1 /* 2 * Copyright (c) 2005, 2010, 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/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp" 27 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp" 28 #include "gc_implementation/parNew/asParNewGeneration.hpp" 29 #include "gc_implementation/parNew/parNewGeneration.hpp" 30 #include "gc_implementation/shared/markSweep.inline.hpp" 31 #include "gc_implementation/shared/spaceDecorator.hpp" 32 #include "memory/defNewGeneration.inline.hpp" 33 #include "memory/referencePolicy.hpp" 34 #include "oops/markOop.inline.hpp" 35 #include "oops/oop.pcgc.inline.hpp" 36 37 ASParNewGeneration::ASParNewGeneration(ReservedSpace rs, 38 size_t initial_byte_size, 39 size_t min_byte_size, 40 int level) : 41 ParNewGeneration(rs, initial_byte_size, level), 42 _min_gen_size(min_byte_size) {} 43 44 const char* ASParNewGeneration::name() const { 45 return "adaptive size par new generation"; 46 } 47 48 void ASParNewGeneration::adjust_desired_tenuring_threshold() { 49 assert(UseAdaptiveSizePolicy, 50 "Should only be used with UseAdaptiveSizePolicy"); 51 } 52 53 void ASParNewGeneration::resize(size_t eden_size, size_t survivor_size) { 54 // Resize the generation if needed. If the generation resize 55 // reports false, do not attempt to resize the spaces. 56 if (resize_generation(eden_size, survivor_size)) { 57 // Then we lay out the spaces inside the generation 58 resize_spaces(eden_size, survivor_size); 59 60 space_invariants(); 61 62 if (PrintAdaptiveSizePolicy && Verbose) { 63 gclog_or_tty->print_cr("Young generation size: " 64 "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT 65 " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT 66 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT, 67 eden_size, survivor_size, used(), capacity(), 68 max_gen_size(), min_gen_size()); 69 } 70 } 71 } 72 73 size_t ASParNewGeneration::available_to_min_gen() { 74 assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant"); 75 return virtual_space()->committed_size() - min_gen_size(); 76 } 77 78 // This method assumes that from-space has live data and that 79 // any shrinkage of the young gen is limited by location of 80 // from-space. 81 size_t ASParNewGeneration::available_to_live() const { 82 #undef SHRINKS_AT_END_OF_EDEN 83 #ifdef SHRINKS_AT_END_OF_EDEN 84 size_t delta_in_survivor = 0; 85 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 86 const size_t space_alignment = heap->intra_heap_alignment(); 87 const size_t gen_alignment = heap->object_heap_alignment(); 88 89 MutableSpace* space_shrinking = NULL; 90 if (from_space()->end() > to_space()->end()) { 91 space_shrinking = from_space(); 92 } else { 93 space_shrinking = to_space(); 94 } 95 96 // Include any space that is committed but not included in 97 // the survivor spaces. 98 assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(), 99 "Survivor space beyond high end"); 100 size_t unused_committed = pointer_delta(virtual_space()->high(), 101 space_shrinking->end(), sizeof(char)); 102 103 if (space_shrinking->is_empty()) { 104 // Don't let the space shrink to 0 105 assert(space_shrinking->capacity_in_bytes() >= space_alignment, 106 "Space is too small"); 107 delta_in_survivor = space_shrinking->capacity_in_bytes() - space_alignment; 108 } else { 109 delta_in_survivor = pointer_delta(space_shrinking->end(), 110 space_shrinking->top(), 111 sizeof(char)); 112 } 113 114 size_t delta_in_bytes = unused_committed + delta_in_survivor; 115 delta_in_bytes = align_size_down(delta_in_bytes, gen_alignment); 116 return delta_in_bytes; 117 #else 118 // The only space available for shrinking is in to-space if it 119 // is above from-space. 