1 /* 2 * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/symbolTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "code/codeCache.hpp" 29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" 30 #include "gc_implementation/parallelScavenge/generationSizer.hpp" 31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp" 32 #include "gc_implementation/parallelScavenge/pcTasks.hpp" 33 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" 34 #include "gc_implementation/parallelScavenge/psCompactionManager.inline.hpp" 35 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" 36 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp" 37 #include "gc_implementation/parallelScavenge/psOldGen.hpp" 38 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp" 39 #include "gc_implementation/parallelScavenge/psPermGen.hpp" 40 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp" 41 #include "gc_implementation/parallelScavenge/psScavenge.hpp" 42 #include "gc_implementation/parallelScavenge/psYoungGen.hpp" 43 #include "gc_implementation/shared/gcHeapSummary.hpp" 44 #include "gc_implementation/shared/gcTimer.hpp" 45 #include "gc_implementation/shared/gcTrace.hpp" 46 #include "gc_implementation/shared/gcTraceTime.hpp" 47 #include "gc_implementation/shared/isGCActiveMark.hpp" 48 #include "gc_interface/gcCause.hpp" 49 #include "memory/gcLocker.inline.hpp" 50 #include "memory/referencePolicy.hpp" 51 #include "memory/referenceProcessor.hpp" 52 #include "oops/methodDataOop.hpp" 53 #include "oops/oop.inline.hpp" 54 #include "oops/oop.pcgc.inline.hpp" 55 #include "runtime/fprofiler.hpp" 56 #include "runtime/safepoint.hpp" 57 #include "runtime/vmThread.hpp" 58 #include "services/management.hpp" 59 #include "services/memoryService.hpp" 60 #include "services/memTracker.hpp" 61 #include "utilities/events.hpp" 62 #include "utilities/stack.inline.hpp" 63 64 #include <math.h> 65 66 // All sizes are in HeapWords. 67 const size_t ParallelCompactData::Log2RegionSize = 9; // 512 words 68 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize; 69 const size_t ParallelCompactData::RegionSizeBytes = 70 RegionSize << LogHeapWordSize; 71 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1; 72 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1; 73 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask; 74 75 const ParallelCompactData::RegionData::region_sz_t 76 ParallelCompactData::RegionData::dc_shift = 27; 77 78 const ParallelCompactData::RegionData::region_sz_t 79 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift; 80 81 const ParallelCompactData::RegionData::region_sz_t 82 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift; 83 84 const ParallelCompactData::RegionData::region_sz_t 85 ParallelCompactData::RegionData::los_mask = ~dc_mask; 86 87 const ParallelCompactData::RegionData::region_sz_t 88 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift; 89 90 const ParallelCompactData::RegionData::region_sz_t 91 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift; 92 93 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; 94 bool PSParallelCompact::_print_phases = false; 95 96 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; 97 klassOop PSParallelCompact::_updated_int_array_klass_obj = NULL; 98 99 double PSParallelCompact::_dwl_mean; 100 double PSParallelCompact::_dwl_std_dev; 101 double PSParallelCompact::_dwl_first_term; 102 double PSParallelCompact::_dwl_adjustment; 103 #ifdef ASSERT 104 bool PSParallelCompact::_dwl_initialized = false; 105 #endif // #ifdef ASSERT 106 107 #ifdef VALIDATE_MARK_SWEEP 108 GrowableArray<void*>* PSParallelCompact::_root_refs_stack = NULL; 109 GrowableArray<oop> * PSParallelCompact::_live_oops = NULL; 110 GrowableArray<oop> * PSParallelCompact::_live_oops_moved_to = NULL; 111 GrowableArray<size_t>* PSParallelCompact::_live_oops_size = NULL; 112 size_t PSParallelCompact::_live_oops_index = 0; 113 size_t PSParallelCompact::_live_oops_index_at_perm = 0; 114 GrowableArray<void*>* PSParallelCompact::_other_refs_stack = NULL; 115 GrowableArray<void*>* PSParallelCompact::_adjusted_pointers = NULL; 116 bool PSParallelCompact::_pointer_tracking = false; 117 bool PSParallelCompact::_root_tracking = true; 118 119 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL; 120 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL; 121 GrowableArray<size_t> * PSParallelCompact::_cur_gc_live_oops_size = NULL; 122 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL; 123 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL; 124 GrowableArray<size_t> * PSParallelCompact::_last_gc_live_oops_size = NULL; 125 #endif 126 127 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size, 128 HeapWord* destination) 129 { 130 assert(src_region_idx != 0, "invalid src_region_idx"); 131 assert(partial_obj_size != 0, "invalid partial_obj_size argument"); 132 assert(destination != NULL, "invalid destination argument"); 133 134 _src_region_idx = src_region_idx; 135 _partial_obj_size = partial_obj_size; 136 _destination = destination; 137 138 // These fields may not be updated below, so make sure they're clear. 139 assert(_dest_region_addr == NULL, "should have been cleared"); 140 assert(_first_src_addr == NULL, "should have been cleared"); 141 142 // Determine the number of destination regions for the partial object. 143 HeapWord* const last_word = destination + partial_obj_size - 1; 144 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 145 HeapWord* const beg_region_addr = sd.region_align_down(destination); 146 HeapWord* const end_region_addr = sd.region_align_down(last_word); 147 148 if (beg_region_addr == end_region_addr) { 149 // One destination region. 150 _destination_count = 1; 151 if (end_region_addr == destination) { 152 // The destination falls on a region boundary, thus the first word of the 153 // partial object will be the first word copied to the destination region. 154 _dest_region_addr = end_region_addr; 155 _first_src_addr = sd.region_to_addr(src_region_idx); 156 } 157 } else { 158 // Two destination regions. When copied, the partial object will cross a 159 // destination region boundary, so a word somewhere within the partial 160 // object will be the first word copied to the second destination region. 161 _destination_count = 2; 162 _dest_region_addr = end_region_addr; 163 const size_t ofs = pointer_delta(end_region_addr, destination); 164 assert(ofs < _partial_obj_size, "sanity"); 165 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs; 166 } 167 } 168 169 void SplitInfo::clear() 170 { 171 _src_region_idx = 0; 172 _partial_obj_size = 0; 173 _destination = NULL; 174 _destination_count = 0; 175 _dest_region_addr = NULL; 176 _first_src_addr = NULL; 177 assert(!is_valid(), "sanity"); 178 } 179 180 #ifdef ASSERT 181 void SplitInfo::verify_clear() 182 { 183 assert(_src_region_idx == 0, "not clear"); 184 assert(_partial_obj_size == 0, "not clear"); 185 assert(_destination == NULL, "not clear"); 186 assert(_destination_count == 0, "not clear"); 187 assert(_dest_region_addr == NULL, "not clear"); 188 assert(_first_src_addr == NULL, "not clear"); 189 } 190 #endif // #ifdef ASSERT 191 192 193 #ifndef PRODUCT 194 const char* PSParallelCompact::space_names[] = { 195 "perm", "old ", "eden", "from", "to " 196 }; 197 198 void PSParallelCompact::print_region_ranges() 199 { 200 tty->print_cr("space bottom top end new_top"); 201 tty->print_cr("------ ---------- ---------- ---------- ----------"); 202 203 for (unsigned int id = 0; id < last_space_id; ++id) { 204 const MutableSpace* space = _space_info[id].space(); 205 tty->print_cr("%u %s " 206 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " 207 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", 208 id, space_names[id], 209 summary_data().addr_to_region_idx(space->bottom()), 210 summary_data().addr_to_region_idx(space->top()), 211 summary_data().addr_to_region_idx(space->end()), 212 summary_data().addr_to_region_idx(_space_info[id].new_top())); 213 } 214 } 215 216 void 217 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c) 218 { 219 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7) 220 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5) 221 222 ParallelCompactData& sd = PSParallelCompact::summary_data(); 223 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0; 224 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " " 225 REGION_IDX_FORMAT " " PTR_FORMAT " " 226 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " " 227 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d", 228 i, c->data_location(), dci, c->destination(), 229 c->partial_obj_size(), c->live_obj_size(), 230 c->data_size(), c->source_region(), c->destination_count()); 231 232 #undef REGION_IDX_FORMAT 233 #undef REGION_DATA_FORMAT 234 } 235 236 void 237 print_generic_summary_data(ParallelCompactData& summary_data, 238 HeapWord* const beg_addr, 239 HeapWord* const end_addr) 240 { 241 size_t total_words = 0; 242 size_t i = summary_data.addr_to_region_idx(beg_addr); 243 const size_t last = summary_data.addr_to_region_idx(end_addr); 244 HeapWord* pdest = 0; 245 246 while (i <= last) { 247 ParallelCompactData::RegionData* c = summary_data.region(i); 248 if (c->data_size() != 0 || c->destination() != pdest) { 249 print_generic_summary_region(i, c); 250 total_words += c->data_size(); 251 pdest = c->destination(); 252 } 253 ++i; 254 } 255 256 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); 257 } 258 259 void 260 print_generic_summary_data(ParallelCompactData& summary_data, 261 SpaceInfo* space_info) 262 { 263 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { 264 const MutableSpace* space = space_info[id].space(); 265 print_generic_summary_data(summary_data, space->bottom(), 266 MAX2(space->top(), space_info[id].new_top())); 267 } 268 } 269 270 void 271 print_initial_summary_region(size_t i, 272 const ParallelCompactData::RegionData* c, 273 bool newline = true) 274 { 275 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " " 276 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " 277 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", 278 i, c->destination(), 279 c->partial_obj_size(), c->live_obj_size(), 280 c->data_size(), c->source_region(), c->destination_count()); 281 if (newline) tty->cr(); 282 } 283 284 void 285 print_initial_summary_data(ParallelCompactData& summary_data, 286 const MutableSpace* space) { 287 if (space->top() == space->bottom()) { 288 return; 289 } 290 291 const size_t region_size = ParallelCompactData::RegionSize; 292 typedef ParallelCompactData::RegionData RegionData; 293 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top()); 294 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up); 295 const RegionData* c = summary_data.region(end_region - 1); 296 HeapWord* end_addr = c->destination() + c->data_size(); 297 const size_t live_in_space = pointer_delta(end_addr, space->bottom()); 298 299 // Print (and count) the full regions at the beginning of the space. 300 size_t full_region_count = 0; 301 size_t i = summary_data.addr_to_region_idx(space->bottom()); 302 while (i < end_region && summary_data.region(i)->data_size() == region_size) { 303 print_initial_summary_region(i, summary_data.region(i)); 304 ++full_region_count; 305 ++i; 306 } 307 308 size_t live_to_right = live_in_space - full_region_count * region_size; 309 310 double max_reclaimed_ratio = 0.0; 311 size_t max_reclaimed_ratio_region = 0; 312 size_t max_dead_to_right = 0; 313 size_t max_live_to_right = 0; 314 315 // Print the 'reclaimed ratio' for regions while there is something live in 316 // the region or to the right of it. The remaining regions are empty (and 317 // uninteresting), and computing the ratio will result in division by 0. 318 while (i < end_region && live_to_right > 0) { 319 c = summary_data.region(i); 320 HeapWord* const region_addr = summary_data.region_to_addr(i); 321 const size_t used_to_right = pointer_delta(space->top(), region_addr); 322 const size_t dead_to_right = used_to_right - live_to_right; 323 const double reclaimed_ratio = double(dead_to_right) / live_to_right; 324 325 if (reclaimed_ratio > max_reclaimed_ratio) { 326 max_reclaimed_ratio = reclaimed_ratio; 327 max_reclaimed_ratio_region = i; 328 max_dead_to_right = dead_to_right; 329 max_live_to_right = live_to_right; 330 } 331 332 print_initial_summary_region(i, c, false); 333 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), 334 reclaimed_ratio, dead_to_right, live_to_right); 335 336 live_to_right -= c->data_size(); 337 ++i; 338 } 339 340 // Any remaining regions are empty. Print one more if there is one. 341 if (i < end_region) { 342 print_initial_summary_region(i, summary_data.region(i)); 343 } 344 345 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " " 346 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", 347 max_reclaimed_ratio_region, max_dead_to_right, 348 max_live_to_right, max_reclaimed_ratio); 349 } 350 351 void 352 print_initial_summary_data(ParallelCompactData& summary_data, 353 SpaceInfo* space_info) { 354 unsigned int id = PSParallelCompact::perm_space_id; 355 const MutableSpace* space; 356 do { 357 space = space_info[id].space(); 358 print_initial_summary_data(summary_data, space); 359 } while (++id < PSParallelCompact::eden_space_id); 360 361 do { 362 space = space_info[id].space(); 363 print_generic_summary_data(summary_data, space->bottom(), space->top()); 364 } while (++id < PSParallelCompact::last_space_id); 365 } 366 #endif // #ifndef PRODUCT 367 368 #ifdef ASSERT 369 size_t add_obj_count; 370 size_t add_obj_size; 371 size_t mark_bitmap_count; 372 size_t mark_bitmap_size; 373 #endif // #ifdef ASSERT 374 375 ParallelCompactData::ParallelCompactData() 376 { 377 _region_start = 0; 378 379 _region_vspace = 0; 380 _region_data = 0; 381 _region_count = 0; 382 } 383 384 bool ParallelCompactData::initialize(MemRegion covered_region) 385 { 386 _region_start = covered_region.start(); 387 const size_t region_size = covered_region.word_size(); 388 DEBUG_ONLY(_region_end = _region_start + region_size;) 389 390 assert(region_align_down(_region_start) == _region_start, 391 "region start not aligned"); 392 assert((region_size & RegionSizeOffsetMask) == 0, 393 "region size not a multiple of RegionSize"); 394 395 bool result = initialize_region_data(region_size); 396 397 return result; 398 } 399 400 PSVirtualSpace* 401 ParallelCompactData::create_vspace(size_t count, size_t element_size) 402 { 403 const size_t raw_bytes = count * element_size; 404 const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10); 405 const size_t granularity = os::vm_allocation_granularity(); 406 const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity)); 407 408 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : 409 MAX2(page_sz, granularity); 410 ReservedSpace rs(bytes, rs_align, rs_align > 0); 411 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(), 412 rs.size()); 413 414 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); 415 416 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); 417 if (vspace != 0) { 418 if (vspace->expand_by(bytes)) { 419 return vspace; 420 } 421 delete vspace; 422 // Release memory reserved in the space. 423 rs.release(); 424 } 425 426 return 0; 427 } 428 429 bool ParallelCompactData::initialize_region_data(size_t region_size) 430 { 431 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize; 432 _region_vspace = create_vspace(count, sizeof(RegionData)); 433 if (_region_vspace != 0) { 434 _region_data = (RegionData*)_region_vspace->reserved_low_addr(); 435 _region_count = count; 436 return true; 437 } 438 return false; 439 } 440 441 void ParallelCompactData::clear() 442 { 443 memset(_region_data, 0, _region_vspace->committed_size()); 444 } 445 446 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) { 447 assert(beg_region <= _region_count, "beg_region out of range"); 448 assert(end_region <= _region_count, "end_region out of range"); 449 450 const size_t region_cnt = end_region - beg_region; 451 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData)); 452 } 453 454 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const 455 { 456 const RegionData* cur_cp = region(region_idx); 457 const RegionData* const end_cp = region(region_count() - 1); 458 459 HeapWord* result = region_to_addr(region_idx); 460 if (cur_cp < end_cp) { 461 do { 462 result += cur_cp->partial_obj_size(); 463 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp); 464 } 465 return result; 466 } 467 468 void ParallelCompactData::add_obj(HeapWord* addr, size_t len) 469 { 470 const size_t obj_ofs = pointer_delta(addr, _region_start); 471 const size_t beg_region = obj_ofs >> Log2RegionSize; 472 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize; 473 474 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);) 475 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);) 476 477 if (beg_region == end_region) { 478 // All in one region. 