1 /* 2 * Copyright (c) 2005, 2019, 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 #ifndef SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP 26 #define SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP 27 28 #include "gc/parallel/mutableSpace.hpp" 29 #include "gc/parallel/objectStartArray.hpp" 30 #include "gc/parallel/parMarkBitMap.hpp" 31 #include "gc/parallel/parallelScavengeHeap.hpp" 32 #include "gc/shared/collectedHeap.hpp" 33 #include "gc/shared/collectorCounters.hpp" 34 #include "oops/oop.hpp" 35 #include "runtime/atomic.hpp" 36 #include "runtime/orderAccess.hpp" 37 38 class ParallelScavengeHeap; 39 class PSAdaptiveSizePolicy; 40 class PSYoungGen; 41 class PSOldGen; 42 class ParCompactionManager; 43 class ParallelTaskTerminator; 44 class PSParallelCompact; 45 class PreGCValues; 46 class MoveAndUpdateClosure; 47 class RefProcTaskExecutor; 48 class ParallelOldTracer; 49 class STWGCTimer; 50 51 // The SplitInfo class holds the information needed to 'split' a source region 52 // so that the live data can be copied to two destination *spaces*. Normally, 53 // all the live data in a region is copied to a single destination space (e.g., 54 // everything live in a region in eden is copied entirely into the old gen). 55 // However, when the heap is nearly full, all the live data in eden may not fit 56 // into the old gen. Copying only some of the regions from eden to old gen 57 // requires finding a region that does not contain a partial object (i.e., no 58 // live object crosses the region boundary) somewhere near the last object that 59 // does fit into the old gen. Since it's not always possible to find such a 60 // region, splitting is necessary for predictable behavior. 61 // 62 // A region is always split at the end of the partial object. This avoids 63 // additional tests when calculating the new location of a pointer, which is a 64 // very hot code path. The partial object and everything to its left will be 65 // copied to another space (call it dest_space_1). The live data to the right 66 // of the partial object will be copied either within the space itself, or to a 67 // different destination space (distinct from dest_space_1). 68 // 69 // Split points are identified during the summary phase, when region 70 // destinations are computed: data about the split, including the 71 // partial_object_size, is recorded in a SplitInfo record and the 72 // partial_object_size field in the summary data is set to zero. The zeroing is 73 // possible (and necessary) since the partial object will move to a different 74 // destination space than anything to its right, thus the partial object should 75 // not affect the locations of any objects to its right. 76 // 77 // The recorded data is used during the compaction phase, but only rarely: when 78 // the partial object on the split region will be copied across a destination 79 // region boundary. This test is made once each time a region is filled, and is 80 // a simple address comparison, so the overhead is negligible (see 81 // PSParallelCompact::first_src_addr()). 82 // 83 // Notes: 84 // 85 // Only regions with partial objects are split; a region without a partial 86 // object does not need any extra bookkeeping. 87 // 88 // At most one region is split per space, so the amount of data required is 89 // constant. 90 // 91 // A region is split only when the destination space would overflow. Once that 92 // happens, the destination space is abandoned and no other data (even from 93 // other source spaces) is targeted to that destination space. Abandoning the 94 // destination space may leave a somewhat large unused area at the end, if a 95 // large object caused the overflow. 96 // 97 // Future work: 98 // 99 // More bookkeeping would be required to continue to use the destination space. 100 // The most general solution would allow data from regions in two different 101 // source spaces to be "joined" in a single destination region. At the very 102 // least, additional code would be required in next_src_region() to detect the 103 // join and skip to an out-of-order source region. If the join region was also 104 // the last destination region to which a split region was copied (the most 105 // likely case), then additional work would be needed to get fill_region() to 106 // stop iteration and switch to a new source region at the right point. Basic 107 // idea would be to use a fake value for the top of the source space. It is 108 // doable, if a bit tricky. 109 // 110 // A simpler (but less general) solution would fill the remainder of the 111 // destination region with a dummy object and continue filling the next 112 // destination region. 113 114 class SplitInfo 115 { 116 public: 117 // Return true if this split info is valid (i.e., if a split has been 118 // recorded). The very first region cannot have a partial object and thus is 119 // never split, so 0 is the 'invalid' value. 120 bool is_valid() const { return _src_region_idx > 0; } 121 122 // Return true if this split holds data for the specified source region. 123 inline bool is_split(size_t source_region) const; 124 125 // The index of the split region, the size of the partial object on that 126 // region and the destination of the partial object. 127 size_t src_region_idx() const { return _src_region_idx; } 128 size_t partial_obj_size() const { return _partial_obj_size; } 129 HeapWord* destination() const { return _destination; } 130 131 // The destination count of the partial object referenced by this split 132 // (either 1 or 2). This must be added to the destination count of the 133 // remainder of the source region. 134 unsigned int destination_count() const { return _destination_count; } 135 136 // If a word within the partial object will be written to the first word of a 137 // destination region, this is the address of the destination region; 138 // otherwise this is NULL. 139 HeapWord* dest_region_addr() const { return _dest_region_addr; } 140 141 // If a word within the partial object will be written to the first word of a 142 // destination region, this is the address of that word within the partial 143 // object; otherwise this is NULL. 144 HeapWord* first_src_addr() const { return _first_src_addr; } 145 146 // Record the data necessary to split the region src_region_idx. 147 void record(size_t src_region_idx, size_t partial_obj_size, 148 HeapWord* destination); 149 150 void clear(); 151 152 DEBUG_ONLY(void verify_clear();) 153 154 private: 155 size_t _src_region_idx; 156 size_t _partial_obj_size; 157 HeapWord* _destination; 158 unsigned int _destination_count; 159 HeapWord* _dest_region_addr; 160 HeapWord* _first_src_addr; 161 }; 162 163 inline bool SplitInfo::is_split(size_t region_idx) const 164 { 165 return _src_region_idx == region_idx && is_valid(); 166 } 167 168 class SpaceInfo 169 { 170 public: 171 MutableSpace* space() const { return _space; } 172 173 // Where the free space will start after the collection. Valid only after the 174 // summary phase completes. 