120 if (to()->bottom() > from()->bottom()) { 121 const size_t alignment = os::vm_page_size(); 122 if (to()->capacity() < alignment) { 123 return 0; 124 } else { 125 return to()->capacity() - alignment; 126 } 127 } else { 128 return 0; 129 } 130 #endif 131 } 132 133 // Return the number of bytes available for resizing down the young 134 // generation. This is the minimum of 135 // input "bytes" 136 // bytes to the minimum young gen size 137 // bytes to the size currently being used + some small extra 138 size_t ASParNewGeneration::limit_gen_shrink (size_t bytes) { 139 // Allow shrinkage into the current eden but keep eden large enough 140 // to maintain the minimum young gen size 141 bytes = MIN3(bytes, available_to_min_gen(), available_to_live()); 142 return align_size_down(bytes, os::vm_page_size()); 143 } 144 145 // Note that the the alignment used is the OS page size as 146 // opposed to an alignment associated with the virtual space 147 // (as is done in the ASPSYoungGen/ASPSOldGen) 148 bool ASParNewGeneration::resize_generation(size_t eden_size, 149 size_t survivor_size) { 150 const size_t alignment = os::vm_page_size(); 151 size_t orig_size = virtual_space()->committed_size(); 152 bool size_changed = false; 153 154 // There used to be this guarantee there. 155 // guarantee ((eden_size + 2*survivor_size) <= _max_gen_size, "incorrect input arguments"); 156 // Code below forces this requirement. In addition the desired eden 157 // size and disired survivor sizes are desired goals and may 158 // exceed the total generation size. 159 160 assert(min_gen_size() <= orig_size && orig_size <= max_gen_size(), 161 "just checking"); 162 163 // Adjust new generation size 164 const size_t eden_plus_survivors = 165 align_size_up(eden_size + 2 * survivor_size, alignment); 166 size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_gen_size()), 167 min_gen_size()); 168 assert(desired_size <= max_gen_size(), "just checking"); 169 170 if (desired_size > orig_size) { 171 // Grow the generation 172 size_t change = desired_size - orig_size; 173 assert(change % alignment == 0, "just checking"); 174 if (expand(change)) { 175 return false; // Error if we fail to resize! 176 } 177 size_changed = true; 178 } else if (desired_size < orig_size) { 179 size_t desired_change = orig_size - desired_size; 180 assert(desired_change % alignment == 0, "just checking"); 181 182 desired_change = limit_gen_shrink(desired_change); 183 184 if (desired_change > 0) { 185 virtual_space()->shrink_by(desired_change); 186 reset_survivors_after_shrink(); 187 188 size_changed = true; 189 } 190 } else { 191 if (Verbose && PrintGC) { 192 if (orig_size == max_gen_size()) { 193 gclog_or_tty->print_cr("ASParNew generation size at maximum: " 194 SIZE_FORMAT "K", orig_size/K); 195 } else if (orig_size == min_gen_size()) { 196 gclog_or_tty->print_cr("ASParNew generation size at minium: " 197 SIZE_FORMAT "K", orig_size/K); 198 } 199 } 200 } 201 202 if (size_changed) { 203 MemRegion cmr((HeapWord*)virtual_space()->low(), 204 (HeapWord*)virtual_space()->high()); 205 GenCollectedHeap::heap()->barrier_set()->resize_covered_region(cmr); 206 207 if (Verbose && PrintGC) { 208 size_t current_size = virtual_space()->committed_size(); 209 gclog_or_tty->print_cr("ASParNew generation size changed: " 210 SIZE_FORMAT "K->" SIZE_FORMAT "K", 211 orig_size/K, current_size/K); 212 } 213 } 214 215 guarantee(eden_plus_survivors <= virtual_space()->committed_size() || 216 virtual_space()->committed_size() == max_gen_size(), "Sanity"); 217 218 return true; 219 } 220 221 void ASParNewGeneration::reset_survivors_after_shrink() { 222 223 GenCollectedHeap* gch = GenCollectedHeap::heap(); 224 HeapWord* new_end = (HeapWord*)virtual_space()->high(); 225 226 if (from()->end() > to()->end()) { 227 assert(new_end >= from()->end(), "Shrinking past from-space"); 228 } else { 229 assert(new_end >= to()->bottom(), "Shrink was too large"); 230 // Was there a shrink of the survivor space? 