479 _region_data[beg_region].add_live_obj(len); 480 return; 481 } 482 483 // First region. 484 const size_t beg_ofs = region_offset(addr); 485 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs); 486 487 klassOop klass = ((oop)addr)->klass(); 488 // Middle regions--completely spanned by this object. 489 for (size_t region = beg_region + 1; region < end_region; ++region) { 490 _region_data[region].set_partial_obj_size(RegionSize); 491 _region_data[region].set_partial_obj_addr(addr); 492 } 493 494 // Last region. 495 const size_t end_ofs = region_offset(addr + len - 1); 496 _region_data[end_region].set_partial_obj_size(end_ofs + 1); 497 _region_data[end_region].set_partial_obj_addr(addr); 498 } 499 500 void 501 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) 502 { 503 assert(region_offset(beg) == 0, "not RegionSize aligned"); 504 assert(region_offset(end) == 0, "not RegionSize aligned"); 505 506 size_t cur_region = addr_to_region_idx(beg); 507 const size_t end_region = addr_to_region_idx(end); 508 HeapWord* addr = beg; 509 while (cur_region < end_region) { 510 _region_data[cur_region].set_destination(addr); 511 _region_data[cur_region].set_destination_count(0); 512 _region_data[cur_region].set_source_region(cur_region); 513 _region_data[cur_region].set_data_location(addr); 514 515 // Update live_obj_size so the region appears completely full. 516 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size(); 517 _region_data[cur_region].set_live_obj_size(live_size); 518 519 ++cur_region; 520 addr += RegionSize; 521 } 522 } 523 524 // Find the point at which a space can be split and, if necessary, record the 525 // split point. 526 // 527 // If the current src region (which overflowed the destination space) doesn't 528 // have a partial object, the split point is at the beginning of the current src 529 // region (an "easy" split, no extra bookkeeping required). 530 // 531 // If the current src region has a partial object, the split point is in the 532 // region where that partial object starts (call it the split_region). If 533 // split_region has a partial object, then the split point is just after that 534 // partial object (a "hard" split where we have to record the split data and 535 // zero the partial_obj_size field). With a "hard" split, we know that the 536 // partial_obj ends within split_region because the partial object that caused 537 // the overflow starts in split_region. If split_region doesn't have a partial 538 // obj, then the split is at the beginning of split_region (another "easy" 539 // split). 540 HeapWord* 541 ParallelCompactData::summarize_split_space(size_t src_region, 542 SplitInfo& split_info, 543 HeapWord* destination, 544 HeapWord* target_end, 545 HeapWord** target_next) 546 { 547 assert(destination <= target_end, "sanity"); 548 assert(destination + _region_data[src_region].data_size() > target_end, 549 "region should not fit into target space"); 550 assert(is_region_aligned(target_end), "sanity"); 551 552 size_t split_region = src_region; 553 HeapWord* split_destination = destination; 554 size_t partial_obj_size = _region_data[src_region].partial_obj_size(); 555 556 if (destination + partial_obj_size > target_end) { 557 // The split point is just after the partial object (if any) in the 558 // src_region that contains the start of the object that overflowed the 559 // destination space. 560 // 561 // Find the start of the "overflow" object and set split_region to the 562 // region containing it. 563 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr(); 564 split_region = addr_to_region_idx(overflow_obj); 565 566 // Clear the source_region field of all destination regions whose first word 567 // came from data after the split point (a non-null source_region field 568 // implies a region must be filled). 569 // 570 // An alternative to the simple loop below: clear during post_compact(), 571 // which uses memcpy instead of individual stores, and is easy to 572 // parallelize. (The downside is that it clears the entire RegionData 573 // object as opposed to just one field.) 574 // 575 // post_compact() would have to clear the summary data up to the highest 576 // address that was written during the summary phase, which would be 577 // 578 // max(top, max(new_top, clear_top)) 579 // 580 // where clear_top is a new field in SpaceInfo. Would have to set clear_top 581 // to target_end. 582 const RegionData* const sr = region(split_region); 583 const size_t beg_idx = 584 addr_to_region_idx(region_align_up(sr->destination() + 585 sr->partial_obj_size())); 586 const size_t end_idx = addr_to_region_idx(target_end); 587 588 if (TraceParallelOldGCSummaryPhase) { 589 gclog_or_tty->print_cr("split: clearing source_region field in [" 590 SIZE_FORMAT ", " SIZE_FORMAT ")", 591 beg_idx, end_idx); 592 } 593 for (size_t idx = beg_idx; idx < end_idx; ++idx) { 594 _region_data[idx].set_source_region(0); 595 } 596 597 // Set split_destination and partial_obj_size to reflect the split region. 598 split_destination = sr->destination(); 599 partial_obj_size = sr->partial_obj_size(); 600 } 601 602 // The split is recorded only if a partial object extends onto the region. 603 if (partial_obj_size != 0) { 604 _region_data[split_region].set_partial_obj_size(0); 605 split_info.record(split_region, partial_obj_size, split_destination); 606 } 607 608 // Setup the continuation addresses. 609 *target_next = split_destination + partial_obj_size; 610 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size; 611 612 if (TraceParallelOldGCSummaryPhase) { 613 const char * split_type = partial_obj_size == 0 ? "easy" : "hard"; 614 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT 615 " pos=" SIZE_FORMAT, 616 split_type, source_next, split_region, 617 partial_obj_size); 618 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT 619 " tn=" PTR_FORMAT, 620 split_type, split_destination, 621 addr_to_region_idx(split_destination), 622 *target_next); 623 624 if (partial_obj_size != 0) { 625 HeapWord* const po_beg = split_info.destination(); 626 HeapWord* const po_end = po_beg + split_info.partial_obj_size(); 627 gclog_or_tty->print_cr("%s split: " 628 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " " 629 "po_end=" PTR_FORMAT " " SIZE_FORMAT, 630 split_type, 631 po_beg, addr_to_region_idx(po_beg), 632 po_end, addr_to_region_idx(po_end)); 633 } 634 } 635 636 return source_next; 637 } 638 639 bool ParallelCompactData::summarize(SplitInfo& split_info, 640 HeapWord* source_beg, HeapWord* source_end, 641 HeapWord** source_next, 642 HeapWord* target_beg, HeapWord* target_end, 643 HeapWord** target_next) 644 { 645 if (TraceParallelOldGCSummaryPhase) { 646 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next; 647 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT 648 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT, 649 source_beg, source_end, source_next_val, 650 target_beg, target_end, *target_next); 651 } 652 653 size_t cur_region = addr_to_region_idx(source_beg); 654 const size_t end_region = addr_to_region_idx(region_align_up(source_end)); 655 656 HeapWord *dest_addr = target_beg; 657 while (cur_region < end_region) { 658 // The destination must be set even if the region has no data. 659 _region_data[cur_region].set_destination(dest_addr); 660 661 size_t words = _region_data[cur_region].data_size(); 662 if (words > 0) { 663 // If cur_region does not fit entirely into the target space, find a point 664 // at which the source space can be 'split' so that part is copied to the 665 // target space and the rest is copied elsewhere. 666 if (dest_addr + words > target_end) { 667 assert(source_next != NULL, "source_next is NULL when splitting"); 668 *source_next = summarize_split_space(cur_region, split_info, dest_addr, 669 target_end, target_next); 670 return false; 671 } 672 673 // Compute the destination_count for cur_region, and if necessary, update 674 // source_region for a destination region. The source_region field is 675 // updated if cur_region is the first (left-most) region to be copied to a 676 // destination region. 677 // 678 // The destination_count calculation is a bit subtle. A region that has 679 // data that compacts into itself does not count itself as a destination. 680 // This maintains the invariant that a zero count means the region is 681 // available and can be claimed and then filled. 682 uint destination_count = 0; 683 if (split_info.is_split(cur_region)) { 684 // The current region has been split: the partial object will be copied 685 // to one destination space and the remaining data will be copied to 686 // another destination space. Adjust the initial destination_count and, 687 // if necessary, set the source_region field if the partial object will 688 // cross a destination region boundary. 689 destination_count = split_info.destination_count(); 690 if (destination_count == 2) { 691 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr()); 692 _region_data[dest_idx].set_source_region(cur_region); 693 } 694 } 695 696 HeapWord* const last_addr = dest_addr + words - 1; 697 const size_t dest_region_1 = addr_to_region_idx(dest_addr); 698 const size_t dest_region_2 = addr_to_region_idx(last_addr); 699 700 // Initially assume that the destination regions will be the same and 701 // adjust the value below if necessary. Under this assumption, if 702 // cur_region == dest_region_2, then cur_region will be compacted 703 // completely into itself. 704 destination_count += cur_region == dest_region_2 ? 0 : 1; 705 if (dest_region_1 != dest_region_2) { 706 // Destination regions differ; adjust destination_count. 707 destination_count += 1; 708 // Data from cur_region will be copied to the start of dest_region_2. 709 _region_data[dest_region_2].set_source_region(cur_region); 710 } else if (region_offset(dest_addr) == 0) { 711 // Data from cur_region will be copied to the start of the destination 712 // region. 713 _region_data[dest_region_1].set_source_region(cur_region); 714 } 715 716 _region_data[cur_region].set_destination_count(destination_count); 717 _region_data[cur_region].set_data_location(region_to_addr(cur_region)); 718 dest_addr += words; 719 } 720 721 ++cur_region; 722 } 723 724 *target_next = dest_addr; 725 return true; 726 } 727 728 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) { 729 assert(addr != NULL, "Should detect NULL oop earlier"); 730 assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap"); 731 #ifdef ASSERT 732 if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) { 733 gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr); 734 } 735 #endif 736 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked"); 737 738 // Region covering the object. 739 size_t region_index = addr_to_region_idx(addr); 740 const RegionData* const region_ptr = region(region_index); 741 HeapWord* const region_addr = region_align_down(addr); 742 743 assert(addr < region_addr + RegionSize, "Region does not cover object"); 744 assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check"); 745 746 HeapWord* result = region_ptr->destination(); 747 748 // If all the data in the region is live, then the new location of the object 749 // can be calculated from the destination of the region plus the offset of the 750 // object in the region. 751 if (region_ptr->data_size() == RegionSize) { 752 result += pointer_delta(addr, region_addr); 753 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);) 754 return result; 755 } 756 757 // The new location of the object is 758 // region destination + 759 // size of the partial object extending onto the region + 760 // sizes of the live objects in the Region that are to the left of addr 761 const size_t partial_obj_size = region_ptr->partial_obj_size(); 762 HeapWord* const search_start = region_addr + partial_obj_size; 763 764 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); 765 size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr)); 766 767 result += partial_obj_size + live_to_left; 768 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);) 769 return result; 770 } 771 772 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) { 773 klassOop updated_klass; 774 if (PSParallelCompact::should_update_klass(old_klass)) { 775 updated_klass = (klassOop) calc_new_pointer(old_klass); 776 } else { 777 updated_klass = old_klass; 778 } 779 780 return updated_klass; 781 } 782 783 #ifdef ASSERT 784 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) 785 { 786 const size_t* const beg = (const size_t*)vspace->committed_low_addr(); 787 const size_t* const end = (const size_t*)vspace->committed_high_addr(); 788 for (const size_t* p = beg; p < end; ++p) { 789 assert(*p == 0, "not zero"); 790 } 791 } 792 793 void ParallelCompactData::verify_clear() 794 { 795 verify_clear(_region_vspace); 796 } 797 #endif // #ifdef ASSERT 798 799 #ifdef NOT_PRODUCT 800 ParallelCompactData::RegionData* debug_region(size_t region_index) { 801 ParallelCompactData& sd = PSParallelCompact::summary_data(); 802 return sd.region(region_index); 803 } 804 #endif 805 806 STWGCTimer PSParallelCompact::_gc_timer; 807 ParallelOldTracer PSParallelCompact::_gc_tracer; 808 elapsedTimer PSParallelCompact::_accumulated_time; 809 unsigned int PSParallelCompact::_total_invocations = 0; 810 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; 811 jlong PSParallelCompact::_time_of_last_gc = 0; 812 CollectorCounters* PSParallelCompact::_counters = NULL; 813 ParMarkBitMap PSParallelCompact::_mark_bitmap; 814 ParallelCompactData PSParallelCompact::_summary_data; 815 816 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; 817 818 void PSParallelCompact::IsAliveClosure::do_object(oop p) { ShouldNotReachHere(); } 819 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } 820 821 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); } 822 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); } 823 824 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true); 825 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false); 826 827 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p, _is_root); } 828 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); } 829 830 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); } 831 832 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) { mark_and_push(_compaction_manager, p); } 833 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); } 834 835 void PSParallelCompact::post_initialize() { 836 ParallelScavengeHeap* heap = gc_heap(); 837 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 838 839 MemRegion mr = heap->reserved_region(); 840 _ref_processor = 841 new ReferenceProcessor(mr, // span 842 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 843 (int) ParallelGCThreads, // mt processing degree 844 true, // mt discovery 845 (int) ParallelGCThreads, // mt discovery degree 846 true, // atomic_discovery 847 &_is_alive_closure, // non-header is alive closure 848 false); // write barrier for next field updates 849 _counters = new CollectorCounters("PSParallelCompact", 1); 850 851 // Initialize static fields in ParCompactionManager. 852 ParCompactionManager::initialize(mark_bitmap()); 853 } 854 855 bool PSParallelCompact::initialize() { 856 ParallelScavengeHeap* heap = gc_heap(); 857 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 858 MemRegion mr = heap->reserved_region(); 859 860 // Was the old gen get allocated successfully? 861 if (!heap->old_gen()->is_allocated()) { 862 return false; 863 } 864 865 initialize_space_info(); 866 initialize_dead_wood_limiter(); 867 868 if (!_mark_bitmap.initialize(mr)) { 869 vm_shutdown_during_initialization("Unable to allocate bit map for " 870 "parallel garbage collection for the requested heap size."); 871 return false; 872 } 873 874 if (!_summary_data.initialize(mr)) { 875 vm_shutdown_during_initialization("Unable to allocate tables for " 876 "parallel garbage collection for the requested heap size."); 877 return false; 878 } 879 880 return true; 881 } 882 883 void PSParallelCompact::initialize_space_info() 884 { 885 memset(&_space_info, 0, sizeof(_space_info)); 886 887 ParallelScavengeHeap* heap = gc_heap(); 888 PSYoungGen* young_gen = heap->young_gen(); 889 MutableSpace* perm_space = heap->perm_gen()->object_space(); 890 891 _space_info[perm_space_id].set_space(perm_space); 892 _space_info[old_space_id].set_space(heap->old_gen()->object_space()); 893 _space_info[eden_space_id].set_space(young_gen->eden_space()); 894 _space_info[from_space_id].set_space(young_gen->from_space()); 895 _space_info[to_space_id].set_space(young_gen->to_space()); 896 897 _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array()); 898 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); 899 900 _space_info[perm_space_id].set_min_dense_prefix(perm_space->top()); 901 if (TraceParallelOldGCDensePrefix) { 902 tty->print_cr("perm min_dense_prefix=" PTR_FORMAT, 903 _space_info[perm_space_id].min_dense_prefix()); 904 } 905 } 906 907 void PSParallelCompact::initialize_dead_wood_limiter() 908 { 909 const size_t max = 100; 910 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; 911 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; 912 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); 913 DEBUG_ONLY(_dwl_initialized = true;) 914 _dwl_adjustment = normal_distribution(1.0); 915 } 916 917 // Simple class for storing info about the heap at the start of GC, to be used 918 // after GC for comparison/printing. 