175 HeapWord* new_top() const { return _new_top; } 176 177 // Allows new_top to be set. 178 HeapWord** new_top_addr() { return &_new_top; } 179 180 // Where the smallest allowable dense prefix ends (used only for perm gen). 181 HeapWord* min_dense_prefix() const { return _min_dense_prefix; } 182 183 // Where the dense prefix ends, or the compacted region begins. 184 HeapWord* dense_prefix() const { return _dense_prefix; } 185 186 // The start array for the (generation containing the) space, or NULL if there 187 // is no start array. 188 ObjectStartArray* start_array() const { return _start_array; } 189 190 SplitInfo& split_info() { return _split_info; } 191 192 void set_space(MutableSpace* s) { _space = s; } 193 void set_new_top(HeapWord* addr) { _new_top = addr; } 194 void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; } 195 void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; } 196 void set_start_array(ObjectStartArray* s) { _start_array = s; } 197 198 void publish_new_top() const { _space->set_top(_new_top); } 199 200 private: 201 MutableSpace* _space; 202 HeapWord* _new_top; 203 HeapWord* _min_dense_prefix; 204 HeapWord* _dense_prefix; 205 ObjectStartArray* _start_array; 206 SplitInfo _split_info; 207 }; 208 209 class ParallelCompactData 210 { 211 public: 212 // Sizes are in HeapWords, unless indicated otherwise. 213 static const size_t Log2RegionSize; 214 static const size_t RegionSize; 215 static const size_t RegionSizeBytes; 216 217 // Mask for the bits in a size_t to get an offset within a region. 218 static const size_t RegionSizeOffsetMask; 219 // Mask for the bits in a pointer to get an offset within a region. 220 static const size_t RegionAddrOffsetMask; 221 // Mask for the bits in a pointer to get the address of the start of a region. 222 static const size_t RegionAddrMask; 223 224 static const size_t Log2BlockSize; 225 static const size_t BlockSize; 226 static const size_t BlockSizeBytes; 227 228 static const size_t BlockSizeOffsetMask; 229 static const size_t BlockAddrOffsetMask; 230 static const size_t BlockAddrMask; 231 232 static const size_t BlocksPerRegion; 233 static const size_t Log2BlocksPerRegion; 234 235 class RegionData 236 { 237 public: 238 // Destination address of the region. 239 HeapWord* destination() const { return _destination; } 240 241 // The first region containing data destined for this region. 242 size_t source_region() const { return _source_region; } 243 244 // Reuse _source_region to store the corresponding shadow region index 245 size_t shadow_region() const { return _source_region; } 246 247 // The object (if any) starting in this region and ending in a different 248 // region that could not be updated during the main (parallel) compaction 249 // phase. This is different from _partial_obj_addr, which is an object that 250 // extends onto a source region. However, the two uses do not overlap in 251 // time, so the same field is used to save space. 252 HeapWord* deferred_obj_addr() const { return _partial_obj_addr; } 253 254 // The starting address of the partial object extending onto the region. 255 HeapWord* partial_obj_addr() const { return _partial_obj_addr; } 256 257 // Size of the partial object extending onto the region (words). 258 size_t partial_obj_size() const { return _partial_obj_size; } 259 260 // Size of live data that lies within this region due to objects that start 261 // in this region (words). This does not include the partial object 262 // extending onto the region (if any), or the part of an object that extends 263 // onto the next region (if any). 264 size_t live_obj_size() const { return _dc_and_los & los_mask; } 265 266 // Total live data that lies within the region (words). 267 size_t data_size() const { return partial_obj_size() + live_obj_size(); } 268 269 // The destination_count is the number of other regions to which data from 270 // this region will be copied. At the end of the summary phase, the valid 271 // values of destination_count are 272 // 273 // 0 - data from the region will be compacted completely into itself, or the 274 // region is empty. The region can be claimed and then filled. 275 // 1 - data from the region will be compacted into 1 other region; some 276 // data from the region may also be compacted into the region itself. 277 // 2 - data from the region will be copied to 2 other regions. 278 // 279 // During compaction as regions are emptied, the destination_count is 280 // decremented (atomically) and when it reaches 0, it can be claimed and 281 // then filled. 282 // 283 // A region is claimed for processing by atomically changing the 284 // destination_count to the claimed value (dc_claimed). After a region has 285 // been filled, the destination_count should be set to the completed value 286 // (dc_completed). 287 inline uint destination_count() const; 288 inline uint destination_count_raw() const; 289 290 // Whether the block table for this region has been filled. 291 inline bool blocks_filled() const; 292 293 // Number of times the block table was filled. 294 DEBUG_ONLY(inline size_t blocks_filled_count() const;) 295 296 // The location of the java heap data that corresponds to this region. 297 inline HeapWord* data_location() const; 298 299 // The highest address referenced by objects in this region. 300 inline HeapWord* highest_ref() const; 301 302 // Whether this region is available to be claimed, has been claimed, or has 303 // been completed. 304 // 305 // Minor subtlety: claimed() returns true if the region is marked 306 // completed(), which is desirable since a region must be claimed before it 307 // can be completed. 308 bool available() const { return _dc_and_los < dc_one; } 309 bool claimed() const { return _dc_and_los >= dc_claimed; } 310 bool completed() const { return _dc_and_los >= dc_completed; } 311 312 // These are not atomic. 313 void set_destination(HeapWord* addr) { _destination = addr; } 314 void set_source_region(size_t region) { _source_region = region; } 315 void set_shadow_region(size_t region) { _source_region = region; } 316 void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } 317 void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } 318 void set_partial_obj_size(size_t words) { 319 _partial_obj_size = (region_sz_t) words; 320 } 321 inline void set_blocks_filled(); 322 323 inline void set_destination_count(uint count); 324 inline void set_live_obj_size(size_t words); 325 inline void set_data_location(HeapWord* addr); 326 inline void set_completed(); 327 inline bool claim_unsafe(); 328 329 // These are atomic. 