231 if (new_end < to()->end()) { 232 MemRegion mr(to()->bottom(), new_end); 233 to()->initialize(mr, 234 SpaceDecorator::DontClear, 235 SpaceDecorator::DontMangle); 236 } 237 } 238 } 239 void ASParNewGeneration::resize_spaces(size_t requested_eden_size, 240 size_t requested_survivor_size) { 241 assert(UseAdaptiveSizePolicy, "sanity check"); 242 assert(requested_eden_size > 0 && requested_survivor_size > 0, 243 "just checking"); 244 CollectedHeap* heap = Universe::heap(); 245 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Sanity"); 246 247 248 // We require eden and to space to be empty 249 if ((!eden()->is_empty()) || (!to()->is_empty())) { 250 return; 251 } 252 253 size_t cur_eden_size = eden()->capacity(); 254 255 if (PrintAdaptiveSizePolicy && Verbose) { 256 gclog_or_tty->print_cr("ASParNew::resize_spaces(requested_eden_size: " 257 SIZE_FORMAT 258 ", requested_survivor_size: " SIZE_FORMAT ")", 259 requested_eden_size, requested_survivor_size); 260 gclog_or_tty->print_cr(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " 261 SIZE_FORMAT, 262 eden()->bottom(), 263 eden()->end(), 264 pointer_delta(eden()->end(), 265 eden()->bottom(), 266 sizeof(char))); 267 gclog_or_tty->print_cr(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " 268 SIZE_FORMAT, 269 from()->bottom(), 270 from()->end(), 271 pointer_delta(from()->end(), 272 from()->bottom(), 273 sizeof(char))); 274 gclog_or_tty->print_cr(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " 275 SIZE_FORMAT, 276 to()->bottom(), 277 to()->end(), 278 pointer_delta( to()->end(), 279 to()->bottom(), 280 sizeof(char))); 281 } 282 283 // There's nothing to do if the new sizes are the same as the current 284 if (requested_survivor_size == to()->capacity() && 285 requested_survivor_size == from()->capacity() && 286 requested_eden_size == eden()->capacity()) { 287 if (PrintAdaptiveSizePolicy && Verbose) { 288 gclog_or_tty->print_cr(" capacities are the right sizes, returning"); 289 } 290 return; 291 } 292 293 char* eden_start = (char*)eden()->bottom(); 294 char* eden_end = (char*)eden()->end(); 295 char* from_start = (char*)from()->bottom(); 296 char* from_end = (char*)from()->end(); 297 char* to_start = (char*)to()->bottom(); 298 char* to_end = (char*)to()->end(); 299 300 const size_t alignment = os::vm_page_size(); 301 const bool maintain_minimum = 302 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size(); 303 304 // Check whether from space is below to space 305 if (from_start < to_start) { 306 // Eden, from, to 307 if (PrintAdaptiveSizePolicy && Verbose) { 308 gclog_or_tty->print_cr(" Eden, from, to:"); 309 } 310 311 // Set eden 312 // "requested_eden_size" is a goal for the size of eden 313 // and may not be attainable. "eden_size" below is 314 // calculated based on the location of from-space and 315 // the goal for the size of eden. from-space is 316 // fixed in place because it contains live data. 317 // The calculation is done this way to avoid 32bit 318 // overflow (i.e., eden_start + requested_eden_size 319 // may too large for representation in 32bits). 320 size_t eden_size; 321 if (maintain_minimum) { 322 // Only make eden larger than the requested size if 323 // the minimum size of the generation has to be maintained. 324 // This could be done in general but policy at a higher 325 // level is determining a requested size for eden and that 326 // should be honored unless there is a fundamental reason. 327 eden_size = pointer_delta(from_start, 328 eden_start, 329 sizeof(char)); 330 } else { 331 eden_size = MIN2(requested_eden_size, 332 pointer_delta(from_start, eden_start, sizeof(char))); 333 } 334 335 eden_size = align_size_down(eden_size, alignment); 336 eden_end = eden_start + eden_size; 337 assert(eden_end >= eden_start, "addition overflowed"); 338 339 // To may resize into from space as long as it is clear of live data. 340 // From space must remain page aligned, though, so we need to do some 341 // extra calculations. 