919 class PreGCValues { 920 public: 921 PreGCValues() { } 922 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); } 923 924 void fill(ParallelScavengeHeap* heap) { 925 _heap_used = heap->used(); 926 _young_gen_used = heap->young_gen()->used_in_bytes(); 927 _old_gen_used = heap->old_gen()->used_in_bytes(); 928 _perm_gen_used = heap->perm_gen()->used_in_bytes(); 929 }; 930 931 size_t heap_used() const { return _heap_used; } 932 size_t young_gen_used() const { return _young_gen_used; } 933 size_t old_gen_used() const { return _old_gen_used; } 934 size_t perm_gen_used() const { return _perm_gen_used; } 935 936 private: 937 size_t _heap_used; 938 size_t _young_gen_used; 939 size_t _old_gen_used; 940 size_t _perm_gen_used; 941 }; 942 943 void 944 PSParallelCompact::clear_data_covering_space(SpaceId id) 945 { 946 // At this point, top is the value before GC, new_top() is the value that will 947 // be set at the end of GC. The marking bitmap is cleared to top; nothing 948 // should be marked above top. The summary data is cleared to the larger of 949 // top & new_top. 950 MutableSpace* const space = _space_info[id].space(); 951 HeapWord* const bot = space->bottom(); 952 HeapWord* const top = space->top(); 953 HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); 954 955 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); 956 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top)); 957 _mark_bitmap.clear_range(beg_bit, end_bit); 958 959 const size_t beg_region = _summary_data.addr_to_region_idx(bot); 960 const size_t end_region = 961 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top)); 962 _summary_data.clear_range(beg_region, end_region); 963 964 // Clear the data used to 'split' regions. 965 SplitInfo& split_info = _space_info[id].split_info(); 966 if (split_info.is_valid()) { 967 split_info.clear(); 968 } 969 DEBUG_ONLY(split_info.verify_clear();) 970 } 971 972 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values) 973 { 974 // Update the from & to space pointers in space_info, since they are swapped 975 // at each young gen gc. Do the update unconditionally (even though a 976 // promotion failure does not swap spaces) because an unknown number of minor 977 // collections will have swapped the spaces an unknown number of times. 978 GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer); 979 ParallelScavengeHeap* heap = gc_heap(); 980 _space_info[from_space_id].set_space(heap->young_gen()->from_space()); 981 _space_info[to_space_id].set_space(heap->young_gen()->to_space()); 982 983 pre_gc_values->fill(heap); 984 985 ParCompactionManager::reset(); 986 NOT_PRODUCT(_mark_bitmap.reset_counters()); 987 DEBUG_ONLY(add_obj_count = add_obj_size = 0;) 988 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;) 989 990 // Increment the invocation count 991 heap->increment_total_collections(true); 992 993 // We need to track unique mark sweep invocations as well. 994 _total_invocations++; 995 996 heap->print_heap_before_gc(); 997 heap->trace_heap_before_gc(&_gc_tracer); 998 999 // Fill in TLABs 1000 heap->accumulate_statistics_all_tlabs(); 1001 heap->ensure_parsability(true); // retire TLABs 1002 1003 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 1004 HandleMark hm; // Discard invalid handles created during verification 1005 gclog_or_tty->print(" VerifyBeforeGC:"); 1006 Universe::verify(); 1007 } 1008 1009 // Verify object start arrays 1010 if (VerifyObjectStartArray && 1011 VerifyBeforeGC) { 1012 heap->old_gen()->verify_object_start_array(); 1013 heap->perm_gen()->verify_object_start_array(); 1014 } 1015 1016 DEBUG_ONLY(mark_bitmap()->verify_clear();) 1017 DEBUG_ONLY(summary_data().verify_clear();) 1018 1019 // Have worker threads release resources the next time they run a task. 1020 gc_task_manager()->release_all_resources(); 1021 } 1022 1023 void PSParallelCompact::post_compact() 1024 { 1025 GCTraceTime tm("post compact", print_phases(), true, &_gc_timer); 1026 1027 for (unsigned int id = perm_space_id; id < last_space_id; ++id) { 1028 // Clear the marking bitmap, summary data and split info. 1029 clear_data_covering_space(SpaceId(id)); 1030 // Update top(). Must be done after clearing the bitmap and summary data. 1031 _space_info[id].publish_new_top(); 1032 } 1033 1034 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1035 MutableSpace* const from_space = _space_info[from_space_id].space(); 1036 MutableSpace* const to_space = _space_info[to_space_id].space(); 1037 1038 ParallelScavengeHeap* heap = gc_heap(); 1039 bool eden_empty = eden_space->is_empty(); 1040 if (!eden_empty) { 1041 eden_empty = absorb_live_data_from_eden(heap->size_policy(), 1042 heap->young_gen(), heap->old_gen()); 1043 } 1044 1045 // Update heap occupancy information which is used as input to the soft ref 1046 // clearing policy at the next gc. 1047 Universe::update_heap_info_at_gc(); 1048 1049 bool young_gen_empty = eden_empty && from_space->is_empty() && 1050 to_space->is_empty(); 1051 1052 BarrierSet* bs = heap->barrier_set(); 1053 if (bs->is_a(BarrierSet::ModRef)) { 1054 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs; 1055 MemRegion old_mr = heap->old_gen()->reserved(); 1056 MemRegion perm_mr = heap->perm_gen()->reserved(); 1057 assert(perm_mr.end() <= old_mr.start(), "Generations out of order"); 1058 1059 if (young_gen_empty) { 1060 modBS->clear(MemRegion(perm_mr.start(), old_mr.end())); 1061 } else { 1062 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end())); 1063 } 1064 } 1065 1066 Threads::gc_epilogue(); 1067 CodeCache::gc_epilogue(); 1068 JvmtiExport::gc_epilogue(); 1069 1070 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 1071 1072 ref_processor()->enqueue_discovered_references(NULL); 1073 1074 if (ZapUnusedHeapArea) { 1075 heap->gen_mangle_unused_area(); 1076 } 1077 1078 // Update time of last GC 1079 reset_millis_since_last_gc(); 1080 } 1081 1082 HeapWord* 1083 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, 1084 bool maximum_compaction) 1085 { 1086 const size_t region_size = ParallelCompactData::RegionSize; 1087 const ParallelCompactData& sd = summary_data(); 1088 1089 const MutableSpace* const space = _space_info[id].space(); 1090 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 1091 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom()); 1092 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up); 1093 1094 // Skip full regions at the beginning of the space--they are necessarily part 1095 // of the dense prefix. 1096 size_t full_count = 0; 1097 const RegionData* cp; 1098 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) { 1099 ++full_count; 1100 } 1101 1102 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1103 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1104 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; 1105 if (maximum_compaction || cp == end_cp || interval_ended) { 1106 _maximum_compaction_gc_num = total_invocations(); 1107 return sd.region_to_addr(cp); 1108 } 1109 1110 HeapWord* const new_top = _space_info[id].new_top(); 1111 const size_t space_live = pointer_delta(new_top, space->bottom()); 1112 const size_t space_used = space->used_in_words(); 1113 const size_t space_capacity = space->capacity_in_words(); 1114 1115 const double cur_density = double(space_live) / space_capacity; 1116 const double deadwood_density = 1117 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; 1118 const size_t deadwood_goal = size_t(space_capacity * deadwood_density); 1119 1120 if (TraceParallelOldGCDensePrefix) { 1121 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, 1122 cur_density, deadwood_density, deadwood_goal); 1123 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1124 "space_cap=" SIZE_FORMAT, 1125 space_live, space_used, 1126 space_capacity); 1127 } 1128 1129 // XXX - Use binary search? 1130 HeapWord* dense_prefix = sd.region_to_addr(cp); 1131 const RegionData* full_cp = cp; 1132 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1); 1133 while (cp < end_cp) { 1134 HeapWord* region_destination = cp->destination(); 1135 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination); 1136 if (TraceParallelOldGCDensePrefix && Verbose) { 1137 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " 1138 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8), 1139 sd.region(cp), region_destination, 1140 dense_prefix, cur_deadwood); 1141 } 1142 1143 if (cur_deadwood >= deadwood_goal) { 1144 // Found the region that has the correct amount of deadwood to the left. 1145 // This typically occurs after crossing a fairly sparse set of regions, so 1146 // iterate backwards over those sparse regions, looking for the region 1147 // that has the lowest density of live objects 'to the right.' 1148 size_t space_to_left = sd.region(cp) * region_size; 1149 size_t live_to_left = space_to_left - cur_deadwood; 1150 size_t space_to_right = space_capacity - space_to_left; 1151 size_t live_to_right = space_live - live_to_left; 1152 double density_to_right = double(live_to_right) / space_to_right; 1153 while (cp > full_cp) { 1154 --cp; 1155 const size_t prev_region_live_to_right = live_to_right - 1156 cp->data_size(); 1157 const size_t prev_region_space_to_right = space_to_right + region_size; 1158 double prev_region_density_to_right = 1159 double(prev_region_live_to_right) / prev_region_space_to_right; 1160 if (density_to_right <= prev_region_density_to_right) { 1161 return dense_prefix; 1162 } 1163 if (TraceParallelOldGCDensePrefix && Verbose) { 1164 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " 1165 "pc_d2r=%10.8f", sd.region(cp), density_to_right, 1166 prev_region_density_to_right); 1167 } 1168 dense_prefix -= region_size; 1169 live_to_right = prev_region_live_to_right; 1170 space_to_right = prev_region_space_to_right; 1171 density_to_right = prev_region_density_to_right; 1172 } 1173 return dense_prefix; 1174 } 1175 1176 dense_prefix += region_size; 1177 ++cp; 1178 } 1179 1180 return dense_prefix; 1181 } 1182 1183 #ifndef PRODUCT 1184 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, 1185 const SpaceId id, 1186 const bool maximum_compaction, 1187 HeapWord* const addr) 1188 { 1189 const size_t region_idx = summary_data().addr_to_region_idx(addr); 1190 RegionData* const cp = summary_data().region(region_idx); 1191 const MutableSpace* const space = _space_info[id].space(); 1192 HeapWord* const new_top = _space_info[id].new_top(); 1193 1194 const size_t space_live = pointer_delta(new_top, space->bottom()); 1195 const size_t dead_to_left = pointer_delta(addr, cp->destination()); 1196 const size_t space_cap = space->capacity_in_words(); 1197 const double dead_to_left_pct = double(dead_to_left) / space_cap; 1198 const size_t live_to_right = new_top - cp->destination(); 1199 const size_t dead_to_right = space->top() - addr - live_to_right; 1200 1201 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " 1202 "spl=" SIZE_FORMAT " " 1203 "d2l=" SIZE_FORMAT " d2l%%=%6.4f " 1204 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT 1205 " ratio=%10.8f", 1206 algorithm, addr, region_idx, 1207 space_live, 1208 dead_to_left, dead_to_left_pct, 1209 dead_to_right, live_to_right, 1210 double(dead_to_right) / live_to_right); 1211 } 1212 #endif // #ifndef PRODUCT 1213 1214 // Return a fraction indicating how much of the generation can be treated as 1215 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution 1216 // based on the density of live objects in the generation to determine a limit, 1217 // which is then adjusted so the return value is min_percent when the density is 1218 // 1. 1219 // 1220 // The following table shows some return values for a different values of the 1221 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and 1222 // min_percent is 1. 1223 // 1224 // fraction allowed as dead wood 1225 // ----------------------------------------------------------------- 1226 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 1227 // ------- ---------- ---------- ---------- ---------- ---------- ---------- 1228 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1229 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1230 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1231 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1232 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1233 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1234 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1235 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1236 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1237 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1238 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 1239 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 1240 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 1241 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 1242 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 1243 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 1244 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 1245 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 1246 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 1247 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 1248 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 1249 1250 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) 1251 { 1252 assert(_dwl_initialized, "uninitialized"); 1253 1254 // The raw limit is the value of the normal distribution at x = density. 1255 const double raw_limit = normal_distribution(density); 1256 1257 // Adjust the raw limit so it becomes the minimum when the density is 1. 1258 // 1259 // First subtract the adjustment value (which is simply the precomputed value 1260 // normal_distribution(1.0)); this yields a value of 0 when the density is 1. 1261 // Then add the minimum value, so the minimum is returned when the density is 1262 // 1. Finally, prevent negative values, which occur when the mean is not 0.5. 1263 const double min = double(min_percent) / 100.0; 1264 const double limit = raw_limit - _dwl_adjustment + min; 1265 return MAX2(limit, 0.0); 1266 } 1267 1268 ParallelCompactData::RegionData* 1269 PSParallelCompact::first_dead_space_region(const RegionData* beg, 1270 const RegionData* end) 1271 { 1272 const size_t region_size = ParallelCompactData::RegionSize; 1273 ParallelCompactData& sd = summary_data(); 1274 size_t left = sd.region(beg); 1275 size_t right = end > beg ? sd.region(end) - 1 : left; 1276 1277 // Binary search. 1278 while (left < right) { 1279 // Equivalent to (left + right) / 2, but does not overflow. 1280 const size_t middle = left + (right - left) / 2; 1281 RegionData* const middle_ptr = sd.region(middle); 1282 HeapWord* const dest = middle_ptr->destination(); 1283 HeapWord* const addr = sd.region_to_addr(middle); 1284 assert(dest != NULL, "sanity"); 1285 assert(dest <= addr, "must move left"); 1286 1287 if (middle > left && dest < addr) { 1288 right = middle - 1; 1289 } else if (middle < right && middle_ptr->data_size() == region_size) { 1290 left = middle + 1; 1291 } else { 1292 return middle_ptr; 1293 } 1294 } 1295 return sd.region(left); 1296 } 1297 1298 ParallelCompactData::RegionData* 1299 PSParallelCompact::dead_wood_limit_region(const RegionData* beg, 1300 const RegionData* end, 1301 size_t dead_words) 1302 { 1303 ParallelCompactData& sd = summary_data(); 1304 size_t left = sd.region(beg); 1305 size_t right = end > beg ? sd.region(end) - 1 : left; 1306 1307 // Binary search. 1308 while (left < right) { 1309 // Equivalent to (left + right) / 2, but does not overflow. 1310 const size_t middle = left + (right - left) / 2; 1311 RegionData* const middle_ptr = sd.region(middle); 1312 HeapWord* const dest = middle_ptr->destination(); 1313 HeapWord* const addr = sd.region_to_addr(middle); 1314 assert(dest != NULL, "sanity"); 1315 assert(dest <= addr, "must move left"); 1316 1317 const size_t dead_to_left = pointer_delta(addr, dest); 1318 if (middle > left && dead_to_left > dead_words) { 1319 right = middle - 1; 1320 } else if (middle < right && dead_to_left < dead_words) { 1321 left = middle + 1; 1322 } else { 1323 return middle_ptr; 1324 } 1325 } 1326 return sd.region(left); 1327 } 1328 1329 // The result is valid during the summary phase, after the initial summarization 1330 // of each space into itself, and before final summarization. 