330 inline void add_live_obj(size_t words); 331 inline void set_highest_ref(HeapWord* addr); 332 inline void decrement_destination_count(); 333 inline bool claim(); 334 335 // Possible values of _shadow_state, and transition is as follows 336 // Normal Path: 337 // UnusedRegion -> mark_normal() -> NormalRegion 338 // Shadow Path: 339 // UnusedRegion -> mark_shadow() -> ShadowRegion -> 340 // mark_filled() -> FilledShadow -> mark_copied() -> CopiedShadow 341 static const int UnusedRegion = 0; // The region is not collected yet 342 static const int ShadowRegion = 1; // Stolen by an idle thread, and a shadow region is created for it 343 static const int FilledShadow = 2; // Its shadow region has been filled and ready to be copied back 344 static const int CopiedShadow = 3; // The data of the shadow region has been copied back 345 static const int NormalRegion = 4; // The region will be collected by the original parallel algorithm 346 347 // Mark the current region as normal or shadow to enter different processing paths 348 inline bool mark_normal(); 349 inline bool mark_shadow(); 350 // Mark the shadow region as filled and ready to be copied back 351 inline void mark_filled(); 352 // Mark the shadow region as copied back to avoid double copying. 353 inline bool mark_copied(); 354 // Special case: see the comment in PSParallelCompact::fill_and_update_shadow_region. 355 // Return to the normal path here 356 inline void shadow_to_normal(); 357 358 359 int shadow_state() { return _shadow_state; } 360 361 private: 362 // The type used to represent object sizes within a region. 363 typedef uint region_sz_t; 364 365 // Constants for manipulating the _dc_and_los field, which holds both the 366 // destination count and live obj size. The live obj size lives at the 367 // least significant end so no masking is necessary when adding. 368 static const region_sz_t dc_shift; // Shift amount. 369 static const region_sz_t dc_mask; // Mask for destination count. 370 static const region_sz_t dc_one; // 1, shifted appropriately. 371 static const region_sz_t dc_claimed; // Region has been claimed. 372 static const region_sz_t dc_completed; // Region has been completed. 373 static const region_sz_t los_mask; // Mask for live obj size. 374 375 HeapWord* _destination; 376 size_t _source_region; 377 HeapWord* _partial_obj_addr; 378 region_sz_t _partial_obj_size; 379 region_sz_t volatile _dc_and_los; 380 bool volatile _blocks_filled; 381 int volatile _shadow_state; 382 383 #ifdef ASSERT 384 size_t _blocks_filled_count; // Number of block table fills. 385 386 // These enable optimizations that are only partially implemented. Use 387 // debug builds to prevent the code fragments from breaking. 388 HeapWord* _data_location; 389 HeapWord* _highest_ref; 390 #endif // #ifdef ASSERT 391 392 #ifdef ASSERT 393 public: 394 uint _pushed; // 0 until region is pushed onto a stack 395 private: 396 #endif 397 }; 398 399 // "Blocks" allow shorter sections of the bitmap to be searched. Each Block 400 // holds an offset, which is the amount of live data in the Region to the left 401 // of the first live object that starts in the Block. 402 class BlockData 403 { 404 public: 405 typedef unsigned short int blk_ofs_t; 406 407 blk_ofs_t offset() const { return _offset; } 408 void set_offset(size_t val) { _offset = (blk_ofs_t)val; } 409 410 private: 411 blk_ofs_t _offset; 412 }; 413 414 public: 415 ParallelCompactData(); 416 bool initialize(MemRegion covered_region); 417 418 size_t region_count() const { return _region_count; } 419 size_t reserved_byte_size() const { return _reserved_byte_size; } 420 421 // Convert region indices to/from RegionData pointers. 422 inline RegionData* region(size_t region_idx) const; 423 inline size_t region(const RegionData* const region_ptr) const; 424 425 size_t block_count() const { return _block_count; } 426 inline BlockData* block(size_t block_idx) const; 427 inline size_t block(const BlockData* block_ptr) const; 428 429 void add_obj(HeapWord* addr, size_t len); 430 void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); } 431 432 // Fill in the regions covering [beg, end) so that no data moves; i.e., the 433 // destination of region n is simply the start of region n. The argument beg 434 // must be region-aligned; end need not be. 435 void summarize_dense_prefix(HeapWord* beg, HeapWord* end); 436 437 HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info, 438 HeapWord* destination, HeapWord* target_end, 439 HeapWord** target_next); 440 bool summarize(SplitInfo& split_info, 441 HeapWord* source_beg, HeapWord* source_end, 442 HeapWord** source_next, 443 HeapWord* target_beg, HeapWord* target_end, 444 HeapWord** target_next); 445 446 void clear(); 447 void clear_range(size_t beg_region, size_t end_region); 448 void clear_range(HeapWord* beg, HeapWord* end) { 449 clear_range(addr_to_region_idx(beg), addr_to_region_idx(end)); 450 } 451 452 // Return the number of words between addr and the start of the region 453 // containing addr. 454 inline size_t region_offset(const HeapWord* addr) const; 455 456 // Convert addresses to/from a region index or region pointer. 457 inline size_t addr_to_region_idx(const HeapWord* addr) const; 458 inline RegionData* addr_to_region_ptr(const HeapWord* addr) const; 459 inline HeapWord* region_to_addr(size_t region) const; 460 inline HeapWord* region_to_addr(size_t region, size_t offset) const; 461 inline HeapWord* region_to_addr(const RegionData* region) const; 462 463 inline HeapWord* region_align_down(HeapWord* addr) const; 464 inline HeapWord* region_align_up(HeapWord* addr) const; 465 inline bool is_region_aligned(HeapWord* addr) const; 466 467 // Analogous to region_offset() for blocks. 468 size_t block_offset(const HeapWord* addr) const; 469 size_t addr_to_block_idx(const HeapWord* addr) const; 470 size_t addr_to_block_idx(const oop obj) const { 471 return addr_to_block_idx((HeapWord*) obj); 472 } 473 inline BlockData* addr_to_block_ptr(const HeapWord* addr) const; 474 inline HeapWord* block_to_addr(size_t block) const; 475 inline size_t region_to_block_idx(size_t region) const; 476 477 inline HeapWord* block_align_down(HeapWord* addr) const; 478 inline HeapWord* block_align_up(HeapWord* addr) const; 479 inline bool is_block_aligned(HeapWord* addr) const; 480 481 // Return the address one past the end of the partial object. 482 HeapWord* partial_obj_end(size_t region_idx) const; 483 484 // Return the location of the object after compaction. 