342 343 // First calculate an optimal to-space 344 to_end = (char*)virtual_space()->high(); 345 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size, 346 sizeof(char)); 347 348 // Does the optimal to-space overlap from-space? 349 if (to_start < (char*)from()->end()) { 350 // Calculate the minimum offset possible for from_end 351 size_t from_size = pointer_delta(from()->top(), from_start, sizeof(char)); 352 353 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME! 354 if (from_size == 0) { 355 from_size = alignment; 356 } else { 357 from_size = align_size_up(from_size, alignment); 358 } 359 360 from_end = from_start + from_size; 361 assert(from_end > from_start, "addition overflow or from_size problem"); 362 363 guarantee(from_end <= (char*)from()->end(), "from_end moved to the right"); 364 365 // Now update to_start with the new from_end 366 to_start = MAX2(from_end, to_start); 367 } else { 368 // If shrinking, move to-space down to abut the end of from-space 369 // so that shrinking will move to-space down. If not shrinking 370 // to-space is moving up to allow for growth on the next expansion. 371 if (requested_eden_size <= cur_eden_size) { 372 to_start = from_end; 373 if (to_start + requested_survivor_size > to_start) { 374 to_end = to_start + requested_survivor_size; 375 } 376 } 377 // else leave to_end pointing to the high end of the virtual space. 378 } 379 380 guarantee(to_start != to_end, "to space is zero sized"); 381 382 if (PrintAdaptiveSizePolicy && Verbose) { 383 gclog_or_tty->print_cr(" [eden_start .. eden_end): " 384 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 385 eden_start, 386 eden_end, 387 pointer_delta(eden_end, eden_start, sizeof(char))); 388 gclog_or_tty->print_cr(" [from_start .. from_end): " 389 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 390 from_start, 391 from_end, 392 pointer_delta(from_end, from_start, sizeof(char))); 393 gclog_or_tty->print_cr(" [ to_start .. to_end): " 394 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 395 to_start, 396 to_end, 397 pointer_delta( to_end, to_start, sizeof(char))); 398 } 399 } else { 400 // Eden, to, from 401 if (PrintAdaptiveSizePolicy && Verbose) { 402 gclog_or_tty->print_cr(" Eden, to, from:"); 403 } 404 405 // Calculate the to-space boundaries based on 406 // the start of from-space. 407 to_end = from_start; 408 to_start = (char*)pointer_delta(from_start, 409 (char*)requested_survivor_size, 410 sizeof(char)); 411 // Calculate the ideal eden boundaries. 412 // eden_end is already at the bottom of the generation 413 assert(eden_start == virtual_space()->low(), 414 "Eden is not starting at the low end of the virtual space"); 415 if (eden_start + requested_eden_size >= eden_start) { 416 eden_end = eden_start + requested_eden_size; 417 } else { 418 eden_end = to_start; 419 } 420 421 // Does eden intrude into to-space? to-space 422 // gets priority but eden is not allowed to shrink 423 // to 0. 424 if (eden_end > to_start) { 425 eden_end = to_start; 426 } 427 428 // Don't let eden shrink down to 0 or less. 429 eden_end = MAX2(eden_end, eden_start + alignment); 430 assert(eden_start + alignment >= eden_start, "Overflow"); 431 432 size_t eden_size; 433 if (maintain_minimum) { 434 // Use all the space available. 435 eden_end = MAX2(eden_end, to_start); 436 eden_size = pointer_delta(eden_end, eden_start, sizeof(char)); 437 eden_size = MIN2(eden_size, cur_eden_size); 438 } else { 439 eden_size = pointer_delta(eden_end, eden_start, sizeof(char)); 440 } 441 eden_size = align_size_down(eden_size, alignment); 442 assert(maintain_minimum || eden_size <= requested_eden_size, 443 "Eden size is too large"); 444 assert(eden_size >= alignment, "Eden size is too small"); 445 eden_end = eden_start + eden_size; 446 447 // Move to-space down to eden. 448 if (requested_eden_size < cur_eden_size) { 449 to_start = eden_end; 450 if (to_start + requested_survivor_size > to_start) { 451 to_end = MIN2(from_start, to_start + requested_survivor_size); 452 } else { 453 to_end = from_start; 454 } 455 } 456 457 // eden_end may have moved so again make sure 458 // the to-space and eden don't overlap. 