1331 inline double 1332 PSParallelCompact::reclaimed_ratio(const RegionData* const cp, 1333 HeapWord* const bottom, 1334 HeapWord* const top, 1335 HeapWord* const new_top) 1336 { 1337 ParallelCompactData& sd = summary_data(); 1338 1339 assert(cp != NULL, "sanity"); 1340 assert(bottom != NULL, "sanity"); 1341 assert(top != NULL, "sanity"); 1342 assert(new_top != NULL, "sanity"); 1343 assert(top >= new_top, "summary data problem?"); 1344 assert(new_top > bottom, "space is empty; should not be here"); 1345 assert(new_top >= cp->destination(), "sanity"); 1346 assert(top >= sd.region_to_addr(cp), "sanity"); 1347 1348 HeapWord* const destination = cp->destination(); 1349 const size_t dense_prefix_live = pointer_delta(destination, bottom); 1350 const size_t compacted_region_live = pointer_delta(new_top, destination); 1351 const size_t compacted_region_used = pointer_delta(top, 1352 sd.region_to_addr(cp)); 1353 const size_t reclaimable = compacted_region_used - compacted_region_live; 1354 1355 const double divisor = dense_prefix_live + 1.25 * compacted_region_live; 1356 return double(reclaimable) / divisor; 1357 } 1358 1359 // Return the address of the end of the dense prefix, a.k.a. the start of the 1360 // compacted region. The address is always on a region boundary. 1361 // 1362 // Completely full regions at the left are skipped, since no compaction can 1363 // occur in those regions. Then the maximum amount of dead wood to allow is 1364 // computed, based on the density (amount live / capacity) of the generation; 1365 // the region with approximately that amount of dead space to the left is 1366 // identified as the limit region. Regions between the last completely full 1367 // region and the limit region are scanned and the one that has the best 1368 // (maximum) reclaimed_ratio() is selected. 1369 HeapWord* 1370 PSParallelCompact::compute_dense_prefix(const SpaceId id, 1371 bool maximum_compaction) 1372 { 1373 if (ParallelOldGCSplitALot) { 1374 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) { 1375 // The value was chosen to provoke splitting a young gen space; use it. 1376 return _space_info[id].dense_prefix(); 1377 } 1378 } 1379 1380 const size_t region_size = ParallelCompactData::RegionSize; 1381 const ParallelCompactData& sd = summary_data(); 1382 1383 const MutableSpace* const space = _space_info[id].space(); 1384 HeapWord* const top = space->top(); 1385 HeapWord* const top_aligned_up = sd.region_align_up(top); 1386 HeapWord* const new_top = _space_info[id].new_top(); 1387 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top); 1388 HeapWord* const bottom = space->bottom(); 1389 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom); 1390 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 1391 const RegionData* const new_top_cp = 1392 sd.addr_to_region_ptr(new_top_aligned_up); 1393 1394 // Skip full regions at the beginning of the space--they are necessarily part 1395 // of the dense prefix. 1396 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp); 1397 assert(full_cp->destination() == sd.region_to_addr(full_cp) || 1398 space->is_empty(), "no dead space allowed to the left"); 1399 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1, 1400 "region must have dead space"); 1401 1402 // The gc number is saved whenever a maximum compaction is done, and used to 1403 // determine when the maximum compaction interval has expired. This avoids 1404 // successive max compactions for different reasons. 1405 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); 1406 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; 1407 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || 1408 total_invocations() == HeapFirstMaximumCompactionCount; 1409 if (maximum_compaction || full_cp == top_cp || interval_ended) { 1410 _maximum_compaction_gc_num = total_invocations(); 1411 return sd.region_to_addr(full_cp); 1412 } 1413 1414 const size_t space_live = pointer_delta(new_top, bottom); 1415 const size_t space_used = space->used_in_words(); 1416 const size_t space_capacity = space->capacity_in_words(); 1417 1418 const double density = double(space_live) / double(space_capacity); 1419 const size_t min_percent_free = 1420 id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio; 1421 const double limiter = dead_wood_limiter(density, min_percent_free); 1422 const size_t dead_wood_max = space_used - space_live; 1423 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), 1424 dead_wood_max); 1425 1426 if (TraceParallelOldGCDensePrefix) { 1427 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " 1428 "space_cap=" SIZE_FORMAT, 1429 space_live, space_used, 1430 space_capacity); 1431 tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f " 1432 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, 1433 density, min_percent_free, limiter, 1434 dead_wood_max, dead_wood_limit); 1435 } 1436 1437 // Locate the region with the desired amount of dead space to the left. 1438 const RegionData* const limit_cp = 1439 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit); 1440 1441 // Scan from the first region with dead space to the limit region and find the 1442 // one with the best (largest) reclaimed ratio. 1443 double best_ratio = 0.0; 1444 const RegionData* best_cp = full_cp; 1445 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) { 1446 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); 1447 if (tmp_ratio > best_ratio) { 1448 best_cp = cp; 1449 best_ratio = tmp_ratio; 1450 } 1451 } 1452 1453 #if 0 1454 // Something to consider: if the region with the best ratio is 'close to' the 1455 // first region w/free space, choose the first region with free space 1456 // ("first-free"). The first-free region is usually near the start of the 1457 // heap, which means we are copying most of the heap already, so copy a bit 1458 // more to get complete compaction. 1459 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) { 1460 _maximum_compaction_gc_num = total_invocations(); 1461 best_cp = full_cp; 1462 } 1463 #endif // #if 0 1464 1465 return sd.region_to_addr(best_cp); 1466 } 1467 1468 #ifndef PRODUCT 1469 void 1470 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start, 1471 size_t words) 1472 { 1473 if (TraceParallelOldGCSummaryPhase) { 1474 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") " 1475 SIZE_FORMAT, start, start + words, words); 1476 } 1477 1478 ObjectStartArray* const start_array = _space_info[id].start_array(); 1479 CollectedHeap::fill_with_objects(start, words); 1480 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) { 1481 _mark_bitmap.mark_obj(p, words); 1482 _summary_data.add_obj(p, words); 1483 start_array->allocate_block(p); 1484 } 1485 } 1486 1487 void 1488 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start) 1489 { 1490 ParallelCompactData& sd = summary_data(); 1491 MutableSpace* space = _space_info[id].space(); 1492 1493 // Find the source and destination start addresses. 1494 HeapWord* const src_addr = sd.region_align_down(start); 1495 HeapWord* dst_addr; 1496 if (src_addr < start) { 1497 dst_addr = sd.addr_to_region_ptr(src_addr)->destination(); 1498 } else if (src_addr > space->bottom()) { 1499 // The start (the original top() value) is aligned to a region boundary so 1500 // the associated region does not have a destination. Compute the 1501 // destination from the previous region. 1502 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1; 1503 dst_addr = cp->destination() + cp->data_size(); 1504 } else { 1505 // Filling the entire space. 1506 dst_addr = space->bottom(); 1507 } 1508 assert(dst_addr != NULL, "sanity"); 1509 1510 // Update the summary data. 1511 bool result = _summary_data.summarize(_space_info[id].split_info(), 1512 src_addr, space->top(), NULL, 1513 dst_addr, space->end(), 1514 _space_info[id].new_top_addr()); 1515 assert(result, "should not fail: bad filler object size"); 1516 } 1517 1518 void 1519 PSParallelCompact::provoke_split_fill_survivor(SpaceId id) 1520 { 1521 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) { 1522 return; 1523 } 1524 1525 MutableSpace* const space = _space_info[id].space(); 1526 if (space->is_empty()) { 1527 HeapWord* b = space->bottom(); 1528 HeapWord* t = b + space->capacity_in_words() / 2; 1529 space->set_top(t); 1530 if (ZapUnusedHeapArea) { 1531 space->set_top_for_allocations(); 1532 } 1533 1534 size_t min_size = CollectedHeap::min_fill_size(); 1535 size_t obj_len = min_size; 1536 while (b + obj_len <= t) { 1537 CollectedHeap::fill_with_object(b, obj_len); 1538 mark_bitmap()->mark_obj(b, obj_len); 1539 summary_data().add_obj(b, obj_len); 1540 b += obj_len; 1541 obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ... 1542 } 1543 if (b < t) { 1544 // The loop didn't completely fill to t (top); adjust top downward. 1545 space->set_top(b); 1546 if (ZapUnusedHeapArea) { 1547 space->set_top_for_allocations(); 1548 } 1549 } 1550 1551 HeapWord** nta = _space_info[id].new_top_addr(); 1552 bool result = summary_data().summarize(_space_info[id].split_info(), 1553 space->bottom(), space->top(), NULL, 1554 space->bottom(), space->end(), nta); 1555 assert(result, "space must fit into itself"); 1556 } 1557 } 1558 1559 void 1560 PSParallelCompact::provoke_split(bool & max_compaction) 1561 { 1562 if (total_invocations() % ParallelOldGCSplitInterval != 0) { 1563 return; 1564 } 1565 1566 const size_t region_size = ParallelCompactData::RegionSize; 1567 ParallelCompactData& sd = summary_data(); 1568 1569 MutableSpace* const eden_space = _space_info[eden_space_id].space(); 1570 MutableSpace* const from_space = _space_info[from_space_id].space(); 1571 const size_t eden_live = pointer_delta(eden_space->top(), 1572 _space_info[eden_space_id].new_top()); 1573 const size_t from_live = pointer_delta(from_space->top(), 1574 _space_info[from_space_id].new_top()); 1575 1576 const size_t min_fill_size = CollectedHeap::min_fill_size(); 1577 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top()); 1578 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0; 1579 const size_t from_free = pointer_delta(from_space->end(), from_space->top()); 1580 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0; 1581 1582 // Choose the space to split; need at least 2 regions live (or fillable). 1583 SpaceId id; 1584 MutableSpace* space; 1585 size_t live_words; 1586 size_t fill_words; 1587 if (eden_live + eden_fillable >= region_size * 2) { 1588 id = eden_space_id; 1589 space = eden_space; 1590 live_words = eden_live; 1591 fill_words = eden_fillable; 1592 } else if (from_live + from_fillable >= region_size * 2) { 1593 id = from_space_id; 1594 space = from_space; 1595 live_words = from_live; 1596 fill_words = from_fillable; 1597 } else { 1598 return; // Give up. 1599 } 1600 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity"); 1601 1602 if (live_words < region_size * 2) { 1603 // Fill from top() to end() w/live objects of mixed sizes. 1604 HeapWord* const fill_start = space->top(); 1605 live_words += fill_words; 1606 1607 space->set_top(fill_start + fill_words); 1608 if (ZapUnusedHeapArea) { 1609 space->set_top_for_allocations(); 1610 } 1611 1612 HeapWord* cur_addr = fill_start; 1613 while (fill_words > 0) { 1614 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size; 1615 size_t cur_size = MIN2(align_object_size_(r), fill_words); 1616 if (fill_words - cur_size < min_fill_size) { 1617 cur_size = fill_words; // Avoid leaving a fragment too small to fill. 1618 } 1619 1620 CollectedHeap::fill_with_object(cur_addr, cur_size); 1621 mark_bitmap()->mark_obj(cur_addr, cur_size); 1622 sd.add_obj(cur_addr, cur_size); 1623 1624 cur_addr += cur_size; 1625 fill_words -= cur_size; 1626 } 1627 1628 summarize_new_objects(id, fill_start); 1629 } 1630 1631 max_compaction = false; 1632 1633 // Manipulate the old gen so that it has room for about half of the live data 1634 // in the target young gen space (live_words / 2). 1635 id = old_space_id; 1636 space = _space_info[id].space(); 1637 const size_t free_at_end = space->free_in_words(); 1638 const size_t free_target = align_object_size(live_words / 2); 1639 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top()); 1640 1641 if (free_at_end >= free_target + min_fill_size) { 1642 // Fill space above top() and set the dense prefix so everything survives. 1643 HeapWord* const fill_start = space->top(); 1644 const size_t fill_size = free_at_end - free_target; 1645 space->set_top(space->top() + fill_size); 1646 if (ZapUnusedHeapArea) { 1647 space->set_top_for_allocations(); 1648 } 1649 fill_with_live_objects(id, fill_start, fill_size); 1650 summarize_new_objects(id, fill_start); 1651 _space_info[id].set_dense_prefix(sd.region_align_down(space->top())); 1652 } else if (dead + free_at_end > free_target) { 1653 // Find a dense prefix that makes the right amount of space available. 1654 HeapWord* cur = sd.region_align_down(space->top()); 1655 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination(); 1656 size_t dead_to_right = pointer_delta(space->end(), cur_destination); 1657 while (dead_to_right < free_target) { 1658 cur -= region_size; 1659 cur_destination = sd.addr_to_region_ptr(cur)->destination(); 1660 dead_to_right = pointer_delta(space->end(), cur_destination); 1661 } 1662 _space_info[id].set_dense_prefix(cur); 1663 } 1664 } 1665 #endif // #ifndef PRODUCT 1666 1667 void PSParallelCompact::summarize_spaces_quick() 1668 { 1669 for (unsigned int i = 0; i < last_space_id; ++i) { 1670 const MutableSpace* space = _space_info[i].space(); 1671 HeapWord** nta = _space_info[i].new_top_addr(); 1672 bool result = _summary_data.summarize(_space_info[i].split_info(), 1673 space->bottom(), space->top(), NULL, 1674 space->bottom(), space->end(), nta); 1675 assert(result, "space must fit into itself"); 1676 _space_info[i].set_dense_prefix(space->bottom()); 1677 } 1678 1679 #ifndef PRODUCT 1680 if (ParallelOldGCSplitALot) { 1681 provoke_split_fill_survivor(to_space_id); 1682 } 1683 #endif // #ifndef PRODUCT 1684 } 1685 1686 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) 1687 { 1688 HeapWord* const dense_prefix_end = dense_prefix(id); 1689 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end); 1690 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); 1691 if (dead_space_crosses_boundary(region, dense_prefix_bit)) { 1692 // Only enough dead space is filled so that any remaining dead space to the 1693 // left is larger than the minimum filler object. (The remainder is filled 1694 // during the copy/update phase.) 1695 // 1696 // The size of the dead space to the right of the boundary is not a 1697 // concern, since compaction will be able to use whatever space is 1698 // available. 1699 // 1700 // Here '||' is the boundary, 'x' represents a don't care bit and a box 1701 // surrounds the space to be filled with an object. 1702 // 1703 // In the 32-bit VM, each bit represents two 32-bit words: 1704 // +---+ 1705 // a) beg_bits: ... x x x | 0 | || 0 x x ... 1706 // end_bits: ... x x x | 0 | || 0 x x ... 1707 // +---+ 1708 // 1709 // In the 64-bit VM, each bit represents one 64-bit word: 1710 // +------------+ 1711 // b) beg_bits: ... x x x | 0 || 0 | x x ... 1712 // end_bits: ... x x 1 | 0 || 0 | x x ... 1713 // +------------+ 1714 // +-------+ 1715 // c) beg_bits: ... x x | 0 0 | || 0 x x ... 1716 // end_bits: ... x 1 | 0 0 | || 0 x x ... 1717 // +-------+ 1718 // +-----------+ 1719 // d) beg_bits: ... x | 0 0 0 | || 0 x x ... 1720 // end_bits: ... 1 | 0 0 0 | || 0 x x ... 1721 // +-----------+ 1722 // +-------+ 1723 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... 1724 // end_bits: ... 0 0 | 0 0 | || 0 x x ... 1725 // +-------+ 1726 1727 // Initially assume case a, c or e will apply. 1728 size_t obj_len = CollectedHeap::min_fill_size(); 1729 HeapWord* obj_beg = dense_prefix_end - obj_len; 1730 1731 #ifdef _LP64 1732 if (MinObjAlignment > 1) { // object alignment > heap word size 1733 // Cases a, c or e. 1734 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { 1735 // Case b above. 1736 obj_beg = dense_prefix_end - 1; 1737 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && 1738 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { 1739 // Case d above. 