485 HeapWord* calc_new_pointer(HeapWord* addr, ParCompactionManager* cm); 486 487 HeapWord* calc_new_pointer(oop p, ParCompactionManager* cm) { 488 return calc_new_pointer((HeapWord*) p, cm); 489 } 490 491 #ifdef ASSERT 492 void verify_clear(const PSVirtualSpace* vspace); 493 void verify_clear(); 494 #endif // #ifdef ASSERT 495 496 private: 497 bool initialize_block_data(); 498 bool initialize_region_data(size_t region_size); 499 PSVirtualSpace* create_vspace(size_t count, size_t element_size); 500 501 private: 502 HeapWord* _region_start; 503 #ifdef ASSERT 504 HeapWord* _region_end; 505 #endif // #ifdef ASSERT 506 507 PSVirtualSpace* _region_vspace; 508 size_t _reserved_byte_size; 509 RegionData* _region_data; 510 size_t _region_count; 511 512 PSVirtualSpace* _block_vspace; 513 BlockData* _block_data; 514 size_t _block_count; 515 }; 516 517 inline uint 518 ParallelCompactData::RegionData::destination_count_raw() const 519 { 520 return _dc_and_los & dc_mask; 521 } 522 523 inline uint 524 ParallelCompactData::RegionData::destination_count() const 525 { 526 return destination_count_raw() >> dc_shift; 527 } 528 529 inline bool 530 ParallelCompactData::RegionData::blocks_filled() const 531 { 532 bool result = _blocks_filled; 533 OrderAccess::acquire(); 534 return result; 535 } 536 537 #ifdef ASSERT 538 inline size_t 539 ParallelCompactData::RegionData::blocks_filled_count() const 540 { 541 return _blocks_filled_count; 542 } 543 #endif // #ifdef ASSERT 544 545 inline void 546 ParallelCompactData::RegionData::set_blocks_filled() 547 { 548 OrderAccess::release(); 549 _blocks_filled = true; 550 // Debug builds count the number of times the table was filled. 551 DEBUG_ONLY(Atomic::inc(&_blocks_filled_count)); 552 } 553 554 inline void 555 ParallelCompactData::RegionData::set_destination_count(uint count) 556 { 557 assert(count <= (dc_completed >> dc_shift), "count too large"); 558 const region_sz_t live_sz = (region_sz_t) live_obj_size(); 559 _dc_and_los = (count << dc_shift) | live_sz; 560 } 561 562 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words) 563 { 564 assert(words <= los_mask, "would overflow"); 565 _dc_and_los = destination_count_raw() | (region_sz_t)words; 566 } 567 568 inline void ParallelCompactData::RegionData::decrement_destination_count() 569 { 570 assert(_dc_and_los < dc_claimed, "already claimed"); 571 assert(_dc_and_los >= dc_one, "count would go negative"); 572 Atomic::add(&_dc_and_los, dc_mask); 573 } 574 575 inline HeapWord* ParallelCompactData::RegionData::data_location() const 576 { 577 DEBUG_ONLY(return _data_location;) 578 NOT_DEBUG(return NULL;) 579 } 580 581 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const 582 { 583 DEBUG_ONLY(return _highest_ref;) 584 NOT_DEBUG(return NULL;) 585 } 586 587 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr) 588 { 589 DEBUG_ONLY(_data_location = addr;) 590 } 591 592 inline void ParallelCompactData::RegionData::set_completed() 593 { 594 assert(claimed(), "must be claimed first"); 595 _dc_and_los = dc_completed | (region_sz_t) live_obj_size(); 596 } 597 598 // MT-unsafe claiming of a region. Should only be used during single threaded 599 // execution. 600 inline bool ParallelCompactData::RegionData::claim_unsafe() 601 { 602 if (available()) { 603 _dc_and_los |= dc_claimed; 604 return true; 605 } 606 return false; 607 } 608 609 inline void ParallelCompactData::RegionData::add_live_obj(size_t words) 610 { 611 assert(words <= (size_t)los_mask - live_obj_size(), "overflow"); 612 Atomic::add(&_dc_and_los, static_cast<region_sz_t>(words)); 613 } 614 615 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr) 616 { 617 #ifdef ASSERT 618 HeapWord* tmp = _highest_ref; 619 while (addr > tmp) { 620 tmp = Atomic::cmpxchg(&_highest_ref, tmp, addr); 621 } 622 #endif // #ifdef ASSERT 623 } 624 625 inline bool ParallelCompactData::RegionData::claim() 626 { 627 const region_sz_t los = static_cast<region_sz_t>(live_obj_size()); 628 const region_sz_t old = Atomic::cmpxchg(&_dc_and_los, los, dc_claimed | los); 629 return old == los; 630 } 631 632 inline bool ParallelCompactData::RegionData::mark_normal() { 633 return Atomic::cmpxchg(&_shadow_state, UnusedRegion, NormalRegion, memory_order_relaxed) == UnusedRegion; 634 } 635 636 inline bool ParallelCompactData::RegionData::mark_shadow() { 637 if (_shadow_state != UnusedRegion) return false; 638 return Atomic::cmpxchg(&_shadow_state, UnusedRegion, ShadowRegion, memory_order_relaxed) == UnusedRegion; 639 } 640 641 inline void ParallelCompactData::RegionData::mark_filled() { 642 int old = Atomic::cmpxchg(&_shadow_state, ShadowRegion, FilledShadow, memory_order_relaxed); 643 assert(old == ShadowRegion, "Fail to mark the region as filled"); 644 } 645 646 inline bool ParallelCompactData::RegionData::mark_copied() { 647 return Atomic::cmpxchg(&_shadow_state, FilledShadow, CopiedShadow, memory_order_relaxed) == FilledShadow; 648 } 649 650 void ParallelCompactData::RegionData::shadow_to_normal() { 651 int old = Atomic::cmpxchg(&_shadow_state, ShadowRegion, NormalRegion, memory_order_relaxed); 652 assert(old == ShadowRegion, "Fail to mark the region as finish"); 653 } 654 655 inline ParallelCompactData::RegionData* 656 ParallelCompactData::region(size_t region_idx) const 657 { 658 assert(region_idx <= region_count(), "bad arg"); 659 return _region_data + region_idx; 660 } 661 662 inline size_t 663 ParallelCompactData::region(const RegionData* const region_ptr) const 664 { 665 assert(region_ptr >= _region_data, "bad arg"); 666 assert(region_ptr <= _region_data + region_count(), "bad arg"); 667 return pointer_delta(region_ptr, _region_data, sizeof(RegionData)); 668 } 669 670 inline ParallelCompactData::BlockData* 671 ParallelCompactData::block(size_t n) const { 672 assert(n < block_count(), "bad arg"); 673 return _block_data + n; 674 } 675 676 inline size_t 677 ParallelCompactData::region_offset(const HeapWord* addr) const 678 { 679 assert(addr >= _region_start, "bad addr"); 680 assert(addr <= _region_end, "bad addr"); 681 return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize; 682 } 683 684 inline size_t 685 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const 686 { 687 assert(addr >= _region_start, "bad addr " PTR_FORMAT " _region_start " PTR_FORMAT, p2i(addr), p2i(_region_start)); 688 assert(addr <= _region_end, "bad addr " PTR_FORMAT " _region_end " PTR_FORMAT, p2i(addr), p2i(_region_end)); 689 return pointer_delta(addr, _region_start) >> Log2RegionSize; 690 } 691 692 inline ParallelCompactData::RegionData* 693 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const 694 { 695 return region(addr_to_region_idx(addr)); 696 } 697 698 inline HeapWord* 699 ParallelCompactData::region_to_addr(size_t region) const 700 { 701 assert(region <= _region_count, "region out of range"); 702 return _region_start + (region << Log2RegionSize); 703 } 704 705 inline HeapWord* 706 ParallelCompactData::region_to_addr(const RegionData* region) const 707 { 708 return region_to_addr(pointer_delta(region, _region_data, 709 sizeof(RegionData))); 710 } 711 712 inline HeapWord* 713 ParallelCompactData::region_to_addr(size_t region, size_t offset) const 714 { 715 assert(region <= _region_count, "region out of range"); 716 assert(offset < RegionSize, "offset too big"); // This may be too strict. 