). 2450 ParallelCompactData& sd = summary_data(); 2451 SpaceInfo si = _space_info[space_id]; 2452 HeapWord* new_top_addr = sd.region_align_up(si.new_top()); 2453 HeapWord* old_top_addr = sd.region_align_up(si.space()->top()); 2454 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom()); 2455 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr); 2456 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr); 2457 2458 bool issued_a_warning = false; 2459 2460 size_t cur_region; 2461 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) { 2462 const RegionData* const c = sd.region(cur_region); 2463 if (!c->completed()) { 2464 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u", 2465 cur_region, c->destination_count()); 2466 issued_a_warning = true; 2467 } 2468 } 2469 2470 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) { 2471 const RegionData* const c = sd.region(cur_region); 2472 if (!c->available()) { 2473 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u", 2474 cur_region, c->destination_count()); 2475 issued_a_warning = true; 2476 } 2477 } 2478 2479 if (issued_a_warning) { 2480 print_region_ranges(); 2481 } 2482 } 2483 #endif // #ifdef ASSERT 2484 2485 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) { 2486 _start_array->allocate_block(addr); 2487 compaction_manager()->update_contents(oop(addr)); 2488 } 2489 2490 // Update interior oops in the ranges of regions [beg_region, end_region). 2491 void 2492 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 2493 SpaceId space_id, 2494 size_t beg_region, 2495 size_t end_region) { 2496 ParallelCompactData& sd = summary_data(); 2497 ParMarkBitMap* const mbm = mark_bitmap(); 2498 2499 HeapWord* beg_addr = sd.region_to_addr(beg_region); 2500 HeapWord* const end_addr = sd.region_to_addr(end_region); 2501 assert(beg_region <= end_region, "bad region range"); 2502 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); 2503 2504 #ifdef ASSERT 2505 // Claim the regions to avoid triggering an assert when they are marked as 2506 // filled. 2507 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) { 2508 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed"); 2509 } 2510 #endif // #ifdef ASSERT 2511 2512 if (beg_addr != space(space_id)->bottom()) { 2513 // Find the first live object or block of dead space that *starts* in this 2514 // range of regions. If a partial object crosses onto the region, skip it; 2515 // it will be marked for 'deferred update' when the object head is 2516 // processed. If dead space crosses onto the region, it is also skipped; it 2517 // will be filled when the prior region is processed. If neither of those 2518 // apply, the first word in the region is the start of a live object or dead 2519 // space. 2520 assert(beg_addr > space(space_id)->bottom(), "sanity"); 2521 const RegionData* const cp = sd.region(beg_region); 2522 if (cp->partial_obj_size() != 0) { 2523 beg_addr = sd.partial_obj_end(beg_region); 2524 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) { 2525 beg_addr = mbm->find_obj_beg(beg_addr, end_addr); 2526 } 2527 } 2528 2529 if (beg_addr < end_addr) { 2530 // A live object or block of dead space starts in this range of Regions. 2531 HeapWord* const dense_prefix_end = dense_prefix(space_id); 2532 2533 // Create closures and iterate. 2534 UpdateOnlyClosure update_closure(mbm, cm, space_id); 2535 FillClosure fill_closure(cm, space_id); 2536 ParMarkBitMap::IterationStatus status; 2537 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, 2538 dense_prefix_end); 2539 if (status == ParMarkBitMap::incomplete) { 2540 update_closure.do_addr(update_closure.source()); 2541 } 2542 } 2543 2544 // Mark the regions as filled. 2545 RegionData* const beg_cp = sd.region(beg_region); 2546 RegionData* const end_cp = sd.region(end_region); 2547 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) { 2548 cp->set_completed(); 2549 } 2550 } 2551 2552 // Return the SpaceId for the space containing addr. If addr is not in the 2553 // heap, last_space_id is returned. In debug mode it expects the address to be 2554 // in the heap and asserts such. 2555 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) { 2556 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap"); 2557 2558 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2559 if (_space_info[id].space()->contains(addr)) { 2560 return SpaceId(id); 2561 } 2562 } 2563 2564 assert(false, "no space contains the addr"); 2565 return last_space_id; 2566 } 2567 2568 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm, 2569 SpaceId id) { 2570 assert(id < last_space_id, "bad space id"); 2571 2572 ParallelCompactData& sd = summary_data(); 2573 const SpaceInfo* const space_info = _space_info + id; 2574 ObjectStartArray* const start_array = space_info->start_array(); 2575 2576 const MutableSpace* const space = space_info->space(); 2577 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set"); 2578 HeapWord* const beg_addr = space_info->dense_prefix(); 2579 HeapWord* const end_addr = sd.region_align_up(space_info->new_top()); 2580 2581 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr); 2582 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr); 2583 const RegionData* cur_region; 2584 for (cur_region = beg_region; cur_region < end_region; ++cur_region) { 2585 HeapWord* const addr = cur_region->deferred_obj_addr(); 2586 if (addr != NULL) { 2587 if (start_array != NULL) { 2588 start_array->allocate_block(addr); 2589 } 2590 cm->update_contents(oop(addr)); 2591 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr))); 2592 } 2593 } 2594 } 2595 2596 // Skip over count live words starting from beg, and return the address of the 2597 // next live word. Unless marked, the word corresponding to beg is assumed to 2598 // be dead. Callers must either ensure beg does not correspond to the middle of 2599 // an object, or account for those live words in some other way. Callers must 2600 // also ensure that there are enough live words in the range [beg, end) to skip. 2601 HeapWord* 2602 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count) 2603 { 2604 assert(count > 0, "sanity"); 2605 2606 ParMarkBitMap* m = mark_bitmap(); 2607 idx_t bits_to_skip = m->words_to_bits(count); 2608 idx_t cur_beg = m->addr_to_bit(beg); 2609 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end)); 2610 2611 do { 2612 cur_beg = m->find_obj_beg(cur_beg, search_end); 2613 idx_t cur_end = m->find_obj_end(cur_beg, search_end); 2614 const size_t obj_bits = cur_end - cur_beg + 1; 2615 if (obj_bits > bits_to_skip) { 2616 return m->bit_to_addr(cur_beg + bits_to_skip); 2617 } 2618 bits_to_skip -= obj_bits; 2619 cur_beg = cur_end + 1; 2620 } while (bits_to_skip > 0); 2621 2622 // Skipping the desired number of words landed just past the end of an object. 2623 // Find the start of the next object. 2624 cur_beg = m->find_obj_beg(cur_beg, search_end); 2625 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip"); 2626 return m->bit_to_addr(cur_beg); 2627 } 2628 2629 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr, 2630 SpaceId src_space_id, 2631 size_t src_region_idx) 2632 { 2633 assert(summary_data().is_region_aligned(dest_addr), "not aligned"); 2634 2635 const SplitInfo& split_info = _space_info[src_space_id].split_info(); 2636 if (split_info.dest_region_addr() == dest_addr) { 2637 // The partial object ending at the split point contains the first word to 2638 // be copied to dest_addr. 2639 return split_info.first_src_addr(); 2640 } 2641 2642 const ParallelCompactData& sd = summary_data(); 2643 ParMarkBitMap* const bitmap = mark_bitmap(); 2644 const size_t RegionSize = ParallelCompactData::RegionSize; 2645 2646 assert(sd.is_region_aligned(dest_addr), "not aligned"); 2647 const RegionData* const src_region_ptr = sd.region(src_region_idx); 2648 const size_t partial_obj_size = src_region_ptr->partial_obj_size(); 2649 HeapWord* const src_region_destination = src_region_ptr->destination(); 2650 2651 assert(dest_addr >= src_region_destination, "wrong src region"); 2652 assert(src_region_ptr->data_size() > 0, "src region cannot be empty"); 2653 2654 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx); 2655 HeapWord* const src_region_end = src_region_beg + RegionSize; 2656 2657 HeapWord* addr = src_region_beg; 2658 if (dest_addr == src_region_destination) { 2659 // Return the first live word in the source region. 2660 if (partial_obj_size == 0) { 2661 addr = bitmap->find_obj_beg(addr, src_region_end); 2662 assert(addr < src_region_end, "no objects start in src region"); 2663 } 2664 return addr; 2665 } 2666 2667 // Must skip some live data. 2668 size_t words_to_skip = dest_addr - src_region_destination; 2669 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region"); 2670 2671 if (partial_obj_size >= words_to_skip) { 2672 // All the live words to skip are part of the partial object. 2673 addr += words_to_skip; 2674 if (partial_obj_size == words_to_skip) { 2675 // Find the first live word past the partial object. 2676 addr = bitmap->find_obj_beg(addr, src_region_end); 2677 assert(addr < src_region_end, "wrong src region"); 2678 } 2679 return addr; 2680 } 2681 2682 // Skip over the partial object (if any). 2683 if (partial_obj_size != 0) { 2684 words_to_skip -= partial_obj_size; 2685 addr += partial_obj_size; 2686 } 2687 2688 // Skip over live words due to objects that start in the region. 