1 /* 2 * Copyright (c) 2001, 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 "gc_implementation/g1/g1BlockOffsetTable.inline.hpp" 27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 28 #include "gc_implementation/g1/g1OopClosures.inline.hpp" 29 #include "gc_implementation/g1/heapRegion.inline.hpp" 30 #include "gc_implementation/g1/heapRegionRemSet.hpp" 31 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 32 #include "memory/genOopClosures.inline.hpp" 33 #include "memory/iterator.hpp" 34 #include "oops/oop.inline.hpp" 35 36 int HeapRegion::LogOfHRGrainBytes = 0; 37 int HeapRegion::LogOfHRGrainWords = 0; 38 size_t HeapRegion::GrainBytes = 0; 39 size_t HeapRegion::GrainWords = 0; 40 size_t HeapRegion::CardsPerRegion = 0; 41 42 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1, 43 HeapRegion* hr, ExtendedOopClosure* cl, 44 CardTableModRefBS::PrecisionStyle precision, 45 FilterKind fk) : 46 ContiguousSpaceDCTOC(hr, cl, precision, NULL), 47 _hr(hr), _fk(fk), _g1(g1) { } 48 49 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r, 50 OopClosure* oc) : 51 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { } 52 53 class VerifyLiveClosure: public OopClosure { 54 private: 55 G1CollectedHeap* _g1h; 56 CardTableModRefBS* _bs; 57 oop _containing_obj; 58 bool _failures; 59 int _n_failures; 60 VerifyOption _vo; 61 public: 62 // _vo == UsePrevMarking -> use "prev" marking information, 63 // _vo == UseNextMarking -> use "next" marking information, 64 // _vo == UseMarkWord -> use mark word from object header. 65 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) : 66 _g1h(g1h), _bs(NULL), _containing_obj(NULL), 67 _failures(false), _n_failures(0), _vo(vo) 68 { 69 BarrierSet* bs = _g1h->barrier_set(); 70 if (bs->is_a(BarrierSet::CardTableModRef)) 71 _bs = (CardTableModRefBS*)bs; 72 } 73 74 void set_containing_obj(oop obj) { 75 _containing_obj = obj; 76 } 77 78 bool failures() { return _failures; } 79 int n_failures() { return _n_failures; } 80 81 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 82 virtual void do_oop( oop* p) { do_oop_work(p); } 83 84 void print_object(outputStream* out, oop obj) { 85 #ifdef PRODUCT 86 Klass* k = obj->klass(); 87 const char* class_name = InstanceKlass::cast(k)->external_name(); 88 out->print_cr("class name %s", class_name); 89 #else // PRODUCT 90 obj->print_on(out); 91 #endif // PRODUCT 92 } 93 94 template <class T> 95 void do_oop_work(T* p) { 96 assert(_containing_obj != NULL, "Precondition"); 97 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo), 98 "Precondition"); 99 T heap_oop = oopDesc::load_heap_oop(p); 100 if (!oopDesc::is_null(heap_oop)) { 101 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 102 bool failed = false; 103 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) { 104 MutexLockerEx x(ParGCRareEvent_lock, 105 Mutex::_no_safepoint_check_flag); 106 107 if (!_failures) { 108 gclog_or_tty->print_cr(""); 109 gclog_or_tty->print_cr("----------"); 110 } 111 if (!_g1h->is_in_closed_subset(obj)) { 112 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 113 gclog_or_tty->print_cr("Field "PTR_FORMAT 114 " of live obj "PTR_FORMAT" in region " 115 "["PTR_FORMAT", "PTR_FORMAT")", 116 p, (void*) _containing_obj, 117 from->bottom(), from->end()); 118 print_object(gclog_or_tty, _containing_obj); 119 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap", 120 (void*) obj); 121 } else { 122 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 123 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj); 124 gclog_or_tty->print_cr("Field "PTR_FORMAT 125 " of live obj "PTR_FORMAT" in region " 126 "["PTR_FORMAT", "PTR_FORMAT")", 127 p, (void*) _containing_obj, 128 from->bottom(), from->end()); 129 print_object(gclog_or_tty, _containing_obj); 130 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region " 131 "["PTR_FORMAT", "PTR_FORMAT")", 132 (void*) obj, to->bottom(), to->end()); 133 print_object(gclog_or_tty, obj); 134 } 135 gclog_or_tty->print_cr("----------"); 136 gclog_or_tty->flush(); 137 _failures = true; 138 failed = true; 139 _n_failures++; 140 } 141 142 if (!