717 return region_to_addr(region) + offset; 718 } 719 720 inline HeapWord* 721 ParallelCompactData::region_align_down(HeapWord* addr) const 722 { 723 assert(addr >= _region_start, "bad addr"); 724 assert(addr < _region_end + RegionSize, "bad addr"); 725 return (HeapWord*)(size_t(addr) & RegionAddrMask); 726 } 727 728 inline HeapWord* 729 ParallelCompactData::region_align_up(HeapWord* addr) const 730 { 731 assert(addr >= _region_start, "bad addr"); 732 assert(addr <= _region_end, "bad addr"); 733 return region_align_down(addr + RegionSizeOffsetMask); 734 } 735 736 inline bool 737 ParallelCompactData::is_region_aligned(HeapWord* addr) const 738 { 739 return region_offset(addr) == 0; 740 } 741 742 inline size_t 743 ParallelCompactData::block_offset(const HeapWord* addr) const 744 { 745 assert(addr >= _region_start, "bad addr"); 746 assert(addr <= _region_end, "bad addr"); 747 return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize; 748 } 749 750 inline size_t 751 ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const 752 { 753 assert(addr >= _region_start, "bad addr"); 754 assert(addr <= _region_end, "bad addr"); 755 return pointer_delta(addr, _region_start) >> Log2BlockSize; 756 } 757 758 inline ParallelCompactData::BlockData* 759 ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const 760 { 761 return block(addr_to_block_idx(addr)); 762 } 763 764 inline HeapWord* 765 ParallelCompactData::block_to_addr(size_t block) const 766 { 767 assert(block < _block_count, "block out of range"); 768 return _region_start + (block << Log2BlockSize); 769 } 770 771 inline size_t 772 ParallelCompactData::region_to_block_idx(size_t region) const 773 { 774 return region << Log2BlocksPerRegion; 775 } 776 777 inline HeapWord* 778 ParallelCompactData::block_align_down(HeapWord* addr) const 779 { 780 assert(addr >= _region_start, "bad addr"); 781 assert(addr < _region_end + RegionSize, "bad addr"); 782 return (HeapWord*)(size_t(addr) & BlockAddrMask); 783 } 784 785 inline HeapWord* 786 ParallelCompactData::block_align_up(HeapWord* addr) const 787 { 788 assert(addr >= _region_start, "bad addr"); 789 assert(addr <= _region_end, "bad addr"); 790 return block_align_down(addr + BlockSizeOffsetMask); 791 } 792 793 inline bool 794 ParallelCompactData::is_block_aligned(HeapWord* addr) const 795 { 796 return block_offset(addr) == 0; 797 } 798 799 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the 800 // do_addr() method. 801 // 802 // The closure is initialized with the number of heap words to process 803 // (words_remaining()), and becomes 'full' when it reaches 0. The do_addr() 804 // methods in subclasses should update the total as words are processed. Since 805 // only one subclass actually uses this mechanism to terminate iteration, the 806 // default initial value is > 0. The implementation is here and not in the 807 // single subclass that uses it to avoid making is_full() virtual, and thus 808 // adding a virtual call per live object. 809 810 class ParMarkBitMapClosure: public StackObj { 811 public: 812 typedef ParMarkBitMap::idx_t idx_t; 813 typedef ParMarkBitMap::IterationStatus IterationStatus; 814 815 public: 816 inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm, 817 size_t words = max_uintx); 818 819 inline ParCompactionManager* compaction_manager() const; 820 inline ParMarkBitMap* bitmap() const; 821 inline size_t words_remaining() const; 822 inline bool is_full() const; 823 inline HeapWord* source() const; 824 825 inline void set_source(HeapWord* addr); 826 827 virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0; 828 829 protected: 830 inline void decrement_words_remaining(size_t words); 831 832 private: 833 ParMarkBitMap* const _bitmap; 834 ParCompactionManager* const _compaction_manager; 835 DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger. 836 size_t _words_remaining; // Words left to copy. 837 838 protected: 839 HeapWord* _source; // Next addr that would be read. 840 }; 841 842 inline 843 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap, 844 ParCompactionManager* cm, 845 size_t words): 846 _bitmap(bitmap), _compaction_manager(cm) 847 #ifdef ASSERT 848 , _initial_words_remaining(words) 849 #endif 850 { 851 _words_remaining = words; 852 _source = NULL; 853 } 854 855 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const { 856 return _compaction_manager; 857 } 858 859 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const { 860 return _bitmap; 861 } 862 863 inline size_t ParMarkBitMapClosure::words_remaining() const { 864 return _words_remaining; 865 } 866 867 inline bool ParMarkBitMapClosure::is_full() const { 868 return words_remaining() == 0; 869 } 870 871 inline HeapWord* ParMarkBitMapClosure::source() const { 872 return _source; 873 } 874 875 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) { 876 _source = addr; 877 } 878 879 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) { 880 assert(_words_remaining >= words, "processed too many words"); 881 _words_remaining -= words; 882 } 883 884 // The UseParallelOldGC collector is a stop-the-world garbage collector that 885 // does parts of the collection using parallel threads. The collection includes 886 // the tenured generation and the young generation. The permanent generation is 887 // collected at the same time as the other two generations but the permanent 888 // generation is collect by a single GC thread. The permanent generation is 889 // collected serially because of the requirement that during the processing of a 890 // klass AAA, any objects reference by AAA must already have been processed. 891 // This requirement is enforced by a left (lower address) to right (higher 892 // address) sliding compaction. 893 // 894 // There are four phases of the collection. 895 // 896 // - marking phase 897 // - summary phase 898 // - compacting phase 899 // - clean up phase 900 // 901 // Roughly speaking these phases correspond, respectively, to 902 // - mark all the live objects 903 // - calculate the destination of each object at the end of the collection 904 // - move the objects to their destination 905 // - update some references and reinitialize some variables 906 // 907 // These three phases are invoked in PSParallelCompact::invoke_no_policy(). The 908 // marking phase is implemented in PSParallelCompact::marking_phase() and does a 909 // complete marking of the heap. The summary phase is implemented in 910 // PSParallelCompact::summary_phase(). The move and update phase is implemented 911 // in PSParallelCompact::compact(). 912 // 913 // A space that is being collected is divided into regions and with each region 914 // is associated an object of type ParallelCompactData. Each region is of a 915 // fixed size and typically will contain more than 1 object and may have parts 916 // of objects at the front and back of the region. 