2689 addr = skip_live_words(addr, src_region_end, words_to_skip); 2690 assert(addr < src_region_end, "wrong src region"); 2691 return addr; 2692 } 2693 2694 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, 2695 SpaceId src_space_id, 2696 size_t beg_region, 2697 HeapWord* end_addr) 2698 { 2699 ParallelCompactData& sd = summary_data(); 2700 2701 #ifdef ASSERT 2702 MutableSpace* const src_space = _space_info[src_space_id].space(); 2703 HeapWord* const beg_addr = sd.region_to_addr(beg_region); 2704 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(), 2705 "src_space_id does not match beg_addr"); 2706 assert(src_space->contains(end_addr) || end_addr == src_space->end(), 2707 "src_space_id does not match end_addr"); 2708 #endif // #ifdef ASSERT 2709 2710 RegionData* const beg = sd.region(beg_region); 2711 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr)); 2712 2713 // Regions up to new_top() are enqueued if they become available. 2714 HeapWord* const new_top = _space_info[src_space_id].new_top(); 2715 RegionData* const enqueue_end = 2716 sd.addr_to_region_ptr(sd.region_align_up(new_top)); 2717 2718 for (RegionData* cur = beg; cur < end; ++cur) { 2719 assert(cur->data_size() > 0, "region must have live data"); 2720 cur->decrement_destination_count(); 2721 if (cur < enqueue_end && cur->available() && cur->claim()) { 2722 cm->push_region(sd.region(cur)); 2723 } 2724 } 2725 } 2726 2727 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure, 2728 SpaceId& src_space_id, 2729 HeapWord*& src_space_top, 2730 HeapWord* end_addr) 2731 { 2732 typedef ParallelCompactData::RegionData RegionData; 2733 2734 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2735 const size_t region_size = ParallelCompactData::RegionSize; 2736 2737 size_t src_region_idx = 0; 2738 2739 // Skip empty regions (if any) up to the top of the space. 2740 HeapWord* const src_aligned_up = sd.region_align_up(end_addr); 2741 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up); 2742 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top); 2743 const RegionData* const top_region_ptr = 2744 sd.addr_to_region_ptr(top_aligned_up); 2745 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) { 2746 ++src_region_ptr; 2747 } 2748 2749 if (src_region_ptr < top_region_ptr) { 2750 // The next source region is in the current space. Update src_region_idx 2751 // and the source address to match src_region_ptr. 2752 src_region_idx = sd.region(src_region_ptr); 2753 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx); 2754 if (src_region_addr > closure.source()) { 2755 closure.set_source(src_region_addr); 2756 } 2757 return src_region_idx; 2758 } 2759 2760 // Switch to a new source space and find the first non-empty region. 2761 unsigned int space_id = src_space_id + 1; 2762 assert(space_id < last_space_id, "not enough spaces"); 2763 2764 HeapWord* const destination = closure.destination(); 2765 2766 do { 2767 MutableSpace* space = _space_info[space_id].space(); 2768 HeapWord* const bottom = space->bottom(); 2769 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom); 2770 2771 // Iterate over the spaces that do not compact into themselves. 2772 if (bottom_cp->destination() != bottom) { 2773 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 2774 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 2775 2776 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) { 2777 if (src_cp->live_obj_size() > 0) { 2778 // Found it. 2779 assert(src_cp->destination() == destination, 2780 "first live obj in the space must match the destination"); 2781 assert(src_cp->partial_obj_size() == 0, 2782 "a space cannot begin with a partial obj"); 2783 2784 src_space_id = SpaceId(space_id); 2785 src_space_top = space->top(); 2786 const size_t src_region_idx = sd.region(src_cp); 2787 closure.set_source(sd.region_to_addr(src_region_idx)); 2788 return src_region_idx; 2789 } else { 2790 assert(src_cp->data_size() == 0, "sanity"); 2791 } 2792 } 2793 } 2794 } while (++space_id < last_space_id); 2795 2796 assert(false, "no source region was found"); 2797 return 0; 2798 } 2799 2800 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx) 2801 { 2802 typedef ParMarkBitMap::IterationStatus IterationStatus; 2803 const size_t RegionSize = ParallelCompactData::RegionSize; 2804 ParMarkBitMap* const bitmap = mark_bitmap(); 2805 ParallelCompactData& sd = summary_data(); 2806 RegionData* const region_ptr = sd.region(region_idx); 2807 2808 // Get the items needed to construct the closure. 