_g1h->full_collection()) { 143 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 144 HeapRegion* to = _g1h->heap_region_containing(obj); 145 if (from != NULL && to != NULL && 146 from != to && 147 !to->isHumongous()) { 148 jbyte cv_obj = *_bs->byte_for_const(_containing_obj); 149 jbyte cv_field = *_bs->byte_for_const(p); 150 const jbyte dirty = CardTableModRefBS::dirty_card_val(); 151 152 bool is_bad = !(from->is_young() 153 || to->rem_set()->contains_reference(p) 154 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed 155 (_containing_obj->is_objArray() ? 156 cv_field == dirty 157 : cv_obj == dirty || cv_field == dirty)); 158 if (is_bad) { 159 MutexLockerEx x(ParGCRareEvent_lock, 160 Mutex::_no_safepoint_check_flag); 161 162 if (!_failures) { 163 gclog_or_tty->print_cr(""); 164 gclog_or_tty->print_cr("----------"); 165 } 166 gclog_or_tty->print_cr("Missing rem set entry:"); 167 gclog_or_tty->print_cr("Field "PTR_FORMAT" " 168 "of obj "PTR_FORMAT", " 169 "in region "HR_FORMAT, 170 p, (void*) _containing_obj, 171 HR_FORMAT_PARAMS(from)); 172 _containing_obj->print_on(gclog_or_tty); 173 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" " 174 "in region "HR_FORMAT, 175 (void*) obj, 176 HR_FORMAT_PARAMS(to)); 177 obj->print_on(gclog_or_tty); 178 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.", 179 cv_obj, cv_field); 180 gclog_or_tty->print_cr("----------"); 181 gclog_or_tty->flush(); 182 _failures = true; 183 if (!failed) _n_failures++; 184 } 185 } 186 } 187 } 188 } 189 }; 190 191 template<class ClosureType> 192 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h, 193 HeapRegion* hr, 194 HeapWord* cur, HeapWord* top) { 195 oop cur_oop = oop(cur); 196 int oop_size = cur_oop->size(); 197 HeapWord* next_obj = cur + oop_size; 198 while (next_obj < top) { 199 // Keep filtering the remembered set. 200 if (!g1h->is_obj_dead(cur_oop, hr)) { 201 // Bottom lies entirely below top, so we can call the 202 // non-memRegion version of oop_iterate below. 203 cur_oop->oop_iterate(cl); 204 } 205 cur = next_obj; 206 cur_oop = oop(cur); 207 oop_size = cur_oop->size(); 208 next_obj = cur + oop_size; 209 } 210 return cur; 211 } 212 213 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr, 214 HeapWord* bottom, 215 HeapWord* top, 216 ExtendedOopClosure* cl) { 217 G1CollectedHeap* g1h = _g1; 218 int oop_size; 219 ExtendedOopClosure* cl2 = NULL; 220 221 FilterIntoCSClosure intoCSFilt(this, g1h, cl); 222 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl); 223 224 switch (_fk) { 225 case NoFilterKind: cl2 = cl; break; 226 case IntoCSFilterKind: cl2 = &intoCSFilt; break; 227 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break; 228 default: ShouldNotReachHere(); 229 } 230 231 // Start filtering what we add to the remembered set. If the object is 232 // not considered dead, either because it is marked (in the mark bitmap) 233 // or it was allocated after marking finished, then we add it. Otherwise 234 // we can safely ignore the object. 235 if (!g1h->is_obj_dead(oop(bottom), _hr)) { 236 oop_size = oop(bottom)->oop_iterate(cl2, mr); 237 } else { 238 oop_size = oop(bottom)->size(); 239 } 240 241 bottom += oop_size; 242 243 if (bottom < top) { 244 // We replicate the loop below for several kinds of possible filters. 245 switch (_fk) { 246 case NoFilterKind: 247 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top); 248 break; 249 250 case IntoCSFilterKind: { 251 FilterIntoCSClosure filt(this, g1h, cl); 252 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); 253 break; 254 } 255 256 case OutOfRegionFilterKind: { 257 FilterOutOfRegionClosure filt(_hr, cl); 258 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); 259 break; 260 } 261 262 default: 263 ShouldNotReachHere(); 264 } 265 266 // Last object. Need to do dead-obj filtering here too. 267 if (!g1h->is_obj_dead(oop(bottom), _hr)) { 268 oop(bottom)->oop_iterate(cl2, mr); 269 } 270 } 271 } 272 273 // Minimum region size; we won't go lower than that. 274 // We might want to decrease this in the future, to deal with small 275 // heaps a bit more efficiently. 