917 // 918 // region -----+---------------------+---------- 919 // objects covered [ AAA )[ BBB )[ CCC )[ DDD ) 920 // 921 // The marking phase does a complete marking of all live objects in the heap. 922 // The marking also compiles the size of the data for all live objects covered 923 // by the region. This size includes the part of any live object spanning onto 924 // the region (part of AAA if it is live) from the front, all live objects 925 // contained in the region (BBB and/or CCC if they are live), and the part of 926 // any live objects covered by the region that extends off the region (part of 927 // DDD if it is live). The marking phase uses multiple GC threads and marking 928 // is done in a bit array of type ParMarkBitMap. The marking of the bit map is 929 // done atomically as is the accumulation of the size of the live objects 930 // covered by a region. 931 // 932 // The summary phase calculates the total live data to the left of each region 933 // XXX. Based on that total and the bottom of the space, it can calculate the 934 // starting location of the live data in XXX. The summary phase calculates for 935 // each region XXX quantities such as 936 // 937 // - the amount of live data at the beginning of a region from an object 938 // entering the region. 939 // - the location of the first live data on the region 940 // - a count of the number of regions receiving live data from XXX. 941 // 942 // See ParallelCompactData for precise details. The summary phase also 943 // calculates the dense prefix for the compaction. The dense prefix is a 944 // portion at the beginning of the space that is not moved. The objects in the 945 // dense prefix do need to have their object references updated. See method 946 // summarize_dense_prefix(). 947 // 948 // The summary phase is done using 1 GC thread. 949 // 950 // The compaction phase moves objects to their new location and updates all 951 // references in the object. 952 // 953 // A current exception is that objects that cross a region boundary are moved 954 // but do not have their references updated. References are not updated because 955 // it cannot easily be determined if the klass pointer KKK for the object AAA 956 // has been updated. KKK likely resides in a region to the left of the region 957 // containing AAA. These AAA's have there references updated at the end in a 958 // clean up phase. See the method PSParallelCompact::update_deferred_objects(). 959 // An alternate strategy is being investigated for this deferral of updating. 960 // 961 // Compaction is done on a region basis. A region that is ready to be filled is 962 // put on a ready list and GC threads take region off the list and fill them. A 963 // region is ready to be filled if it empty of live objects. Such a region may 964 // have been initially empty (only contained dead objects) or may have had all 965 // its live objects copied out already. A region that compacts into itself is 966 // also ready for filling. The ready list is initially filled with empty 967 // regions and regions compacting into themselves. There is always at least 1 968 // region that can be put on the ready list. The regions are atomically added 969 // and removed from the ready list. 970 971 class TaskQueue; 972 973 class PSParallelCompact : AllStatic { 974 public: 975 // Convenient access to type names. 976 typedef ParMarkBitMap::idx_t idx_t; 977 typedef ParallelCompactData::RegionData RegionData; 978 typedef ParallelCompactData::BlockData BlockData; 979 980 typedef enum { 981 old_space_id, eden_space_id, 982 from_space_id, to_space_id, last_space_id 983 } SpaceId; 984 985 struct UpdateDensePrefixTask : public CHeapObj<mtGC> { 986 SpaceId _space_id; 987 size_t _region_index_start; 988 size_t _region_index_end; 989 990 UpdateDensePrefixTask() : 991 _space_id(SpaceId(0)), 992 _region_index_start(0), 993 _region_index_end(0) {} 994 995 UpdateDensePrefixTask(SpaceId space_id, 996 size_t region_index_start, 997 size_t region_index_end) : 998 _space_id(space_id), 999 _region_index_start(region_index_start), 1000 _region_index_end(region_index_end) {} 1001 }; 1002 1003 public: 1004 // Inline closure decls 1005 // 1006 class IsAliveClosure: public BoolObjectClosure { 1007 public: 1008 virtual bool do_object_b(oop p); 1009 }; 1010 1011 friend class RefProcTaskProxy; 1012 friend class PSParallelCompactTest; 1013 1014 private: 1015 static STWGCTimer _gc_timer; 1016 static ParallelOldTracer _gc_tracer; 1017 static elapsedTimer _accumulated_time; 1018 static unsigned int _total_invocations; 1019 static unsigned int _maximum_compaction_gc_num; 1020 static jlong _time_of_last_gc; // ms 1021 static CollectorCounters* _counters; 1022 static ParMarkBitMap _mark_bitmap; 1023 static ParallelCompactData _summary_data; 1024 static IsAliveClosure _is_alive_closure; 1025 static SpaceInfo _space_info[last_space_id]; 1026 1027 // Reference processing (used in ...follow_contents) 1028 static SpanSubjectToDiscoveryClosure _span_based_discoverer; 1029 static ReferenceProcessor* _ref_processor; 1030 1031 // Values computed at initialization and used by dead_wood_limiter(). 1032 static double _dwl_mean; 1033 static double _dwl_std_dev; 1034 static double _dwl_first_term; 1035 static double _dwl_adjustment; 1036 #ifdef ASSERT 1037 static bool _dwl_initialized; 1038 #endif // #ifdef ASSERT 1039 1040 public: 1041 static ParallelOldTracer* gc_tracer() { return &_gc_tracer; } 1042 1043 private: 1044 1045 static void initialize_space_info(); 1046 1047 // Clear the marking bitmap and summary data that cover the specified space. 1048 static void clear_data_covering_space(SpaceId id); 1049 1050 static void pre_compact(); 1051 static void post_compact(); 1052 1053 // Mark live objects 1054 static void marking_phase(ParCompactionManager* cm, 1055 bool maximum_heap_compaction, 1056 ParallelOldTracer *gc_tracer); 1057 1058 // Compute the dense prefix for the designated space. This is an experimental 1059 // implementation currently not used in production. 1060 static HeapWord* compute_dense_prefix_via_density(const SpaceId id, 1061 bool maximum_compaction); 1062 1063 // Methods used to compute the dense prefix. 1064 1065 // Compute the value of the normal distribution at x = density. The mean and 1066 // standard deviation are values saved by initialize_dead_wood_limiter(). 1067 static inline double normal_distribution(double density); 1068 1069 // Initialize the static vars used by dead_wood_limiter(). 1070 static void initialize_dead_wood_limiter(); 1071 1072 // Return the percentage of space that can be treated as "dead wood" (i.e., 1073 // not reclaimed). 