2809 HeapWord* dest_addr = sd.region_to_addr(region_idx); 2810 SpaceId dest_space_id = space_id(dest_addr); 2811 ObjectStartArray* start_array = _space_info[dest_space_id].start_array(); 2812 HeapWord* new_top = _space_info[dest_space_id].new_top(); 2813 assert(dest_addr < new_top, "sanity"); 2814 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize); 2815 2816 // Get the source region and related info. 2817 size_t src_region_idx = region_ptr->source_region(); 2818 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx)); 2819 HeapWord* src_space_top = _space_info[src_space_id].space()->top(); 2820 2821 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 2822 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx)); 2823 2824 // Adjust src_region_idx to prepare for decrementing destination counts (the 2825 // destination count is not decremented when a region is copied to itself). 2826 if (src_region_idx == region_idx) { 2827 src_region_idx += 1; 2828 } 2829 2830 if (bitmap->is_unmarked(closure.source())) { 2831 // The first source word is in the middle of an object; copy the remainder 2832 // of the object or as much as will fit. The fact that pointer updates were 2833 // deferred will be noted when the object header is processed. 2834 HeapWord* const old_src_addr = closure.source(); 2835 closure.copy_partial_obj(); 2836 if (closure.is_full()) { 2837 decrement_destination_counts(cm, src_space_id, src_region_idx, 2838 closure.source()); 2839 region_ptr->set_deferred_obj_addr(NULL); 2840 region_ptr->set_completed(); 2841 return; 2842 } 2843 2844 HeapWord* const end_addr = sd.region_align_down(closure.source()); 2845 if (sd.region_align_down(old_src_addr) != end_addr) { 2846 // The partial object was copied from more than one source region. 2847 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2848 2849 // Move to the next source region, possibly switching spaces as well. All 2850 // args except end_addr may be modified. 2851 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2852 end_addr); 2853 } 2854 } 2855 2856 do { 2857 HeapWord* const cur_addr = closure.source(); 2858 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1), 2859 src_space_top); 2860 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr); 2861 2862 if (status == ParMarkBitMap::incomplete) { 2863 // The last obj that starts in the source region does not end in the 2864 // region. 2865 assert(closure.source() < end_addr, "sanity"); 2866 HeapWord* const obj_beg = closure.source(); 2867 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(), 2868 src_space_top); 2869 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end); 2870 if (obj_end < range_end) { 2871 // The end was found; the entire object will fit. 2872 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end)); 2873 assert(status != ParMarkBitMap::would_overflow, "sanity"); 2874 } else { 2875 // The end was not found; the object will not fit. 2876 assert(range_end < src_space_top, "obj cannot cross space boundary"); 2877 status = ParMarkBitMap::would_overflow; 2878 } 2879 } 2880 2881 if (status == ParMarkBitMap::would_overflow) { 2882 // The last object did not fit. Note that interior oop updates were 2883 // deferred, then copy enough of the object to fill the region. 2884 region_ptr->set_deferred_obj_addr(closure.destination()); 2885 status = closure.copy_until_full(); // copies from closure.source() 2886 2887 decrement_destination_counts(cm, src_space_id, src_region_idx, 2888 closure.source()); 2889 region_ptr->set_completed(); 2890 return; 2891 } 2892 2893 if (status == ParMarkBitMap::full) { 2894 decrement_destination_counts(cm, src_space_id, src_region_idx, 2895 closure.source()); 2896 region_ptr->set_deferred_obj_addr(NULL); 2897 region_ptr->set_completed(); 2898 return; 2899 } 2900 2901 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 2902 2903 // Move to the next source region, possibly switching spaces as well. All 2904 // args except end_addr may be modified. 2905 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 2906 end_addr); 2907 } while (true); 2908 } 2909 2910 void PSParallelCompact::fill_blocks(size_t region_idx) 2911 { 2912 // Fill in the block table elements for the specified region. Each block 2913 // table element holds the number of live words in the region that are to the 2914 // left of the first object that starts in the block. Thus only blocks in 2915 // which an object starts need to be filled. 2916 // 2917 // The algorithm scans the section of the bitmap that corresponds to the 2918 // region, keeping a running total of the live words. When an object start is 2919 // found, if it's the first to start in the block that contains it, the 2920 // current total is written to the block table element. 