276 #define MIN_REGION_SIZE ( 1024 * 1024 ) 277 278 // Maximum region size; we don't go higher than that. There's a good 279 // reason for having an upper bound. We don't want regions to get too 280 // large, otherwise cleanup's effectiveness would decrease as there 281 // will be fewer opportunities to find totally empty regions after 282 // marking. 283 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 ) 284 285 // The automatic region size calculation will try to have around this 286 // many regions in the heap (based on the min heap size). 287 #define TARGET_REGION_NUMBER 2048 288 289 void HeapRegion::setup_heap_region_size(uintx min_heap_size) { 290 // region_size in bytes 291 uintx region_size = G1HeapRegionSize; 292 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) { 293 // We base the automatic calculation on the min heap size. This 294 // can be problematic if the spread between min and max is quite 295 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on 296 // the max size, the region size might be way too large for the 297 // min size. Either way, some users might have to set the region 298 // size manually for some -Xms / -Xmx combos. 299 300 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER, 301 (uintx) MIN_REGION_SIZE); 302 } 303 304 int region_size_log = log2_long((jlong) region_size); 305 // Recalculate the region size to make sure it's a power of 306 // 2. This means that region_size is the largest power of 2 that's 307 // <= what we've calculated so far. 308 region_size = ((uintx)1 << region_size_log); 309 310 // Now make sure that we don't go over or under our limits. 311 if (region_size < MIN_REGION_SIZE) { 312 region_size = MIN_REGION_SIZE; 313 } else if (region_size > MAX_REGION_SIZE) { 314 region_size = MAX_REGION_SIZE; 315 } 316 317 // And recalculate the log. 318 region_size_log = log2_long((jlong) region_size); 319 320 // Now, set up the globals. 321 guarantee(LogOfHRGrainBytes == 0, "we should only set it once"); 322 LogOfHRGrainBytes = region_size_log; 323 324 guarantee(LogOfHRGrainWords == 0, "we should only set it once"); 325 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize; 326 327 guarantee(GrainBytes == 0, "we should only set it once"); 328 // The cast to int is safe, given that we've bounded region_size by 329 // MIN_REGION_SIZE and MAX_REGION_SIZE. 330 GrainBytes = (size_t)region_size; 331 332 guarantee(GrainWords == 0, "we should only set it once"); 333 GrainWords = GrainBytes >> LogHeapWordSize; 334 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity"); 335 336 guarantee(CardsPerRegion == 0, "we should only set it once"); 337 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift; 338 } 339 340 void HeapRegion::reset_after_compaction() { 341 G1OffsetTableContigSpace::reset_after_compaction(); 342 // After a compaction the mark bitmap is invalid, so we must 343 // treat all objects as being inside the unmarked area. 344 zero_marked_bytes(); 345 init_top_at_mark_start(); 346 } 347 348 void HeapRegion::hr_clear(bool par, bool clear_space) { 349 assert(_humongous_type == NotHumongous, 350 "we should have already filtered out humongous regions"); 351 assert(_humongous_start_region == NULL, 352 "we should have already filtered out humongous regions"); 353 assert(_end == _orig_end, 354 "we should have already filtered out humongous regions"); 355 356 _in_collection_set = false; 357 358 set_young_index_in_cset(-1); 359 uninstall_surv_rate_group(); 360 set_young_type(NotYoung); 361 reset_pre_dummy_top(); 362 363 if (!par) { 364 // If this is parallel, this will be done later. 