1740 obj_beg = dense_prefix_end - 3; 1741 obj_len = 3; 1742 } 1743 #endif // #ifdef _LP64 1744 1745 CollectedHeap::fill_with_object(obj_beg, obj_len); 1746 _mark_bitmap.mark_obj(obj_beg, obj_len); 1747 _summary_data.add_obj(obj_beg, obj_len); 1748 assert(start_array(id) != NULL, "sanity"); 1749 start_array(id)->allocate_block(obj_beg); 1750 } 1751 } 1752 1753 void 1754 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr) 1755 { 1756 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr); 1757 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr); 1758 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up); 1759 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) { 1760 cur->set_source_region(0); 1761 } 1762 } 1763 1764 void 1765 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) 1766 { 1767 assert(id < last_space_id, "id out of range"); 1768 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() || 1769 ParallelOldGCSplitALot && id == old_space_id, 1770 "should have been reset in summarize_spaces_quick()"); 1771 1772 const MutableSpace* space = _space_info[id].space(); 1773 if (_space_info[id].new_top() != space->bottom()) { 1774 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); 1775 _space_info[id].set_dense_prefix(dense_prefix_end); 1776 1777 #ifndef PRODUCT 1778 if (TraceParallelOldGCDensePrefix) { 1779 print_dense_prefix_stats("ratio", id, maximum_compaction, 1780 dense_prefix_end); 1781 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); 1782 print_dense_prefix_stats("density", id, maximum_compaction, addr); 1783 } 1784 #endif // #ifndef PRODUCT 1785 1786 // Recompute the summary data, taking into account the dense prefix. If 1787 // every last byte will be reclaimed, then the existing summary data which 1788 // compacts everything can be left in place. 1789 if (!maximum_compaction && dense_prefix_end != space->bottom()) { 1790 // If dead space crosses the dense prefix boundary, it is (at least 1791 // partially) filled with a dummy object, marked live and added to the 1792 // summary data. This simplifies the copy/update phase and must be done 1793 // before the final locations of objects are determined, to prevent 1794 // leaving a fragment of dead space that is too small to fill. 1795 fill_dense_prefix_end(id); 1796 1797 // Compute the destination of each Region, and thus each object. 1798 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); 1799 _summary_data.summarize(_space_info[id].split_info(), 1800 dense_prefix_end, space->top(), NULL, 1801 dense_prefix_end, space->end(), 1802 _space_info[id].new_top_addr()); 1803 } 1804 } 1805 1806 if (TraceParallelOldGCSummaryPhase) { 1807 const size_t region_size = ParallelCompactData::RegionSize; 1808 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); 1809 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end); 1810 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); 1811 HeapWord* const new_top = _space_info[id].new_top(); 1812 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top); 1813 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); 1814 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " 1815 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " 1816 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, 1817 id, space->capacity_in_words(), dense_prefix_end, 1818 dp_region, dp_words / region_size, 1819 cr_words / region_size, new_top); 1820 } 1821 } 1822 1823 #ifndef PRODUCT 1824 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id, 1825 HeapWord* dst_beg, HeapWord* dst_end, 1826 SpaceId src_space_id, 1827 HeapWord* src_beg, HeapWord* src_end) 1828 { 1829 if (TraceParallelOldGCSummaryPhase) { 1830 tty->print_cr("summarizing %d [%s] into %d [%s]: " 1831 "src=" PTR_FORMAT "-" PTR_FORMAT " " 1832 SIZE_FORMAT "-" SIZE_FORMAT " " 1833 "dst=" PTR_FORMAT "-" PTR_FORMAT " " 1834 SIZE_FORMAT "-" SIZE_FORMAT, 1835 src_space_id, space_names[src_space_id], 1836 dst_space_id, space_names[dst_space_id], 1837 src_beg, src_end, 1838 _summary_data.addr_to_region_idx(src_beg), 1839 _summary_data.addr_to_region_idx(src_end), 1840 dst_beg, dst_end, 1841 _summary_data.addr_to_region_idx(dst_beg), 1842 _summary_data.addr_to_region_idx(dst_end)); 1843 } 1844 } 1845 #endif // #ifndef PRODUCT 1846 1847 void PSParallelCompact::summary_phase(ParCompactionManager* cm, 1848 bool maximum_compaction) 1849 { 1850 GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer); 1851 // trace("2"); 1852 1853 #ifdef ASSERT 1854 if (TraceParallelOldGCMarkingPhase) { 1855 tty->print_cr("add_obj_count=" SIZE_FORMAT " " 1856 "add_obj_bytes=" SIZE_FORMAT, 1857 add_obj_count, add_obj_size * HeapWordSize); 1858 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " " 1859 "mark_bitmap_bytes=" SIZE_FORMAT, 1860 mark_bitmap_count, mark_bitmap_size * HeapWordSize); 1861 } 1862 #endif // #ifdef ASSERT 1863 1864 // Quick summarization of each space into itself, to see how much is live. 1865 summarize_spaces_quick(); 1866 1867 if (TraceParallelOldGCSummaryPhase) { 1868 tty->print_cr("summary_phase: after summarizing each space to self"); 1869 Universe::print(); 1870 NOT_PRODUCT(print_region_ranges()); 1871 if (Verbose) { 1872 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); 1873 } 1874 } 1875 1876 // The amount of live data that will end up in old space (assuming it fits). 1877 size_t old_space_total_live = 0; 1878 assert(perm_space_id < old_space_id, "should not count perm data here"); 1879 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 1880 old_space_total_live += pointer_delta(_space_info[id].new_top(), 1881 _space_info[id].space()->bottom()); 1882 } 1883 1884 MutableSpace* const old_space = _space_info[old_space_id].space(); 1885 const size_t old_capacity = old_space->capacity_in_words(); 1886 if (old_space_total_live > old_capacity) { 1887 // XXX - should also try to expand 1888 maximum_compaction = true; 1889 } 1890 #ifndef PRODUCT 1891 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) { 1892 provoke_split(maximum_compaction); 1893 } 1894 #endif // #ifndef PRODUCT 1895 1896 // Permanent and Old generations. 1897 summarize_space(perm_space_id, maximum_compaction); 1898 summarize_space(old_space_id, maximum_compaction); 1899 1900 // Summarize the remaining spaces in the young gen. The initial target space 1901 // is the old gen. If a space does not fit entirely into the target, then the 1902 // remainder is compacted into the space itself and that space becomes the new 1903 // target. 1904 SpaceId dst_space_id = old_space_id; 1905 HeapWord* dst_space_end = old_space->end(); 1906 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr(); 1907 for (unsigned int id = eden_space_id; id < last_space_id; ++id) { 1908 const MutableSpace* space = _space_info[id].space(); 1909 const size_t live = pointer_delta(_space_info[id].new_top(), 1910 space->bottom()); 1911 const size_t available = pointer_delta(dst_space_end, *new_top_addr); 1912 1913 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end, 1914 SpaceId(id), space->bottom(), space->top());) 1915 if (live > 0 && live <= available) { 1916 // All the live data will fit. 1917 bool done = _summary_data.summarize(_space_info[id].split_info(), 1918 space->bottom(), space->top(), 1919 NULL, 1920 *new_top_addr, dst_space_end, 1921 new_top_addr); 1922 assert(done, "space must fit into old gen"); 1923 1924 // Reset the new_top value for the space. 1925 _space_info[id].set_new_top(space->bottom()); 1926 } else if (live > 0) { 1927 // Attempt to fit part of the source space into the target space. 1928 HeapWord* next_src_addr = NULL; 1929 bool done = _summary_data.summarize(_space_info[id].split_info(), 1930 space->bottom(), space->top(), 1931 &next_src_addr, 1932 *new_top_addr, dst_space_end, 1933 new_top_addr); 1934 assert(!done, "space should not fit into old gen"); 1935 assert(next_src_addr != NULL, "sanity"); 1936 1937 // The source space becomes the new target, so the remainder is compacted 1938 // within the space itself. 1939 dst_space_id = SpaceId(id); 1940 dst_space_end = space->end(); 1941 new_top_addr = _space_info[id].new_top_addr(); 1942 NOT_PRODUCT(summary_phase_msg(dst_space_id, 1943 space->bottom(), dst_space_end, 1944 SpaceId(id), next_src_addr, space->top());) 1945 done = _summary_data.summarize(_space_info[id].split_info(), 1946 next_src_addr, space->top(), 1947 NULL, 1948 space->bottom(), dst_space_end, 1949 new_top_addr); 1950 assert(done, "space must fit when compacted into itself"); 1951 assert(*new_top_addr <= space->top(), "usage should not grow"); 1952 } 1953 } 1954 1955 if (TraceParallelOldGCSummaryPhase) { 1956 tty->print_cr("summary_phase: after final summarization"); 1957 Universe::print(); 1958 NOT_PRODUCT(print_region_ranges()); 1959 if (Verbose) { 1960 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info)); 1961 } 1962 } 1963 } 1964 1965 // This method should contain all heap-specific policy for invoking a full 1966 // collection. invoke_no_policy() will only attempt to compact the heap; it 1967 // will do nothing further. If we need to bail out for policy reasons, scavenge 1968 // before full gc, or any other specialized behavior, it needs to be added here. 1969 // 1970 // Note that this method should only be called from the vm_thread while at a 1971 // safepoint. 1972 // 1973 // Note that the all_soft_refs_clear flag in the collector policy 1974 // may be true because this method can be called without intervening 1975 // activity. For example when the heap space is tight and full measure 1976 // are being taken to free space. 1977 void PSParallelCompact::invoke(bool maximum_heap_compaction) { 1978 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 1979 assert(Thread::current() == (Thread*)VMThread::vm_thread(), 1980 "should be in vm thread"); 1981 1982 ParallelScavengeHeap* heap = gc_heap(); 1983 GCCause::Cause gc_cause = heap->gc_cause(); 1984 assert(!heap->is_gc_active(), "not reentrant"); 1985 1986 PSAdaptiveSizePolicy* policy = heap->size_policy(); 1987 IsGCActiveMark mark; 1988 1989 if (ScavengeBeforeFullGC) { 1990 PSScavenge::invoke_no_policy(); 1991 } 1992 1993 const bool clear_all_soft_refs = 1994 heap->collector_policy()->should_clear_all_soft_refs(); 1995 1996 PSParallelCompact::invoke_no_policy(clear_all_soft_refs || 1997 maximum_heap_compaction); 1998 } 1999 2000 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) { 2001 size_t addr_region_index = addr_to_region_idx(addr); 2002 return region_index == addr_region_index; 2003 } 2004 2005 // This method contains no policy. You should probably 2006 // be calling invoke() instead. 2007 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { 2008 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); 2009 assert(ref_processor() != NULL, "Sanity"); 2010 2011 if (GC_locker::check_active_before_gc()) { 2012 return false; 2013 } 2014 2015 ParallelScavengeHeap* heap = gc_heap(); 2016 2017 _gc_timer.register_gc_start(os::elapsed_counter()); 2018 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 2019 2020 TimeStamp marking_start; 2021 TimeStamp compaction_start; 2022 TimeStamp collection_exit; 2023 2024 GCCause::Cause gc_cause = heap->gc_cause(); 2025 PSYoungGen* young_gen = heap->young_gen(); 2026 PSOldGen* old_gen = heap->old_gen(); 2027 PSPermGen* perm_gen = heap->perm_gen(); 2028 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 2029 2030 // The scope of casr should end after code that can change 2031 // CollectorPolicy::_should_clear_all_soft_refs. 2032 ClearedAllSoftRefs casr(maximum_heap_compaction, 2033 heap->collector_policy()); 2034 2035 if (ZapUnusedHeapArea) { 2036 // Save information needed to minimize mangling 2037 heap->record_gen_tops_before_GC(); 2038 } 2039 2040 heap->pre_full_gc_dump(&_gc_timer); 2041 2042 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes; 2043 2044 // Make sure data structures are sane, make the heap parsable, and do other 2045 // miscellaneous bookkeeping. 2046 PreGCValues pre_gc_values; 2047 pre_compact(&pre_gc_values); 2048 2049 // Get the compaction manager reserved for the VM thread. 2050 ParCompactionManager* const vmthread_cm = 2051 ParCompactionManager::manager_array(gc_task_manager()->workers()); 2052 2053 // Place after pre_compact() where the number of invocations is incremented. 2054 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 2055 2056 { 2057 ResourceMark rm; 2058 HandleMark hm; 2059 2060 // Set the number of GC threads to be used in this collection 2061 gc_task_manager()->set_active_gang(); 2062 gc_task_manager()->task_idle_workers(); 2063 heap->set_par_threads(gc_task_manager()->active_workers()); 2064 2065 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 2066 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL); 2067 TraceCollectorStats tcs(counters()); 2068 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause); 2069 2070 if (TraceGen1Time) accumulated_time()->start(); 2071 2072 // Let the size policy know we're starting 2073 size_policy->major_collection_begin(); 2074 2075 // When collecting the permanent generation methodOops may be moving, 2076 // so we either have to flush all bcp data or convert it into bci. 2077 CodeCache::gc_prologue(); 2078 Threads::gc_prologue(); 2079 2080 COMPILER2_PRESENT(DerivedPointerTable::clear()); 2081 2082 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 2083 ref_processor()->setup_policy(maximum_heap_compaction); 2084 2085 bool marked_for_unloading = false; 2086 2087 marking_start.update(); 2088 marking_phase(vmthread_cm, maximum_heap_compaction); 2089 2090 #ifndef PRODUCT 2091 if (TraceParallelOldGCMarkingPhase) { 2092 gclog_or_tty->print_cr("marking_phase: cas_tries %d cas_retries %d " 2093 "cas_by_another %d", 2094 mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(), 2095 mark_bitmap()->cas_by_another()); 2096 } 2097 #endif // #ifndef PRODUCT 2098 2099 bool max_on_system_gc = UseMaximumCompactionOnSystemGC 2100 && gc_cause == GCCause::_java_lang_system_gc; 2101 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc); 2102 2103 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); 2104 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); 2105 2106 // adjust_roots() updates Universe::_intArrayKlassObj which is 2107 // needed by the compaction for filling holes in the dense prefix. 2108 adjust_roots(); 2109 2110 compaction_start.update(); 2111 // Does the perm gen always have to be done serially because 2112 // klasses are used in the update of an object? 2113 compact_perm(vmthread_cm); 2114 2115 compact(); 2116 2117 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be 2118 // done before resizing. 2119 post_compact(); 2120 2121 // Let the size policy know we're done 2122 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); 2123 2124 if (UseAdaptiveSizePolicy) { 2125 if (PrintAdaptiveSizePolicy) { 2126 gclog_or_tty->print("AdaptiveSizeStart: "); 2127 gclog_or_tty->stamp(); 2128 gclog_or_tty->print_cr(" collection: %d ", 2129 heap->total_collections()); 2130 if (Verbose) { 2131 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" 2132 " perm_gen_capacity: %d ", 2133 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), 2134 perm_gen->capacity_in_bytes()); 2135 } 2136 } 2137 2138 // Don't check if the size_policy is ready here. Let 2139 // the size_policy check that internally. 2140 if (UseAdaptiveGenerationSizePolicyAtMajorCollection && 2141 ((gc_cause != GCCause::_java_lang_system_gc) || 2142 UseAdaptiveSizePolicyWithSystemGC)) { 2143 // Calculate optimal free space amounts 2144 assert(young_gen->max_size() > 2145 young_gen->from_space()->capacity_in_bytes() + 2146 young_gen->to_space()->capacity_in_bytes(), 2147 "Sizes of space in young gen are out-of-bounds"); 2148 size_t max_eden_size = young_gen->max_size() - 2149 young_gen->from_space()->capacity_in_bytes() - 2150 young_gen->to_space()->capacity_in_bytes(); 2151 size_policy->compute_generation_free_space( 2152 young_gen->used_in_bytes(), 2153 young_gen->eden_space()->used_in_bytes(), 2154 old_gen->used_in_bytes(), 2155 perm_gen->used_in_bytes(), 2156 young_gen->eden_space()->capacity_in_bytes(), 2157 old_gen->max_gen_size(), 2158 max_eden_size, 2159 true /* full gc*/, 2160 gc_cause, 2161 heap->collector_policy()); 2162 2163 heap->resize_old_gen( 2164 size_policy->calculated_old_free_size_in_bytes()); 2165 2166 // Don't resize the young generation at an major collection. A 2167 // desired young generation size may have been calculated but 2168 // resizing the young generation complicates the code because the 2169 // resizing of the old generation may have moved the boundary 2170 // between the young generation and the old generation. Let the 2171 // young generation resizing happen at the minor collections. 2172 } 2173 if (PrintAdaptiveSizePolicy) { 2174 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 2175 heap->total_collections()); 2176 } 2177 } 2178 2179 if (UsePerfData) { 2180 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 2181 counters->update_counters(); 2182 counters->update_old_capacity(old_gen->capacity_in_bytes()); 2183 counters->update_young_capacity(young_gen->capacity_in_bytes()); 2184 } 2185 2186 heap->resize_all_tlabs(); 2187 2188 // We collected the perm gen, so we'll resize it here. 2189 perm_gen->compute_new_size(pre_gc_values.perm_gen_used()); 2190 2191 if (TraceGen1Time) accumulated_time()->stop(); 2192 2193 if (PrintGC) { 2194 if (PrintGCDetails) { 2195 // No GC timestamp here. This is after GC so it would be confusing. 