459 to_start = MAX2(eden_end, to_start); 460 461 // from-space 462 size_t from_used = from()->used(); 463 if (requested_survivor_size > from_used) { 464 if (from_start + requested_survivor_size >= from_start) { 465 from_end = from_start + requested_survivor_size; 466 } 467 if (from_end > virtual_space()->high()) { 468 from_end = virtual_space()->high(); 469 } 470 } 471 472 assert(to_start >= eden_end, "to-space should be above eden"); 473 if (PrintAdaptiveSizePolicy && Verbose) { 474 gclog_or_tty->print_cr(" [eden_start .. eden_end): " 475 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 476 eden_start, 477 eden_end, 478 pointer_delta(eden_end, eden_start, sizeof(char))); 479 gclog_or_tty->print_cr(" [ to_start .. to_end): " 480 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 481 to_start, 482 to_end, 483 pointer_delta( to_end, to_start, sizeof(char))); 484 gclog_or_tty->print_cr(" [from_start .. from_end): " 485 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 486 from_start, 487 from_end, 488 pointer_delta(from_end, from_start, sizeof(char))); 489 } 490 } 491 492 493 guarantee((HeapWord*)from_start <= from()->bottom(), 494 "from start moved to the right"); 495 guarantee((HeapWord*)from_end >= from()->top(), 496 "from end moved into live data"); 497 assert(is_object_aligned((intptr_t)eden_start), "checking alignment"); 498 assert(is_object_aligned((intptr_t)from_start), "checking alignment"); 499 assert(is_object_aligned((intptr_t)to_start), "checking alignment"); 500 501 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end); 502 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end); 503 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end); 504 505 // Let's make sure the call to initialize doesn't reset "top"! 506 HeapWord* old_from_top = from()->top(); 507 508 // For PrintAdaptiveSizePolicy block below 509 size_t old_from = from()->capacity(); 510 size_t old_to = to()->capacity(); 511 512 // If not clearing the spaces, do some checking to verify that 513 // the spaces are already mangled. 514 515 // Must check mangling before the spaces are reshaped. Otherwise, 516 // the bottom or end of one space may have moved into another 517 // a failure of the check may not correctly indicate which space 518 // is not properly mangled. 519 if (ZapUnusedHeapArea) { 520 HeapWord* limit = (HeapWord*) virtual_space()->high(); 521 eden()->check_mangled_unused_area(limit); 522 from()->check_mangled_unused_area(limit); 523 to()->check_mangled_unused_area(limit); 524 } 525 526 // The call to initialize NULL's the next compaction space 527 eden()->initialize(edenMR, 528 SpaceDecorator::Clear, 529 SpaceDecorator::DontMangle); 530 eden()->set_next_compaction_space(from()); 531 to()->initialize(toMR , 532 SpaceDecorator::Clear, 533 SpaceDecorator::DontMangle); 534 from()->initialize(fromMR, 535 SpaceDecorator::DontClear, 536 SpaceDecorator::DontMangle); 537 538 assert(from()->top() == old_from_top, "from top changed!"); 539 540 if (PrintAdaptiveSizePolicy) { 541 GenCollectedHeap* gch = GenCollectedHeap::heap(); 542 assert(gch->kind() == CollectedHeap::GenCollectedHeap, "Sanity"); 543 544 gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: " 545 "collection: %d " 546 "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> " 547 "(" SIZE_FORMAT ", " SIZE_FORMAT ") ", 548 gch->total_collections(), 549 old_from, old_to, 550 from()->capacity(), 551 to()->capacity()); 552 gclog_or_tty->cr(); 553 } 554 } 555 556 void ASParNewGeneration::compute_new_size() { 557 GenCollectedHeap* gch = GenCollectedHeap::heap(); 558 