365 HeapRegionRemSet* hrrs = rem_set(); 366 if (hrrs != NULL) hrrs->clear(); 367 _claimed = InitialClaimValue; 368 } 369 zero_marked_bytes(); 370 371 _offsets.resize(HeapRegion::GrainWords); 372 init_top_at_mark_start(); 373 if (clear_space) clear(SpaceDecorator::Mangle); 374 } 375 376 void HeapRegion::par_clear() { 377 assert(used() == 0, "the region should have been already cleared"); 378 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal"); 379 HeapRegionRemSet* hrrs = rem_set(); 380 hrrs->clear(); 381 CardTableModRefBS* ct_bs = 382 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set(); 383 ct_bs->clear(MemRegion(bottom(), end())); 384 } 385 386 void HeapRegion::calc_gc_efficiency() { 387 // GC efficiency is the ratio of how much space would be 388 // reclaimed over how long we predict it would take to reclaim it. 389 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 390 G1CollectorPolicy* g1p = g1h->g1_policy(); 391 392 // Retrieve a prediction of the elapsed time for this region for 393 // a mixed gc because the region will only be evacuated during a 394 // mixed gc. 395 double region_elapsed_time_ms = 396 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */); 397 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms; 398 } 399 400 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) { 401 assert(!isHumongous(), "sanity / pre-condition"); 402 assert(end() == _orig_end, 403 "Should be normal before the humongous object allocation"); 404 assert(top() == bottom(), "should be empty"); 405 assert(bottom() <= new_top && new_top <= new_end, "pre-condition"); 406 407 _humongous_type = StartsHumongous; 408 _humongous_start_region = this; 409 410 set_end(new_end); 411 _offsets.set_for_starts_humongous(new_top); 412 } 413 414 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) { 415 assert(!isHumongous(), "sanity / pre-condition"); 416 assert(end() == _orig_end, 417 "Should be normal before the humongous object allocation"); 418 assert(top() == bottom(), "should be empty"); 419 assert(first_hr->startsHumongous(), "pre-condition"); 420 421 _humongous_type = ContinuesHumongous; 422 _humongous_start_region = first_hr; 423 } 424 425 void HeapRegion::set_notHumongous() { 426 assert(isHumongous(), "pre-condition"); 427 428 if (startsHumongous()) { 429 assert(top() <= end(), "pre-condition"); 430 set_end(_orig_end); 431 if (top() > end()) { 432 // at least one "continues humongous" region after it 433 set_top(end()); 434 } 435 } else { 436 // continues humongous 437 assert(end() == _orig_end, "sanity"); 438 } 439 440 assert(capacity() == HeapRegion::GrainBytes, "pre-condition"); 441 _humongous_type = NotHumongous; 442 _humongous_start_region = NULL; 443 } 444 445 bool HeapRegion::claimHeapRegion(jint claimValue) { 446 jint current = _claimed; 447 if (current != claimValue) { 448 jint res = Atomic::cmpxchg(claimValue, &_claimed, current); 449 if (res == current) { 450 return true; 451 } 452 } 453 return false; 454 } 455 456 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) { 457 HeapWord* low = addr; 458 HeapWord* high = end(); 459 while (low < high) { 460 size_t diff = pointer_delta(high, low); 461 // Must add one below to bias toward the high amount. Otherwise, if 462 // "high" were at the desired value, and "low" were one less, we 463 // would not converge on "high". This is not symmetric, because 464 // we set "high" to a block start, which might be the right one, 465 // which we don't do for "low". 466 HeapWord* middle = low + (diff+1)/2; 467 if (middle == high) return high; 468 HeapWord* mid_bs = block_start_careful(middle); 469 if (mid_bs < addr) { 470 low = middle; 471 } else { 472 high = mid_bs; 473 } 474 } 475 assert(low == high && low >= addr, "Didn't work."); 476 return low; 477 } 478 479 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 480 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 481 #endif // _MSC_VER 482 483 484 HeapRegion::HeapRegion(uint hrs_index, 485 G1BlockOffsetSharedArray* sharedOffsetArray, 486 MemRegion mr) : 487 G1OffsetTableContigSpace(sharedOffsetArray, mr), 488 _hrs_index(hrs_index), 