2196 young_gen->print_used_change(pre_gc_values.young_gen_used()); 2197 old_gen->print_used_change(pre_gc_values.old_gen_used()); 2198 heap->print_heap_change(pre_gc_values.heap_used()); 2199 // Print perm gen last (print_heap_change() excludes the perm gen). 2200 perm_gen->print_used_change(pre_gc_values.perm_gen_used()); 2201 } else { 2202 heap->print_heap_change(pre_gc_values.heap_used()); 2203 } 2204 } 2205 2206 // Track memory usage and detect low memory 2207 MemoryService::track_memory_usage(); 2208 heap->update_counters(); 2209 gc_task_manager()->release_idle_workers(); 2210 } 2211 2212 #ifdef ASSERT 2213 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) { 2214 ParCompactionManager* const cm = 2215 ParCompactionManager::manager_array(int(i)); 2216 assert(cm->marking_stack()->is_empty(), "should be empty"); 2217 assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty"); 2218 assert(cm->revisit_klass_stack()->is_empty(), "should be empty"); 2219 } 2220 #endif // ASSERT 2221 2222 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 2223 HandleMark hm; // Discard invalid handles created during verification 2224 gclog_or_tty->print(" VerifyAfterGC:"); 2225 Universe::verify(); 2226 } 2227 2228 // Re-verify object start arrays 2229 if (VerifyObjectStartArray && 2230 VerifyAfterGC) { 2231 old_gen->verify_object_start_array(); 2232 perm_gen->verify_object_start_array(); 2233 } 2234 2235 if (ZapUnusedHeapArea) { 2236 old_gen->object_space()->check_mangled_unused_area_complete(); 2237 perm_gen->object_space()->check_mangled_unused_area_complete(); 2238 } 2239 2240 NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); 2241 2242 collection_exit.update(); 2243 2244 heap->print_heap_after_gc(); 2245 heap->trace_heap_after_gc(&_gc_tracer); 2246 2247 if (PrintGCTaskTimeStamps) { 2248 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " 2249 INT64_FORMAT, 2250 marking_start.ticks(), compaction_start.ticks(), 2251 collection_exit.ticks()); 2252 gc_task_manager()->print_task_time_stamps(); 2253 } 2254 2255 heap->post_full_gc_dump(&_gc_timer); 2256 2257 #ifdef TRACESPINNING 2258 ParallelTaskTerminator::print_termination_counts(); 2259 #endif 2260 2261 _gc_timer.register_gc_end(os::elapsed_counter()); 2262 2263 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id)); 2264 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 2265 2266 return true; 2267 } 2268 2269 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 2270 PSYoungGen* young_gen, 2271 PSOldGen* old_gen) { 2272 MutableSpace* const eden_space = young_gen->eden_space(); 2273 assert(!eden_space->is_empty(), "eden must be non-empty"); 2274 assert(young_gen->virtual_space()->alignment() == 2275 old_gen->virtual_space()->alignment(), "alignments do not match"); 2276 2277 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { 2278 return false; 2279 } 2280 2281 // Both generations must be completely committed. 2282 if (young_gen->virtual_space()->uncommitted_size() != 0) { 2283 return false; 2284 } 2285 if (old_gen->virtual_space()->uncommitted_size() != 0) { 2286 return false; 2287 } 2288 2289 // Figure out how much to take from eden. Include the average amount promoted 2290 // in the total; otherwise the next young gen GC will simply bail out to a 2291 // full GC. 2292 const size_t alignment = old_gen->virtual_space()->alignment(); 2293 const size_t eden_used = eden_space->used_in_bytes(); 2294 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); 2295 const size_t absorb_size = align_size_up(eden_used + promoted, alignment); 2296 const size_t eden_capacity = eden_space->capacity_in_bytes(); 2297 2298 if (absorb_size >= eden_capacity) { 2299 return false; // Must leave some space in eden. 2300 } 2301 2302 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; 2303 if (new_young_size < young_gen->min_gen_size()) { 2304 return false; // Respect young gen minimum size. 2305 } 2306 2307 if (TraceAdaptiveGCBoundary && Verbose) { 2308 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: " 2309 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " 2310 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " 2311 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", 2312 absorb_size / K, 2313 eden_capacity / K, (eden_capacity - absorb_size) / K, 2314 young_gen->from_space()->used_in_bytes() / K, 2315 young_gen->to_space()->used_in_bytes() / K, 2316 young_gen->capacity_in_bytes() / K, new_young_size / K); 2317 } 2318 2319 // Fill the unused part of the old gen. 2320 MutableSpace* const old_space = old_gen->object_space(); 2321 HeapWord* const unused_start = old_space->top(); 2322 size_t const unused_words = pointer_delta(old_space->end(), unused_start); 2323 2324 if (unused_words > 0) { 2325 if (unused_words < CollectedHeap::min_fill_size()) { 2326 return false; // If the old gen cannot be filled, must give up. 2327 } 2328 CollectedHeap::fill_with_objects(unused_start, unused_words); 2329 } 2330 2331 // Take the live data from eden and set both top and end in the old gen to 2332 // eden top. (Need to set end because reset_after_change() mangles the region 2333 // from end to virtual_space->high() in debug builds). 2334 HeapWord* const new_top = eden_space->top(); 2335 old_gen->virtual_space()->expand_into(young_gen->virtual_space(), 2336 absorb_size); 2337 young_gen->reset_after_change(); 2338 old_space->set_top(new_top); 2339 old_space->set_end(new_top); 2340 old_gen->reset_after_change(); 2341 2342 // Update the object start array for the filler object and the data from eden. 2343 ObjectStartArray* const start_array = old_gen->start_array(); 2344 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) { 2345 start_array->allocate_block(p); 2346 } 2347 2348 // Could update the promoted average here, but it is not typically updated at 2349 // full GCs and the value to use is unclear. Something like 2350 // 2351 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. 2352 2353 size_policy->set_bytes_absorbed_from_eden(absorb_size); 2354 return true; 2355 } 2356 2357 GCTaskManager* const PSParallelCompact::gc_task_manager() { 2358 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 2359 "shouldn't return NULL"); 2360 return ParallelScavengeHeap::gc_task_manager(); 2361 } 2362 2363 void PSParallelCompact::marking_phase(ParCompactionManager* cm, bool maximum_heap_compaction) { 2364 // Recursively traverse all live objects and mark them 2365 GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer); 2366 2367 ParallelScavengeHeap* heap = gc_heap(); 2368 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2369 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2370 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2371 ParallelTaskTerminator terminator(active_gc_threads, qset); 2372 2373 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm); 2374 PSParallelCompact::FollowStackClosure follow_stack_closure(cm); 2375 2376 { 2377 GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer); 2378 2379 ParallelScavengeHeap::ParStrongRootsScope psrs; 2380 2381 GCTaskQueue* q = GCTaskQueue::create(); 2382 2383 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe)); 2384 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles)); 2385 // We scan the thread roots in parallel 2386 Threads::create_thread_roots_marking_tasks(q); 2387 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer)); 2388 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler)); 2389 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management)); 2390 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary)); 2391 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti)); 2392 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache)); 2393 2394 if (active_gc_threads > 1) { 2395 for (uint j = 0; j < active_gc_threads; j++) { 2396 q->enqueue(new StealMarkingTask(&terminator)); 2397 } 2398 } 2399 2400 gc_task_manager()->execute_and_wait(q); 2401 } 2402 2403 // Process reference objects found during marking 2404 { 2405 GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer); 2406 2407 ReferenceProcessorStats stats; 2408 if (ref_processor()->processing_is_mt()) { 2409 RefProcTaskExecutor task_executor; 2410 stats = ref_processor()->process_discovered_references( 2411 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, 2412 &task_executor, &_gc_timer); 2413 } else { 2414 stats = ref_processor()->process_discovered_references( 2415 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL, 2416 &_gc_timer); 2417 } 2418 2419 _gc_tracer.report_gc_reference_stats(stats); 2420 } 2421 2422 GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer); 2423 2424 // Follow system dictionary roots and unload classes. 2425 bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); 2426 2427 // Follow code cache roots. 2428 CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure, 2429 purged_class); 2430 cm->follow_marking_stacks(); // Flush marking stack. 2431 2432 // Update subklass/sibling/implementor links of live klasses 2433 // revisit_klass_stack is used in follow_weak_klass_links(). 2434 follow_weak_klass_links(); 2435 2436 // Revisit memoized MDO's and clear any unmarked weak refs 2437 follow_mdo_weak_refs(); 2438 2439 // Visit interned string tables and delete unmarked oops 2440 StringTable::unlink(is_alive_closure()); 2441 // Clean up unreferenced symbols in symbol table. 2442 SymbolTable::unlink(); 2443 2444 assert(cm->marking_stacks_empty(), "marking stacks should be empty"); 2445 _gc_tracer.report_object_count_after_gc(is_alive_closure()); 2446 } 2447 2448 // This should be moved to the shared markSweep code! 2449 class PSAlwaysTrueClosure: public BoolObjectClosure { 2450 public: 2451 void do_object(oop p) { ShouldNotReachHere(); } 2452 bool do_object_b(oop p) { return true; } 2453 }; 2454 static PSAlwaysTrueClosure always_true; 2455 2456 void PSParallelCompact::adjust_roots() { 2457 // Adjust the pointers to reflect the new locations 2458 GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer); 2459 2460 // General strong roots. 2461 Universe::oops_do(adjust_root_pointer_closure()); 2462 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles 2463 Threads::oops_do(adjust_root_pointer_closure(), NULL); 2464 ObjectSynchronizer::oops_do(adjust_root_pointer_closure()); 2465 FlatProfiler::oops_do(adjust_root_pointer_closure()); 2466 Management::oops_do(adjust_root_pointer_closure()); 2467 JvmtiExport::oops_do(adjust_root_pointer_closure()); 2468 // SO_AllClasses 2469 SystemDictionary::oops_do(adjust_root_pointer_closure()); 2470 2471 // Now adjust pointers in remaining weak roots. (All of which should 2472 // have been cleared if they pointed to non-surviving objects.) 2473 // Global (weak) JNI handles 2474 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure()); 2475 2476 CodeCache::oops_do(adjust_pointer_closure()); 2477 StringTable::oops_do(adjust_root_pointer_closure()); 2478 ref_processor()->weak_oops_do(adjust_root_pointer_closure()); 2479 // Roots were visited so references into the young gen in roots 2480 // may have been scanned. Process them also. 2481 // Should the reference processor have a span that excludes 2482 // young gen objects? 2483 PSScavenge::reference_processor()->weak_oops_do( 2484 adjust_root_pointer_closure()); 2485 } 2486 2487 void PSParallelCompact::compact_perm(ParCompactionManager* cm) { 2488 GCTraceTime tm("compact perm gen", print_phases(), true, &_gc_timer); 2489 // trace("4"); 2490 2491 gc_heap()->perm_gen()->start_array()->reset(); 2492 move_and_update(cm, perm_space_id); 2493 } 2494 2495 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q, 2496 uint parallel_gc_threads) 2497 { 2498 GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer); 2499 2500 // Find the threads that are active 2501 unsigned int which = 0; 2502 2503 const uint task_count = MAX2(parallel_gc_threads, 1U); 2504 for (uint j = 0; j < task_count; j++) { 2505 q->enqueue(new DrainStacksCompactionTask(j)); 2506 ParCompactionManager::verify_region_list_empty(j); 2507 // Set the region stacks variables to "no" region stack values 2508 // so that they will be recognized and needing a region stack 2509 // in the stealing tasks if they do not get one by executing 2510 // a draining stack. 2511 ParCompactionManager* cm = ParCompactionManager::manager_array(j); 2512 cm->set_region_stack(NULL); 2513 cm->set_region_stack_index((uint)max_uintx); 2514 } 2515 ParCompactionManager::reset_recycled_stack_index(); 2516 2517 // Find all regions that are available (can be filled immediately) and 2518 // distribute them to the thread stacks. The iteration is done in reverse 2519 // order (high to low) so the regions will be removed in ascending order. 2520 2521 const ParallelCompactData& sd = PSParallelCompact::summary_data(); 2522 2523 size_t fillable_regions = 0; // A count for diagnostic purposes. 2524 // A region index which corresponds to the tasks created above. 2525 // "which" must be 0 <= which < task_count 2526 2527 which = 0; 2528 for (unsigned int id = to_space_id; id > perm_space_id; --id) { 2529 SpaceInfo* const space_info = _space_info + id; 2530 MutableSpace* const space = space_info->space(); 2531 HeapWord* const new_top = space_info->new_top(); 2532 2533 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix()); 2534 const size_t end_region = 2535 sd.addr_to_region_idx(sd.region_align_up(new_top)); 2536 assert(end_region > 0, "perm gen cannot be empty"); 2537 2538 for (size_t cur = end_region - 1; cur >= beg_region; --cur) { 2539 if (sd.region(cur)->claim_unsafe()) { 2540 ParCompactionManager::region_list_push(which, cur); 2541 2542 if (TraceParallelOldGCCompactionPhase && Verbose) { 2543 const size_t count_mod_8 = fillable_regions & 7; 2544 if (count_mod_8 == 0) gclog_or_tty->print("fillable: "); 2545 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur); 2546 if (count_mod_8 == 7) gclog_or_tty->cr(); 2547 } 2548 2549 NOT_PRODUCT(++fillable_regions;) 2550 2551 // Assign regions to tasks in round-robin fashion. 2552 if (++which == task_count) { 2553 assert(which <= parallel_gc_threads, 2554 "Inconsistent number of workers"); 2555 which = 0; 2556 } 2557 } 2558 } 2559 } 2560 2561 if (TraceParallelOldGCCompactionPhase) { 2562 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr(); 2563 gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions); 2564 } 2565 } 2566 2567 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 2568 2569 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q, 2570 uint parallel_gc_threads) { 2571 GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer); 2572 2573 ParallelCompactData& sd = PSParallelCompact::summary_data(); 2574 2575 // Iterate over all the spaces adding tasks for updating 2576 // regions in the dense prefix. Assume that 1 gc thread 2577 // will work on opening the gaps and the remaining gc threads 2578 // will work on the dense prefix. 2579 unsigned int space_id; 2580 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) { 2581 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); 2582 const MutableSpace* const space = _space_info[space_id].space(); 2583 2584 if (dense_prefix_end == space->bottom()) { 2585 // There is no dense prefix for this space. 2586 continue; 2587 } 2588 2589 // The dense prefix is before this region. 2590 size_t region_index_end_dense_prefix = 2591 sd.addr_to_region_idx(dense_prefix_end); 2592 RegionData* const dense_prefix_cp = 2593 sd.region(region_index_end_dense_prefix); 2594 assert(dense_prefix_end == space->end() || 2595 dense_prefix_cp->available() || 2596 dense_prefix_cp->claimed(), 2597 "The region after the dense prefix should always be ready to fill"); 2598 2599 size_t region_index_start = sd.addr_to_region_idx(space->bottom()); 2600 2601 // Is there dense prefix work? 2602 size_t total_dense_prefix_regions = 2603 region_index_end_dense_prefix - region_index_start; 2604 // How many regions of the dense prefix should be given to 2605 // each thread? 2606 if (total_dense_prefix_regions > 0) { 2607 uint tasks_for_dense_prefix = 1; 2608 if (total_dense_prefix_regions <= 2609 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { 2610 // Don't over partition. This assumes that 2611 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value 2612 // so there are not many regions to process. 