assert(gch->kind() == CollectedHeap::GenCollectedHeap, 559 "not a CMS generational heap"); 560 561 562 CMSAdaptiveSizePolicy* size_policy = 563 (CMSAdaptiveSizePolicy*)gch->gen_policy()->size_policy(); 564 assert(size_policy->is_gc_cms_adaptive_size_policy(), 565 "Wrong type of size policy"); 566 567 size_t survived = from()->used(); 568 if (!survivor_overflow()) { 569 // Keep running averages on how much survived 570 size_policy->avg_survived()->sample(survived); 571 } else { 572 size_t promoted = 573 (size_t) next_gen()->gc_stats()->avg_promoted()->last_sample(); 574 assert(promoted < gch->capacity(), "Conversion problem?"); 575 size_t survived_guess = survived + promoted; 576 size_policy->avg_survived()->sample(survived_guess); 577 } 578 579 size_t survivor_limit = max_survivor_size(); 580 _tenuring_threshold = 581 size_policy->compute_survivor_space_size_and_threshold( 582 _survivor_overflow, 583 _tenuring_threshold, 584 survivor_limit); 585 size_policy->avg_young_live()->sample(used()); 586 size_policy->avg_eden_live()->sample(eden()->used()); 587 588 size_policy->compute_young_generation_free_space(eden()->capacity(), 589 max_gen_size()); 590 591 resize(size_policy->calculated_eden_size_in_bytes(), 592 size_policy->calculated_survivor_size_in_bytes()); 593 594 if (UsePerfData) { 595 CMSGCAdaptivePolicyCounters* counters = 596 (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters(); 597 assert(counters->kind() == 598 GCPolicyCounters::CMSGCAdaptivePolicyCountersKind, 599 "Wrong kind of counters"); 600 counters->update_tenuring_threshold(_tenuring_threshold); 601 counters->update_survivor_overflowed(_survivor_overflow); 602 counters->update_young_capacity(capacity()); 603 } 604 } 605 606 607 #ifndef PRODUCT 608 // Changes from PSYoungGen version 609 // value of "alignment" 610 void ASParNewGeneration::space_invariants() { 611 const size_t alignment = os::vm_page_size(); 612 613 // Currently, our eden size cannot shrink to zero 614 guarantee(eden()->capacity() >= alignment, "eden too small"); 615 guarantee(from()->capacity() >= alignment, "from too small"); 616 guarantee(to()->capacity() >= alignment, "to too small"); 617 618 // Relationship of spaces to each other 619 char* eden_start = (char*)eden()->bottom(); 620 char* eden_end = (char*)eden()->end(); 621 char* from_start = (char*)from()->bottom(); 622 char* from_end = (char*)from()->end(); 623 char* to_start = (char*)to()->bottom(); 624 char* to_end = (char*)to()->end(); 625 626 guarantee(eden_start >= virtual_space()->low(), "eden bottom"); 627 guarantee(eden_start < eden_end, "eden space consistency"); 628 guarantee(from_start < from_end, "from space consistency"); 629 guarantee(to_start < to_end, "to space consistency"); 630 631 // Check whether from space is below to space 632 if (from_start < to_start) { 633 // Eden, from, to 634 guarantee(eden_end <= from_start, "eden/from boundary"); 635 guarantee(from_end <= to_start, "from/to boundary"); 636 guarantee(to_end <= virtual_space()->high(), "to end"); 637 } else { 638 // Eden, to, from 639 guarantee(eden_end <= to_start, "eden/to boundary"); 640 guarantee(to_end <= from_start, "to/from boundary"); 641 guarantee(from_end <= virtual_space()->high(), "from end"); 642 } 643 644 // More checks that the virtual space is consistent with the spaces 645 assert(virtual_space()->committed_size() >= 646 (eden()->capacity() + 647 to()->capacity() + 648 from()->capacity()), "Committed size is inconsistent"); 649 assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(), 650 "Space invariant"); 651 char* eden_top = (char*)eden()->top(); 652 char* from_top = (char*)from()->top(); 653 char* to_top = (char*)to()->top(); 654 assert(eden_top <= virtual_space()->high(), "eden top"); 655 assert(from_top <= virtual_space()->high(), "from top"); 656 assert(to_top <= virtual_space()->high(), "to top"); 657 } 658 #endif