1 /* 2 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/symbolTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "code/codeCache.hpp" 29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" 30 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp" 31 #include "gc_implementation/parallelScavenge/pcTasks.hpp" 32 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" 33 #include "gc_implementation/parallelScavenge/psCompactionManager.inline.hpp" 34 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" 35 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp" 36 #include "gc_implementation/parallelScavenge/psOldGen.hpp" 37 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp" 38 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp" 39 #include "gc_implementation/parallelScavenge/psScavenge.hpp" 40 #include "gc_implementation/parallelScavenge/psYoungGen.hpp" 41 #include "gc_implementation/shared/gcHeapSummary.hpp" 42 #include "gc_implementation/shared/gcTimer.hpp" 43 #include "gc_implementation/shared/gcTrace.hpp" 44 #include "gc_implementation/shared/gcTraceTime.hpp" 45 #include "gc_implementation/shared/isGCActiveMark.hpp" 46 #include "gc_interface/gcCause.hpp" 47 #include "memory/gcLocker.inline.hpp" 48 #include "memory/referencePolicy.hpp" 49 #include "memory/referenceProcessor.hpp" 50 #include "oops/methodData.hpp" 51 #include "oops/oop.inline.hpp" 52 #include "oops/oop.pcgc.inline.hpp" 53 #include "runtime/fprofiler.hpp" 54 #include "runtime/safepoint.hpp" 55 #include "runtime/vmThread.hpp" 56 #include "services/management.hpp" 57 #include "services/memoryService.hpp" 58 #include "services/memTracker.hpp" 59 #include "utilities/events.hpp" 60 #include "utilities/stack.inline.hpp" 61 62 #include <math.h> 63 64 // All sizes are in HeapWords. 65 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words 66 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize; 67 const size_t ParallelCompactData::RegionSizeBytes = 68 RegionSize << LogHeapWordSize; 69 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1; 70 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1; 71 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask; 72 73 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words 74 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize; 75 const size_t ParallelCompactData::BlockSizeBytes = 76 BlockSize << LogHeapWordSize; 77 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1; 78 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1; 79 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask; 80 81 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize; 82 const size_t ParallelCompactData::Log2BlocksPerRegion = 83 Log2RegionSize - Log2BlockSize; 84 85 const ParallelCompactData::RegionData::region_sz_t 86 ParallelCompactData::RegionData::dc_shift = 27; 87 88 const ParallelCompactData::RegionData::region_sz_t 89 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift; 90 91 const ParallelCompactData::RegionData::region_sz_t 92 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift; 93 94 const ParallelCompactData::RegionData::region_sz_t 95 ParallelCompactData::RegionData::los_mask = ~dc_mask; 96 97 const ParallelCompactData::RegionData::region_sz_t 98 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift; 99 100 const ParallelCompactData::RegionData::region_sz_t 101 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift; 102 103 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; 104 bool PSParallelCompact::_print_phases = false; 105 106 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; 107 Klass* PSParallelCompact::_updated_int_array_klass_obj = NULL; 108 109 double PSParallelCompact::_dwl_mean; 110 double PSParallelCompact::_dwl_std_dev; 111 double PSParallelCompact::_dwl_first_term; 112 double PSParallelCompact::_dwl_adjustment; 113 #ifdef ASSERT 114 bool PSParallelCompact::_dwl_initialized = false; 115 #endif // #ifdef ASSERT 116 117 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size, 118 HeapWord* destination) 119 { 120 assert(src_region_idx != 0, "invalid src_region_idx"); 121 assert(partial_obj_size != 0, "invalid partial_obj_size argument"); 122 assert(destination != NULL, "invalid destination argument"); 123 124 _src_region_idx = src_region_idx; 125 _partial_obj_size = partial_obj_size; 126 _destination = destination; 127 128 // These fields may not be updated below, so make sure they're clear. 129 assert(_dest_region_addr == NULL, "should have been cleared"); 130 assert(_first_src_addr == NULL, "should have been cleared"); 131 132 // Determine the number of destination regions for the partial object. 133 HeapWord* const last_word = destination + partial_obj_size - 1; 134 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 135 HeapWord* const beg_region_addr = sd.region_align_down(destination); 136 HeapWord* const end_region_addr = sd.region_align_down(last_word); 137 138 if (beg_region_addr == end_region_addr) { 139 // One destination region. 140 _destination_count = 1; 141 if (end_region_addr == destination) { 142 // The destination falls on a region boundary, thus the first word of the 143 // partial object will be the first word copied to the destination region. 144 _dest_region_addr = end_region_addr; 145 _first_src_addr = sd.region_to_addr(src_region_idx); 146 } 147 } else { 148 // Two destination regions. When copied, the partial object will cross a 149 // destination region boundary, so a word somewhere within the partial 150 // object will be the first word copied to the second destination region. 151 _destination_count = 2; 152 _dest_region_addr = end_region_addr; 153 const size_t ofs = pointer_delta(end_region_addr, destination); 154 assert(ofs < _partial_obj_size, "sanity"); 155 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs; 156 } 157 } 158 159 void SplitInfo::clear() 160 { 161 _src_region_idx = 0; 162 _partial_obj_size = 0; 163 _destination = NULL; 164 _destination_count = 0; 165 _dest_region_addr = NULL; 166 _first_src_addr = NULL; 167 assert(!is_valid(), "sanity"); 168 } 169 170 #ifdef ASSERT 171 void SplitInfo::verify_clear() 172 { 173 assert(_src_region_idx == 0, "not clear"); 174 assert(_partial_obj_size == 0, "not clear"); 175 assert(_destination == NULL, "not clear"); 176 assert(_destination_count == 0, "not clear"); 177 assert(_dest_region_addr == NULL, "not clear"); 178 assert(_first_src_addr == NULL, "not clear"); 179 } 180 #endif // #ifdef ASSERT 181 182 183 void PSParallelCompact::print_on_error(outputStream* st) { 184 _mark_bitmap.print_on_error(st); 185 } 186 187 #ifndef PRODUCT 188 const char* PSParallelCompact::space_names[] = { 189 "old ", "eden", "from", "to " 190 }; 191 192 void PSParallelCompact::print_region_ranges() 193 { 194 tty->print_cr("space bottom top end new_top"); 195 tty->print_cr("------ ---------- ---------- ---------- ----------"); 196 197 for (unsigned int id = 0; id < last_space_id; ++id) { 198 const MutableSpace* space = _space_info[id].space(); 199 tty->print_cr("%u %s " 200 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " 201 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", 202 id, space_names[id], 203 summary_data().addr_to_region_idx(space->bottom()), 204 summary_data().addr_to_region_idx(space->top()), 205 summary_data().addr_to_region_idx(space->end()), 206 summary_data().addr_to_region_idx(_space_info[id].new_top())); 207 } 208 } 209 210 void 211 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c) 212 { 213 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7) 214 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5) 215 216 ParallelCompactData& sd = PSParallelCompact::summary_data(); 217 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0; 218 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " " 219 REGION_IDX_FORMAT " " PTR_FORMAT " " 220 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " " 221 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d", 222 i, c->data_location(), dci, c->destination(), 223 c->partial_obj_size(), c->live_obj_size(), 224 c->data_size(), c->source_region(), c->destination_count()); 225 226 #undef REGION_IDX_FORMAT 227 #undef REGION_DATA_FORMAT 228 } 229 230 void 231 print_generic_summary_data(ParallelCompactData& summary_data, 232 HeapWord* const beg_addr, 233 HeapWord* const end_addr) 234 { 235 size_t total_words = 0; 236 size_t i = summary_data.addr_to_region_idx(beg_addr); 237 const size_t last = summary_data.addr_to_region_idx(end_addr); 238 HeapWord* pdest = 0; 239 240 while (i <= last) { 241 ParallelCompactData::RegionData* c = summary_data.region(i); 242 if (c->data_size() != 0 || c->destination() != pdest) { 243 print_generic_summary_region(i, c); 244 total_words += c->data_size(); 245 pdest = c->destination(); 246 } 247 ++i; 248 } 249 250 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); 251 } 252 253 void 254 print_generic_summary_data(ParallelCompactData& summary_data, 255 SpaceInfo* space_info) 256 { 257 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { 258 const MutableSpace* space = space_info[id].space(); 259 print_generic_summary_data(summary_data, space->bottom(), 260 MAX2(space->top(), space_info[id].new_top())); 261 } 262 } 263 264 void 265 print_initial_summary_region(size_t i, 266 const ParallelCompactData::RegionData* c, 267 bool newline = true) 268 { 269 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " " 270 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " 271 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 272 i, c->destination(), 273 c->partial_obj_size(), c->live_obj_size(), 274 c->data_size(), c->source_region(), c->destination_count()); 275 if (newline) tty->cr(); 276 } 277 278 void 279 print_initial_summary_data(ParallelCompactData& summary_data, 280 const MutableSpace* space) { 281 if (space->top() == space->bottom()) { 282 return; 283 } 284 285 const size_t region_size = ParallelCompactData::RegionSize; 286 typedef ParallelCompactData::RegionData RegionData; 287 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top()); 288 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up); 289 const RegionData* c = summary_data.region(end_region - 1); 290 HeapWord* end_addr = c->destination() + c->data_size(); 291 const size_t live_in_space = pointer_delta(end_addr, space->bottom()); 292 293 // Print (and count) the full regions at the beginning of the space. 294 size_t full_region_count = 0; 295 size_t i = summary_data.addr_to_region_idx(space->bottom()); 296 while (i < end_region && summary_data.region(i)->data_size() == region_size) { 297 print_initial_summary_region(i, summary_data.region(i)); 298 ++full_region_count; 299 ++i; 300 } 301 302 size_t live_to_right = live_in_space - full_region_count * region_size; 303 304 double max_reclaimed_ratio = 0.0; 305 size_t max_reclaimed_ratio_region = 0; 306 size_t max_dead_to_right = 0; 307 size_t max_live_to_right = 0; 308 309 // Print the 'reclaimed ratio' for regions while there is something live in 310 // the region or to the right of it. The remaining regions are empty (and 311 // uninteresting), and computing the ratio will result in division by 0. 312 while (i < end_region && live_to_right > 0) { 313 c = summary_data.region(i); 314 HeapWord* const region_addr = summary_data.region_to_addr(i); 315 const size_t used_to_right = pointer_delta(space->top(), region_addr); 316 const size_t dead_to_right = used_to_right - live_to_right; 317 const double reclaimed_ratio = double(dead_to_right) / live_to_right; 318 319 if (reclaimed_ratio > max_reclaimed_ratio) { 320 max_reclaimed_ratio = reclaimed_ratio; 321 max_reclaimed_ratio_region = i; 322 max_dead_to_right = dead_to_right; 323 max_live_to_right = live_to_right; 324 } 325 326 print_initial_summary_region(i, c, false); 327 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), 328 reclaimed_ratio, dead_to_right, live_to_right); 329 330 live_to_right -= c->data_size(); 331 ++i; 332 } 333 334 // Any remaining regions are empty. Print one more if there is one. 335 if (i < end_region) { 336 print_initial_summary_region(i, summary_data.region(i)); 337 } 338 339 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " " 340 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", 341 max_reclaimed_ratio_region, max_dead_to_right, 342 max_live_to_right, max_reclaimed_ratio); 343 } 344 345 void 346 print_initial_summary_data(ParallelCompactData& summary_data, 347 SpaceInfo* space_info) { 348 unsigned int id = PSParallelCompact::old_space_id; 349 const MutableSpace* space; 350 do { 351 space = space_info[id].space(); 352 print_initial_summary_data(summary_data, space); 353 } while (++id < PSParallelCompact::eden_space_id); 354 355 do { 356 space = space_info[id].space(); 357 print_generic_summary_data(summary_data, space->bottom(), space->top()); 358 } while (++id < PSParallelCompact::last_space_id); 359 } 360 #endif // #ifndef PRODUCT 361 362 #ifdef ASSERT 363 size_t add_obj_count; 364 size_t add_obj_size; 365 size_t mark_bitmap_count; 366 size_t mark_bitmap_size; 367 #endif // #ifdef ASSERT 368 369 ParallelCompactData::ParallelCompactData() 370 { 371 _region_start = 0; 372 373 _region_vspace = 0; 374 _reserved_byte_size = 0; 375 _region_data = 0; 376 _region_count = 0; 377 378 _block_vspace = 0; 379 _block_data = 0; 380 _block_count = 0; 381 } 382 383 bool ParallelCompactData::initialize(MemRegion covered_region) 384 { 385 _region_start = covered_region.start(); 386 const size_t region_size = covered_region.word_size(); 387 DEBUG_ONLY(_region_end = _region_start + region_size;) 388 389 assert(region_align_down(_region_start) == _region_start, 390 "region start not aligned"); 391 assert((region_size & RegionSizeOffsetMask) == 0, 392 "region size not a multiple of RegionSize"); 393 394 bool result = initialize_region_data(region_size) && initialize_block_data(); 395 return result; 396 } 397 398 PSVirtualSpace* 399 ParallelCompactData::create_vspace(size_t count, size_t element_size) 400 { 401 const size_t raw_bytes = count * element_size; 402 const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10); 403 const size_t granularity = os::vm_allocation_granularity(); 404 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity)); 405 406 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : 407 MAX2(page_sz, granularity); 408 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0); 409 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(), 410 rs.size()); 411 412 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 413 414 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); 415 if (vspace != 0) { 416 if (vspace->expand_by(_reserved_byte_size)) { 417 return vspace; 418 } 419 delete vspace; 420 // Release memory reserved in the space. 421 rs.release(); 422 } 423 424 return 0; 425 } 426 427 bool ParallelCompactData::initialize_region_data(size_t region_size) 428 { 429 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize; 430 _region_vspace = create_vspace(count, sizeof(RegionData)); 431 if (_region_vspace != 0) { 432 _region_data = (RegionData*)_region_vspace->reserved_low_addr(); 433 _region_count = count; 434 return true; 435 } 436 return false; 437 } 438 439 bool ParallelCompactData::initialize_block_data() 440 { 441 assert(_region_count != 0, "region data must be initialized first"); 442 const size_t count = _region_count << Log2BlocksPerRegion; 443 _block_vspace = create_vspace(count, sizeof(BlockData)); 444 if (_block_vspace != 0) { 445 _block_data = (BlockData*)_block_vspace->reserved_low_addr(); 446 _block_count = count; 447 return true; 448 } 449 return false; 450 } 451 452 void ParallelCompactData::clear() 453 { 454 memset(_region_data, 0, _region_vspace->committed_size()); 455 memset(_block_data, 0, _block_vspace->committed_size()); 456 } 457 458 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) { 459 assert(beg_region <= _region_count, "beg_region out of range"); 460 assert(end_region <= _region_count, "end_region out of range"); 461 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize"); 462 463 const size_t region_cnt = end_region - beg_region; 464 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData)); 465 466 const size_t beg_block = beg_region * BlocksPerRegion; 467 const size_t block_cnt = region_cnt * BlocksPerRegion; 468 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData)); 469 } 470 471 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const 472 { 473 const RegionData* cur_cp = region(region_idx); 474 const RegionData* const end_cp = region(region_count() - 1); 475 476 HeapWord* result = region_to_addr(region_idx); 477 if (cur_cp < end_cp) { 478 do { 479 result += cur_cp->partial_obj_size(); 480 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp); 481 } 482 return result; 483 } 484 485 void ParallelCompactData::add_obj(HeapWord* addr, size_t len) 486 { 487 const size_t obj_ofs = pointer_delta(addr, _region_start); 488 const size_t beg_region = obj_ofs >> Log2RegionSize; 489 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize; 490 491 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);) 492 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);) 493 494 if (beg_region == end_region) { 495 // All in one region. 