2613 tasks_for_dense_prefix = parallel_gc_threads; 2614 } else { 2615 // Over partition 2616 tasks_for_dense_prefix = parallel_gc_threads * 2617 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; 2618 } 2619 size_t regions_per_thread = total_dense_prefix_regions / 2620 tasks_for_dense_prefix; 2621 // Give each thread at least 1 region. 2622 if (regions_per_thread == 0) { 2623 regions_per_thread = 1; 2624 } 2625 2626 for (uint k = 0; k < tasks_for_dense_prefix; k++) { 2627 if (region_index_start >= region_index_end_dense_prefix) { 2628 break; 2629 } 2630 // region_index_end is not processed 2631 size_t region_index_end = MIN2(region_index_start + regions_per_thread, 2632 region_index_end_dense_prefix); 2633 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2634 region_index_start, 2635 region_index_end)); 2636 region_index_start = region_index_end; 2637 } 2638 } 2639 // This gets any part of the dense prefix that did not 2640 // fit evenly. 2641 if (region_index_start < region_index_end_dense_prefix) { 2642 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id), 2643 region_index_start, 2644 region_index_end_dense_prefix)); 2645 } 2646 } 2647 } 2648 2649 void PSParallelCompact::enqueue_region_stealing_tasks( 2650 GCTaskQueue* q, 2651 ParallelTaskTerminator* terminator_ptr, 2652 uint parallel_gc_threads) { 2653 GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer); 2654 2655 // Once a thread has drained it's stack, it should try to steal regions from 2656 // other threads. 2657 if (parallel_gc_threads > 1) { 2658 for (uint j = 0; j < parallel_gc_threads; j++) { 2659 q->enqueue(new StealRegionCompactionTask(terminator_ptr)); 2660 } 2661 } 2662 } 2663 2664 void PSParallelCompact::compact() { 2665 // trace("5"); 2666 GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer); 2667 2668 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 2669 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 2670 PSOldGen* old_gen = heap->old_gen(); 2671 old_gen->start_array()->reset(); 2672 uint parallel_gc_threads = heap->gc_task_manager()->workers(); 2673 uint active_gc_threads = heap->gc_task_manager()->active_workers(); 2674 TaskQueueSetSuper* qset = ParCompactionManager::region_array(); 2675 ParallelTaskTerminator terminator(active_gc_threads, qset); 2676 2677 GCTaskQueue* q = GCTaskQueue::create(); 2678 enqueue_region_draining_tasks(q, active_gc_threads); 2679 enqueue_dense_prefix_tasks(q, active_gc_threads); 2680 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads); 2681 2682 { 2683 GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer); 2684 2685 gc_task_manager()->execute_and_wait(q); 2686 2687 #ifdef ASSERT 2688 // Verify that all regions have been processed before the deferred updates. 2689 // Note that perm_space_id is skipped; this type of verification is not 2690 // valid until the perm gen is compacted by regions. 2691 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2692 verify_complete(SpaceId(id)); 2693 } 2694 #endif 2695 } 2696 2697 { 2698 // Update the deferred objects, if any. Any compaction manager can be used. 2699 GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer); 2700 ParCompactionManager* cm = ParCompactionManager::manager_array(0); 2701 for (unsigned int id = old_space_id; id < last_space_id; ++id) { 2702 update_deferred_objects(cm, SpaceId(id)); 2703 } 2704 } 2705 } 2706 2707 #ifdef ASSERT 2708 void PSParallelCompact::verify_complete(SpaceId space_id) { 2709 // All Regions between space bottom() to new_top() should be marked as filled 2710 // and all Regions between new_top() and top() should be available (i.e., 2711 // should have been emptied). 2712 ParallelCompactData& sd = summary_data(); 2713 SpaceInfo si = _space_info[space_id]; 2714 HeapWord* new_top_addr = sd.region_align_up(si.new_top()); 2715 HeapWord* old_top_addr = sd.region_align_up(si.space()->top()); 2716 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom()); 2717 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr); 2718 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr); 2719 2720 bool issued_a_warning = false; 2721 2722 size_t cur_region; 2723 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) { 2724 const RegionData* const c = sd.region(cur_region); 2725 if (!c->completed()) { 2726 warning("region " SIZE_FORMAT " not filled: " 2727 "destination_count=" SIZE_FORMAT, 2728 cur_region, c->destination_count()); 2729 issued_a_warning = true; 2730 } 2731 } 2732 2733 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) { 2734 const RegionData* const c = sd.region(cur_region); 2735 if (!c->available()) { 2736 warning("region " SIZE_FORMAT " not empty: " 2737 "destination_count=" SIZE_FORMAT, 2738 cur_region, c->destination_count()); 2739 issued_a_warning = true; 2740 } 2741 } 2742 2743 if (issued_a_warning) { 2744 print_region_ranges(); 2745 } 2746 } 2747 #endif // #ifdef ASSERT 2748 2749 void 2750 PSParallelCompact::follow_weak_klass_links() { 2751 // All klasses on the revisit stack are marked at this point. 2752 // Update and follow all subklass, sibling and implementor links. 2753 // Check all the stacks here even if not all the workers are active. 2754 // There is no accounting which indicates which stacks might have 2755 // contents to be followed. 2756 if (PrintRevisitStats) { 2757 gclog_or_tty->print_cr("#classes in system dictionary = %d", 2758 SystemDictionary::number_of_classes()); 2759 } 2760 for (uint i = 0; i < ParallelGCThreads + 1; i++) { 2761 ParCompactionManager* cm = ParCompactionManager::manager_array(i); 2762 KeepAliveClosure keep_alive_closure(cm); 2763 Stack<Klass*, mtGC>* const rks = cm->revisit_klass_stack(); 2764 if (PrintRevisitStats) { 2765 gclog_or_tty->print_cr("Revisit klass stack[%u] length = " SIZE_FORMAT, 2766 i, rks->size()); 2767 } 2768 while (!rks->is_empty()) { 2769 Klass* const k = rks->pop(); 2770 k->follow_weak_klass_links(is_alive_closure(), &keep_alive_closure); 2771 } 2772 2773 cm->follow_marking_stacks(); 2774 } 2775 } 2776 2777 void 2778 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) { 2779 cm->revisit_klass_stack()->push(k); 2780 } 2781 2782 void PSParallelCompact::revisit_mdo(ParCompactionManager* cm, DataLayout* p) { 2783 cm->revisit_mdo_stack()->push(p); 2784 } 2785 2786 void PSParallelCompact::follow_mdo_weak_refs() { 2787 // All strongly reachable oops have been marked at this point; 2788 // we can visit and clear any weak references from MDO's which 2789 // we memoized during the strong marking phase. 2790 if (PrintRevisitStats) { 2791 gclog_or_tty->print_cr("#classes in system dictionary = %d", 2792 SystemDictionary::number_of_classes()); 2793 } 2794 for (uint i = 0; i < ParallelGCThreads + 1; i++) { 2795 ParCompactionManager* cm = ParCompactionManager::manager_array(i); 2796 Stack<DataLayout*, mtGC>* rms = cm->revisit_mdo_stack(); 2797 if (PrintRevisitStats) { 2798 gclog_or_tty->print_cr("Revisit MDO stack[%u] size = " SIZE_FORMAT, 2799 i, rms->size()); 2800 } 2801 while (!rms->is_empty()) { 2802 rms->pop()->follow_weak_refs(is_alive_closure()); 2803 } 2804 2805 cm->follow_marking_stacks(); 2806 } 2807 } 2808 2809 2810 #ifdef VALIDATE_MARK_SWEEP 2811 2812 void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) { 2813 if (!ValidateMarkSweep) 2814 return; 2815 2816 if (!isroot) { 2817 if (_pointer_tracking) { 2818 guarantee(_adjusted_pointers->contains(p), "should have seen this pointer"); 2819 _adjusted_pointers->remove(p); 2820 } 2821 } else { 2822 ptrdiff_t index = _root_refs_stack->find(p); 2823 if (index != -1) { 2824 int l = _root_refs_stack->length(); 2825 if (l > 0 && l - 1 != index) { 2826 void* last = _root_refs_stack->pop(); 2827 assert(last != p, "should be different"); 2828 _root_refs_stack->at_put(index, last); 2829 } else { 2830 _root_refs_stack->remove(p); 2831 } 2832 } 2833 } 2834 } 2835 2836 2837 void PSParallelCompact::check_adjust_pointer(void* p) { 2838 _adjusted_pointers->push(p); 2839 } 2840 2841 2842 class AdjusterTracker: public OopClosure { 2843 public: 2844 AdjusterTracker() {}; 2845 void do_oop(oop* o) { PSParallelCompact::check_adjust_pointer(o); } 2846 void do_oop(narrowOop* o) { PSParallelCompact::check_adjust_pointer(o); } 2847 }; 2848 2849 2850 void PSParallelCompact::track_interior_pointers(oop obj) { 2851 if (ValidateMarkSweep) { 2852 _adjusted_pointers->clear(); 2853 _pointer_tracking = true; 2854 2855 AdjusterTracker checker; 2856 obj->oop_iterate(&checker); 2857 } 2858 } 2859 2860 2861 void PSParallelCompact::check_interior_pointers() { 2862 if (ValidateMarkSweep) { 2863 _pointer_tracking = false; 2864 guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers"); 2865 } 2866 } 2867 2868 2869 void PSParallelCompact::reset_live_oop_tracking(bool at_perm) { 2870 if (ValidateMarkSweep) { 2871 guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops"); 2872 _live_oops_index = at_perm ? _live_oops_index_at_perm : 0; 2873 } 2874 } 2875 2876 2877 void PSParallelCompact::register_live_oop(oop p, size_t size) { 2878 if (ValidateMarkSweep) { 2879 _live_oops->push(p); 2880 _live_oops_size->push(size); 2881 _live_oops_index++; 2882 } 2883 } 2884 2885 void PSParallelCompact::validate_live_oop(oop p, size_t size) { 2886 if (ValidateMarkSweep) { 2887 oop obj = _live_oops->at((int)_live_oops_index); 2888 guarantee(obj == p, "should be the same object"); 2889 guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size"); 2890 _live_oops_index++; 2891 } 2892 } 2893 2894 void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size, 2895 HeapWord* compaction_top) { 2896 assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top), 2897 "should be moved to forwarded location"); 2898 if (ValidateMarkSweep) { 2899 PSParallelCompact::validate_live_oop(oop(q), size); 2900 _live_oops_moved_to->push(oop(compaction_top)); 2901 } 2902 if (RecordMarkSweepCompaction) { 2903 _cur_gc_live_oops->push(q); 2904 _cur_gc_live_oops_moved_to->push(compaction_top); 2905 _cur_gc_live_oops_size->push(size); 2906 } 2907 } 2908 2909 2910 void PSParallelCompact::compaction_complete() { 2911 if (RecordMarkSweepCompaction) { 2912 GrowableArray<HeapWord*>* _tmp_live_oops = _cur_gc_live_oops; 2913 GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to; 2914 GrowableArray<size_t> * _tmp_live_oops_size = _cur_gc_live_oops_size; 2915 2916 _cur_gc_live_oops = _last_gc_live_oops; 2917 _cur_gc_live_oops_moved_to = _last_gc_live_oops_moved_to; 2918 _cur_gc_live_oops_size = _last_gc_live_oops_size; 2919 _last_gc_live_oops = _tmp_live_oops; 2920 _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to; 2921 _last_gc_live_oops_size = _tmp_live_oops_size; 2922 } 2923 } 2924 2925 2926 void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) { 2927 if (!RecordMarkSweepCompaction) { 2928 tty->print_cr("Requires RecordMarkSweepCompaction to be enabled"); 2929 return; 2930 } 2931 2932 if (_last_gc_live_oops == NULL) { 2933 tty->print_cr("No compaction information gathered yet"); 2934 return; 2935 } 2936 2937 for (int i = 0; i < _last_gc_live_oops->length(); i++) { 2938 HeapWord* old_oop = _last_gc_live_oops->at(i); 2939 size_t sz = _last_gc_live_oops_size->at(i); 2940 if (old_oop <= q && q < (old_oop + sz)) { 2941 HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i); 2942 size_t offset = (q - old_oop); 2943 tty->print_cr("Address " PTR_FORMAT, q); 2944 tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset); 2945 tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset); 2946 return; 2947 } 2948 } 2949 2950 tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q); 2951 } 2952 #endif //VALIDATE_MARK_SWEEP 2953 2954 // Update interior oops in the ranges of regions [beg_region, end_region). 2955 void 2956 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 2957 SpaceId space_id, 2958 size_t beg_region, 2959 size_t end_region) { 2960 ParallelCompactData& sd = summary_data(); 2961 ParMarkBitMap* const mbm = mark_bitmap(); 2962 2963 HeapWord* beg_addr = sd.region_to_addr(beg_region); 2964 HeapWord* const end_addr = sd.region_to_addr(end_region); 2965 assert(beg_region <= end_region, "bad region range"); 2966 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); 2967 2968 #ifdef ASSERT 2969 // Claim the regions to avoid triggering an assert when they are marked as 2970 // filled. 2971 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) { 2972 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed"); 2973 } 2974 #endif // #ifdef ASSERT 2975 2976 if (beg_addr != space(space_id)->bottom()) { 2977 // Find the first live object or block of dead space that *starts* in this 2978 // range of regions. If a partial object crosses onto the region, skip it; 2979 // it will be marked for 'deferred update' when the object head is 2980 // processed. If dead space crosses onto the region, it is also skipped; it 2981 // will be filled when the prior region is processed. If neither of those 2982 // apply, the first word in the region is the start of a live object or dead 2983 // space. 2984 assert(beg_addr > space(space_id)->bottom(), "sanity"); 2985 const RegionData* const cp = sd.region(beg_region); 2986 if (cp->partial_obj_size() != 0) { 2987 beg_addr = sd.partial_obj_end(beg_region); 2988 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) { 2989 beg_addr = mbm->find_obj_beg(beg_addr, end_addr); 2990 } 2991 } 2992 2993 if (beg_addr < end_addr) { 2994 // A live object or block of dead space starts in this range of Regions. 2995 HeapWord* const dense_prefix_end = dense_prefix(space_id); 2996 2997 // Create closures and iterate. 2998 UpdateOnlyClosure update_closure(mbm, cm, space_id); 2999 FillClosure fill_closure(cm, space_id); 3000 ParMarkBitMap::IterationStatus status; 3001 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, 3002 dense_prefix_end); 3003 if (status == ParMarkBitMap::incomplete) { 3004 update_closure.do_addr(update_closure.source()); 3005 } 3006 } 3007 3008 // Mark the regions as filled. 3009 RegionData* const beg_cp = sd.region(beg_region); 3010 RegionData* const end_cp = sd.region(end_region); 3011 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) { 3012 cp->set_completed(); 3013 } 3014 } 3015 3016 // Return the SpaceId for the space containing addr. If addr is not in the 3017 // heap, last_space_id is returned. In debug mode it expects the address to be 3018 // in the heap and asserts such. 3019 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) { 3020 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap"); 3021 3022 for (unsigned int id = perm_space_id; id < last_space_id; ++id) { 3023 if (_space_info[id].space()->contains(addr)) { 3024 return SpaceId(id); 3025 } 3026 } 3027 3028 assert(false, "no space contains the addr"); 3029 return last_space_id; 3030 } 3031 3032 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm, 3033 SpaceId id) { 3034 assert(id < last_space_id, "bad space id"); 3035 3036 ParallelCompactData& sd = summary_data(); 3037 const SpaceInfo* const space_info = _space_info + id; 3038 ObjectStartArray* const start_array = space_info->start_array(); 3039 3040 const MutableSpace* const space = space_info->space(); 3041 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set"); 3042 HeapWord* const beg_addr = space_info->dense_prefix(); 3043 HeapWord* const end_addr = sd.region_align_up(space_info->new_top()); 3044 3045 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr); 3046 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr); 3047 const RegionData* cur_region; 3048 for (cur_region = beg_region; cur_region < end_region; ++cur_region) { 3049 HeapWord* const addr = cur_region->deferred_obj_addr(); 3050 if (addr != NULL) { 3051 if (start_array != NULL) { 3052 start_array->allocate_block(addr); 3053 } 3054 oop(addr)->update_contents(cm); 3055 assert(oop(addr)->is_oop_or_null(), "should be an oop now"); 3056 } 3057 } 3058 } 3059 3060 // Skip over count live words starting from beg, and return the address of the 3061 // next live word. Unless marked, the word corresponding to beg is assumed to 3062 // be dead. Callers must either ensure beg does not correspond to the middle of 3063 // an object, or account for those live words in some other way. Callers must 3064 // also ensure that there are enough live words in the range [beg, end) to skip. 3065 HeapWord* 3066 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count) 3067 { 3068 assert(count > 0, "sanity"); 3069 3070 ParMarkBitMap* m = mark_bitmap(); 3071 idx_t bits_to_skip = m->words_to_bits(count); 3072 idx_t cur_beg = m->addr_to_bit(beg); 3073 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end)); 3074 3075 do { 3076 cur_beg = m->find_obj_beg(cur_beg, search_end); 3077 idx_t cur_end = m->find_obj_end(cur_beg, search_end); 3078 const size_t obj_bits = cur_end - cur_beg + 1; 3079 if (obj_bits > bits_to_skip) { 3080 return m->bit_to_addr(cur_beg + bits_to_skip); 3081 } 3082 bits_to_skip -= obj_bits; 3083 cur_beg = cur_end + 1; 3084 } while (bits_to_skip > 0); 3085 3086 // Skipping the desired number of words landed just past the end of an object. 