489 _humongous_type(NotHumongous), _humongous_start_region(NULL), 490 _in_collection_set(false), 491 _next_in_special_set(NULL), _orig_end(NULL), 492 _claimed(InitialClaimValue), _evacuation_failed(false), 493 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0), 494 _young_type(NotYoung), _next_young_region(NULL), 495 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false), 496 #ifdef ASSERT 497 _containing_set(NULL), 498 #endif // ASSERT 499 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1), 500 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0), 501 _predicted_bytes_to_copy(0) 502 { 503 _orig_end = mr.end(); 504 // Note that initialize() will set the start of the unmarked area of the 505 // region. 506 hr_clear(false /*par*/, false /*clear_space*/); 507 set_top(bottom()); 508 set_saved_mark(); 509 510 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this); 511 512 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant."); 513 } 514 515 CompactibleSpace* HeapRegion::next_compaction_space() const { 516 // We're not using an iterator given that it will wrap around when 517 // it reaches the last region and this is not what we want here. 518 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 519 uint index = hrs_index() + 1; 520 while (index < g1h->n_regions()) { 521 HeapRegion* hr = g1h->region_at(index); 522 if (!hr->isHumongous()) { 523 return hr; 524 } 525 index += 1; 526 } 527 return NULL; 528 } 529 530 void HeapRegion::save_marks() { 531 set_saved_mark(); 532 } 533 534 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) { 535 HeapWord* p = mr.start(); 536 HeapWord* e = mr.end(); 537 oop obj; 538 while (p < e) { 539 obj = oop(p); 540 p += obj->oop_iterate(cl); 541 } 542 assert(p == e, "bad memregion: doesn't end on obj boundary"); 543 } 544 545 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ 546 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ 547 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \ 548 } 549 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN) 550 551 552 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) { 553 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl); 554 } 555 556 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark, 557 bool during_conc_mark) { 558 // We always recreate the prev marking info and we'll explicitly 559 // mark all objects we find to be self-forwarded on the prev 560 // bitmap. So all objects need to be below PTAMS. 561 _prev_top_at_mark_start = top(); 562 _prev_marked_bytes = 0; 563 564 if (during_initial_mark) { 565 // During initial-mark, we'll also explicitly mark all objects 566 // we find to be self-forwarded on the next bitmap. So all 567 // objects need to be below NTAMS. 568 _next_top_at_mark_start = top(); 569 _next_marked_bytes = 0; 570 } else if (during_conc_mark) { 571 // During concurrent mark, all objects in the CSet (including 572 // the ones we find to be self-forwarded) are implicitly live. 573 // So all objects need to be above NTAMS. 574 _next_top_at_mark_start = bottom(); 575 _next_marked_bytes = 0; 576 } 577 } 578 579 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark, 580 bool during_conc_mark, 581 size_t marked_bytes) { 582 assert(0 <= marked_bytes && marked_bytes <= used(), 583 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT, 584 marked_bytes, used())); 585 _prev_marked_bytes = marked_bytes; 586 } 587 588 HeapWord* 589 HeapRegion::object_iterate_mem_careful(MemRegion mr, 590 ObjectClosure* cl) { 591 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 592 // We used to use "block_start_careful" here. But we're actually happy 593 // to update the BOT while we do this... 594 HeapWord* cur = block_start(mr.start()); 595 mr = mr.intersection(used_region()); 596 if (mr.is_empty()) return NULL; 597 // Otherwise, find the obj that extends onto mr.start(). 