2921 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize; 2922 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize; 2923 const size_t RegionSize = ParallelCompactData::RegionSize; 2924 2925 ParallelCompactData& sd = summary_data(); 2926 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size(); 2927 if (partial_obj_size >= RegionSize) { 2928 return; // No objects start in this region. 2929 } 2930 2931 // Ensure the first loop iteration decides that the block has changed. 2932 size_t cur_block = sd.block_count(); 2933 2934 const ParMarkBitMap* const bitmap = mark_bitmap(); 2935 2936 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment; 2937 assert((size_t)1 << Log2BitsPerBlock == 2938 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity"); 2939 2940 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize); 2941 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize); 2942 size_t live_bits = bitmap->words_to_bits(partial_obj_size); 2943 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end); 2944 while (beg_bit < range_end) { 2945 const size_t new_block = beg_bit >> Log2BitsPerBlock; 2946 if (new_block != cur_block) { 2947 cur_block = new_block; 2948 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits)); 2949 } 2950 2951 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end); 2952 if (end_bit < range_end - 1) { 2953 live_bits += end_bit - beg_bit + 1; 2954 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end); 2955 } else { 2956 return; 2957 } 2958 } 2959 } 2960 2961 void 2962 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) { 2963 const MutableSpace* sp = space(space_id); 2964 if (sp->is_empty()) { 2965 return; 2966 } 2967 2968 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2969 ParMarkBitMap* const bitmap = mark_bitmap(); 2970 HeapWord* const dp_addr = dense_prefix(space_id); 2971 HeapWord* beg_addr = sp->bottom(); 2972 HeapWord* end_addr = sp->top(); 2973 2974 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix"); 2975 2976 const size_t beg_region = sd.addr_to_region_idx(beg_addr); 2977 const size_t dp_region = sd.addr_to_region_idx(dp_addr); 2978 if (beg_region < dp_region) { 2979 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region); 2980 } 2981 2982 // The destination of the first live object that starts in the region is one 2983 // past the end of the partial object entering the region (if any). 2984 HeapWord* const dest_addr = sd.partial_obj_end(dp_region); 2985 HeapWord* const new_top = _space_info[space_id].new_top(); 2986 assert(new_top >= dest_addr, "bad new_top value"); 2987 const size_t words = pointer_delta(new_top, dest_addr); 2988 2989 if (words > 0) { 2990 ObjectStartArray* start_array = _space_info[space_id].start_array(); 2991 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 2992 2993 ParMarkBitMap::IterationStatus status; 2994 status = bitmap->iterate(&closure, dest_addr, end_addr); 2995 assert(status == ParMarkBitMap::full, "iteration not complete"); 2996 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr, 2997 "live objects skipped because closure is full"); 2998 } 2999 } 3000 3001 jlong PSParallelCompact::millis_since_last_gc() { 3002 // We need a monotonically non-decreasing time in ms but 3003 // os::javaTimeMillis() does not guarantee monotonicity. 3004 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3005 jlong ret_val = now - _time_of_last_gc; 3006 // XXX See note in genCollectedHeap::millis_since_last_gc(). 3007 if (ret_val < 0) { 3008 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);) 3009 return 0; 3010 } 3011 return ret_val; 3012 } 3013 3014 void PSParallelCompact::reset_millis_since_last_gc() { 3015 // We need a monotonically non-decreasing time in ms but 3016 // os::javaTimeMillis() does not guarantee monotonicity. 3017 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3018 } 3019 3020 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() 3021 { 3022 if (source() != destination()) { 3023 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3024 Copy::aligned_conjoint_words(source(), destination(), words_remaining()); 3025 } 3026 update_state(words_remaining()); 3027 assert(is_full(), "sanity"); 3028 return ParMarkBitMap::full; 3029 } 3030 3031 void MoveAndUpdateClosure::copy_partial_obj() 3032 { 3033 size_t words = words_remaining(); 3034 3035 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end()); 3036 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end); 3037 if (end_addr < range_end) { 3038 words = bitmap()->obj_size(source(), end_addr); 3039 } 3040 3041 // This test is necessary; if omitted, the pointer updates to a partial object 3042 // that crosses the dense prefix boundary could be overwritten. 