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