598 599 assert(cur <= mr.start() 600 && (oop(cur)->klass_or_null() == NULL || 601 cur + oop(cur)->size() > mr.start()), 602 "postcondition of block_start"); 603 oop obj; 604 while (cur < mr.end()) { 605 obj = oop(cur); 606 if (obj->klass_or_null() == NULL) { 607 // Ran into an unparseable point. 608 return cur; 609 } else if (!g1h->is_obj_dead(obj)) { 610 cl->do_object(obj); 611 } 612 if (cl->abort()) return cur; 613 // The check above must occur before the operation below, since an 614 // abort might invalidate the "size" operation. 615 cur += obj->size(); 616 } 617 return NULL; 618 } 619 620 HeapWord* 621 HeapRegion:: 622 oops_on_card_seq_iterate_careful(MemRegion mr, 623 FilterOutOfRegionClosure* cl, 624 bool filter_young, 625 jbyte* card_ptr) { 626 // Currently, we should only have to clean the card if filter_young 627 // is true and vice versa. 628 if (filter_young) { 629 assert(card_ptr != NULL, "pre-condition"); 630 } else { 631 assert(card_ptr == NULL, "pre-condition"); 632 } 633 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 634 635 // If we're within a stop-world GC, then we might look at a card in a 636 // GC alloc region that extends onto a GC LAB, which may not be 637 // parseable. Stop such at the "saved_mark" of the region. 638 if (g1h->is_gc_active()) { 639 mr = mr.intersection(used_region_at_save_marks()); 640 } else { 641 mr = mr.intersection(used_region()); 642 } 643 if (mr.is_empty()) return NULL; 644 // Otherwise, find the obj that extends onto mr.start(). 645 646 // The intersection of the incoming mr (for the card) and the 647 // allocated part of the region is non-empty. This implies that 648 // we have actually allocated into this region. The code in 649 // G1CollectedHeap.cpp that allocates a new region sets the 650 // is_young tag on the region before allocating. Thus we 651 // safely know if this region is young. 652 if (is_young() && filter_young) { 653 return NULL; 654 } 655 656 assert(!is_young(), "check value of filter_young"); 657 658 // We can only clean the card here, after we make the decision that 659 // the card is not young. And we only clean the card if we have been 660 // asked to (i.e., card_ptr != NULL). 661 if (card_ptr != NULL) { 662 *card_ptr = CardTableModRefBS::clean_card_val(); 663 // We must complete this write before we do any of the reads below. 664 OrderAccess::storeload(); 665 } 666 667 // Cache the boundaries of the memory region in some const locals 668 HeapWord* const start = mr.start(); 669 HeapWord* const end = mr.end(); 670 671 // We used to use "block_start_careful" here. But we're actually happy 672 // to update the BOT while we do this... 673 HeapWord* cur = block_start(start); 674 assert(cur <= start, "Postcondition"); 675 676 oop obj; 677 678 HeapWord* next = cur; 679 while (next <= start) { 680 cur = next; 681 obj = oop(cur); 682 if (obj->klass_or_null() == NULL) { 683 // Ran into an unparseable point. 684 return cur; 685 } 686 // Otherwise... 687 next = (cur + obj->size()); 688 } 689 690 // If we finish the above loop...We have a parseable object that 691 // begins on or before the start of the memory region, and ends 692 // inside or spans the entire region. 693 694 assert(obj == oop(cur), "sanity"); 695 assert(cur <= start && 696 obj->klass_or_null() != NULL && 697 (cur + obj->size()) > start, 698 "Loop postcondition"); 699 700 if (!g1h->is_obj_dead(obj)) { 701 obj->oop_iterate(cl, mr); 702 } 703 704 while (cur < end) { 705 obj = oop(cur); 706 if (obj->klass_or_null() == NULL) { 707 // Ran into an unparseable point. 708 return cur; 709 }; 710 711 // Otherwise: 712 next = (cur + obj->size()); 713 714 if (!g1h->is_obj_dead(obj)) { 715 if (next < end || !obj->is_objArray()) { 716 // This object either does not span the MemRegion 717 // boundary, or if it does it's not an array. 718 // Apply closure to whole object. 719 obj->oop_iterate(cl); 720 } else { 721 // This obj is an array that spans the boundary. 722 // Stop at the boundary. 