3043 if (source() != destination()) { 3044 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3045 Copy::aligned_conjoint_words(source(), destination(), words); 3046 } 3047 update_state(words); 3048 } 3049 3050 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3051 PSParallelCompact::AdjustPointerClosure closure(cm); 3052 oop_oop_iterate_oop_maps<true>(obj, &closure); 3053 } 3054 3055 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3056 InstanceKlass::oop_pc_update_pointers(obj, cm); 3057 3058 PSParallelCompact::AdjustPointerClosure closure(cm); 3059 oop_oop_iterate_statics<true>(obj, &closure); 3060 } 3061 3062 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3063 InstanceKlass::oop_pc_update_pointers(obj, cm); 3064 } 3065 3066 #ifdef ASSERT 3067 template <class T> static void trace_reference_gc(const char *s, oop obj, 3068 T* referent_addr, 3069 T* next_addr, 3070 T* discovered_addr) { 3071 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj)); 3072 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3073 p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL); 3074 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3075 p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL); 3076 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT, 3077 p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL); 3078 } 3079 #endif 3080 3081 template <class T> 3082 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) { 3083 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj); 3084 PSParallelCompact::adjust_pointer(referent_addr, cm); 3085 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj); 3086 PSParallelCompact::adjust_pointer(next_addr, cm); 3087 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj); 3088 PSParallelCompact::adjust_pointer(discovered_addr, cm); 3089 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj, 3090 referent_addr, next_addr, discovered_addr);) 3091 } 3092 3093 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3094 InstanceKlass::oop_pc_update_pointers(obj, cm); 3095 3096 if (UseCompressedOops) { 3097 oop_pc_update_pointers_specialized<narrowOop>(obj, cm); 3098 } else { 3099 oop_pc_update_pointers_specialized<oop>(obj, cm); 3100 } 3101 } 3102 3103 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3104 assert(obj->is_objArray(), "obj must be obj array"); 3105 PSParallelCompact::AdjustPointerClosure closure(cm); 3106 oop_oop_iterate_elements<true>(objArrayOop(obj), &closure); 3107 } 3108 3109 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) { 3110 assert(obj->is_typeArray(),"must be a type array"); 3111 } 3112 3113 ParMarkBitMapClosure::IterationStatus 3114 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) { 3115 assert(destination() != NULL, "sanity"); 3116 assert(bitmap()->obj_size(addr) == words, "bad size"); 3117 3118 _source = addr; 3119 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) == 3120 destination(), "wrong destination"); 3121 3122 if (words > words_remaining()) { 3123 return ParMarkBitMap::would_overflow; 3124 } 3125 3126 // The start_array must be updated even if the object is not moving. 3127 if (_start_array != NULL) { 3128 _start_array->allocate_block(destination()); 3129 } 3130 3131 if (destination() != source()) { 3132 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3133 Copy::aligned_conjoint_words(source(), destination(), words); 3134 } 3135 3136 oop moved_oop = (oop) destination(); 3137 compaction_manager()->update_contents(moved_oop); 3138 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop)); 3139 3140 update_state(words); 3141 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity"); 3142 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete; 3143 } 3144 3145 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm, 3146 ParCompactionManager* cm, 3147 PSParallelCompact::SpaceId space_id) : 3148 ParMarkBitMapClosure(mbm, cm), 3149 _space_id(space_id), 3150 _start_array(PSParallelCompact::start_array(space_id)) 3151 { 3152 } 3153 3154 // Updates the references in the object to their new values. 3155 ParMarkBitMapClosure::IterationStatus 3156 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) { 3157 do_addr(addr); 3158 return ParMarkBitMap::incomplete; 3159 } 3160 3161 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : 3162 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), 3163 _start_array(PSParallelCompact::start_array(space_id)) 3164 { 3165 assert(space_id == PSParallelCompact::old_space_id, 3166 "cannot use FillClosure in the young gen"); 3167 } 3168 3169 ParMarkBitMapClosure::IterationStatus 3170 FillClosure::do_addr(HeapWord* addr, size_t size) { 3171 CollectedHeap::fill_with_objects(addr, size); 3172 HeapWord* const end = addr + size; 3173 do { 3174 _start_array->allocate_block(addr); 3175 addr += oop(addr)->size(); 3176 } while (addr < end); 3177 return ParMarkBitMap::incomplete; 3178 }