1074 static double dead_wood_limiter(double density, size_t min_percent); 1075 1076 // Find the first (left-most) region in the range [beg, end) that has at least 1077 // dead_words of dead space to the left. The argument beg must be the first 1078 // region in the space that is not completely live. 1079 static RegionData* dead_wood_limit_region(const RegionData* beg, 1080 const RegionData* end, 1081 size_t dead_words); 1082 1083 // Return a pointer to the first region in the range [beg, end) that is not 1084 // completely full. 1085 static RegionData* first_dead_space_region(const RegionData* beg, 1086 const RegionData* end); 1087 1088 // Return a value indicating the benefit or 'yield' if the compacted region 1089 // were to start (or equivalently if the dense prefix were to end) at the 1090 // candidate region. Higher values are better. 1091 // 1092 // The value is based on the amount of space reclaimed vs. the costs of (a) 1093 // updating references in the dense prefix plus (b) copying objects and 1094 // updating references in the compacted region. 1095 static inline double reclaimed_ratio(const RegionData* const candidate, 1096 HeapWord* const bottom, 1097 HeapWord* const top, 1098 HeapWord* const new_top); 1099 1100 // Compute the dense prefix for the designated space. 1101 static HeapWord* compute_dense_prefix(const SpaceId id, 1102 bool maximum_compaction); 1103 1104 // Return true if dead space crosses onto the specified Region; bit must be 1105 // the bit index corresponding to the first word of the Region. 1106 static inline bool dead_space_crosses_boundary(const RegionData* region, 1107 idx_t bit); 1108 1109 // Summary phase utility routine to fill dead space (if any) at the dense 1110 // prefix boundary. Should only be called if the the dense prefix is 1111 // non-empty. 1112 static void fill_dense_prefix_end(SpaceId id); 1113 1114 static void summarize_spaces_quick(); 1115 static void summarize_space(SpaceId id, bool maximum_compaction); 1116 static void summary_phase(ParCompactionManager* cm, bool maximum_compaction); 1117 1118 // Adjust addresses in roots. Does not adjust addresses in heap. 1119 static void adjust_roots(ParCompactionManager* cm); 1120 1121 DEBUG_ONLY(static void write_block_fill_histogram();) 1122 1123 // Move objects to new locations. 1124 static void compact_perm(ParCompactionManager* cm); 1125 static void compact(); 1126 1127 // Add available regions to the stack and draining tasks to the task queue. 1128 static void prepare_region_draining_tasks(uint parallel_gc_threads); 1129 1130 // Add dense prefix update tasks to the task queue. 1131 static void enqueue_dense_prefix_tasks(TaskQueue& task_queue, 1132 uint parallel_gc_threads); 1133 1134 // If objects are left in eden after a collection, try to move the boundary 1135 // and absorb them into the old gen. Returns true if eden was emptied. 1136 static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, 1137 PSYoungGen* young_gen, 1138 PSOldGen* old_gen); 1139 1140 // Reset time since last full gc 1141 static void reset_millis_since_last_gc(); 1142 1143 #ifndef PRODUCT 1144 // Print generic summary data 1145 static void print_generic_summary_data(ParallelCompactData& summary_data, 1146 HeapWord* const beg_addr, 1147 HeapWord* const end_addr); 1148 #endif // #ifndef PRODUCT 1149 1150 public: 1151 1152 PSParallelCompact(); 1153 1154 static void invoke(bool maximum_heap_compaction); 1155 static bool invoke_no_policy(bool maximum_heap_compaction); 1156 1157 static void post_initialize(); 1158 // Perform initialization for PSParallelCompact that requires 1159 // allocations. This should be called during the VM initialization 1160 // at a pointer where it would be appropriate to return a JNI_ENOMEM 1161 // in the event of a failure. 1162 static bool initialize(); 1163 1164 // Closure accessors 1165 static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; } 1166 1167 // Public accessors 1168 static elapsedTimer* accumulated_time() { return &_accumulated_time; } 1169 static unsigned int total_invocations() { return _total_invocations; } 1170 static CollectorCounters* counters() { return _counters; } 1171 1172 // Marking support 1173 static inline bool mark_obj(oop obj); 1174 static inline bool is_marked(oop obj); 1175 1176 template <class T> static inline void adjust_pointer(T* p, ParCompactionManager* cm); 1177 1178 // Compaction support. 1179 // Return true if p is in the range [beg_addr, end_addr). 1180 static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr); 1181 static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr); 1182 1183 // Convenience wrappers for per-space data kept in _space_info. 1184 static inline MutableSpace* space(SpaceId space_id); 1185 static inline HeapWord* new_top(SpaceId space_id); 1186 static inline HeapWord* dense_prefix(SpaceId space_id); 1187 static inline ObjectStartArray* start_array(SpaceId space_id); 1188 1189 // Process the end of the given region range in the dense prefix. 1190 // This includes saving any object not updated. 1191 static void dense_prefix_regions_epilogue(ParCompactionManager* cm, 1192 size_t region_start_index, 1193 size_t region_end_index, 1194 idx_t exiting_object_offset, 1195 idx_t region_offset_start, 1196 idx_t region_offset_end); 1197 1198 // Update a region in the dense prefix. For each live object 1199 // in the region, update it's interior references. For each 1200 // dead object, fill it with deadwood. Dead space at the end 1201 // of a region range will be filled to the start of the next 1202 // live object regardless of the region_index_end. None of the 1203 // objects in the dense prefix move and dead space is dead 1204 // (holds only dead objects that don't need any processing), so 1205 // dead space can be filled in any order. 1206 static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, 1207 SpaceId space_id, 1208 size_t region_index_start, 1209 size_t region_index_end); 1210 1211 // Return the address of the count + 1st live word in the range [beg, end). 1212 static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count); 1213 1214 // Return the address of the word to be copied to dest_addr, which must be 1215 // aligned to a region boundary. 1216 static HeapWord* first_src_addr(HeapWord* const dest_addr, 1217 SpaceId src_space_id, 1218 size_t src_region_idx); 1219 1220 // Determine the next source region, set closure.source() to the start of the 1221 // new region return the region index. Parameter end_addr is the address one 1222 // beyond the end of source range just processed. If necessary, switch to a 1223 // new source space and set src_space_id (in-out parameter) and src_space_top 1224 // (out parameter) accordingly. 