723 obj->oop_iterate(cl, mr); 724 } 725 } 726 cur = next; 727 } 728 return NULL; 729 } 730 731 void HeapRegion::print() const { print_on(gclog_or_tty); } 732 void HeapRegion::print_on(outputStream* st) const { 733 if (isHumongous()) { 734 if (startsHumongous()) 735 st->print(" HS"); 736 else 737 st->print(" HC"); 738 } else { 739 st->print(" "); 740 } 741 if (in_collection_set()) 742 st->print(" CS"); 743 else 744 st->print(" "); 745 if (is_young()) 746 st->print(is_survivor() ? " SU" : " Y "); 747 else 748 st->print(" "); 749 if (is_empty()) 750 st->print(" F"); 751 else 752 st->print(" "); 753 st->print(" TS %5d", _gc_time_stamp); 754 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT, 755 prev_top_at_mark_start(), next_top_at_mark_start()); 756 G1OffsetTableContigSpace::print_on(st); 757 } 758 759 void HeapRegion::verify() const { 760 bool dummy = false; 761 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy); 762 } 763 764 // This really ought to be commoned up into OffsetTableContigSpace somehow. 765 // We would need a mechanism to make that code skip dead objects. 766 767 void HeapRegion::verify(VerifyOption vo, 768 bool* failures) const { 769 G1CollectedHeap* g1 = G1CollectedHeap::heap(); 770 *failures = false; 771 HeapWord* p = bottom(); 772 HeapWord* prev_p = NULL; 773 VerifyLiveClosure vl_cl(g1, vo); 774 bool is_humongous = isHumongous(); 775 bool do_bot_verify = !is_young(); 776 size_t object_num = 0; 777 while (p < top()) { 778 oop obj = oop(p); 779 size_t obj_size = obj->size(); 780 object_num += 1; 781 782 if (is_humongous != g1->isHumongous(obj_size)) { 783 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size (" 784 SIZE_FORMAT" words) in a %shumongous region", 785 p, g1->isHumongous(obj_size) ? "" : "non-", 786 obj_size, is_humongous ? "" : "non-"); 787 *failures = true; 788 return; 789 } 790 791 // If it returns false, verify_for_object() will output the 792 // appropriate messasge. 793 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) { 794 *failures = true; 795 return; 796 } 797 798 if (!g1->is_obj_dead_cond(obj, this, vo)) { 799 if (obj->is_oop()) { 800 Klass* klass = obj->klass(); 801 if (!klass->is_metadata()) { 802 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" " 803 "not metadata", klass, obj); 804 *failures = true; 805 return; 806 } else if (!klass->is_klass()) { 807 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" " 808 "not a klass", klass, obj); 809 *failures = true; 810 return; 811 } else { 812 vl_cl.set_containing_obj(obj); 813 obj->oop_iterate_no_header(&vl_cl); 814 if (vl_cl.failures()) { 815 *failures = true; 816 } 817 if (G1MaxVerifyFailures >= 0 && 818 vl_cl.n_failures() >= G1MaxVerifyFailures) { 819 return; 820 } 821 } 822 } else { 823 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj); 824 *failures = true; 825 return; 826 } 827 } 828 prev_p = p; 829 p += obj_size; 830 } 831 832 if (p != top()) { 833 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" " 834 "does not match top "PTR_FORMAT, p, top()); 835 *failures = true; 836 return; 837 } 838 839 HeapWord* the_end = end(); 840 assert(p == top(), "it should still hold"); 841 // Do some extra BOT consistency checking for addresses in the 842 // range [top, end). BOT look-ups in this range should yield 843 // top. No point in doing that if top == end (there's nothing there). 844 if (p < the_end) { 845 // Look up top 846 HeapWord* addr_1 = p; 847 HeapWord* b_start_1 = _offsets.block_start_const(addr_1); 848 if (b_start_1 != p) { 849 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" " 850 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 851 addr_1, b_start_1, p); 852 *failures = true; 853 return; 854 } 855 856 // Look up top + 1 857 HeapWord* addr_2 = p + 1; 858 if (addr_2 < the_end) { 859 HeapWord* b_start_2 = _offsets.block_start_const(addr_2); 860 if (b_start_2 != p) { 861 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" " 862 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 863 addr_2, b_start_2, p); 864 *failures = true; 865 return; 866 } 867 } 868 869 // Look up an address between