496 _region_data[beg_region].add_live_obj(len); 497 return; 498 } 499 500 // First region. 501 const size_t beg_ofs = region_offset(addr); 502 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs); 503 504 Klass* klass = ((oop)addr)->klass(); 505 // Middle regions--completely spanned by this object. 506 for (size_t region = beg_region + 1; region < end_region; ++region) { 507 _region_data[region].set_partial_obj_size(RegionSize); 508 _region_data[region].set_partial_obj_addr(addr); 509 } 510 511 // Last region. 512 const size_t end_ofs = region_offset(addr + len - 1); 513 _region_data[end_region].set_partial_obj_size(end_ofs + 1); 514 _region_data[end_region].set_partial_obj_addr(addr); 515 } 516 517 void 518 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) 519 { 520 assert(region_offset(beg) == 0, "not RegionSize aligned"); 521 assert(region_offset(end) == 0, "not RegionSize aligned"); 522 523 size_t cur_region = addr_to_region_idx(beg); 524 const size_t end_region = addr_to_region_idx(end); 525 HeapWord* addr = beg; 526 while (cur_region < end_region) { 527 _region_data[cur_region].set_destination(addr); 528 _region_data[cur_region].set_destination_count(0); 529 _region_data[cur_region].set_source_region(cur_region); 530 _region_data[cur_region].set_data_location(addr); 531 532 // Update live_obj_size so the region appears completely full. 533 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size(); 534 _region_data[cur_region].set_live_obj_size(live_size); 535 536 ++cur_region; 537 addr += RegionSize; 538 } 539 } 540 541 // Find the point at which a space can be split and, if necessary, record the 542 // split point. 543 // 544 // If the current src region (which overflowed the destination space) doesn't 545 // have a partial object, the split point is at the beginning of the current src 546 // region (an "easy" split, no extra bookkeeping required). 547 // 548 // If the current src region has a partial object, the split point is in the 549 // region where that partial object starts (call it the split_region). If 550 // split_region has a partial object, then the split point is just after that 551 // partial object (a "hard" split where we have to record the split data and 552 // zero the partial_obj_size field). With a "hard" split, we know that the 553 // partial_obj ends within split_region because the partial object that caused 554 // the overflow starts in split_region. If split_region doesn't have a partial 555 // obj, then the split is at the beginning of split_region (another "easy" 556 // split). 557 HeapWord* 558 ParallelCompactData::summarize_split_space(size_t src_region, 559 SplitInfo& split_info, 560 HeapWord* destination, 561 HeapWord* target_end, 562 HeapWord** target_next) 563 { 564 assert(destination <= target_end, "sanity"); 565 assert(destination + _region_data[src_region].data_size() > target_end, 566 "region should not fit into target space"); 567 assert(is_region_aligned(target_end), "sanity"); 568 569 size_t split_region = src_region; 570 HeapWord* split_destination = destination; 571 size_t partial_obj_size = _region_data[src_region].partial_obj_size(); 572 573 if (destination + partial_obj_size > target_end) { 574 // The split point is just after the partial object (if any) in the 575 // src_region that contains the start of the object that overflowed the 576 // destination space. 577 // 578 // Find the start of the "overflow" object and set split_region to the 579 // region containing it. 580 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr(); 581 split_region = addr_to_region_idx(overflow_obj); 582 583 // Clear the source_region field of all destination regions whose first word 584 // came from data after the split point (a non-null source_region field 585 // implies a region must be filled). 586 // 587 // An alternative to the simple loop below: clear during post_compact(), 588 // which uses memcpy instead of individual stores, and is easy to 589 // parallelize. (The downside is that it clears the entire RegionData 590 // object as opposed to just one field.) 591 // 592 // post_compact() would have to clear the summary data up to the highest 593 // address that was written during the summary phase, which would be 594 // 595 // max(top, max(new_top, clear_top)) 596 // 597 // where clear_top is a new field in SpaceInfo. Would have to set clear_top 598 // to target_end. 599 const RegionData* const sr = region(split_region); 600 const size_t beg_idx = 601 addr_to_region_idx(region_align_up(sr->destination() + 602 sr->partial_obj_size())); 603 const size_t end_idx = addr_to_region_idx(target_end); 604 605 if (TraceParallelOldGCSummaryPhase) { 606 gclog_or_tty->print_cr("split: clearing source_region field in [" 607 SIZE_FORMAT ", " SIZE_FORMAT ")", 608 beg_idx, end_idx); 609 } 610 for (size_t idx = beg_idx; idx < end_idx; ++idx) { 611 _region_data[idx].set_source_region(0); 612 } 613 614 // Set split_destination and partial_obj_size to reflect the split region. 615 split_destination = sr->destination(); 616 partial_obj_size = sr->partial_obj_size(); 617 } 618 619 // The split is recorded only if a partial object extends onto the region. 620 if (partial_obj_size != 0) { 621 _region_data[split_region].set_partial_obj_size(0); 622 split_info.record(split_region, partial_obj_size, split_destination); 623 } 624 625 // Setup the continuation addresses. 626 *target_next = split_destination + partial_obj_size; 627 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size; 628 629 if (TraceParallelOldGCSummaryPhase) { 630 const char * split_type = partial_obj_size == 0 ? "easy" : "hard"; 631 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT 632 " pos=" SIZE_FORMAT, 633 split_type, source_next, split_region, 634 partial_obj_size); 635 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT 636 " tn=" PTR_FORMAT, 637 split_type, split_destination, 638 addr_to_region_idx(split_destination), 639 *target_next); 640 641 if (partial_obj_size != 0) { 642 HeapWord* const po_beg = split_info.destination(); 643 HeapWord* const po_end = po_beg + split_info.partial_obj_size(); 644 gclog_or_tty->print_cr("%s split: " 645 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " " 646 "po_end=" PTR_FORMAT " " SIZE_FORMAT, 647 split_type, 648 po_beg, addr_to_region_idx(po_beg), 649 po_end, addr_to_region_idx(po_end)); 650 } 651 } 652 653 return source_next; 654 } 655 656 bool ParallelCompactData::summarize(SplitInfo& split_info, 657 HeapWord* source_beg, HeapWord* source_end, 658 HeapWord** source_next, 659 HeapWord* target_beg, HeapWord* target_end, 660 HeapWord** target_next) 661 { 662 if (TraceParallelOldGCSummaryPhase) { 663 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next; 664 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT 665 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT, 666 source_beg, source_end, source_next_val, 667 target_beg, target_end, *target_next); 668 } 669 670 size_t cur_region = addr_to_region_idx(source_beg); 671 const size_t end_region = addr_to_region_idx(region_align_up(source_end)); 672 673 HeapWord *dest_addr = target_beg; 674 while (cur_region < end_region) { 675 // The destination must be set even if the region has no data. 676 _region_data[cur_region].set_destination(dest_addr); 677 678 size_t words = _region_data[cur_region].data_size(); 679 if (words > 0) { 680 // If cur_region does not fit entirely into the target space, find a point 681 // at which the source space can be 'split' so that part is copied to the 682 // target space and the rest is copied elsewhere. 683 if (dest_addr + words > target_end) { 684 assert(source_next != NULL, "source_next is NULL when splitting"); 685 *source_next = summarize_split_space(cur_region, split_info, dest_addr, 686 target_end, target_next); 687 return false; 688 } 689 690 // Compute the destination_count for cur_region, and if necessary, update 691 // source_region for a destination region. The source_region field is 692 // updated if cur_region is the first (left-most) region to be copied to a 693 // destination region. 694 // 695 // The destination_count calculation is a bit subtle. A region that has 696 // data that compacts into itself does not count itself as a destination. 697 // This maintains the invariant that a zero count means the region is 698 // available and can be claimed and then filled. 699 uint destination_count = 0; 700 if (split_info.is_split(cur_region)) { 701 // The current region has been split: the partial object will be copied 702 // to one destination space and the remaining data will be copied to 703 // another destination space. Adjust the initial destination_count and, 704 // if necessary, set the source_region field if the partial object will 705 // cross a destination region boundary. 706 destination_count = split_info.destination_count(); 707 if (destination_count == 2) { 708 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr()); 709 _region_data[dest_idx].set_source_region(cur_region); 710 } 711 } 712 713 HeapWord* const last_addr = dest_addr + words - 1; 714 const size_t dest_region_1 = addr_to_region_idx(dest_addr); 715 const size_t dest_region_2 = addr_to_region_idx(last_addr); 716 717 // Initially assume that the destination regions will be the same and 718 // adjust the value below if necessary. Under this assumption, if 719 // cur_region == dest_region_2, then cur_region will be compacted 720 // completely into itself. 721 destination_count += cur_region == dest_region_2 ? 0 : 1; 722 if (dest_region_1 != dest_region_2) { 723 // Destination regions differ; adjust destination_count. 724 destination_count += 1; 725 // Data from cur_region will be copied to the start of dest_region_2. 726 _region_data[dest_region_2].set_source_region(cur_region); 727 } else if (region_offset(dest_addr) == 0) { 728 // Data from cur_region will be copied to the start of the destination 729 // region. 730 _region_data[dest_region_1].set_source_region(cur_region); 731 } 732 733 _region_data[cur_region].set_destination_count(destination_count); 734 _region_data[cur_region].set_data_location(region_to_addr(cur_region)); 735 dest_addr += words; 736 } 737 738 ++cur_region; 739 } 740 741 *target_next = dest_addr; 742 return true; 743 } 744 745 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) { 746 assert(addr != NULL, "Should detect NULL oop earlier"); 747 assert(PSParallelCompact::gc_heap()->is_in(addr), "not in heap"); 748 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked"); 749 750 // Region covering the object. 751 RegionData* const region_ptr = addr_to_region_ptr(addr); 752 HeapWord* result = region_ptr->destination(); 753 754 // If the entire Region is live, the new location is region->destination + the 755 // offset of the object within in the Region. 756 757 // Run some performance tests to determine if this special case pays off. It 758 // is worth it for pointers into the dense prefix. If the optimization to 759 // avoid pointer updates in regions that only point to the dense prefix is 760 // ever implemented, this should be revisited. 761 if (region_ptr->data_size() == RegionSize) { 762 result += region_offset(addr); 763 return result; 764 } 765 766 // Otherwise, the new location is region->destination + block offset + the 767 // number of live words in the Block that are (a) to the left of addr and (b) 768 // due to objects that start in the Block. 769 770 // Fill in the block table if necessary. This is unsynchronized, so multiple 771 // threads may fill the block table for a region (harmless, since it is 772 // idempotent). 773 if (!region_ptr->blocks_filled()) { 774 PSParallelCompact::fill_blocks(addr_to_region_idx(addr)); 775 region_ptr->set_blocks_filled(); 776 } 777 778 HeapWord* const search_start = block_align_down(addr); 779 const size_t block_offset = addr_to_block_ptr(addr)->offset(); 780 781 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); 782 const size_t live = bitmap->live_words_in_range(search_start, oop(addr)); 783 result += block_offset + live; 784 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result)); 785 return result; 786 } 787 788 #ifdef ASSERT 789 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) 790 { 791 const size_t* const beg = (const size_t*)vspace->committed_low_addr(); 792 const size_t* const end = (const size_t*)vspace->committed_high_addr(); 793 for (const size_t* p = beg; p < end; ++p) { 794 assert(*p == 0, "not zero"); 795 } 796 } 797 798 void ParallelCompactData::verify_clear() 799 { 800 verify_clear(_region_vspace); 801 verify_clear(_block_vspace); 802 } 803 #endif // #ifdef ASSERT 804 805 STWGCTimer PSParallelCompact::_gc_timer; 806 ParallelOldTracer PSParallelCompact::_gc_tracer; 807 elapsedTimer PSParallelCompact::_accumulated_time; 808 unsigned int PSParallelCompact::_total_invocations = 0; 809 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; 810 jlong PSParallelCompact::_time_of_last_gc = 0; 811 CollectorCounters* PSParallelCompact::_counters = NULL; 812 ParMarkBitMap PSParallelCompact::_mark_bitmap; 813 ParallelCompactData PSParallelCompact::_summary_data; 814 815 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; 816 817 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } 818 819 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); } 820 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); } 821 822 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure; 823 PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure; 824 825 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p); } 826 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p); } 827 828 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); } 829 830 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) { 831 mark_and_push(_compaction_manager, p); 832 } 833 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); } 834 835 void PSParallelCompact::FollowKlassClosure::do_klass(Klass* klass) { 836 klass->oops_do(_mark_and_push_closure); 837 } 838 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) { 839 klass->oops_do(&PSParallelCompact::_adjust_pointer_closure); 840 } 841 842 void PSParallelCompact::post_initialize() { 843 ParallelScavengeHeap* heap = gc_heap(); 844 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 845 846 MemRegion mr = heap->reserved_region(); 847 _ref_processor = 848 new ReferenceProcessor(mr, // span 849 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 850 (int) ParallelGCThreads, // mt processing degree 851 true, // mt discovery 852 (int) ParallelGCThreads, // mt discovery degree 853 true, // atomic_discovery 854 &_is_alive_closure, // non-header is alive closure 855 false); // write barrier for next field updates 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 = gc_heap(); 864 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 865 MemRegion mr = heap->reserved_region(); 866 867 // Was the old gen get allocated successfully? 868 if (!heap->old_gen()->is_allocated()) { 869 return false; 870 } 871 872 initialize_space_info(); 873 initialize_dead_wood_limiter(); 874 875 if (!