3087 // Find the start of the next object. 3088 cur_beg = m->find_obj_beg(cur_beg, search_end); 3089 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip"); 3090 return m->bit_to_addr(cur_beg); 3091 } 3092 3093 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr, 3094 SpaceId src_space_id, 3095 size_t src_region_idx) 3096 { 3097 assert(summary_data().is_region_aligned(dest_addr), "not aligned"); 3098 3099 const SplitInfo& split_info = _space_info[src_space_id].split_info(); 3100 if (split_info.dest_region_addr() == dest_addr) { 3101 // The partial object ending at the split point contains the first word to 3102 // be copied to dest_addr. 3103 return split_info.first_src_addr(); 3104 } 3105 3106 const ParallelCompactData& sd = summary_data(); 3107 ParMarkBitMap* const bitmap = mark_bitmap(); 3108 const size_t RegionSize = ParallelCompactData::RegionSize; 3109 3110 assert(sd.is_region_aligned(dest_addr), "not aligned"); 3111 const RegionData* const src_region_ptr = sd.region(src_region_idx); 3112 const size_t partial_obj_size = src_region_ptr->partial_obj_size(); 3113 HeapWord* const src_region_destination = src_region_ptr->destination(); 3114 3115 assert(dest_addr >= src_region_destination, "wrong src region"); 3116 assert(src_region_ptr->data_size() > 0, "src region cannot be empty"); 3117 3118 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx); 3119 HeapWord* const src_region_end = src_region_beg + RegionSize; 3120 3121 HeapWord* addr = src_region_beg; 3122 if (dest_addr == src_region_destination) { 3123 // Return the first live word in the source region. 3124 if (partial_obj_size == 0) { 3125 addr = bitmap->find_obj_beg(addr, src_region_end); 3126 assert(addr < src_region_end, "no objects start in src region"); 3127 } 3128 return addr; 3129 } 3130 3131 // Must skip some live data. 3132 size_t words_to_skip = dest_addr - src_region_destination; 3133 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region"); 3134 3135 if (partial_obj_size >= words_to_skip) { 3136 // All the live words to skip are part of the partial object. 3137 addr += words_to_skip; 3138 if (partial_obj_size == words_to_skip) { 3139 // Find the first live word past the partial object. 3140 addr = bitmap->find_obj_beg(addr, src_region_end); 3141 assert(addr < src_region_end, "wrong src region"); 3142 } 3143 return addr; 3144 } 3145 3146 // Skip over the partial object (if any). 3147 if (partial_obj_size != 0) { 3148 words_to_skip -= partial_obj_size; 3149 addr += partial_obj_size; 3150 } 3151 3152 // Skip over live words due to objects that start in the region. 3153 addr = skip_live_words(addr, src_region_end, words_to_skip); 3154 assert(addr < src_region_end, "wrong src region"); 3155 return addr; 3156 } 3157 3158 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, 3159 SpaceId src_space_id, 3160 size_t beg_region, 3161 HeapWord* end_addr) 3162 { 3163 ParallelCompactData& sd = summary_data(); 3164 3165 #ifdef ASSERT 3166 MutableSpace* const src_space = _space_info[src_space_id].space(); 3167 HeapWord* const beg_addr = sd.region_to_addr(beg_region); 3168 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(), 3169 "src_space_id does not match beg_addr"); 3170 assert(src_space->contains(end_addr) || end_addr == src_space->end(), 3171 "src_space_id does not match end_addr"); 3172 #endif // #ifdef ASSERT 3173 3174 RegionData* const beg = sd.region(beg_region); 3175 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr)); 3176 3177 // Regions up to new_top() are enqueued if they become available. 3178 HeapWord* const new_top = _space_info[src_space_id].new_top(); 3179 RegionData* const enqueue_end = 3180 sd.addr_to_region_ptr(sd.region_align_up(new_top)); 3181 3182 for (RegionData* cur = beg; cur < end; ++cur) { 3183 assert(cur->data_size() > 0, "region must have live data"); 3184 cur->decrement_destination_count(); 3185 if (cur < enqueue_end && cur->available() && cur->claim()) { 3186 cm->push_region(sd.region(cur)); 3187 } 3188 } 3189 } 3190 3191 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure, 3192 SpaceId& src_space_id, 3193 HeapWord*& src_space_top, 3194 HeapWord* end_addr) 3195 { 3196 typedef ParallelCompactData::RegionData RegionData; 3197 3198 ParallelCompactData& sd = PSParallelCompact::summary_data(); 3199 const size_t region_size = ParallelCompactData::RegionSize; 3200 3201 size_t src_region_idx = 0; 3202 3203 // Skip empty regions (if any) up to the top of the space. 3204 HeapWord* const src_aligned_up = sd.region_align_up(end_addr); 3205 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up); 3206 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top); 3207 const RegionData* const top_region_ptr = 3208 sd.addr_to_region_ptr(top_aligned_up); 3209 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) { 3210 ++src_region_ptr; 3211 } 3212 3213 if (src_region_ptr < top_region_ptr) { 3214 // The next source region is in the current space. Update src_region_idx 3215 // and the source address to match src_region_ptr. 3216 src_region_idx = sd.region(src_region_ptr); 3217 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx); 3218 if (src_region_addr > closure.source()) { 3219 closure.set_source(src_region_addr); 3220 } 3221 return src_region_idx; 3222 } 3223 3224 // Switch to a new source space and find the first non-empty region. 3225 unsigned int space_id = src_space_id + 1; 3226 assert(space_id < last_space_id, "not enough spaces"); 3227 3228 HeapWord* const destination = closure.destination(); 3229 3230 do { 3231 MutableSpace* space = _space_info[space_id].space(); 3232 HeapWord* const bottom = space->bottom(); 3233 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom); 3234 3235 // Iterate over the spaces that do not compact into themselves. 3236 if (bottom_cp->destination() != bottom) { 3237 HeapWord* const top_aligned_up = sd.region_align_up(space->top()); 3238 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up); 3239 3240 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) { 3241 if (src_cp->live_obj_size() > 0) { 3242 // Found it. 3243 assert(src_cp->destination() == destination, 3244 "first live obj in the space must match the destination"); 3245 assert(src_cp->partial_obj_size() == 0, 3246 "a space cannot begin with a partial obj"); 3247 3248 src_space_id = SpaceId(space_id); 3249 src_space_top = space->top(); 3250 const size_t src_region_idx = sd.region(src_cp); 3251 closure.set_source(sd.region_to_addr(src_region_idx)); 3252 return src_region_idx; 3253 } else { 3254 assert(src_cp->data_size() == 0, "sanity"); 3255 } 3256 } 3257 } 3258 } while (++space_id < last_space_id); 3259 3260 assert(false, "no source region was found"); 3261 return 0; 3262 } 3263 3264 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx) 3265 { 3266 typedef ParMarkBitMap::IterationStatus IterationStatus; 3267 const size_t RegionSize = ParallelCompactData::RegionSize; 3268 ParMarkBitMap* const bitmap = mark_bitmap(); 3269 ParallelCompactData& sd = summary_data(); 3270 RegionData* const region_ptr = sd.region(region_idx); 3271 3272 // Get the items needed to construct the closure. 3273 HeapWord* dest_addr = sd.region_to_addr(region_idx); 3274 SpaceId dest_space_id = space_id(dest_addr); 3275 ObjectStartArray* start_array = _space_info[dest_space_id].start_array(); 3276 HeapWord* new_top = _space_info[dest_space_id].new_top(); 3277 assert(dest_addr < new_top, "sanity"); 3278 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize); 3279 3280 // Get the source region and related info. 3281 size_t src_region_idx = region_ptr->source_region(); 3282 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx)); 3283 HeapWord* src_space_top = _space_info[src_space_id].space()->top(); 3284 3285 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 3286 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx)); 3287 3288 // Adjust src_region_idx to prepare for decrementing destination counts (the 3289 // destination count is not decremented when a region is copied to itself). 3290 if (src_region_idx == region_idx) { 3291 src_region_idx += 1; 3292 } 3293 3294 if (bitmap->is_unmarked(closure.source())) { 3295 // The first source word is in the middle of an object; copy the remainder 3296 // of the object or as much as will fit. The fact that pointer updates were 3297 // deferred will be noted when the object header is processed. 3298 HeapWord* const old_src_addr = closure.source(); 3299 closure.copy_partial_obj(); 3300 if (closure.is_full()) { 3301 decrement_destination_counts(cm, src_space_id, src_region_idx, 3302 closure.source()); 3303 region_ptr->set_deferred_obj_addr(NULL); 3304 region_ptr->set_completed(); 3305 return; 3306 } 3307 3308 HeapWord* const end_addr = sd.region_align_down(closure.source()); 3309 if (sd.region_align_down(old_src_addr) != end_addr) { 3310 // The partial object was copied from more than one source region. 3311 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 3312 3313 // Move to the next source region, possibly switching spaces as well. All 3314 // args except end_addr may be modified. 3315 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 3316 end_addr); 3317 } 3318 } 3319 3320 do { 3321 HeapWord* const cur_addr = closure.source(); 3322 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1), 3323 src_space_top); 3324 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr); 3325 3326 if (status == ParMarkBitMap::incomplete) { 3327 // The last obj that starts in the source region does not end in the 3328 // region. 3329 assert(closure.source() < end_addr, "sanity"); 3330 HeapWord* const obj_beg = closure.source(); 3331 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(), 3332 src_space_top); 3333 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end); 3334 if (obj_end < range_end) { 3335 // The end was found; the entire object will fit. 3336 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end)); 3337 assert(status != ParMarkBitMap::would_overflow, "sanity"); 3338 } else { 3339 // The end was not found; the object will not fit. 3340 assert(range_end < src_space_top, "obj cannot cross space boundary"); 3341 status = ParMarkBitMap::would_overflow; 3342 } 3343 } 3344 3345 if (status == ParMarkBitMap::would_overflow) { 3346 // The last object did not fit. Note that interior oop updates were 3347 // deferred, then copy enough of the object to fill the region. 3348 region_ptr->set_deferred_obj_addr(closure.destination()); 3349 status = closure.copy_until_full(); // copies from closure.source() 3350 3351 decrement_destination_counts(cm, src_space_id, src_region_idx, 3352 closure.source()); 3353 region_ptr->set_completed(); 3354 return; 3355 } 3356 3357 if (status == ParMarkBitMap::full) { 3358 decrement_destination_counts(cm, src_space_id, src_region_idx, 3359 closure.source()); 3360 region_ptr->set_deferred_obj_addr(NULL); 3361 region_ptr->set_completed(); 3362 return; 3363 } 3364 3365 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr); 3366 3367 // Move to the next source region, possibly switching spaces as well. All 3368 // args except end_addr may be modified. 3369 src_region_idx = next_src_region(closure, src_space_id, src_space_top, 3370 end_addr); 3371 } while (true); 3372 } 3373 3374 void 3375 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) { 3376 const MutableSpace* sp = space(space_id); 3377 if (sp->is_empty()) { 3378 return; 3379 } 3380 3381 ParallelCompactData& sd = PSParallelCompact::summary_data(); 3382 ParMarkBitMap* const bitmap = mark_bitmap(); 3383 HeapWord* const dp_addr = dense_prefix(space_id); 3384 HeapWord* beg_addr = sp->bottom(); 3385 HeapWord* end_addr = sp->top(); 3386 3387 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix"); 3388 3389 const size_t beg_region = sd.addr_to_region_idx(beg_addr); 3390 const size_t dp_region = sd.addr_to_region_idx(dp_addr); 3391 if (beg_region < dp_region) { 3392 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region); 3393 } 3394 3395 // The destination of the first live object that starts in the region is one 3396 // past the end of the partial object entering the region (if any). 3397 HeapWord* const dest_addr = sd.partial_obj_end(dp_region); 3398 HeapWord* const new_top = _space_info[space_id].new_top(); 3399 assert(new_top >= dest_addr, "bad new_top value"); 3400 const size_t words = pointer_delta(new_top, dest_addr); 3401 3402 if (words > 0) { 3403 ObjectStartArray* start_array = _space_info[space_id].start_array(); 3404 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words); 3405 3406 ParMarkBitMap::IterationStatus status; 3407 status = bitmap->iterate(&closure, dest_addr, end_addr); 3408 assert(status == ParMarkBitMap::full, "iteration not complete"); 3409 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr, 3410 "live objects skipped because closure is full"); 3411 } 3412 } 3413 3414 jlong PSParallelCompact::millis_since_last_gc() { 3415 // We need a monotonically non-deccreasing time in ms but 3416 // os::javaTimeMillis() does not guarantee monotonicity. 3417 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3418 jlong ret_val = now - _time_of_last_gc; 3419 // XXX See note in genCollectedHeap::millis_since_last_gc(). 3420 if (ret_val < 0) { 3421 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);) 3422 return 0; 3423 } 3424 return ret_val; 3425 } 3426 3427 void PSParallelCompact::reset_millis_since_last_gc() { 3428 // We need a monotonically non-deccreasing time in ms but 3429 // os::javaTimeMillis() does not guarantee monotonicity. 3430 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 3431 } 3432 3433 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() 3434 { 3435 if (source() != destination()) { 3436 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3437 Copy::aligned_conjoint_words(source(), destination(), words_remaining()); 3438 } 3439 update_state(words_remaining()); 3440 assert(is_full(), "sanity"); 3441 return ParMarkBitMap::full; 3442 } 3443 3444 void MoveAndUpdateClosure::copy_partial_obj() 3445 { 3446 size_t words = words_remaining(); 3447 3448 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end()); 3449 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end); 3450 if (end_addr < range_end) { 3451 words = bitmap()->obj_size(source(), end_addr); 3452 } 3453 3454 // This test is necessary; if omitted, the pointer updates to a partial object 3455 // that crosses the dense prefix boundary could be overwritten. 3456 if (source() != destination()) { 3457 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3458 Copy::aligned_conjoint_words(source(), destination(), words); 3459 } 3460 update_state(words); 3461 } 3462 3463 ParMarkBitMapClosure::IterationStatus 3464 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) { 3465 assert(destination() != NULL, "sanity"); 3466 assert(bitmap()->obj_size(addr) == words, "bad size"); 3467 3468 _source = addr; 3469 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) == 3470 destination(), "wrong destination"); 3471 3472 if (words > words_remaining()) { 3473 return ParMarkBitMap::would_overflow; 3474 } 3475 3476 // The start_array must be updated even if the object is not moving. 3477 if (_start_array != NULL) { 3478 _start_array->allocate_block(destination()); 3479 } 3480 3481 if (destination() != source()) { 3482 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());) 3483 Copy::aligned_conjoint_words(source(), destination(), words); 3484 } 3485 3486 oop moved_oop = (oop) destination(); 3487 moved_oop->update_contents(compaction_manager()); 3488 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point"); 3489 3490 update_state(words); 3491 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity"); 3492 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete; 3493 } 3494 3495 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm, 3496 ParCompactionManager* cm, 3497 PSParallelCompact::SpaceId space_id) : 3498 ParMarkBitMapClosure(mbm, cm), 3499 _space_id(space_id), 3500 _start_array(PSParallelCompact::start_array(space_id)) 3501 { 3502 } 3503 3504 // Updates the references in the object to their new values. 3505 ParMarkBitMapClosure::IterationStatus 3506 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) { 3507 do_addr(addr); 3508 return ParMarkBitMap::incomplete; 3509 } 3510 3511 // Prepare for compaction. This method is executed once 3512 // (i.e., by a single thread) before compaction. 3513 // Save the updated location of the intArrayKlassObj for 3514 // filling holes in the dense prefix. 3515 void PSParallelCompact::compact_prologue() { 3516 _updated_int_array_klass_obj = (klassOop) 3517 summary_data().calc_new_pointer(Universe::intArrayKlassObj()); 3518 }