top and end 870 size_t diff = pointer_delta(the_end, p) / 2; 871 HeapWord* addr_3 = p + diff; 872 if (addr_3 < the_end) { 873 HeapWord* b_start_3 = _offsets.block_start_const(addr_3); 874 if (b_start_3 != p) { 875 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" " 876 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 877 addr_3, b_start_3, p); 878 *failures = true; 879 return; 880 } 881 } 882 883 // Loook up end - 1 884 HeapWord* addr_4 = the_end - 1; 885 HeapWord* b_start_4 = _offsets.block_start_const(addr_4); 886 if (b_start_4 != p) { 887 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" " 888 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 889 addr_4, b_start_4, p); 890 *failures = true; 891 return; 892 } 893 } 894 895 if (is_humongous && object_num > 1) { 896 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous " 897 "but has "SIZE_FORMAT", objects", 898 bottom(), end(), object_num); 899 *failures = true; 900 return; 901 } 902 } 903 904 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go 905 // away eventually. 906 907 void G1OffsetTableContigSpace::clear(bool mangle_space) { 908 ContiguousSpace::clear(mangle_space); 909 _offsets.zero_bottom_entry(); 910 _offsets.initialize_threshold(); 911 } 912 913 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { 914 Space::set_bottom(new_bottom); 915 _offsets.set_bottom(new_bottom); 916 } 917 918 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) { 919 Space::set_end(new_end); 920 _offsets.resize(new_end - bottom()); 921 } 922 923 void G1OffsetTableContigSpace::print() const { 924 print_short(); 925 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 926 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 927 bottom(), top(), _offsets.threshold(), end()); 928 } 929 930 HeapWord* G1OffsetTableContigSpace::initialize_threshold() { 931 return _offsets.initialize_threshold(); 932 } 933 934 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start, 935 HeapWord* end) { 936 _offsets.alloc_block(start, end); 937 return _offsets.threshold(); 938 } 939 940 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const { 941 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 942 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" ); 943 if (_gc_time_stamp < g1h->get_gc_time_stamp()) 944 return top(); 945 else 946 return ContiguousSpace::saved_mark_word(); 947 } 948 949 void G1OffsetTableContigSpace::set_saved_mark() { 950 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 951 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp(); 952 953 if (_gc_time_stamp < curr_gc_time_stamp) { 954 // The order of these is important, as another thread might be 955 // about to start scanning this region. If it does so after 956 // set_saved_mark and before _gc_time_stamp = ..., then the latter 957 // will be false, and it will pick up top() as the high water mark 958 // of region. If it does so after _gc_time_stamp = ..., then it 959 // will pick up the right saved_mark_word() as the high water mark 960 // of the region. Either way, the behaviour will be correct. 961 ContiguousSpace::set_saved_mark(); 962 OrderAccess::storestore(); 963 _gc_time_stamp = curr_gc_time_stamp; 964 // No need to do another barrier to flush the writes above. If 965 // this is called in parallel with other threads trying to 966 // allocate into the region, the caller should call this while 967 // holding a lock and when the lock is released the writes will be 968 // flushed. 969 } 970 } 971 972 G1OffsetTableContigSpace:: 973 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray, 974 MemRegion mr) : 975 _offsets(sharedOffsetArray, mr), 976 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true), 977 _gc_time_stamp(0) 978 { 979 _offsets.set_space(this); 980 // false ==> we'll do the clearing if there's clearing to be done. 981 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle); 982 _offsets.zero_bottom_entry(); 983 _offsets.initialize_threshold(); 984 }