_mark_bitmap.initialize(mr)) { 876 vm_shutdown_during_initialization( 877 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel " 878 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 879 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K)); 880 return false; 881 } 882 883 if (!_summary_data.initialize(mr)) { 884 vm_shutdown_during_initialization( 885 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel " 886 "garbage collection for the requested " SIZE_FORMAT "KB heap.", 887 _summary_data.reserved_byte_size()/K, mr.byte_size()/K)); 888 return false; 889 } 890 891 return true; 892 } 893 894 void PSParallelCompact::initialize_space_info() 895 { 896 memset(&_space_info, 0, sizeof(_space_info)); 897 898 ParallelScavengeHeap* heap = gc_heap(); 899 PSYoungGen* young_gen = heap->young_gen(); 900 901 _space_info[old_space_id].set_space(heap->old_gen()->object_space()); 902 _space_info[eden_space_id].set_space(young_gen->eden_space()); 903 _space_info[from_space_id].set_space(young_gen->from_space()); 904 _space_info[to_space_id].set_space(young_gen->to_space()); 905 906 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); 907 } 908 909 void PSParallelCompact::initialize_dead_wood_limiter() 910 { 911 const size_t max = 100; 912 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; 913 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; 914 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); 915 DEBUG_ONLY(_dwl_initialized = true;) 916 _dwl_adjustment = normal_distribution(1.0); 917 } 918 919 // Simple class for storing info about the heap at the start of GC, to be used 920 // after GC for comparison/printing. 921 class PreGCValues { 922 public: 923 PreGCValues() { } 924 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); } 925 926 void fill(ParallelScavengeHeap* heap) { 927 _heap_used = heap->used(); 928 _young_gen_used = heap->young_gen()->used_in_bytes(); 929 _old_gen_used = heap->old_gen()->used_in_bytes(); 930 _metadata_used = MetaspaceAux::allocated_used_bytes(); 931 }; 932 933 size_t heap_used() const { return _heap_used; } 934 size_t young_gen_used() const { return _young_gen_used; } 935 size_t old_gen_used() const { return _old_gen_used; } 936 size_t metadata_used() const { return _metadata_used; } 937 938 private: 939 size_t _heap_used; 940 size_t _young_gen_used; 941 size_t _old_gen_used; 942 size_t _metadata_used; 943 }; 944 945 void 946 PSParallelCompact::clear_data_covering_space(SpaceId id) 947 { 948 // At this point, top is the value before GC, new_top() is the value that will 949 // be set at the end of GC. The marking bitmap is cleared to top; nothing 950 // should be marked above top. The summary data is cleared to the larger of 951 // top & new_top. 952 MutableSpace* const space = _space_info[id].space(); 953 HeapWord* const bot = space->bottom(); 954 HeapWord* const top = space->top(); 955 HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); 956 957 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); 958 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top)); 959 _mark_bitmap.clear_range(beg_bit, end_bit); 960 961 const size_t beg_region = _summary_data.addr_to_region_idx(bot); 962 const size_t end_region = 963 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top)); 964 _summary_data.clear_range(beg_region, end_region); 965 966 // Clear the data used to 'split' regions. 967 SplitInfo& split_info = _space_info[id].split_info(); 968 if (split_info.is_valid()) { 969 split_info.clear(); 970 } 971 DEBUG_ONLY(split_info.verify_clear();) 972 } 973 974 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values) 975 { 976 // Update the from & to space pointers in space_info, since they are swapped 977 // at each young gen gc. Do the update unconditionally (even though a 978 // promotion failure does not swap spaces) because an unknown number of minor 979 // collections will have swapped the spaces an unknown number of times. 980 GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer); 981 ParallelScavengeHeap* heap = gc_heap(); 982 _space_info[from_space_id].set_space(heap->young_gen()->from_space()); 983 _space_info[to_space_id].set_space(heap->young_gen()->to_space()); 984 985 pre_gc_values->fill(heap); 986 987 DEBUG_ONLY(add_obj_count = add_obj_size = 0;) 988 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;) 989 990 // Increment the invocation count 991 heap->increment_total_collections(true); 992 993 // We need to track unique mark sweep invocations as well. 994 _total_invocations++; 995 996 heap->print_heap_before_gc(); 997 heap->trace_heap_before_gc(&_gc_tracer); 998 999 // Fill in TLABs 1000 heap->accumulate_statistics_all_tlabs(); 1001 heap->ensure_parsability(true); // retire TLABs 1002 1003 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 1004 HandleMark hm; // Discard invalid handles created during verification 1005 Universe::verify(" VerifyBeforeGC:"); 1006 } 1007 1008 // Verify object start arrays 1009 if (VerifyObjectStartArray && 1010 VerifyBeforeGC) { 1011 heap->old_gen()->verify_object_start_array(); 1012 } 1013 1014 DEBUG_ONLY(mark_bitmap()->verify_clear();) 1015 DEBUG_ONLY(summary_data().verify_clear();) 1016 1017 // Have worker threads release resources the next time they run a task. 1018 gc_task_manager()->release_all_resources(); 1019 } 1020 1021 void PSParallelCompact::post_compact() 1022 { 1023 GCTraceTime tm("post compact", print_phases(), true, &_gc_timer); 1024 1025 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1026 // Clear the marking bitmap, summary data and split info. 1027 clear_data_covering_space(SpaceId(id)); 1028 // Update top(). Must be done after clearing the bitmap and summary data. 1029 _space_info[id].publish_new_top(); 1030 } 1031 1032 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1033 MutableSpace* const from_space = _space_info[from_space_id].space(); 1034 MutableSpace* const to_space = _space_info[to_space_id].space(); 1035 1036 ParallelScavengeHeap* heap = gc_heap(); 1037 bool eden_empty = eden_space->is_empty(); 1038 if (!eden_empty) { 1039 eden_empty = absorb_live_data_from_eden(heap->size_policy(), 1040 heap->young_gen(), heap->old_gen()); 1041 } 1042 1043 // Update heap occupancy information which is used as input to the soft ref 1044 // clearing policy at the next gc. 1045 Universe::update_heap_info_at_gc(); 1046 1047 bool young_gen_empty = eden_empty && from_space->is_empty() && 1048 to_space->is_empty(); 1049 1050 BarrierSet* bs = heap->barrier_set(); 1051 if (bs->is_a(BarrierSet::ModRef)) { 1052 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs; 1053 MemRegion old_mr = heap->old_gen()->reserved(); 1054 1055 if (young_gen_empty) { 1056 modBS->clear(MemRegion(old_mr.start(), old_mr.end())); 1057 } else { 1058 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end())); 1059 } 1060 } 1061 1062 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 1063 ClassLoaderDataGraph::purge(); 1064 MetaspaceAux::verify_metrics(); 1065 1066 Threads::gc_epilogue(); 1067 CodeCache::gc_epilogue(); 1068 JvmtiExport::gc_epilogue(); 1069 1070 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1071 1072 ref_processor()->enqueue_discovered_references(NULL); 1073 1074 if (ZapUnusedHeapArea) { 1075 heap->gen_mangle_unused_area(); 1076 } 1077 1078 // Update time of last GC 1079 reset_millis_since_last_gc(); 1080 } 1081 1082 HeapWord* 1083 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, 1084 bool maximum_compaction) 1085 { 1086 const size_t region_size = ParallelCompactData::RegionSize; 1087 const ParallelCompactData& sd = summary_data(); 1088 1089 const MutableSpace* const space = _space_info[id].space(); 1090 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 1091 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom()); 1092 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up); 1093 1094 // Skip full regions at the beginning of the space--they are necessarily part 1095 // of the dense prefix. 1096 size_t full_count = 0; 1097 const RegionData* cp; 1098 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) { 1099 ++full_count; 1100 } 1101 1102 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1103 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1104 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; 1105 if (maximum_compaction || cp == end_cp || interval_ended) { 1106 _maximum_compaction_gc_num = total_invocations(); 1107 return sd.region_to_addr(cp); 1108 } 1109 1110 HeapWord* const new_top = _space_info[id].new_top(); 1111 const size_t space_live = pointer_delta(new_top, space->bottom()); 1112 const size_t space_used = space->used_in_words(); 1113 const size_t space_capacity = space->capacity_in_words(); 1114 1115 const double cur_density = double(space_live) / space_capacity; 1116 const double deadwood_density = 1117 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; 1118 const size_t deadwood_goal = size_t(space_capacity * deadwood_density); 1119 1120 if (TraceParallelOldGCDensePrefix) { 1121 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, 1122 cur_density, deadwood_density, deadwood_goal); 1123 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1124 "space_cap=" SIZE_FORMAT, 1125 space_live, space_used, 1126 space_capacity); 1127 } 1128 1129 // XXX - Use binary search? 1130 HeapWord* dense_prefix = sd.region_to_addr(cp); 1131 const RegionData* full_cp = cp; 1132 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1); 1133 while (cp < end_cp) { 1134 HeapWord* region_destination = cp->destination(); 1135 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination); 1136 if (TraceParallelOldGCDensePrefix && Verbose) { 1137 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " 1138 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8), 1139 sd.region(cp), region_destination, 1140 dense_prefix, cur_deadwood); 1141 } 1142 1143 if (cur_deadwood >= deadwood_goal) { 1144 // Found the region that has the correct amount of deadwood to the left. 1145 // This typically occurs after crossing a fairly sparse set of regions, so 1146 // iterate backwards over those sparse regions, looking for the region 1147 // that has the lowest density of live objects 'to the right.' 1148 size_t space_to_left = sd.region(cp) * region_size; 1149 size_t live_to_left = space_to_left - cur_deadwood; 1150 size_t space_to_right = space_capacity - space_to_left; 1151 size_t live_to_right = space_live - live_to_left; 1152 double density_to_right = double(live_to_right) / space_to_right; 1153 while (cp > full_cp) { 1154 --cp; 1155 const size_t prev_region_live_to_right = live_to_right - 1156 cp->data_size(); 1157 const size_t prev_region_space_to_right = space_to_right + region_size; 1158 double prev_region_density_to_right = 1159 double(prev_region_live_to_right) / prev_region_space_to_right; 1160 if (density_to_right <= prev_region_density_to_right) { 1161 return dense_prefix; 1162 } 1163 if (TraceParallelOldGCDensePrefix && Verbose) { 1164 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " 1165 "pc_d2r=%10.8f", sd.region(cp), density_to_right, 1166 prev_region_density_to_right); 1167 } 1168 dense_prefix -= region_size; 1169 live_to_right = prev_region_live_to_right; 1170 space_to_right = prev_region_space_to_right; 1171 density_to_right = prev_region_density_to_right; 1172 } 1173 return dense_prefix; 1174 } 1175 1176 dense_prefix += region_size; 1177 ++cp; 1178 } 1179 1180 return dense_prefix; 1181 } 1182 1183 #ifndef PRODUCT 1184 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, 1185 const SpaceId id, 1186 const bool maximum_compaction, 1187 HeapWord* const addr) 1188 { 1189 const size_t region_idx = summary_data().addr_to_region_idx(addr); 1190 RegionData* const cp = summary_data().region(region_idx); 1191 const MutableSpace* const space = _space_info[id].space(); 1192 HeapWord* const new_top = _space_info[id].new_top(); 1193 1194 const size_t space_live = pointer_delta(new_top, space->bottom()); 1195 const size_t dead_to_left = pointer_delta(addr, cp->destination()); 1196 const size_t space_cap = space->capacity_in_words(); 1197 const double dead_to_left_pct = double(dead_to_left) / space_cap; 1198 const size_t live_to_right = new_top - cp->destination(); 1199 const size_t dead_to_right = space->top() - addr - live_to_right; 1200 1201 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " 1202 "spl=" SIZE_FORMAT " " 1203 "d2l=" SIZE_FORMAT " d2l%%=%6.4f " 1204 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT 1205 " ratio=%10.8f", 1206 algorithm, addr, region_idx, 1207 space_live, 1208 dead_to_left, dead_to_left_pct, 1209 dead_to_right, live_to_right, 1210 double(dead_to_right) / live_to_right); 1211 } 1212 #endif // #ifndef PRODUCT 1213 1214 // Return a fraction indicating how much of the generation can be treated as 1215 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution 1216 // based on the density of live objects in the generation to determine a limit, 1217 // which is then adjusted so the return value is min_percent when the density is 1218 // 1. 1219 // 1220 // The following table shows some return values for a different values of the 1221 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and 1222 // min_percent is 1. 1223 // 1224 // fraction allowed as dead wood 1225 // ----------------------------------------------------------------- 1226 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 1227 // ------- ---------- ---------- ---------- ---------- ---------- ---------- 1228 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1229 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1230 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1231 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1232 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1233 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1234 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1235 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1236 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1237 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1238 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 1239 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1240 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1241 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1242 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1243 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1244 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1245 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1246 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1247 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1248 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1249 1250 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) 1251 { 1252 assert(_dwl_initialized, "uninitialized"); 1253 1254 // The raw limit is the value of the normal distribution at x = density. 1255 const double raw_limit = normal_distribution(density); 1256 1257 // Adjust the raw limit so it becomes the minimum when the density is 1. 1258 // 1259 // First subtract the adjustment value (which is simply the precomputed value 1260 // normal_distribution(1.0)); this yields a value of 0 when the density is 1. 1261 // Then add the minimum value, so the minimum is returned when the density is 1262 // 1. Finally, prevent negative values, which occur when the mean is not 0.5. 1263 const double min = double(min_percent) / 100.0; 1264 const double limit = raw_limit - _dwl_adjustment + min; 1265 return MAX2(limit, 0.0); 1266 } 1267 1268 ParallelCompactData::RegionData* 1269 PSParallelCompact::first_dead_space_region(const RegionData* beg, 1270 const RegionData* end) 1271 { 1272 const size_t region_size = ParallelCompactData::RegionSize; 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 if (middle > left && dest < addr) { 1288 right = middle - 1; 1289 } else if (middle < right && middle_ptr->data_size() == region_size) { 1290 left = middle + 1; 1291 } else { 1292 return middle_ptr; 1293 } 1294 } 1295 return sd.region(left); 1296 } 1297 1298 ParallelCompactData::RegionData* 1299 PSParallelCompact::dead_wood_limit_region(const RegionData* beg, 1300 const RegionData* end, 1301 size_t dead_words) 1302 { 1303 ParallelCompactData& sd = summary_data(); 1304 size_t left = sd.region(beg); 1305 size_t right = end > beg ? sd.region(end) - 1 : left; 1306 1307 // Binary search. 1308 while (left < right) { 1309 // Equivalent to (left + right) / 2, but does not overflow. 1310 const size_t middle = left + (right - left) / 2; 1311 RegionData* const middle_ptr = sd.region(middle); 1312 HeapWord* const dest = middle_ptr->destination(); 1313 HeapWord* const addr = sd.region_to_addr(middle); 1314 assert(dest != NULL, "sanity"); 1315 assert(dest <= addr, "must move left"); 1316 1317 const size_t dead_to_left = pointer_delta(addr, dest); 1318 if (middle > left && dead_to_left > dead_words) { 1319 right = middle - 1; 1320 } else if (middle < right && dead_to_left < dead_words) { 1321 left = middle + 1; 1322 } else { 1323 return middle_ptr; 1324 } 1325 } 1326 return sd.region(left); 1327 } 1328 1329 // The result is valid during the summary phase, after the initial summarization 1330 // of each space into itself, and before final summarization. 1331 inline double 1332 PSParallelCompact::reclaimed_ratio(const RegionData* const cp, 1333 HeapWord* const bottom, 1334 HeapWord* const top, 1335 HeapWord* const new_top) 1336 { 1337 ParallelCompactData& sd = summary_data(); 1338 1339 assert(cp != NULL, "sanity"); 1340 assert(bottom != NULL, "sanity"); 1341 assert(top != NULL, "sanity"); 1342 assert(new_top != NULL, "sanity"); 1343 assert(top >= new_top, "summary data problem?"); 1344 assert(new_top > bottom, "space is empty; should not be here"); 1345 assert(new_top >= cp->destination(), "sanity"); 1346 assert(top >= sd.region_to_addr(cp), "sanity"); 1347 1348 HeapWord* const destination = cp->destination(); 1349 const size_t dense_prefix_live = pointer_delta(destination, bottom); 1350 const size_t compacted_region_live = pointer_delta(new_top, destination); 1351 const size_t compacted_region_used = pointer_delta(top, 1352 sd.region_to_addr(cp)); 1353 const size_t reclaimable = compacted_region_used - compacted_region_live; 1354 1355 const double divisor = dense_prefix_live + 1.25 * compacted_region_live; 1356 return double(reclaimable) / divisor; 1357 } 1358 1359 // Return the address of the end of the dense prefix, a.k.a. the start of the 1360 // compacted region. The address is always on a region boundary. 1361 // 1362 // Completely full regions at the left are skipped, since no compaction can 1363 // occur in those regions. Then the maximum amount of dead wood to allow is 1364 // computed, based on the density (amount live / capacity) of the generation; 1365 // the region with approximately that amount of dead space to the left is 1366 // identified as the limit region. Regions between the last completely full 1367 // region and the limit region are scanned and the one that has the best 1368 // (maximum) reclaimed_ratio() is selected. 1369 HeapWord* 1370 PSParallelCompact::compute_dense_prefix(const SpaceId id, 1371 bool maximum_compaction) 1372 { 1373 if (ParallelOldGCSplitALot) { 1374 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) { 1375 // The value was chosen to provoke splitting a young gen space; use it. 1376 return _space_info[id].dense_prefix(); 1377 } 1378 } 1379 1380 const size_t region_size = ParallelCompactData::RegionSize; 1381 const ParallelCompactData& sd = summary_data(); 1382 1383 const MutableSpace* const space = _space_info[id].space(); 1384 HeapWord* const top = space->top(); 1385 HeapWord* const top_aligned_up = sd.region_align_up(top); 1386 HeapWord* const new_top = _space_info[id].new_top(); 1387 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top); 1388 HeapWord* const bottom = space->bottom(); 1389 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom); 1390 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 1391 const RegionData* const new_top_cp = 1392 sd.addr_to_region_ptr(new_top_aligned_up); 1393 1394 // Skip full regions at the beginning of the space--they are necessarily part 1395 // of the dense prefix. 1396 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp); 1397 assert(full_cp->destination() == sd.region_to_addr(full_cp) || 1398 space->is_empty(), "no dead space allowed to the left"); 1399 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1, 1400 "region must have dead space"); 1401 1402 // The gc number is saved whenever a maximum compaction is done, and used to 1403 // determine when the maximum compaction interval has expired. This avoids 1404 // successive max compactions for different reasons. 1405 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1406 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1407 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || 1408 total_invocations() == HeapFirstMaximumCompactionCount; 1409 if (maximum_compaction || full_cp == top_cp || interval_ended) { 1410 _maximum_compaction_gc_num = total_invocations(); 1411 return sd.region_to_addr(full_cp); 1412 } 1413 1414 const size_t space_live = pointer_delta(new_top, bottom); 1415 const size_t space_used = space->used_in_words(); 1416 const size_t space_capacity = space->capacity_in_words(); 1417 1418 const double density = double(space_live) / double(space_capacity); 1419 const size_t min_percent_free = MarkSweepDeadRatio; 1420 const double limiter = dead_wood_limiter(density, min_percent_free); 1421 const size_t dead_wood_max = space_used - space_live; 1422 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), 1423 dead_wood_max); 1424 1425 if (TraceParallelOldGCDensePrefix) { 1426 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1427 "space_cap=" SIZE_FORMAT, 1428 space_live, space_used, 1429 space_capacity); 1430 tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f " 1431 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, 1432 density, min_percent_free, limiter, 1433 dead_wood_max, dead_wood_limit); 1434 } 1435 1436 // Locate the region with the desired amount of dead space to the left. 1437 const RegionData* const limit_cp = 1438 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit); 1439 1440 // Scan from the first region with dead space to the limit region and find the 1441 // one with the best (largest) reclaimed ratio. 1442 double best_ratio = 0.0; 1443 const RegionData* best_cp = full_cp; 1444 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) { 1445 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); 1446 if (tmp_ratio > best_ratio) { 1447 best_cp = cp; 1448 best_ratio = tmp_ratio; 1449 } 1450 } 1451 1452 #if 0 1453 // Something to consider: if the region with the best ratio is 'close to' the 1454 // first region w/free space, choose the first region with free space 1455 // ("first-free"). The first-free region is usually near the start of the 1456 // heap, which means we are copying most of the heap already, so copy a bit 1457 // more to get complete compaction. 1458 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) { 1459 _maximum_compaction_gc_num = total_invocations(); 1460 best_cp = full_cp; 1461 } 1462 #endif // #if 0 1463 1464 return sd.region_to_addr(best_cp); 1465 } 1466 1467 #ifndef PRODUCT 1468 void 1469 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start, 1470 size_t words) 1471 { 1472 if (TraceParallelOldGCSummaryPhase) { 1473 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") " 1474 SIZE_FORMAT, start, start + words, words); 1475 } 1476 1477 ObjectStartArray* const start_array = _space_info[id].start_array(); 1478 CollectedHeap::fill_with_objects(start, words); 1479 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) { 1480 _mark_bitmap.mark_obj(p, words); 1481 _summary_data.add_obj(p, words); 1482 start_array->allocate_block(p); 1483 } 1484 } 1485 1486 void 1487 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start) 1488 { 1489 ParallelCompactData& sd = summary_data(); 1490 MutableSpace* space = _space_info[id].space(); 1491 1492 // Find the source and destination start addresses. 1493 HeapWord* const src_addr = sd.region_align_down(start); 1494 HeapWord* dst_addr; 1495 if (src_addr < start) { 1496 dst_addr = sd.addr_to_region_ptr(src_addr)->destination(); 1497 } else if (src_addr > space->bottom()) { 1498 // The start (the original top() value) is aligned to a region boundary so 1499 // the associated region does not have a destination. Compute the 1500 // destination from the previous region. 1501 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1; 1502 dst_addr = cp->destination() + cp->data_size(); 1503 } else { 1504 // Filling the entire space. 1505 dst_addr = space->bottom(); 1506 } 1507 assert(dst_addr != NULL, "sanity"); 1508 1509 // Update the summary data. 1510 bool result = _summary_data.summarize(_space_info[id].split_info(), 1511 src_addr, space->top(), NULL, 1512 dst_addr, space->end(), 1513 _space_info[id].new_top_addr()); 1514 assert(result, "should not fail: bad filler object size"); 1515 } 1516 1517 void 1518 PSParallelCompact::provoke_split_fill_survivor(SpaceId id) 1519 { 1520 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) { 1521 return; 1522 } 1523 1524 MutableSpace* const space = _space_info[id].space(); 1525 if (space->is_empty()) { 1526 HeapWord* b = space->bottom(); 1527 HeapWord* t = b + space->capacity_in_words() / 2; 1528 space->set_top(t); 1529 if (ZapUnusedHeapArea) { 1530 space->set_top_for_allocations(); 1531 } 1532 1533 size_t min_size = CollectedHeap::min_fill_size(); 1534 size_t obj_len = min_size; 1535 while (b + obj_len <= t) { 1536 CollectedHeap::fill_with_object(b, obj_len); 1537 mark_bitmap()->mark_obj(b, obj_len); 1538 summary_data().add_obj(b, obj_len); 1539 b += obj_len; 1540 obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ... 1541 } 1542 if (b < t) { 1543 // The loop didn't completely fill to t (top); adjust top downward. 1544 space->set_top(b); 1545 if (ZapUnusedHeapArea) { 1546 space->set_top_for_allocations(); 1547 } 1548 } 1549 1550 HeapWord** nta = _space_info[id].new_top_addr(); 1551 bool result = summary_data().summarize(_space_info[id].split_info(), 1552 space->bottom(), space->top(), NULL, 1553 space->bottom(), space->end(), nta); 1554 assert(result, "space must fit into itself"); 1555 } 1556 } 1557 1558 void 1559 PSParallelCompact::provoke_split(bool & max_compaction) 1560 { 1561 if (total_invocations() % ParallelOldGCSplitInterval != 0) { 1562 return; 1563 } 1564 1565 const size_t region_size = ParallelCompactData::RegionSize; 1566 ParallelCompactData& sd = summary_data(); 1567 1568 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1569 MutableSpace* const from_space = _space_info[from_space_id].space(); 1570 const size_t eden_live = pointer_delta(eden_space->top(), 1571 _space_info[eden_space_id].new_top()); 1572 const size_t from_live = pointer_delta(from_space->top(), 1573 _space_info[from_space_id].new_top()); 1574 1575 const size_t min_fill_size = CollectedHeap::min_fill_size(); 1576 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top()); 1577 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0; 1578 const size_t from_free = pointer_delta(from_space->end(), from_space->top()); 1579 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0; 1580 1581 // Choose the space to split; need at least 2 regions live (or fillable). 1582 SpaceId id; 1583 MutableSpace* space; 1584 size_t live_words; 1585 size_t fill_words; 1586 if (eden_live + eden_fillable >= region_size * 2) { 1587 id = eden_space_id; 1588 space = eden_space; 1589 live_words = eden_live; 1590 fill_words = eden_fillable; 1591 } else if (from_live + from_fillable >= region_size * 2) { 1592 id = from_space_id; 1593 space = from_space; 1594 live_words = from_live; 1595 fill_words = from_fillable; 1596 } else { 1597 return; // Give up. 1598 } 1599 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity"); 1600 1601 if (live_words < region_size * 2) { 1602 // Fill from top() to end() w/live objects of mixed sizes. 1603 HeapWord* const fill_start = space->top(); 1604 live_words += fill_words; 1605 1606 space->set_top(fill_start + fill_words); 1607 if (ZapUnusedHeapArea) { 1608 space->set_top_for_allocations(); 1609 } 1610 1611 HeapWord* cur_addr = fill_start; 1612 while (fill_words > 0) { 1613 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size; 1614 size_t cur_size = MIN2(align_object_size_(r), fill_words); 1615 if (fill_words - cur_size < min_fill_size) { 1616 cur_size = fill_words; // Avoid leaving a fragment too small to fill. 1617 } 1618 1619 CollectedHeap::fill_with_object(cur_addr, cur_size); 1620 mark_bitmap()->mark_obj(cur_addr, cur_size); 1621 sd.add_obj(cur_addr, cur_size); 1622 1623 cur_addr += cur_size; 1624 fill_words -= cur_size; 1625 } 1626 1627 summarize_new_objects(id, fill_start); 1628 } 1629 1630 max_compaction = false; 1631 1632 // Manipulate the old gen so that it has room for about half of the live data 1633 // in the target young gen space (live_words / 2). 1634 id = old_space_id; 1635 space = _space_info[id].space(); 1636 const size_t free_at_end = space->free_in_words(); 1637 const size_t free_target = align_object_size(live_words / 2); 1638 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top()); 1639 1640 if (free_at_end >= free_target + min_fill_size) { 1641 // Fill space above top() and set the dense prefix so everything survives. 1642 HeapWord* const fill_start = space->top(); 1643 const size_t fill_size = free_at_end - free_target; 1644 space->set_top(space->top() + fill_size); 1645 if (ZapUnusedHeapArea) { 1646 space->set_top_for_allocations(); 1647 } 1648 fill_with_live_objects(id, fill_start, fill_size); 1649 summarize_new_objects(id, fill_start); 1650 _space_info[id].set_dense_prefix(sd.region_align_down(space->top())); 1651 } else if (dead + free_at_end > free_target) { 1652 // Find a dense prefix that makes the right amount of space available. 1653 HeapWord* cur = sd.region_align_down(space->top()); 1654 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination(); 1655 size_t dead_to_right = pointer_delta(space->end(), cur_destination); 1656 while (dead_to_right < free_target) { 1657 cur -= region_size; 1658 cur_destination = sd.addr_to_region_ptr(cur)->destination(); 1659 dead_to_right = pointer_delta(space->end(), cur_destination); 1660 } 1661 _space_info[id].set_dense_prefix(cur); 1662 } 1663 } 1664 #endif // #ifndef PRODUCT 1665 1666 void PSParallelCompact::summarize_spaces_quick() 1667 { 1668 for (unsigned int i = 0; i < last_space_id; ++i) { 1669 const MutableSpace* space = _space_info[i].space(); 1670 HeapWord** nta = _space_info[i].new_top_addr(); 1671 bool result = _summary_data.summarize(_space_info[i].split_info(), 1672 space->bottom(), space->top(), NULL, 1673 space->bottom(), space->end(), nta); 1674 assert(result, "space must fit into itself"); 1675 _space_info[i].set_dense_prefix(space->bottom()); 1676 } 1677 1678 #ifndef PRODUCT 1679 if (ParallelOldGCSplitALot) { 1680 provoke_split_fill_survivor(to_space_id); 1681 } 1682 #endif // #ifndef PRODUCT 1683 } 1684 1685 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) 1686 { 1687 HeapWord* const dense_prefix_end = dense_prefix(id); 1688 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end); 1689 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); 1690 if (dead_space_crosses_boundary(region, dense_prefix_bit)) { 1691 // Only enough dead space is filled so that any remaining dead space to the 1692 // left is larger than the minimum filler object. (The remainder is filled 1693 // during the copy/update phase.) 1694 // 1695 // The size of the dead space to the right of the boundary is not a 1696 // concern, since compaction will be able to use whatever space is 1697 // available. 1698 // 1699 // Here '||' is the boundary, 'x' represents a don't care bit and a box 1700 // surrounds the space to be filled with an object. 1701 // 1702 // In the 32-bit VM, each bit represents two 32-bit words: 1703 // +---+ 1704 // a) beg_bits: ... x x x | 0 | || 0 x x ... 1705 // end_bits: ... x x x | 0 | || 0 x x ... 1706 // +---+ 1707 // 1708 // In the 64-bit VM, each bit represents one 64-bit word: 1709 // +------------+ 1710 // b) beg_bits: ... x x x | 0 || 0 | x x ... 1711 // end_bits: ... x x 1 | 0 || 0 | x x ... 1712 // +------------+ 1713 // +-------+ 1714 // c) beg_bits: ... x x | 0 0 | || 0 x x ... 1715 // end_bits: ... x 1 | 0 0 | || 0 x x ... 1716 // +-------+ 1717 // +-----------+ 1718 // d) beg_bits: ... x | 0 0 0 | || 0 x x ... 1719 // end_bits: ... 1 | 0 0 0 | || 0 x x ... 1720 // +-----------+ 1721 // +-------+ 1722 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... 1723 // end_bits: ... 0 0 | 0 0 | || 0 x x ... 1724 // +-------+ 1725 1726 // Initially assume case a, c or e will apply. 1727 size_t obj_len = CollectedHeap::min_fill_size(); 1728 HeapWord* obj_beg = dense_prefix_end - obj_len; 1729 1730 #ifdef _LP64 1731 if (MinObjAlignment > 1) { // object alignment > heap word size 1732 // Cases a, c or e. 1733 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { 1734 // Case b above. 1735 obj_beg = dense_prefix_end - 1; 1736 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && 1737 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { 1738 // Case d above. 1739 obj_beg = dense_prefix_end - 3; 1740 obj_len = 3; 1741 } 1742 #endif // #ifdef _LP64 1743 1744 CollectedHeap::fill_with_object(obj_beg, obj_len); 1745 _mark_bitmap.mark_obj(obj_beg, obj_len); 1746 _summary_data.add_obj(obj_beg, obj_len); 1747 assert(start_array(id) != NULL, "sanity"); 1748 start_array(id)->allocate_block(obj_beg); 1749 } 1750 } 1751 1752 void 1753 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr) 1754 { 1755 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr); 1756 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr); 1757 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up); 1758 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) { 1759 cur->set_source_region(0); 1760 } 1761 } 1762 1763 void 1764 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) 1765 { 1766 assert(id < last_space_id, "id out of range"); 1767 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() || 1768 ParallelOldGCSplitALot && id == old_space_id, 1769 "should have been reset in summarize_spaces_quick()"); 1770 1771 const MutableSpace* space = _space_info[id].space(); 1772 if (_space_info[id].new_top() != space->bottom()) { 1773 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); 1774 _space_info[id].set_dense_prefix(dense_prefix_end); 1775 1776 #ifndef PRODUCT 1777 if (TraceParallelOldGCDensePrefix) { 1778 print_dense_prefix_stats("ratio", id, maximum_compaction, 1779 dense_prefix_end); 1780 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); 1781 print_dense_prefix_stats("density", id, maximum_compaction, addr); 1782 } 1783 #endif // #ifndef PRODUCT 1784 1785 // Recompute the summary data, taking into account the dense prefix. If 1786 // every last byte will be reclaimed, then the existing summary data which 1787 // compacts everything can be left in place. 1788 if (!maximum_compaction && dense_prefix_end != space->bottom()) { 1789 // If dead space crosses the dense prefix boundary, it is (at least 1790 // partially) filled with a dummy object, marked live and added to the 1791 // summary data. This simplifies the copy/update phase and must be done 1792 // before the final locations of objects are determined, to prevent 1793 // leaving a fragment of dead space that is too small to fill. 1794 fill_dense_prefix_end(id); 1795 1796 // Compute the destination of each Region, and thus each object. 1797 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); 1798 _summary_data.summarize(_space_info[id].split_info(), 1799 dense_prefix_end, space->top(), NULL, 1800 dense_prefix_end, space->end(), 1801 _space_info[id].new_top_addr()); 1802 } 1803 } 1804 1805 if (TraceParallelOldGCSummaryPhase) { 1806 const size_t region_size = ParallelCompactData::RegionSize; 1807 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); 1808 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end); 1809 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); 1810 HeapWord* const new_top = _space_info[id].new_top(); 1811 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top); 1812 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); 1813 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " 1814 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " 1815 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, 1816 id, space->capacity_in_words(), dense_prefix_end, 1817 dp_region, dp_words / region_size, 1818 cr_words / region_size, new_top); 1819 } 1820 } 1821 1822 #ifndef PRODUCT 1823 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id, 1824 HeapWord* dst_beg, HeapWord* dst_end, 1825 SpaceId src_space_id, 1826 HeapWord* src_beg, HeapWord* src_end) 1827 { 1828 if (TraceParallelOldGCSummaryPhase) { 1829 tty->print_cr("summarizing %d [%s] into %d [%s]: " 1830 "src=" PTR_FORMAT "-" PTR_FORMAT " " 1831 SIZE_FORMAT "-" SIZE_FORMAT " " 1832 "dst=" PTR_FORMAT "-" PTR_FORMAT " " 1833 SIZE_FORMAT "-" SIZE_FORMAT, 1834 src_space_id, space_names[src_space_id], 1835 dst_space_id, space_names[dst_space_id], 1836 src_beg, src_end, 1837 _summary_data.addr_to_region_idx(src_beg), 1838 _summary_data.addr_to_region_idx(src_end), 1839 dst_beg, dst_end, 1840 _summary_data.addr_to_region_idx(dst_beg), 1841 _summary_data.addr_to_region_idx(dst_end)); 1842 } 1843 } 1844 #endif // #ifndef PRODUCT 1845 1846 void PSParallelCompact::summary_phase(ParCompactionManager* cm, 1847 bool maximum_compaction) 1848 { 1849 GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer); 1850 // trace("2"); 1851 1852 #ifdef ASSERT 1853 if (TraceParallelOldGCMarkingPhase) { 1854 tty->print_cr("add_obj_count=" SIZE_FORMAT " " 1855 "add_obj_bytes=" SIZE_FORMAT, 1856 add_obj_count, add_obj_size * HeapWordSize); 1857 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " " 1858 "mark_bitmap_bytes=" SIZE_FORMAT, 1859 mark_bitmap_count, mark_bitmap_size * HeapWordSize); 1860 } 1861 #endif // #ifdef ASSERT 1862 1863 // Quick summarization of each space into itself, to see how much is live. 1864 summarize_spaces_quick(); 1865 1866 if (TraceParallelOldGCSummaryPhase) { 1867 tty->print_cr("summary_phase: after summarizing each space to self"); 1868 Universe::print(); 1869 NOT_PRODUCT(print_region_ranges()); 1870 if (Verbose) { 1871 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1872 } 1873 } 1874 1875 // The amount of live data that will end up in old space (assuming it fits). 1876 size_t old_space_total_live = 0; 1877 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1878 old_space_total_live += pointer_delta(_space_info[id].new_top(), 1879 _space_info[id].space()->bottom()); 1880 } 1881 1882 MutableSpace* const old_space = _space_info[old_space_id].space(); 1883 const size_t old_capacity = old_space->capacity_in_words(); 1884 if (old_space_total_live > old_capacity) { 1885 // XXX - should also try to expand 1886 maximum_compaction = true; 1887 } 1888 #ifndef PRODUCT 1889 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) { 1890 provoke_split(maximum_compaction); 1891 } 1892 #endif // #ifndef PRODUCT 1893 1894 // Old generations. 1895 summarize_space(old_space_id, maximum_compaction); 1896 1897 // Summarize the remaining spaces in the young gen. The initial target space 1898 // is the old gen. If a space does not fit entirely into the target, then the 1899 // remainder is compacted into the space itself and that space becomes the new 1900 // target. 1901 SpaceId dst_space_id = old_space_id; 1902 HeapWord* dst_space_end = old_space->end(); 1903 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr(); 1904 for (unsigned int id = eden_space_id; id < last_space_id; ++id) { 1905 const MutableSpace* space = _space_info[id].space(); 1906 const size_t live = pointer_delta(_space_info[id].new_top(), 1907 space->bottom()); 1908 const size_t available = pointer_delta(dst_space_end, *new_top_addr); 1909 1910 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end, 1911 SpaceId(id), space->bottom(), space->top());) 1912 if (live > 0 && live <= available) { 1913 // All the live data will fit. 1914 bool done = _summary_data.summarize(_space_info[id].split_info(), 1915 space->bottom(), space->top(), 1916 NULL, 1917 *new_top_addr, dst_space_end, 1918 new_top_addr); 1919 assert(done, "space must fit into old gen"); 1920 1921 // Reset the new_top value for the space. 1922 _space_info[id].set_new_top(space->bottom()); 1923 } else if (live > 0) { 1924 // Attempt to fit part of the source space into the target space. 1925 HeapWord* next_src_addr = NULL; 1926 bool done = _summary_data.summarize(_space_info[id].split_info(), 1927 space->bottom(), space->top(), 1928 &next_src_addr, 1929 *new_top_addr, dst_space_end, 1930 new_top_addr); 1931 assert(!done, "space should not fit into old gen"); 1932 assert(next_src_addr != NULL, "sanity"); 1933 1934 // The source space becomes the new target, so the remainder is compacted 1935 // within the space itself. 1936 dst_space_id = SpaceId(id); 1937 dst_space_end = space->end(); 1938 new_top_addr = _space_info[id].new_top_addr(); 1939 NOT_PRODUCT(summary_phase_msg(dst_space_id, 1940 space->bottom(), dst_space_end, 1941 SpaceId(id), next_src_addr, space->top());) 1942 done = _summary_data.summarize(_space_info[id].split_info(), 1943 next_src_addr, space->top(), 1944 NULL, 1945 space->bottom(), dst_space_end, 1946 new_top_addr); 1947 assert(done, "space must fit when compacted into itself"); 1948 assert(*new_top_addr <= space->top(), "usage should not grow"); 1949 } 1950 } 1951 1952 if (TraceParallelOldGCSummaryPhase) { 1953 tty->print_cr("summary_phase: after final summarization"); 1954 Universe::print(); 1955 NOT_PRODUCT(print_region_ranges()); 1956 if (Verbose) { 1957 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info)); 1958 } 1959 } 1960 } 1961 1962 // This method should contain all heap-specific policy for invoking a full 1963 // collection. invoke_no_policy() will only attempt to compact the heap; it 1964 // will do nothing further. If we need to bail out for policy reasons, scavenge 1965 // before full gc, or any other specialized behavior, it needs to be added here. 1966 // 1967 // Note that this method should only be called from the vm_thread while at a 1968 // safepoint. 1969 // 1970 // Note that the all_soft_refs_clear flag in the collector policy 1971 // may be true because this method can be called without intervening 1972 // activity. For example when the heap space is tight and full measure 1973 // are being taken to free space. 1974 void PSParallelCompact::invoke(bool maximum_heap_compaction) { 1975 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 1976 assert(Thread::current() == (Thread*)VMThread::vm_thread(), 1977 "should be in vm thread"); 1978 1979 ParallelScavengeHeap* heap = gc_heap(); 1980 GCCause::Cause gc_cause = heap->gc_cause(); 1981 assert(!heap->is_gc_active(), "not reentrant"); 1982 1983 PSAdaptiveSizePolicy* policy = heap->size_policy(); 1984 IsGCActiveMark mark; 1985 1986 if (ScavengeBeforeFullGC) { 1987 PSScavenge::invoke_no_policy(); 1988 } 1989 1990 const bool clear_all_soft_refs = 1991 heap->collector_policy()->should_clear_all_soft_refs(); 1992 1993 PSParallelCompact::invoke_no_policy(clear_all_soft_refs || 1994 maximum_heap_compaction); 1995 } 1996 1997 // This method contains no policy. You should probably 1998 // be calling invoke() instead. 1999 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { 2000 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 2001 assert(ref_processor() != NULL, "Sanity"); 2002 2003 if (GC_locker::check_active_before_gc()) { 2004 return false; 2005 } 2006 2007 ParallelScavengeHeap* heap = gc_heap(); 2008 2009 _gc_timer.register_gc_start(os::elapsed_counter()); 2010 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 2011 2012 TimeStamp marking_start; 2013 TimeStamp compaction_start; 2014 TimeStamp collection_exit; 2015 2016 GCCause::Cause gc_cause = heap->gc_cause(); 2017 PSYoungGen* young_gen = heap->young_gen(); 2018 PSOldGen* old_gen = heap->old_gen(); 2019 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 2020 2021 // The scope of casr should end after code that can change 2022 // CollectorPolicy::_should_clear_all_soft_refs. 2023 ClearedAllSoftRefs casr(maximum_heap_compaction, 2024 heap->collector_policy()); 2025 2026 if (ZapUnusedHeapArea) { 2027 // Save information needed to minimize mangling 2028 heap->record_gen_tops_before_GC(); 2029 } 2030 2031 heap->pre_full_gc_dump(&_gc_timer); 2032 2033 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes; 2034 2035 // Make sure data structures are sane, make the heap parsable, and do other 2036 // miscellaneous bookkeeping. 2037 PreGCValues pre_gc_values; 2038 pre_compact(&pre_gc_values); 2039 2040 // Get the compaction manager reserved for the VM thread. 2041 ParCompactionManager* const vmthread_cm = 2042 ParCompactionManager::manager_array(gc_task_manager()->workers()); 2043 2044 // Place after pre_compact() where the number of invocations is incremented. 2045 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 2046 2047 { 2048 ResourceMark rm; 2049 HandleMark hm; 2050 2051 // Set the number of GC threads to be used in this collection 2052 gc_task_manager()->set_active_gang(); 2053 gc_task_manager()->task_idle_workers(); 2054 heap->set_par_threads(gc_task_manager()->active_workers()); 2055 2056 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 2057 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 2058 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL); 2059 TraceCollectorStats tcs(counters()); 2060 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 2061 2062 if (TraceGen1Time) accumulated_time()->start(); 2063 2064 // Let the size policy know we're starting 2065 size_policy->major_collection_begin(); 2066 2067 CodeCache::gc_prologue(); 2068 Threads::gc_prologue(); 2069 2070 COMPILER2_PRESENT(DerivedPointerTable::clear()); 2071 2072 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 2073 ref_processor()->setup_policy(maximum_heap_compaction); 2074 2075 bool marked_for_unloading = false; 2076 2077 marking_start.update(); 2078 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer); 2079 2080 bool max_on_system_gc = UseMaximumCompactionOnSystemGC 2081 && gc_cause == GCCause::_java_lang_system_gc; 2082 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc); 2083 2084 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); 2085 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); 2086 2087 // adjust_roots() updates Universe::_intArrayKlassObj which is 2088 // needed by the compaction for filling holes in the dense prefix. 2089 adjust_roots(); 2090 2091 compaction_start.update(); 2092 compact(); 2093 2094 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be 2095 // done before resizing. 2096 post_compact(); 2097 2098 // Let the size policy know we're done 2099 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 2100 2101 if (UseAdaptiveSizePolicy) { 2102 if (PrintAdaptiveSizePolicy) { 2103 gclog_or_tty->print("AdaptiveSizeStart: "); 2104 gclog_or_tty->stamp(); 2105 gclog_or_tty->print_cr(" collection: %d ", 2106 heap->total_collections()); 2107 if (Verbose) { 2108 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d", 2109 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 2110 } 2111 } 2112 2113 // Don't check if the size_policy is ready here. Let 2114 // the size_policy check that internally. 2115 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 2116 ((gc_cause != GCCause::_java_lang_system_gc) || 2117 UseAdaptiveSizePolicyWithSystemGC)) { 2118 // Calculate optimal free space amounts 2119 assert(young_gen->max_size() > 2120 young_gen->from_space()->capacity_in_bytes() + 2121 young_gen->to_space()->capacity_in_bytes(), 2122 "Sizes of space in young gen are out-of-bounds"); 2123 2124 size_t young_live = young_gen->used_in_bytes(); 2125 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 2126 size_t old_live = old_gen->used_in_bytes(); 2127 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 2128 size_t max_old_gen_size = old_gen->max_gen_size(); 2129 size_t max_eden_size = young_gen->max_size() - 2130 young_gen->from_space()->capacity_in_bytes() - 2131 young_gen->to_space()->capacity_in_bytes(); 2132 2133 // Used for diagnostics 2134 size_policy->clear_generation_free_space_flags(); 2135 2136 size_policy->compute_generations_free_space(young_live, 2137 eden_live, 2138 old_live, 2139 cur_eden, 2140 max_old_gen_size, 2141 max_eden_size, 2142 true /* full gc*/); 2143 2144 size_policy->check_gc_overhead_limit(young_live, 2145 eden_live, 2146 max_old_gen_size, 2147 max_eden_size, 2148 true /* full gc*/, 2149 gc_cause, 2150 heap->collector_policy()); 2151 2152 size_policy->decay_supplemental_growth(true /* full gc*/); 2153 2154 heap->resize_old_gen( 2155 size_policy->calculated_old_free_size_in_bytes()); 2156 2157 // Don't resize the young generation at an major collection. A 2158 // desired young generation size may have been calculated but 2159 // resizing the young generation complicates the code because the 2160 // resizing of the old generation may have moved the boundary 2161 // between the young generation and the old generation. Let the 2162 // young generation resizing happen at the minor collections. 2163 } 2164 if (PrintAdaptiveSizePolicy) { 2165 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 2166 heap->total_collections()); 2167 } 2168 } 2169 2170 if (UsePerfData) { 2171 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 2172 counters->update_counters(); 2173 counters->update_old_capacity(old_gen->capacity_in_bytes()); 2174 counters->update_young_capacity(young_gen->capacity_in_bytes()); 2175 } 2176 2177 heap->resize_all_tlabs(); 2178 2179 // Resize the metaspace capactiy after a collection 2180 MetaspaceGC::compute_new_size(); 2181 2182 if (TraceGen1Time) accumulated_time()->stop(); 2183 2184 if (PrintGC) { 2185 if (PrintGCDetails) { 2186 // No GC timestamp here. This is after GC so it would be confusing. 2187 young_gen->print_used_change(pre_gc_values.young_gen_used()); 2188 old_gen->print_used_change(pre_gc_values.old_gen_used()); 2189 heap->print_heap_change(pre_gc_values.heap_used()); 2190 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used()); 2191 } else { 2192 heap->print_heap_change(pre_gc_values.heap_used()); 2193 } 2194 } 2195 2196 // Track memory usage and detect low memory 2197 MemoryService::track_memory_usage(); 2198 heap->update_counters(); 2199 gc_task_manager()->release_idle_workers(); 2200 } 2201 2202 #ifdef ASSERT 2203 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) { 2204 ParCompactionManager* const cm = 2205 ParCompactionManager::manager_array(int(i)); 2206 assert(cm->marking_stack()->is_empty(), "should be empty"); 2207 assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty"); 2208 } 2209 #endif // ASSERT 2210 2211 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 2212 HandleMark hm; // Discard invalid handles created during verification 2213 Universe::verify(" VerifyAfterGC:"); 2214 } 2215 2216 // Re-verify object start arrays 2217 if (VerifyObjectStartArray && 2218 VerifyAfterGC) { 2219 old_gen->verify_object_start_array(); 2220 } 2221 2222 if (ZapUnusedHeapArea) { 2223 old_gen->object_space()->check_mangled_unused_area_complete(); 2224 } 2225 2226 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 2227 2228 collection_exit.update(); 2229 2230 heap->print_heap_after_gc(); 2231 heap->trace_heap_after_gc(&_gc_tracer); 2232 2233 if (PrintGCTaskTimeStamps) { 2234 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " 2235 INT64_FORMAT, 2236 marking_start.ticks(), compaction_start.ticks(), 2237 collection_exit.ticks()); 2238 gc_task_manager()->print_task_time_stamps(); 2239 } 2240 2241 heap->post_full_gc_dump(&_gc_timer); 2242 2243 #ifdef TRACESPINNING 2244 ParallelTaskTerminator::print_termination_counts(); 2245 #endif 2246 2247 _gc_timer.register_gc_end(os::elapsed_counter()); 2248 2249 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id)); 2250 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 2251 2252 return true; 2253 } 2254 2255 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 2256 PSYoungGen* young_gen, 2257 PSOldGen* old_gen) { 2258 MutableSpace* const eden_space = young_gen->eden_space(); 2259 assert(!eden_space->is_empty(), "eden must be non-empty"); 2260 assert(young_gen->virtual_space()->alignment() == 2261 old_gen->virtual_space()->alignment(), "alignments do not match"); 2262 2263 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 2264 return false; 2265 } 2266 2267 // Both generations must be completely committed. 2268 if (young_gen->virtual_space()->uncommitted_size() != 0) { 2269 return false; 2270 } 2271 if (old_gen->virtual_space()->uncommitted_size() != 0) { 2272 return false; 2273 } 2274 2275 // Figure out how much to take from eden. Include the average amount promoted 2276 // in the total; otherwise the next young gen GC will simply bail out to a 2277 // full GC. 2278 const size_t alignment = old_gen->virtual_space()->alignment(); 2279 const size_t eden_used = eden_space->used_in_bytes(); 2280 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 2281 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 2282 const size_t eden_capacity = eden_space->capacity_in_bytes(); 2283 2284 if (absorb_size >= eden_capacity) { 2285 return false; // Must leave some space in eden. 2286 } 2287 2288 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 2289 if (new_young_size < young_gen->min_gen_size()) { 2290 return false; // Respect young gen minimum size. 2291 } 2292 2293 if (TraceAdaptiveGCBoundary && Verbose) { 2294 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: " 2295 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 2296 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 2297 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 2298 absorb_size / K, 2299 eden_capacity / K, (eden_capacity - absorb_size) / K, 2300 young_gen->from_space()->used_in_bytes() / K, 2301 young_gen->to_space()->used_in_bytes() / K, 2302 young_gen->capacity_in_bytes() / K, new_young_size / K); 2303 } 2304 2305 // Fill the unused part of the old gen. 2306 MutableSpace* const old_space = old_gen->object_space(); 2307 HeapWord* const unused_start = old_space->top(); 2308 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 2309 2310 if (unused_words > 0) { 2311 if (unused_words < CollectedHeap::min_fill_size()) { 2312 return false; // If the old gen cannot be filled, must give up. 2313 } 2314 CollectedHeap::fill_with_objects(unused_start, unused_words); 2315 } 2316 2317 // Take the live data from eden and set both top and end in the old gen to 2318 // eden top. (Need to set end because reset_after_change() mangles the region 2319 // from end to virtual_space->high() in debug builds). 2320 HeapWord* const new_top = eden_space->top(); 2321 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 2322 absorb_size); 2323 young_gen->reset_after_change(); 2324 old_space->set_top(new_top); 2325 old_space->set_end(new_top); 2326 old_gen->reset_after_change(); 2327 2328 // Update the object start array for the filler object and the data from eden. 2329 ObjectStartArray* const start_array = old_gen->start_array(); 2330 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 2331 start_array->allocate_block(p); 2332 } 2333 2334 // Could update the promoted average here, but it is not typically updated at 2335 // full GCs and the value to use is unclear. Something like 2336 // 2337 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 2338 2339 size_policy->set_bytes_absorbed_from_eden(absorb_size); 2340 return true; 2341 } 2342 2343 GCTaskManager* const PSParallelCompact::gc_task_manager() { 2344 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 2345 "shouldn't return NULL"); 2346 return ParallelScavengeHeap::gc_task_manager(); 2347 } 2348 2349 void PSParallelCompact::marking_phase(ParCompactionManager* cm, 2350 bool maximum_heap_compaction, 2351 ParallelOldTracer *gc_tracer) { 2352 // Recursively traverse all live objects and mark them 2353 GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer); 2354 2355 ParallelScavengeHeap* heap = gc_heap(); 2356 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2357 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2358 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2359 ParallelTaskTerminator terminator(active_gc_threads, qset); 2360 2361 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm); 2362 PSParallelCompact::FollowStackClosure follow_stack_closure(cm); 2363 2364 // Need new claim bits before marking starts. 2365 ClassLoaderDataGraph::clear_claimed_marks(); 2366 2367 { 2368 GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer); 2369 2370 ParallelScavengeHeap::ParStrongRootsScope psrs; 2371 2372 GCTaskQueue* q = GCTaskQueue::create(); 2373 2374 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe)); 2375 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles)); 2376 // We scan the thread roots in parallel 2377 Threads::create_thread_roots_marking_tasks(q); 2378 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer)); 2379 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler)); 2380 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management)); 2381 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary)); 2382 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data)); 2383 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti)); 2384 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache)); 2385 2386 if (active_gc_threads > 1) { 2387 for (uint j = 0; j < active_gc_threads; j++) { 2388 q->enqueue(new StealMarkingTask(&terminator)); 2389 } 2390 } 2391 2392 gc_task_manager()->execute_and_wait(q); 2393 } 2394 2395 // Process reference objects found during marking 2396 { 2397 GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer); 2398 2399 ReferenceProcessorStats stats; 2400 if (ref_processor()->processing_is_mt()) { 2401 RefProcTaskExecutor task_executor; 2402 stats = ref_processor()->process_discovered_references( 2403 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, 2404 &task_executor, &_gc_timer); 2405 } else { 2406 stats = ref_processor()->process_discovered_references( 2407 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL, 2408 &_gc_timer); 2409 } 2410 2411 gc_tracer->report_gc_reference_stats(stats); 2412 } 2413 2414 GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer); 2415 2416 // This is the point where the entire marking should have completed. 2417 assert(cm->marking_stacks_empty(), "Marking should have completed"); 2418 2419 // Follow system dictionary roots and unload classes. 2420 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 2421 2422 // Unload nmethods. 2423 CodeCache::do_unloading(is_alive_closure(), purged_class); 2424 2425 // Prune dead klasses from subklass/sibling/implementor lists. 2426 Klass::clean_weak_klass_links(is_alive_closure()); 2427 2428 // Delete entries for dead interned strings. 2429 StringTable::unlink(is_alive_closure()); 2430 2431 // Clean up unreferenced symbols in symbol table. 2432 SymbolTable::unlink(); 2433 _gc_tracer.report_object_count_after_gc(is_alive_closure()); 2434 } 2435 2436 void PSParallelCompact::follow_klass(ParCompactionManager* cm, Klass* klass) { 2437 ClassLoaderData* cld = klass->class_loader_data(); 2438 // The actual processing of the klass is done when we 2439 // traverse the list of Klasses in the class loader data. 2440 PSParallelCompact::follow_class_loader(cm, cld); 2441 } 2442 2443 void PSParallelCompact::adjust_klass(ParCompactionManager* cm, Klass* klass) { 2444 ClassLoaderData* cld = klass->class_loader_data(); 2445 // The actual processing of the klass is done when we 2446 // traverse the list of Klasses in the class loader data. 2447 PSParallelCompact::adjust_class_loader(cm, cld); 2448 } 2449 2450 void PSParallelCompact::follow_class_loader(ParCompactionManager* cm, 2451 ClassLoaderData* cld) { 2452 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm); 2453 PSParallelCompact::FollowKlassClosure follow_klass_closure(&mark_and_push_closure); 2454 2455 cld->oops_do(&mark_and_push_closure, &follow_klass_closure, true); 2456 } 2457 2458 void PSParallelCompact::adjust_class_loader(ParCompactionManager* cm, 2459 ClassLoaderData* cld) { 2460 cld->oops_do(PSParallelCompact::adjust_pointer_closure(), 2461 PSParallelCompact::adjust_klass_closure(), 2462 true); 2463 } 2464 2465 // This should be moved to the shared markSweep code! 2466 class PSAlwaysTrueClosure: public BoolObjectClosure { 2467 public: 2468 bool do_object_b(oop p) { return true; } 2469 }; 2470 static PSAlwaysTrueClosure always_true; 2471 2472 void PSParallelCompact::adjust_roots() { 2473 // Adjust the pointers to reflect the new locations 2474 GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer); 2475 2476 // Need new claim bits when tracing through and adjusting pointers. 2477 ClassLoaderDataGraph::clear_claimed_marks(); 2478 2479 // General strong roots. 2480 Universe::oops_do(adjust_pointer_closure()); 2481 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles 2482 CLDToOopClosure adjust_from_cld(adjust_pointer_closure()); 2483 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL); 2484 ObjectSynchronizer::oops_do(adjust_pointer_closure()); 2485 FlatProfiler::oops_do(adjust_pointer_closure()); 2486 Management::oops_do(adjust_pointer_closure()); 2487 JvmtiExport::oops_do(adjust_pointer_closure()); 2488 // SO_AllClasses 2489 SystemDictionary::oops_do(adjust_pointer_closure()); 2490 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true); 2491 2492 // Now adjust pointers in remaining weak roots. (All of which should 2493 // have been cleared if they pointed to non-surviving objects.) 2494 // Global (weak) JNI handles 2495 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure()); 2496 2497 CodeCache::oops_do(adjust_pointer_closure()); 2498 StringTable::oops_do(adjust_pointer_closure()); 2499 ref_processor()->weak_oops_do(adjust_pointer_closure()); 2500 // Roots were visited so references into the young gen in roots 2501 // may have been scanned. Process them also. 2502 // Should the reference processor have a span that excludes 2503 // young gen objects? 2504 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure()); 2505 } 2506 2507 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q, 2508 uint parallel_gc_threads) 2509 { 2510 GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer); 2511 2512 // Find the threads that are active 2513 unsigned int which = 0; 2514 2515 const uint task_count = MAX2(parallel_gc_threads, 1U); 2516 for (uint j = 0; j < task_count; j++) { 2517 q->enqueue(new DrainStacksCompactionTask(j)); 2518 ParCompactionManager::verify_region_list_empty(j); 2519 // Set the region stacks variables to "no" region stack values 2520 // so that they will be recognized and needing a region stack 2521 // in the stealing tasks if they do not get one by executing 2522 // a draining stack. 2523 ParCompactionManager* cm = ParCompactionManager::manager_array(j); 2524 cm->set_region_stack(NULL); 2525 cm->set_region_stack_index((uint)max_uintx); 2526 } 2527 ParCompactionManager::reset_recycled_stack_index(); 2528 2529 // Find all regions that are available (can be filled immediately) and 2530 // distribute them to the thread stacks. The iteration is done in reverse 2531 // order (high to low) so the regions will be removed in ascending order. 2532 2533 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 2534 2535 size_t fillable_regions = 0; // A count for diagnostic purposes. 2536 // A region index which corresponds to the tasks created above. 2537 // "which" must be 0 <= which < task_count 2538 2539 which = 0; 2540 // id + 1 is used to test termination so unsigned can 2541 // be used with an old_space_id == 0. 2542 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) { 2543 SpaceInfo* const space_info = _space_info + id; 2544 MutableSpace* const space = space_info->space(); 2545 HeapWord* const new_top = space_info->new_top(); 2546 2547 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix()); 2548 const size_t end_region = 2549 sd.addr_to_region_idx(sd.region_align_up(new_top)); 2550 2551 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) { 2552 if (sd.region(cur)->claim_unsafe()) { 2553 ParCompactionManager::region_list_push(which, cur); 2554 2555 if (TraceParallelOldGCCompactionPhase && Verbose) { 2556 const size_t count_mod_8 = fillable_regions & 7; 2557 if (count_mod_8 == 0) gclog_or_tty->print("fillable: "); 2558 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur); 2559 if (count_mod_8 == 7) gclog_or_tty->cr(); 2560 } 2561 2562 NOT_PRODUCT(++fillable_regions;) 2563 2564 // Assign regions to tasks in round-robin fashion. 2565 if (++which == task_count) { 2566 assert(which <= parallel_gc_threads, 2567 "Inconsistent number of workers"); 2568 which = 0; 2569 } 2570 } 2571 } 2572 } 2573 2574 if (TraceParallelOldGCCompactionPhase) { 2575 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr(); 2576 gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions); 2577 } 2578 } 2579 2580 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 2581 2582 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q, 2583 uint parallel_gc_threads) { 2584 GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer); 2585 2586 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2587 2588 // Iterate over all the spaces adding tasks for updating 2589 // regions in the dense prefix. Assume that 1 gc thread 2590 // will work on opening the gaps and the remaining gc threads 2591 // will work on the dense prefix. 2592 unsigned int space_id; 2593 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) { 2594 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); 2595 const MutableSpace* const space = _space_info[space_id].space(); 2596 2597 if (dense_prefix_end == space->bottom()) { 2598 // There is no dense prefix for this space. 2599 continue; 2600 } 2601 2602 // The dense prefix is before this region. 2603 size_t region_index_end_dense_prefix = 2604 sd.addr_to_region_idx(dense_prefix_end); 2605 RegionData* const dense_prefix_cp = 2606 sd.region(region_index_end_dense_prefix); 2607 assert(dense_prefix_end == space->end() || 2608 dense_prefix_cp->available() || 2609 dense_prefix_cp->claimed(), 2610 "The region after the dense prefix should always be ready to fill"); 2611 2612 size_t region_index_start = sd.addr_to_region_idx(space->bottom()); 2613 2614 // Is there dense prefix work? 2615 size_t total_dense_prefix_regions = 2616 region_index_end_dense_prefix - region_index_start; 2617 // How many regions of the dense prefix should be given to 2618 // each thread? 2619 if (total_dense_prefix_regions > 0) { 2620 uint tasks_for_dense_prefix = 1; 2621 if (total_dense_prefix_regions <= 2622 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { 2623 // Don't over partition. This assumes that 2624 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value 2625 // so there are not many regions to process. 2626 tasks_for_dense_prefix = parallel_gc_threads; 2627 } else { 2628 // Over partition 2629 tasks_for_dense_prefix = parallel_gc_threads * 2630 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; 2631 } 2632 size_t regions_per_thread = total_dense_prefix_regions / 2633 tasks_for_dense_prefix; 2634 // Give each thread at least 1 region. 2635 if (regions_per_thread == 0) { 2636 regions_per_thread = 1; 2637 } 2638 2639 for (uint k = 0; k < tasks_for_dense_prefix; k++) { 2640 if (region_index_start >= region_index_end_dense_prefix) { 2641 break; 2642 } 2643 // region_index_end is not processed 2644 size_t region_index_end = MIN2(region_index_start + regions_per_thread, 2645 region_index_end_dense_prefix); 2646 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2647 region_index_start, 2648 region_index_end)); 2649 region_index_start = region_index_end; 2650 } 2651 } 2652 // This gets any part of the dense prefix that did not 2653 // fit evenly. 2654 if (region_index_start < region_index_end_dense_prefix) { 2655 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2656 region_index_start, 2657 region_index_end_dense_prefix)); 2658 } 2659 } 2660 } 2661 2662 void PSParallelCompact::enqueue_region_stealing_tasks( 2663 GCTaskQueue* q, 2664 ParallelTaskTerminator* terminator_ptr, 2665 uint parallel_gc_threads) { 2666 GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer); 2667 2668 // Once a thread has drained it's stack, it should try to steal regions from 2669 // other threads. 2670 if (parallel_gc_threads > 1) { 2671 for (uint j = 0; j < parallel_gc_threads; j++) { 2672 q->enqueue(new StealRegionCompactionTask(terminator_ptr)); 2673 } 2674 } 2675 } 2676 2677 #ifdef ASSERT 2678 // Write a histogram of the number of times the block table was filled for a 2679 // region. 2680 void PSParallelCompact::write_block_fill_histogram(outputStream* const out) 2681 { 2682 if (!TraceParallelOldGCCompactionPhase) return; 2683 2684 typedef ParallelCompactData::RegionData rd_t; 2685 ParallelCompactData& sd = summary_data(); 2686 2687 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2688 MutableSpace* const spc = _space_info[id].space(); 2689 if (spc->bottom() != spc->top()) { 2690 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom()); 2691 HeapWord* const top_aligned_up = sd.region_align_up(spc->top()); 2692 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up); 2693 2694 size_t histo[5] = { 0, 0, 0, 0, 0 }; 2695 const size_t histo_len = sizeof(histo) / sizeof(size_t); 2696 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t)); 2697 2698 for (const rd_t* cur = beg; cur < end; ++cur) { 2699 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)]; 2700 } 2701 out->print("%u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt); 2702 for (size_t i = 0; i < histo_len; ++i) { 2703 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%", 2704 histo[i], 100.0 * histo[i] / region_cnt); 2705 } 2706 out->cr(); 2707 } 2708 } 2709 } 2710 #endif // #ifdef ASSERT 2711 2712 void PSParallelCompact::compact() { 2713 // trace("5"); 2714 GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer); 2715 2716 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 2717 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 2718 PSOldGen* old_gen = heap->old_gen(); 2719 old_gen->start_array()->reset(); 2720 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2721 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2722 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2723 ParallelTaskTerminator terminator(active_gc_threads, qset); 2724 2725 GCTaskQueue* q = GCTaskQueue::create(); 2726 enqueue_region_draining_tasks(q, active_gc_threads); 2727 enqueue_dense_prefix_tasks(q, active_gc_threads); 2728 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads); 2729 2730 { 2731 GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer); 2732 2733 gc_task_manager()->execute_and_wait(q); 2734 2735 #ifdef ASSERT 2736 // Verify that all regions have been processed before the deferred updates. 2737 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2738 verify_complete(SpaceId(id)); 2739 } 2740 #endif 2741 } 2742 2743 { 2744 // Update the deferred objects, if any. Any compaction manager can be used. 2745 GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer); 2746 ParCompactionManager* cm = ParCompactionManager::manager_array(0); 2747 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2748 update_deferred_objects(cm, SpaceId(id)); 2749 } 2750 } 2751 2752 DEBUG_ONLY(write_block_fill_histogram(gclog_or_tty)); 2753 } 2754 2755 #ifdef ASSERT 2756 void PSParallelCompact::verify_complete(SpaceId space_id) { 2757 // All Regions between space bottom() to new_top() should be marked as filled 2758 // and all Regions between new_top() and top() should be available (i.e., 2759 // should have been emptied). 2760 ParallelCompactData& sd = summary_data(); 2761 SpaceInfo si = _space_info[space_id]; 2762 HeapWord* new_top_addr = sd.region_align_up(si.new_top()); 2763 HeapWord* old_top_addr = sd.region_align_up(si.space()->top()); 2764 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom()); 2765 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr); 2766 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr); 2767 2768 bool issued_a_warning = false; 2769 2770 size_t cur_region; 2771 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) { 2772 const RegionData* const c = sd.region(cur_region); 2773 if (!c->completed()) { 2774 warning("region " SIZE_FORMAT " not filled: " 2775 "destination_count=" SIZE_FORMAT, 2776 cur_region, c->destination_count()); 2777 issued_a_warning = true; 2778 } 2779 } 2780 2781 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) { 2782 const RegionData* const c = sd.region(cur_region); 2783 if (!c->available()) { 2784 warning("region " SIZE_FORMAT " not empty: " 2785 "destination_count=" SIZE_FORMAT, 2786 cur_region, c->destination_count()); 2787 issued_a_warning = true; 2788 } 2789 } 2790 2791 if (issued_a_warning) { 2792 print_region_ranges(); 2793 } 2794 } 2795 #endif // #ifdef ASSERT 2796 2797 // Update interior oops in the ranges of regions [beg_region, end_region). 2798 void 2799 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 2800 SpaceId space_id, 2801 size_t beg_region, 2802 size_t end_region) { 2803 ParallelCompactData& sd = summary_data(); 2804 ParMarkBitMap* const mbm = mark_bitmap(); 2805 2806 HeapWord* beg_addr = sd.region_to_addr(beg_region); 2807 HeapWord* const end_addr = sd.region_to_addr(end_region); 2808 assert(beg_region <= end_region, "bad region range"); 2809 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); 2810 2811 #ifdef ASSERT 2812 // Claim the regions to avoid triggering an assert when they are marked as 2813 // filled. 2814 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) { 2815 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed"); 2816 } 2817 #endif // #ifdef ASSERT 2818 2819 if (beg_addr != space(space_id)->bottom()) { 2820 // Find the first live object or block of dead space that *starts* in this 2821 // range of regions. If a partial object crosses onto the region, skip it; 2822 // it will be marked for 'deferred update' when the object head is 2823 // processed. If dead space crosses onto the region, it is also skipped; it 2824 // will be filled when the prior region is processed. If neither of those 2825 // apply, the first word in the region is the start of a live object or dead 2826 // space. 2827 assert(beg_addr > space(space_id)->bottom(), "sanity"); 2828 const RegionData* const cp = sd.region(beg_region); 2829 if (cp->partial_obj_size() != 0) { 2830 beg_addr = sd.partial_obj_end(beg_region); 2831 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) { 2832 beg_addr = mbm->find_obj_beg(beg_addr, end_addr); 2833 } 2834 } 2835 2836 if (beg_addr < end_addr) { 2837 // A live object or block of dead space starts in this range of Regions. 2838 HeapWord* const dense_prefix_end = dense_prefix(space_id); 2839 2840 // Create closures and iterate. 2841 UpdateOnlyClosure update_closure(mbm, cm, space_id); 2842 FillClosure fill_closure(cm, space_id); 2843 ParMarkBitMap::IterationStatus status; 2844 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, 2845 dense_prefix_end); 2846 if (status == ParMarkBitMap::incomplete) { 2847 update_closure.do_addr(update_closure.source()); 2848 } 2849 } 2850 2851 // Mark the regions as filled. 2852 RegionData* const beg_cp = sd.region(beg_region); 2853 RegionData* const end_cp = sd.region(end_region); 2854 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) { 2855 cp->set_completed(); 2856 } 2857 } 2858 2859 // Return the SpaceId for the space containing addr. If addr is not in the 2860 // heap, last_space_id is returned. In debug mode it expects the address to be 2861 // in the heap and asserts such. 2862 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) { 2863 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap"); 2864 2865 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2866 if (_space_info[id].space()->contains(addr)) { 2867 return SpaceId(id); 2868 } 2869 } 2870 2871 assert(false, "no space contains the addr"); 2872 return last_space_id; 2873 } 2874 2875 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm, 2876 SpaceId id) { 2877 assert(id < last_space_id, "bad space id"); 2878 2879 ParallelCompactData& sd = summary_data(); 2880 const SpaceInfo* const space_info = _space_info + id; 2881 ObjectStartArray* const start_array = space_info->start_array(); 2882 2883 const MutableSpace* const space = space_info->space(); 2884 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set"); 2885 HeapWord* const beg_addr = space_info->dense_prefix(); 2886 HeapWord* const end_addr = sd.region_align_up(space_info->new_top()); 2887 2888 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr); 2889 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr); 2890 const RegionData* cur_region; 2891 for (cur_region = beg_region; cur_region < end_region; ++cur_region) { 2892 HeapWord* const addr = cur_region->deferred_obj_addr(); 2893 if (addr != NULL) { 2894 if (start_array != NULL) { 2895 start_array->allocate_block(addr); 2896 } 2897 oop(addr)->update_contents(cm); 2898 assert(oop(addr)->is_oop_or_null(), "should be an oop now"); 2899 } 2900 } 2901 } 2902 2903 // Skip over count live words starting from beg, and return the address of the 2904 // next live word. Unless marked, the word corresponding to beg is assumed to 2905 // be dead. Callers must either ensure beg does not correspond to the middle of 2906 // an object, or account for those live words in some other way. Callers must 2907 // also ensure that there are enough live words in the range [beg, end) to skip. 2908 HeapWord* 2909 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count) 2910 { 2911 assert(count > 0, "sanity"); 2912 2913 ParMarkBitMap* m = mark_bitmap(); 2914 idx_t bits_to_skip = m->words_to_bits(count); 2915 idx_t cur_beg = m->addr_to_bit(beg); 2916 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end)); 2917 2918 do { 2919 cur_beg = m->find_obj_beg(cur_beg, search_end); 2920 idx_t cur_end = m->find_obj_end(cur_beg, search_end); 2921 const size_t obj_bits = cur_end - cur_beg + 1; 2922 if (obj_bits > bits_to_skip) { 2923 return m->bit_to_addr(cur_beg + bits_to_skip); 2924 } 2925 bits_to_skip -= obj_bits; 2926 cur_beg = cur_end + 1; 2927 } while (bits_to_skip > 0); 2928 2929 // Skipping the desired number of words landed just past the end of an object. 2930 // Find the start of the next object. 2931 cur_beg = m->find_obj_beg(cur_beg, search_end); 2932 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip"); 2933 return m->bit_to_addr(cur_beg); 2934 } 2935 2936 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr, 2937 SpaceId src_space_id, 2938 size_t src_region_idx) 2939 { 2940 assert(summary_data().is_region_aligned(dest_addr), "not aligned"); 2941 2942 const SplitInfo& split_info = _space_info[src_space_id].split_info(); 2943 if (split_info.dest_region_addr() == dest_addr) { 2944 // The partial object ending at the split point contains the first word to 2945 // be copied to dest_addr. 2946 return split_info.first_src_addr(); 2947 } 2948 2949 const ParallelCompactData& sd = summary_data(); 2950 ParMarkBitMap* const bitmap = mark_bitmap(); 2951 const size_t RegionSize = ParallelCompactData::RegionSize; 2952 2953 assert(sd.is_region_aligned(dest_addr), "not aligned"); 2954 const RegionData* const src_region_ptr = sd.region(src_region_idx); 2955 const size_t partial_obj_size = src_region_ptr->partial_obj_size(); 2956 HeapWord* const src_region_destination = src_region_ptr->destination(); 2957 2958 assert(dest_addr >= src_region_destination, "wrong src region"); 2959 assert(src_region_ptr->data_size() > 0, "src region cannot be empty"); 2960 2961 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx); 2962 HeapWord* const src_region_end = src_region_beg + RegionSize; 2963 2964 HeapWord* addr = src_region_beg; 2965 if (dest_addr == src_region_destination) { 2966 // Return the first live word in the source region. 2967 if (partial_obj_size == 0) { 2968 addr = bitmap->find_obj_beg(addr, src_region_end); 2969 assert(addr < src_region_end, "no objects start in src region"); 2970 } 2971 return addr; 2972 } 2973 2974 // Must skip some live data. 2975 size_t words_to_skip = dest_addr - src_region_destination; 2976 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region"); 2977 2978 if (partial_obj_size >= words_to_skip) { 2979 // All the live words to skip are part of the partial object. 2980 addr += words_to_skip; 2981 if (partial_obj_size == words_to_skip) { 2982 // Find the first live word past the partial object. 2983 addr = bitmap->find_obj_beg(addr, src_region_end); 2984 assert(addr < src_region_end, "wrong src region"); 2985 } 2986 return addr; 2987 } 2988 2989 // Skip over the partial object (if any). 2990 if (partial_obj_size != 0) { 2991 words_to_skip -= partial_obj_size; 2992 addr += partial_obj_size; 2993 } 2994 2995 // Skip over live words due to objects that start in the region. 2996 addr = skip_live_words(addr, src_region_end, words_to_skip); 2997 assert(addr < src_region_end, "wrong src region"); 2998 return addr; 2999 } 3000 3001 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, 3002 SpaceId src_space_id, 3003 size_t beg_region, 3004 HeapWord* end_addr) 3005 { 3006 ParallelCompactData& sd = summary_data(); 3007 3008 #ifdef ASSERT 3009 MutableSpace* const src_space = _space_info[src_space_id].space(); 3010 HeapWord* const beg_addr = sd.region_to_addr(beg_region); 3011 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(), 3012 "src_space_id does not match beg_addr"); 3013 assert(src_space->contains(end_addr) || end_addr == src_space->end(), 3014 "src_space_id does not match end_addr"); 3015 #endif // #ifdef ASSERT 3016 3017 RegionData* const beg = sd.region(beg_region); 3018 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr)); 3019 3020 // Regions up to new_top() are enqueued if they become available. 3021 HeapWord* const new_top = _space_info[src_space_id].new_top(); 3022 RegionData* const enqueue_end = 3023 sd.addr_to_region_ptr(sd.region_align_up(new_top)); 3024 3025 for (RegionData* cur = beg; cur < end; ++cur) { 3026 assert(cur->data_size() > 0, "region must have live data"); 3027 cur->decrement_destination_count(); 3028 if (cur < enqueue_end && cur->available() && cur->claim()) { 3029 cm->push_region(sd.region(cur)); 3030 } 3031 } 3032 } 3033 3034 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure, 3035 SpaceId& src_space_id, 3036 HeapWord*& src_space_top, 3037 HeapWord* end_addr) 3038 { 3039 typedef ParallelCompactData::RegionData RegionData; 3040 3041 ParallelCompactData& sd = PSParallelCompact::summary_data(); 3042 const size_t region_size = ParallelCompactData::RegionSize; 3043 3044 size_t src_region_idx = 0; 3045 3046 // Skip empty regions (if any) up to the top of the space. 3047 HeapWord* const src_aligned_up = sd.region_align_up(end_addr); 3048 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up); 3049 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top); 3050 const RegionData* const top_region_ptr = 3051 sd.addr_to_region_ptr(top_aligned_up); 3052 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) { 3053 ++src_region_ptr; 3054 } 3055 3056 if (src_region_ptr < top_region_ptr) { 3057 // The next source region is in the current space. Update src_region_idx 3058 // and the source address to match src_region_ptr. 3059 src_region_idx = sd.region(src_region_ptr); 3060 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx); 3061 if (src_region_addr > closure.source()) { 3062 closure.set_source(src_region_addr); 3063 } 3064 return src_region_idx; 3065 } 3066 3067 // Switch to a new source space and find the first non-empty region. 3068 unsigned int space_id = src_space_id + 1; 3069 assert(space_id < last_space_id, "not enough spaces"); 3070 3071 HeapWord* const destination = closure.destination(); 3072 3073 do { 3074 MutableSpace* space = _space_info[space_id].space(); 3075 HeapWord* const bottom = space->bottom(); 3076 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom); 3077 3078 // Iterate over the spaces that do not compact into themselves. 3079 if (bottom_cp->destination() != bottom) { 3080 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 3081 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 3082 3083 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) { 3084 if (src_cp->live_obj_size() > 0) { 3085 // Found it. 3086 assert(src_cp->destination() == destination, 3087 "first live obj in the space must match the destination"); 3088 assert(src_cp->partial_obj_size() == 0, 3089 "a space cannot begin with a partial obj"); 3090 3091 src_space_id = SpaceId(space_id); 3092 src_space_top = space->top(); 3093 const size_t src_region_idx = sd.region(src_cp); 3094 closure.set_source(sd.region_to_addr(src_region_idx)); 3095 return src_region_idx; 3096 } else { 3097 assert(src_cp->data_size() == 0, "sanity"); 3098 } 3099 } 3100 } 3101 } while (++space_id < last_space_id); 3102 3103 assert(false, "no source region was found"); 3104 return 0; 3105 } 3106 3107 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx) 3108 { 3109 typedef ParMarkBitMap::IterationStatus IterationStatus; 3110 const size_t RegionSize = ParallelCompactData::RegionSize; 3111 ParMarkBitMap* const bitmap = mark_bitmap(); 3112 ParallelCompactData& sd = summary_data(); 3113 RegionData* const region_ptr = sd.region(region_idx); 3114 3115 // Get the items needed to construct the closure. 3116 HeapWord* dest_addr = sd.region_to_addr(region_idx); 3117 SpaceId dest_space_id = space_id(dest_addr); 3118 ObjectStartArray* start_array = _space_info[dest_space_id].start_array(); 3119 HeapWord* new_top = _space_info[dest_space_id].new_top(); 3120 assert(dest_addr < new_top, "sanity"); 3121 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize); 3122 3123 // Get the source region and related info. 3124 size_t src_region_idx = region_ptr->source_region(); 3125 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx)); 3126 HeapWord* src_space_top = _space_info[src_space_id].space()->top(); 3127 3128 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 3129 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx)); 3130 3131 // Adjust src_region_idx to prepare for decrementing destination counts (the 3132 // destination count is not decremented when a region is copied to itself). 3133 if (src_region_idx == region_idx) { 3134 src_region_idx += 1; 3135 } 3136 3137 if (bitmap->is_unmarked(closure.source())) { 3138 // The first source word is in the middle of an object; copy the remainder 3139 // of the object or as much as will fit. The fact that pointer updates were 3140 // deferred will be noted when the object header is processed. 3141 HeapWord* const old_src_addr = closure.source(); 3142 closure.copy_partial_obj(); 3143 if (closure.is_full()) { 3144 decrement_destination_counts(cm, src_space_id, src_region_idx, 3145 closure.source()); 3146 region_ptr->set_deferred_obj_addr(NULL); 3147 region_ptr->set_completed(); 3148 return; 3149 } 3150 3151 HeapWord* const end_addr = sd.region_align_down(closure.source()); 3152 if (sd.region_align_down(old_src_addr) != end_addr) { 3153 // The partial object was copied from more than one source region. 3154 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 3155 3156 // Move to the next source region, possibly switching spaces as well. All 3157 // args except end_addr may be modified. 3158 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 3159 end_addr); 3160 } 3161 } 3162 3163 do { 3164 HeapWord* const cur_addr = closure.source(); 3165 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1), 3166 src_space_top); 3167 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr); 3168 3169 if (status == ParMarkBitMap::incomplete) { 3170 // The last obj that starts in the source region does not end in the 3171 // region. 3172 assert(closure.source() < end_addr, "sanity"); 3173 HeapWord* const obj_beg = closure.source(); 3174 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(), 3175 src_space_top); 3176 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end); 3177 if (obj_end < range_end) { 3178 // The end was found; the entire object will fit. 3179 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end)); 3180 assert(status != ParMarkBitMap::would_overflow, "sanity"); 3181 } else { 3182 // The end was not found; the object will not fit. 3183 assert(range_end < src_space_top, "obj cannot cross space boundary"); 3184 status = ParMarkBitMap::would_overflow; 3185 } 3186 } 3187 3188 if (status == ParMarkBitMap::would_overflow) { 3189 // The last object did not fit. Note that interior oop updates were 3190 // deferred, then copy enough of the object to fill the region. 3191 region_ptr->set_deferred_obj_addr(closure.destination()); 3192 status = closure.copy_until_full(); // copies from closure.source() 3193 3194 decrement_destination_counts(cm, src_space_id, src_region_idx, 3195 closure.source()); 3196 region_ptr->set_completed(); 3197 return; 3198 } 3199 3200 if (status == ParMarkBitMap::full) { 3201 decrement_destination_counts(cm, src_space_id, src_region_idx, 3202 closure.source()); 3203 region_ptr->set_deferred_obj_addr(NULL); 3204 region_ptr->set_completed(); 3205 return; 3206 } 3207 3208 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 3209 3210 // Move to the next source region, possibly switching spaces as well. All 3211 // args except end_addr may be modified. 3212 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 3213 end_addr); 3214 } while (true); 3215 } 3216 3217 void PSParallelCompact::fill_blocks(size_t region_idx) 3218 { 3219 // Fill in the block table elements for the specified region. Each block 3220 // table element holds the number of live words in the region that are to the 3221 // left of the first object that starts in the block. Thus only blocks in 3222 // which an object starts need to be filled. 3223 // 3224 // The algorithm scans the section of the bitmap that corresponds to the 3225 // region, keeping a running total of the live words. When an object start is 3226 // found, if it's the first to start in the block that contains it, the 3227 // current total is written to the block table element. 3228 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize; 3229 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize; 3230 const size_t RegionSize = ParallelCompactData::RegionSize; 3231 3232 ParallelCompactData& sd = summary_data(); 3233 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size(); 3234 if (partial_obj_size >= RegionSize) { 3235 return; // No objects start in this region. 3236 } 3237 3238 // Ensure the first loop iteration decides that the block has changed. 3239 size_t cur_block = sd.block_count(); 3240 3241 const ParMarkBitMap* const bitmap = mark_bitmap(); 3242 3243 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment; 3244 assert((size_t)1 << Log2BitsPerBlock == 3245 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity"); 3246 3247 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize); 3248 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize); 3249 size_t live_bits = bitmap->words_to_bits(partial_obj_size); 3250 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end); 3251 while (beg_bit < range_end) { 3252 const size_t new_block = beg_bit >> Log2BitsPerBlock; 3253 if (new_block != cur_block) { 3254 cur_block = new_block; 3255 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits)); 3256 } 3257 3258 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end); 3259 if (end_bit < range_end - 1) { 3260 live_bits += end_bit - beg_bit + 1; 3261 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end); 3262 } else { 3263 return; 3264 } 3265 } 3266 } 3267 3268 void 3269 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) { 3270 const MutableSpace* sp = space(space_id); 3271 if (sp->is_empty()) { 3272 return; 3273 } 3274 3275 ParallelCompactData& sd = PSParallelCompact::summary_data(); 3276 ParMarkBitMap* const bitmap = mark_bitmap(); 3277 HeapWord* const dp_addr = dense_prefix(space_id); 3278 HeapWord* beg_addr = sp->bottom(); 3279 HeapWord* end_addr = sp->top(); 3280 3281 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix"); 3282 3283 const size_t beg_region = sd.addr_to_region_idx(beg_addr); 3284 const size_t dp_region = sd.addr_to_region_idx(dp_addr); 3285 if (beg_region < dp_region) { 3286 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region); 3287 } 3288 3289 // The destination of the first live object that starts in the region is one 3290 // past the end of the partial object entering the region (if any). 3291 HeapWord* const dest_addr = sd.partial_obj_end(dp_region); 3292 HeapWord* const new_top = _space_info[space_id].new_top(); 3293 assert(new_top >= dest_addr, "bad new_top value"); 3294 const size_t words = pointer_delta(new_top, dest_addr); 3295 3296 if (words > 0) { 3297 ObjectStartArray* start_array = _space_info[space_id].start_array(); 3298 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 3299 3300 ParMarkBitMap::IterationStatus status; 3301 status = bitmap->iterate(&closure, dest_addr, end_addr); 3302 assert(status == ParMarkBitMap::full, "iteration not complete"); 3303 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr, 3304 "live objects skipped because closure is full"); 3305 } 3306 } 3307 3308 jlong PSParallelCompact::millis_since_last_gc() { 3309 // We need a monotonically non-deccreasing time in ms but 3310 // os::javaTimeMillis() does not guarantee monotonicity. 3311 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3312 jlong ret_val = now - _time_of_last_gc; 3313 // XXX See note in genCollectedHeap::millis_since_last_gc(). 3314 if (ret_val < 0) { 3315 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);) 3316 return 0; 3317 } 3318 return ret_val; 3319 } 3320 3321 void PSParallelCompact::reset_millis_since_last_gc() { 3322 // We need a monotonically non-deccreasing time in ms but 3323 // os::javaTimeMillis() does not guarantee monotonicity. 3324 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3325 } 3326 3327 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() 3328 { 3329 if (source() != destination()) { 3330 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3331 Copy::aligned_conjoint_words(source(), destination(), words_remaining()); 3332 } 3333 update_state(words_remaining()); 3334 assert(is_full(), "sanity"); 3335 return ParMarkBitMap::full; 3336 } 3337 3338 void MoveAndUpdateClosure::copy_partial_obj() 3339 { 3340 size_t words = words_remaining(); 3341 3342 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end()); 3343 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end); 3344 if (end_addr < range_end) { 3345 words = bitmap()->obj_size(source(), end_addr); 3346 } 3347 3348 // This test is necessary; if omitted, the pointer updates to a partial object 3349 // that crosses the dense prefix boundary could be overwritten. 3350 if (source() != destination()) { 3351 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3352 Copy::aligned_conjoint_words(source(), destination(), words); 3353 } 3354 update_state(words); 3355 } 3356 3357 ParMarkBitMapClosure::IterationStatus 3358 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) { 3359 assert(destination() != NULL, "sanity"); 3360 assert(bitmap()->obj_size(addr) == words, "bad size"); 3361 3362 _source = addr; 3363 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) == 3364 destination(), "wrong destination"); 3365 3366 if (words > words_remaining()) { 3367 return ParMarkBitMap::would_overflow; 3368 } 3369 3370 // The start_array must be updated even if the object is not moving. 3371 if (_start_array != NULL) { 3372 _start_array->allocate_block(destination()); 3373 } 3374 3375 if (destination() != source()) { 3376 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3377 Copy::aligned_conjoint_words(source(), destination(), words); 3378 } 3379 3380 oop moved_oop = (oop) destination(); 3381 moved_oop->update_contents(compaction_manager()); 3382 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point"); 3383 3384 update_state(words); 3385 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity"); 3386 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete; 3387 } 3388 3389 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm, 3390 ParCompactionManager* cm, 3391 PSParallelCompact::SpaceId space_id) : 3392 ParMarkBitMapClosure(mbm, cm), 3393 _space_id(space_id), 3394 _start_array(PSParallelCompact::start_array(space_id)) 3395 { 3396 } 3397 3398 // Updates the references in the object to their new values. 3399 ParMarkBitMapClosure::IterationStatus 3400 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) { 3401 do_addr(addr); 3402 return ParMarkBitMap::incomplete; 3403 }