1225 static size_t next_src_region(MoveAndUpdateClosure& closure, 1226 SpaceId& src_space_id, 1227 HeapWord*& src_space_top, 1228 HeapWord* end_addr); 1229 1230 // Decrement the destination count for each non-empty source region in the 1231 // range [beg_region, region(region_align_up(end_addr))). If the destination 1232 // count for a region goes to 0 and it needs to be filled, enqueue it. 1233 static void decrement_destination_counts(ParCompactionManager* cm, 1234 SpaceId src_space_id, 1235 size_t beg_region, 1236 HeapWord* end_addr); 1237 1238 static void fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region); 1239 static void fill_and_update_region(ParCompactionManager* cm, size_t region); 1240 1241 static bool steal_unavailable_region(ParCompactionManager* cm, size_t& region_idx); 1242 static void fill_and_update_shadow_region(ParCompactionManager* cm, size_t region); 1243 // Copy the content of a shadow region back to its corresponding heap region 1244 static void copy_back(HeapWord* shadow_addr, HeapWord* region_addr); 1245 // Collect empty regions as shadow regions and initialize the 1246 // _next_shadow_region filed for each compact manager 1247 static void initialize_shadow_regions(uint parallel_gc_threads); 1248 1249 // Fill in the block table for the specified region. 1250 static void fill_blocks(size_t region_idx); 1251 1252 // Update the deferred objects in the space. 1253 static void update_deferred_objects(ParCompactionManager* cm, SpaceId id); 1254 1255 static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; } 1256 static ParallelCompactData& summary_data() { return _summary_data; } 1257 1258 // Reference Processing 1259 static ReferenceProcessor* const ref_processor() { return _ref_processor; } 1260 1261 static STWGCTimer* gc_timer() { return &_gc_timer; } 1262 1263 // Return the SpaceId for the given address. 1264 static SpaceId space_id(HeapWord* addr); 1265 1266 // Time since last full gc (in milliseconds). 1267 static jlong millis_since_last_gc(); 1268 1269 static void print_on_error(outputStream* st); 1270 1271 #ifndef PRODUCT 1272 // Debugging support. 1273 static const char* space_names[last_space_id]; 1274 static void print_region_ranges(); 1275 static void print_dense_prefix_stats(const char* const algorithm, 1276 const SpaceId id, 1277 const bool maximum_compaction, 1278 HeapWord* const addr); 1279 static void summary_phase_msg(SpaceId dst_space_id, 1280 HeapWord* dst_beg, HeapWord* dst_end, 1281 SpaceId src_space_id, 1282 HeapWord* src_beg, HeapWord* src_end); 1283 #endif // #ifndef PRODUCT 1284 1285 #ifdef ASSERT 1286 // Sanity check the new location of a word in the heap. 1287 static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr); 1288 // Verify that all the regions have been emptied. 1289 static void verify_complete(SpaceId space_id); 1290 #endif // #ifdef ASSERT 1291 }; 1292 1293 class MoveAndUpdateClosure: public ParMarkBitMapClosure { 1294 static inline size_t calculate_words_remaining(size_t region); 1295 public: 1296 inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm, 1297 size_t region); 1298 1299 // Accessors. 1300 HeapWord* destination() const { return _destination; } 1301 HeapWord* copy_destination() const { return _destination + _offset; } 1302 1303 // If the object will fit (size <= words_remaining()), copy it to the current 1304 // destination, update the interior oops and the start array and return either 1305 // full (if the closure is full) or incomplete. If the object will not fit, 1306 // return would_overflow. 1307 IterationStatus do_addr(HeapWord* addr, size_t size); 1308 1309 // Copy enough words to fill this closure, starting at source(). Interior 1310 // oops and the start array are not updated. Return full. 1311 IterationStatus copy_until_full(); 1312 1313 // Copy enough words to fill this closure or to the end of an object, 1314 // whichever is smaller, starting at source(). Interior oops and the start 1315 // array are not updated. 1316 void copy_partial_obj(); 1317 1318 virtual void complete_region(ParCompactionManager* cm, HeapWord* dest_addr, 1319 PSParallelCompact::RegionData* region_ptr); 1320 1321 protected: 1322 // Update variables to indicate that word_count words were processed. 1323 inline void update_state(size_t word_count); 1324 1325 protected: 1326 HeapWord* _destination; // Next addr to be written. 1327 ObjectStartArray* const _start_array; 1328 size_t _offset; 1329 }; 1330 1331 inline size_t MoveAndUpdateClosure::calculate_words_remaining(size_t region) { 1332 HeapWord* dest_addr = PSParallelCompact::summary_data().region_to_addr(region); 1333 PSParallelCompact::SpaceId dest_space_id = PSParallelCompact::space_id(dest_addr); 1334 HeapWord* new_top = PSParallelCompact::new_top(dest_space_id); 1335 assert(dest_addr < new_top, "sanity"); 1336 1337 return MIN2(pointer_delta(new_top, dest_addr), ParallelCompactData::RegionSize); 1338 } 1339 1340 inline 1341 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap, 1342 ParCompactionManager* cm, 1343 size_t region_idx) : 1344 ParMarkBitMapClosure(bitmap, cm, calculate_words_remaining(region_idx)), 1345 _destination(PSParallelCompact::summary_data().region_to_addr(region_idx)), 1346 _start_array(PSParallelCompact::start_array(PSParallelCompact::space_id(_destination))), 1347 _offset(0) { } 1348 1349 1350 inline void MoveAndUpdateClosure::update_state(size_t words) 1351 { 1352 decrement_words_remaining(words); 1353 _source += words; 1354 _destination += words; 1355 } 1356 1357 class MoveAndUpdateShadowClosure: public MoveAndUpdateClosure { 1358 inline size_t calculate_shadow_offset(size_t region_idx, size_t shadow_idx); 1359 public: 1360 inline MoveAndUpdateShadowClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm, 1361 size_t region, size_t shadow); 1362 1363 virtual void complete_region(ParCompactionManager* cm, HeapWord* dest_addr, 1364 PSParallelCompact::RegionData* region_ptr); 1365 1366 private: 1367 size_t _shadow; 1368 }; 1369 1370 inline size_t MoveAndUpdateShadowClosure::calculate_shadow_offset(size_t region_idx, size_t shadow_idx) { 1371 ParallelCompactData& sd = PSParallelCompact::summary_data(); 1372 HeapWord* dest_addr = sd.region_to_addr(region_idx); 1373 HeapWord* shadow_addr = sd.region_to_addr(shadow_idx); 1374 return pointer_delta(shadow_addr, dest_addr); 1375 } 1376 1377 inline 1378 MoveAndUpdateShadowClosure::MoveAndUpdateShadowClosure(ParMarkBitMap *bitmap, 1379 ParCompactionManager *cm, 1380 size_t region, 1381 size_t shadow) : 1382 MoveAndUpdateClosure(bitmap, cm, region), 1383 _shadow(shadow) { 1384 _offset = calculate_shadow_offset(region, shadow); 1385 } 1386 1387 class UpdateOnlyClosure: public ParMarkBitMapClosure { 1388 private: 1389 const PSParallelCompact::SpaceId _space_id; 1390 ObjectStartArray* const _start_array; 1391 1392 public: 1393 UpdateOnlyClosure(ParMarkBitMap* mbm, 1394 ParCompactionManager* cm, 1395 PSParallelCompact::SpaceId space_id); 1396 1397 // Update the object. 1398 virtual IterationStatus do_addr(HeapWord* addr, size_t words); 1399 1400 inline void do_addr(HeapWord* addr); 1401 }; 1402 1403 class FillClosure: public ParMarkBitMapClosure { 1404 public: 1405 FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id); 1406 1407 virtual IterationStatus do_addr(HeapWord* addr, size_t size); 1408 1409 private: 1410 ObjectStartArray* const _start_array; 1411 }; 1412 1413 #endif // SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP