1 /* 2 * Copyright (c) 2001, 2020, 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/parallel/mutableNUMASpace.hpp" 27 #include "gc/parallel/parallelScavengeHeap.hpp" 28 #include "gc/parallel/psScavenge.hpp" 29 #include "gc/parallel/psYoungGen.hpp" 30 #include "gc/shared/gcUtil.hpp" 31 #include "gc/shared/genArguments.hpp" 32 #include "gc/shared/spaceDecorator.inline.hpp" 33 #include "logging/log.hpp" 34 #include "oops/oop.inline.hpp" 35 #include "runtime/java.hpp" 36 #include "utilities/align.hpp" 37 38 PSYoungGen::PSYoungGen(size_t initial_size, size_t min_size, size_t max_size) : 39 _reserved(), 40 _virtual_space(NULL), 41 _eden_space(NULL), 42 _from_space(NULL), 43 _to_space(NULL), 44 _init_gen_size(initial_size), 45 _min_gen_size(min_size), 46 _max_gen_size(max_size), 47 _gen_counters(NULL), 48 _eden_counters(NULL), 49 _from_counters(NULL), 50 _to_counters(NULL) 51 {} 52 53 void PSYoungGen::initialize_virtual_space(ReservedSpace rs, size_t alignment) { 54 assert(_init_gen_size != 0, "Should have a finite size"); 55 _virtual_space = new PSVirtualSpace(rs, alignment); 56 if (!virtual_space()->expand_by(_init_gen_size)) { 57 vm_exit_during_initialization("Could not reserve enough space for " 58 "object heap"); 59 } 60 } 61 62 void PSYoungGen::initialize(ReservedSpace rs, size_t alignment) { 63 initialize_virtual_space(rs, alignment); 64 initialize_work(); 65 } 66 67 void PSYoungGen::initialize_work() { 68 69 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(), 70 (HeapWord*)virtual_space()->high_boundary()); 71 72 MemRegion cmr((HeapWord*)virtual_space()->low(), 73 (HeapWord*)virtual_space()->high()); 74 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr); 75 76 if (ZapUnusedHeapArea) { 77 // Mangle newly committed space immediately because it 78 // can be done here more simply that after the new 79 // spaces have been computed. 80 SpaceMangler::mangle_region(cmr); 81 } 82 83 if (UseNUMA) { 84 _eden_space = new MutableNUMASpace(virtual_space()->alignment()); 85 } else { 86 _eden_space = new MutableSpace(virtual_space()->alignment()); 87 } 88 _from_space = new MutableSpace(virtual_space()->alignment()); 89 _to_space = new MutableSpace(virtual_space()->alignment()); 90 91 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL) { 92 vm_exit_during_initialization("Could not allocate a young gen space"); 93 } 94 95 // Generation Counters - generation 0, 3 subspaces 96 _gen_counters = new PSGenerationCounters("new", 0, 3, _min_gen_size, 97 _max_gen_size, _virtual_space); 98 99 // Compute maximum space sizes for performance counters 100 size_t alignment = SpaceAlignment; 101 size_t size = virtual_space()->reserved_size(); 102 103 size_t max_survivor_size; 104 size_t max_eden_size; 105 106 if (UseAdaptiveSizePolicy) { 107 max_survivor_size = size / MinSurvivorRatio; 108 109 // round the survivor space size down to the nearest alignment 110 // and make sure its size is greater than 0. 111 max_survivor_size = align_down(max_survivor_size, alignment); 112 max_survivor_size = MAX2(max_survivor_size, alignment); 113 114 // set the maximum size of eden to be the size of the young gen 115 // less two times the minimum survivor size. The minimum survivor 116 // size for UseAdaptiveSizePolicy is one alignment. 117 max_eden_size = size - 2 * alignment; 118 } else { 119 max_survivor_size = size / InitialSurvivorRatio; 120 121 // round the survivor space size down to the nearest alignment 122 // and make sure its size is greater than 0. 123 max_survivor_size = align_down(max_survivor_size, alignment); 124 max_survivor_size = MAX2(max_survivor_size, alignment); 125 126 // set the maximum size of eden to be the size of the young gen 127 // less two times the survivor size when the generation is 100% 128 // committed. The minimum survivor size for -UseAdaptiveSizePolicy 129 // is dependent on the committed portion (current capacity) of the 130 // generation - the less space committed, the smaller the survivor 131 // space, possibly as small as an alignment. However, we are interested 132 // in the case where the young generation is 100% committed, as this 133 // is the point where eden reaches its maximum size. At this point, 134 // the size of a survivor space is max_survivor_size. 135 max_eden_size = size - 2 * max_survivor_size; 136 } 137 138 _eden_counters = new SpaceCounters("eden", 0, max_eden_size, _eden_space, 139 _gen_counters); 140 _from_counters = new SpaceCounters("s0", 1, max_survivor_size, _from_space, 141 _gen_counters); 142 _to_counters = new SpaceCounters("s1", 2, max_survivor_size, _to_space, 143 _gen_counters); 144 145 compute_initial_space_boundaries(); 146 } 147 148 void PSYoungGen::compute_initial_space_boundaries() { 149 // Compute sizes 150 size_t size = virtual_space()->committed_size(); 151 assert(size >= 3 * SpaceAlignment, "Young space is not large enough for eden + 2 survivors"); 152 153 size_t survivor_size = size / InitialSurvivorRatio; 154 survivor_size = align_down(survivor_size, SpaceAlignment); 155 // ... but never less than an alignment 156 survivor_size = MAX2(survivor_size, SpaceAlignment); 157 158 // Young generation is eden + 2 survivor spaces 159 size_t eden_size = size - (2 * survivor_size); 160 161 // Now go ahead and set 'em. 162 set_space_boundaries(eden_size, survivor_size); 163 space_invariants(); 164 165 if (UsePerfData) { 166 _eden_counters->update_capacity(); 167 _from_counters->update_capacity(); 168 _to_counters->update_capacity(); 169 } 170 } 171 172 void PSYoungGen::set_space_boundaries(size_t eden_size, size_t survivor_size) { 173 assert(eden_size < virtual_space()->committed_size(), "just checking"); 174 assert(eden_size > 0 && survivor_size > 0, "just checking"); 175 176 // Initial layout is Eden, to, from. After swapping survivor spaces, 177 // that leaves us with Eden, from, to, which is step one in our two 178 // step resize-with-live-data procedure. 179 char *eden_start = virtual_space()->low(); 180 char *to_start = eden_start + eden_size; 181 char *from_start = to_start + survivor_size; 182 char *from_end = from_start + survivor_size; 183 184 assert(from_end == virtual_space()->high(), "just checking"); 185 assert(is_object_aligned(eden_start), "checking alignment"); 186 assert(is_object_aligned(to_start), "checking alignment"); 187 assert(is_object_aligned(from_start), "checking alignment"); 188 189 MemRegion eden_mr((HeapWord*)eden_start, (HeapWord*)to_start); 190 MemRegion to_mr ((HeapWord*)to_start, (HeapWord*)from_start); 191 MemRegion from_mr((HeapWord*)from_start, (HeapWord*)from_end); 192 193 eden_space()->initialize(eden_mr, true, ZapUnusedHeapArea); 194 to_space()->initialize(to_mr , true, ZapUnusedHeapArea); 195 from_space()->initialize(from_mr, true, ZapUnusedHeapArea); 196 } 197 198 #ifndef PRODUCT 199 void PSYoungGen::space_invariants() { 200 // Currently, our eden size cannot shrink to zero 201 guarantee(eden_space()->capacity_in_bytes() >= SpaceAlignment, "eden too small"); 202 guarantee(from_space()->capacity_in_bytes() >= SpaceAlignment, "from too small"); 203 guarantee(to_space()->capacity_in_bytes() >= SpaceAlignment, "to too small"); 204 205 // Relationship of spaces to each other 206 char* eden_start = (char*)eden_space()->bottom(); 207 char* eden_end = (char*)eden_space()->end(); 208 char* from_start = (char*)from_space()->bottom(); 209 char* from_end = (char*)from_space()->end(); 210 char* to_start = (char*)to_space()->bottom(); 211 char* to_end = (char*)to_space()->end(); 212 213 guarantee(eden_start >= virtual_space()->low(), "eden bottom"); 214 guarantee(eden_start < eden_end, "eden space consistency"); 215 guarantee(from_start < from_end, "from space consistency"); 216 guarantee(to_start < to_end, "to space consistency"); 217 218 // Check whether from space is below to space 219 if (from_start < to_start) { 220 // Eden, from, to 221 guarantee(eden_end <= from_start, "eden/from boundary"); 222 guarantee(from_end <= to_start, "from/to boundary"); 223 guarantee(to_end <= virtual_space()->high(), "to end"); 224 } else { 225 // Eden, to, from 226 guarantee(eden_end <= to_start, "eden/to boundary"); 227 guarantee(to_end <= from_start, "to/from boundary"); 228 guarantee(from_end <= virtual_space()->high(), "from end"); 229 } 230 231 // More checks that the virtual space is consistent with the spaces 232 assert(virtual_space()->committed_size() >= 233 (eden_space()->capacity_in_bytes() + 234 to_space()->capacity_in_bytes() + 235 from_space()->capacity_in_bytes()), "Committed size is inconsistent"); 236 assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(), 237 "Space invariant"); 238 char* eden_top = (char*)eden_space()->top(); 239 char* from_top = (char*)from_space()->top(); 240 char* to_top = (char*)to_space()->top(); 241 assert(eden_top <= virtual_space()->high(), "eden top"); 242 assert(from_top <= virtual_space()->high(), "from top"); 243 assert(to_top <= virtual_space()->high(), "to top"); 244 245 virtual_space()->verify(); 246 } 247 #endif 248 249 void PSYoungGen::resize(size_t eden_size, size_t survivor_size) { 250 // Resize the generation if needed. If the generation resize 251 // reports false, do not attempt to resize the spaces. 252 if (resize_generation(eden_size, survivor_size)) { 253 // Then we lay out the spaces inside the generation 254 resize_spaces(eden_size, survivor_size); 255 256 space_invariants(); 257 258 log_trace(gc, ergo)("Young generation size: " 259 "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT 260 " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT 261 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT, 262 eden_size, survivor_size, used_in_bytes(), capacity_in_bytes(), 263 _max_gen_size, min_gen_size()); 264 } 265 } 266 267 268 bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) { 269 const size_t alignment = virtual_space()->alignment(); 270 size_t orig_size = virtual_space()->committed_size(); 271 bool size_changed = false; 272 273 // There used to be this guarantee there. 274 // guarantee ((eden_size + 2*survivor_size) <= _max_gen_size, "incorrect input arguments"); 275 // Code below forces this requirement. In addition the desired eden 276 // size and desired survivor sizes are desired goals and may 277 // exceed the total generation size. 278 279 assert(min_gen_size() <= orig_size && orig_size <= max_size(), "just checking"); 280 281 // Adjust new generation size 282 const size_t eden_plus_survivors = 283 align_up(eden_size + 2 * survivor_size, alignment); 284 size_t desired_size = clamp(eden_plus_survivors, min_gen_size(), max_size()); 285 assert(desired_size <= max_size(), "just checking"); 286 287 if (desired_size > orig_size) { 288 // Grow the generation 289 size_t change = desired_size - orig_size; 290 assert(change % alignment == 0, "just checking"); 291 HeapWord* prev_high = (HeapWord*) virtual_space()->high(); 292 if (!virtual_space()->expand_by(change)) { 293 return false; // Error if we fail to resize! 294 } 295 if (ZapUnusedHeapArea) { 296 // Mangle newly committed space immediately because it 297 // can be done here more simply that after the new 298 // spaces have been computed. 299 HeapWord* new_high = (HeapWord*) virtual_space()->high(); 300 MemRegion mangle_region(prev_high, new_high); 301 SpaceMangler::mangle_region(mangle_region); 302 } 303 size_changed = true; 304 } else if (desired_size < orig_size) { 305 size_t desired_change = orig_size - desired_size; 306 assert(desired_change % alignment == 0, "just checking"); 307 308 desired_change = limit_gen_shrink(desired_change); 309 310 if (desired_change > 0) { 311 virtual_space()->shrink_by(desired_change); 312 reset_survivors_after_shrink(); 313 314 size_changed = true; 315 } 316 } else { 317 if (orig_size == gen_size_limit()) { 318 log_trace(gc)("PSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K); 319 } else if (orig_size == min_gen_size()) { 320 log_trace(gc)("PSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K); 321 } 322 } 323 324 if (size_changed) { 325 post_resize(); 326 log_trace(gc)("PSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K", 327 orig_size/K, virtual_space()->committed_size()/K); 328 } 329 330 guarantee(eden_plus_survivors <= virtual_space()->committed_size() || 331 virtual_space()->committed_size() == max_size(), "Sanity"); 332 333 return true; 334 } 335 336 #ifndef PRODUCT 337 // In the numa case eden is not mangled so a survivor space 338 // moving into a region previously occupied by a survivor 339 // may find an unmangled region. Also in the PS case eden 340 // to-space and from-space may not touch (i.e., there may be 341 // gaps between them due to movement while resizing the 342 // spaces). Those gaps must be mangled. 343 void PSYoungGen::mangle_survivors(MutableSpace* s1, 344 MemRegion s1MR, 345 MutableSpace* s2, 346 MemRegion s2MR) { 347 // Check eden and gap between eden and from-space, in deciding 348 // what to mangle in from-space. Check the gap between from-space 349 // and to-space when deciding what to mangle. 350 // 351 // +--------+ +----+ +---+ 352 // | eden | |s1 | |s2 | 353 // +--------+ +----+ +---+ 354 // +-------+ +-----+ 355 // |s1MR | |s2MR | 356 // +-------+ +-----+ 357 // All of survivor-space is properly mangled so find the 358 // upper bound on the mangling for any portion above current s1. 359 HeapWord* delta_end = MIN2(s1->bottom(), s1MR.end()); 360 MemRegion delta1_left; 361 if (s1MR.start() < delta_end) { 362 delta1_left = MemRegion(s1MR.start(), delta_end); 363 s1->mangle_region(delta1_left); 364 } 365 // Find any portion to the right of the current s1. 366 HeapWord* delta_start = MAX2(s1->end(), s1MR.start()); 367 MemRegion delta1_right; 368 if (delta_start < s1MR.end()) { 369 delta1_right = MemRegion(delta_start, s1MR.end()); 370 s1->mangle_region(delta1_right); 371 } 372 373 // Similarly for the second survivor space except that 374 // any of the new region that overlaps with the current 375 // region of the first survivor space has already been 376 // mangled. 377 delta_end = MIN2(s2->bottom(), s2MR.end()); 378 delta_start = MAX2(s2MR.start(), s1->end()); 379 MemRegion delta2_left; 380 if (s2MR.start() < delta_end) { 381 delta2_left = MemRegion(s2MR.start(), delta_end); 382 s2->mangle_region(delta2_left); 383 } 384 delta_start = MAX2(s2->end(), s2MR.start()); 385 MemRegion delta2_right; 386 if (delta_start < s2MR.end()) { 387 s2->mangle_region(delta2_right); 388 } 389 390 // s1 391 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") " 392 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")", 393 p2i(s1->bottom()), p2i(s1->end()), 394 p2i(s1MR.start()), p2i(s1MR.end())); 395 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", " 396 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")", 397 p2i(delta1_left.start()), p2i(delta1_left.end()), 398 p2i(delta1_right.start()), p2i(delta1_right.end())); 399 400 // s2 401 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") " 402 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")", 403 p2i(s2->bottom()), p2i(s2->end()), 404 p2i(s2MR.start()), p2i(s2MR.end())); 405 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", " 406 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")", 407 p2i(delta2_left.start()), p2i(delta2_left.end()), 408 p2i(delta2_right.start()), p2i(delta2_right.end())); 409 } 410 #endif // NOT PRODUCT 411 412 void PSYoungGen::resize_spaces(size_t requested_eden_size, 413 size_t requested_survivor_size) { 414 assert(UseAdaptiveSizePolicy, "sanity check"); 415 assert(requested_eden_size > 0 && requested_survivor_size > 0, 416 "just checking"); 417 418 // We require eden and to space to be empty 419 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) { 420 return; 421 } 422 423 log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: " SIZE_FORMAT ", requested_survivor_size: " SIZE_FORMAT ")", 424 requested_eden_size, requested_survivor_size); 425 log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, 426 p2i(eden_space()->bottom()), 427 p2i(eden_space()->end()), 428 pointer_delta(eden_space()->end(), 429 eden_space()->bottom(), 430 sizeof(char))); 431 log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, 432 p2i(from_space()->bottom()), 433 p2i(from_space()->end()), 434 pointer_delta(from_space()->end(), 435 from_space()->bottom(), 436 sizeof(char))); 437 log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, 438 p2i(to_space()->bottom()), 439 p2i(to_space()->end()), 440 pointer_delta( to_space()->end(), 441 to_space()->bottom(), 442 sizeof(char))); 443 444 // There's nothing to do if the new sizes are the same as the current 445 if (requested_survivor_size == to_space()->capacity_in_bytes() && 446 requested_survivor_size == from_space()->capacity_in_bytes() && 447 requested_eden_size == eden_space()->capacity_in_bytes()) { 448 log_trace(gc, ergo)(" capacities are the right sizes, returning"); 449 return; 450 } 451 452 char* eden_start = (char*)eden_space()->bottom(); 453 char* eden_end = (char*)eden_space()->end(); 454 char* from_start = (char*)from_space()->bottom(); 455 char* from_end = (char*)from_space()->end(); 456 char* to_start = (char*)to_space()->bottom(); 457 char* to_end = (char*)to_space()->end(); 458 459 const bool maintain_minimum = 460 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size(); 461 462 bool eden_from_to_order = from_start < to_start; 463 // Check whether from space is below to space 464 if (eden_from_to_order) { 465 // Eden, from, to 466 eden_from_to_order = true; 467 log_trace(gc, ergo)(" Eden, from, to:"); 468 469 // Set eden 470 // "requested_eden_size" is a goal for the size of eden 471 // and may not be attainable. "eden_size" below is 472 // calculated based on the location of from-space and 473 // the goal for the size of eden. from-space is 474 // fixed in place because it contains live data. 475 // The calculation is done this way to avoid 32bit 476 // overflow (i.e., eden_start + requested_eden_size 477 // may too large for representation in 32bits). 478 size_t eden_size; 479 if (maintain_minimum) { 480 // Only make eden larger than the requested size if 481 // the minimum size of the generation has to be maintained. 482 // This could be done in general but policy at a higher 483 // level is determining a requested size for eden and that 484 // should be honored unless there is a fundamental reason. 485 eden_size = pointer_delta(from_start, 486 eden_start, 487 sizeof(char)); 488 } else { 489 eden_size = MIN2(requested_eden_size, 490 pointer_delta(from_start, eden_start, sizeof(char))); 491 } 492 493 eden_end = eden_start + eden_size; 494 assert(eden_end >= eden_start, "addition overflowed"); 495 496 // To may resize into from space as long as it is clear of live data. 497 // From space must remain page aligned, though, so we need to do some 498 // extra calculations. 499 500 // First calculate an optimal to-space 501 to_end = (char*)virtual_space()->high(); 502 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size, 503 sizeof(char)); 504 505 // Does the optimal to-space overlap from-space? 506 if (to_start < (char*)from_space()->end()) { 507 // Calculate the minimum offset possible for from_end 508 size_t from_size = pointer_delta(from_space()->top(), from_start, sizeof(char)); 509 510 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME! 511 if (from_size == 0) { 512 from_size = SpaceAlignment; 513 } else { 514 from_size = align_up(from_size, SpaceAlignment); 515 } 516 517 from_end = from_start + from_size; 518 assert(from_end > from_start, "addition overflow or from_size problem"); 519 520 guarantee(from_end <= (char*)from_space()->end(), "from_end moved to the right"); 521 522 // Now update to_start with the new from_end 523 to_start = MAX2(from_end, to_start); 524 } 525 526 guarantee(to_start != to_end, "to space is zero sized"); 527 528 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 529 p2i(eden_start), 530 p2i(eden_end), 531 pointer_delta(eden_end, eden_start, sizeof(char))); 532 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 533 p2i(from_start), 534 p2i(from_end), 535 pointer_delta(from_end, from_start, sizeof(char))); 536 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 537 p2i(to_start), 538 p2i(to_end), 539 pointer_delta( to_end, to_start, sizeof(char))); 540 } else { 541 // Eden, to, from 542 log_trace(gc, ergo)(" Eden, to, from:"); 543 544 // To space gets priority over eden resizing. Note that we position 545 // to space as if we were able to resize from space, even though from 546 // space is not modified. 547 // Giving eden priority was tried and gave poorer performance. 548 to_end = (char*)pointer_delta(virtual_space()->high(), 549 (char*)requested_survivor_size, 550 sizeof(char)); 551 to_end = MIN2(to_end, from_start); 552 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size, 553 sizeof(char)); 554 // if the space sizes are to be increased by several times then 555 // 'to_start' will point beyond the young generation. In this case 556 // 'to_start' should be adjusted. 557 to_start = MAX2(to_start, eden_start + SpaceAlignment); 558 559 // Compute how big eden can be, then adjust end. 560 // See comments above on calculating eden_end. 561 size_t eden_size; 562 if (maintain_minimum) { 563 eden_size = pointer_delta(to_start, eden_start, sizeof(char)); 564 } else { 565 eden_size = MIN2(requested_eden_size, 566 pointer_delta(to_start, eden_start, sizeof(char))); 567 } 568 eden_end = eden_start + eden_size; 569 assert(eden_end >= eden_start, "addition overflowed"); 570 571 // Could choose to not let eden shrink 572 // to_start = MAX2(to_start, eden_end); 573 574 // Don't let eden shrink down to 0 or less. 575 eden_end = MAX2(eden_end, eden_start + SpaceAlignment); 576 to_start = MAX2(to_start, eden_end); 577 578 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 579 p2i(eden_start), 580 p2i(eden_end), 581 pointer_delta(eden_end, eden_start, sizeof(char))); 582 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 583 p2i(to_start), 584 p2i(to_end), 585 pointer_delta( to_end, to_start, sizeof(char))); 586 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 587 p2i(from_start), 588 p2i(from_end), 589 pointer_delta(from_end, from_start, sizeof(char))); 590 } 591 592 593 guarantee((HeapWord*)from_start <= from_space()->bottom(), 594 "from start moved to the right"); 595 guarantee((HeapWord*)from_end >= from_space()->top(), 596 "from end moved into live data"); 597 assert(is_object_aligned(eden_start), "checking alignment"); 598 assert(is_object_aligned(from_start), "checking alignment"); 599 assert(is_object_aligned(to_start), "checking alignment"); 600 601 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end); 602 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end); 603 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end); 604 605 // Let's make sure the call to initialize doesn't reset "top"! 606 HeapWord* old_from_top = from_space()->top(); 607 608 // For logging block below 609 size_t old_from = from_space()->capacity_in_bytes(); 610 size_t old_to = to_space()->capacity_in_bytes(); 611 612 if (ZapUnusedHeapArea) { 613 // NUMA is a special case because a numa space is not mangled 614 // in order to not prematurely bind its address to memory to 615 // the wrong memory (i.e., don't want the GC thread to first 616 // touch the memory). The survivor spaces are not numa 617 // spaces and are mangled. 618 if (UseNUMA) { 619 if (eden_from_to_order) { 620 mangle_survivors(from_space(), fromMR, to_space(), toMR); 621 } else { 622 mangle_survivors(to_space(), toMR, from_space(), fromMR); 623 } 624 } 625 626 // If not mangling the spaces, do some checking to verify that 627 // the spaces are already mangled. 628 // The spaces should be correctly mangled at this point so 629 // do some checking here. Note that they are not being mangled 630 // in the calls to initialize(). 631 // Must check mangling before the spaces are reshaped. Otherwise, 632 // the bottom or end of one space may have moved into an area 633 // covered by another space and a failure of the check may 634 // not correctly indicate which space is not properly mangled. 635 HeapWord* limit = (HeapWord*) virtual_space()->high(); 636 eden_space()->check_mangled_unused_area(limit); 637 from_space()->check_mangled_unused_area(limit); 638 to_space()->check_mangled_unused_area(limit); 639 } 640 // When an existing space is being initialized, it is not 641 // mangled because the space has been previously mangled. 642 eden_space()->initialize(edenMR, 643 SpaceDecorator::Clear, 644 SpaceDecorator::DontMangle); 645 to_space()->initialize(toMR, 646 SpaceDecorator::Clear, 647 SpaceDecorator::DontMangle); 648 from_space()->initialize(fromMR, 649 SpaceDecorator::DontClear, 650 SpaceDecorator::DontMangle); 651 652 assert(from_space()->top() == old_from_top, "from top changed!"); 653 654 log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: collection: %d (" SIZE_FORMAT ", " SIZE_FORMAT ") -> (" SIZE_FORMAT ", " SIZE_FORMAT ") ", 655 ParallelScavengeHeap::heap()->total_collections(), 656 old_from, old_to, 657 from_space()->capacity_in_bytes(), 658 to_space()->capacity_in_bytes()); 659 } 660 661 void PSYoungGen::swap_spaces() { 662 MutableSpace* s = from_space(); 663 _from_space = to_space(); 664 _to_space = s; 665 } 666 667 size_t PSYoungGen::capacity_in_bytes() const { 668 return eden_space()->capacity_in_bytes() 669 + from_space()->capacity_in_bytes(); // to_space() is only used during scavenge 670 } 671 672 673 size_t PSYoungGen::used_in_bytes() const { 674 return eden_space()->used_in_bytes() 675 + from_space()->used_in_bytes(); // to_space() is only used during scavenge 676 } 677 678 679 size_t PSYoungGen::free_in_bytes() const { 680 return eden_space()->free_in_bytes() 681 + from_space()->free_in_bytes(); // to_space() is only used during scavenge 682 } 683 684 size_t PSYoungGen::capacity_in_words() const { 685 return eden_space()->capacity_in_words() 686 + from_space()->capacity_in_words(); // to_space() is only used during scavenge 687 } 688 689 690 size_t PSYoungGen::used_in_words() const { 691 return eden_space()->used_in_words() 692 + from_space()->used_in_words(); // to_space() is only used during scavenge 693 } 694 695 696 size_t PSYoungGen::free_in_words() const { 697 return eden_space()->free_in_words() 698 + from_space()->free_in_words(); // to_space() is only used during scavenge 699 } 700 701 void PSYoungGen::object_iterate(ObjectClosure* blk) { 702 eden_space()->object_iterate(blk); 703 from_space()->object_iterate(blk); 704 to_space()->object_iterate(blk); 705 } 706 707 void PSYoungGen::print() const { print_on(tty); } 708 void PSYoungGen::print_on(outputStream* st) const { 709 st->print(" %-15s", "PSYoungGen"); 710 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 711 capacity_in_bytes()/K, used_in_bytes()/K); 712 virtual_space()->print_space_boundaries_on(st); 713 st->print(" eden"); eden_space()->print_on(st); 714 st->print(" from"); from_space()->print_on(st); 715 st->print(" to "); to_space()->print_on(st); 716 } 717 718 size_t PSYoungGen::available_for_expansion() { 719 ShouldNotReachHere(); 720 return 0; 721 } 722 723 size_t PSYoungGen::available_for_contraction() { 724 ShouldNotReachHere(); 725 return 0; 726 } 727 728 size_t PSYoungGen::available_to_min_gen() { 729 assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant"); 730 return virtual_space()->committed_size() - min_gen_size(); 731 } 732 733 // This method assumes that from-space has live data and that 734 // any shrinkage of the young gen is limited by location of 735 // from-space. 736 size_t PSYoungGen::available_to_live() { 737 size_t delta_in_survivor = 0; 738 MutableSpace* space_shrinking = NULL; 739 if (from_space()->end() > to_space()->end()) { 740 space_shrinking = from_space(); 741 } else { 742 space_shrinking = to_space(); 743 } 744 745 // Include any space that is committed but not included in 746 // the survivor spaces. 747 assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(), 748 "Survivor space beyond high end"); 749 size_t unused_committed = pointer_delta(virtual_space()->high(), 750 space_shrinking->end(), sizeof(char)); 751 752 if (space_shrinking->is_empty()) { 753 // Don't let the space shrink to 0 754 assert(space_shrinking->capacity_in_bytes() >= SpaceAlignment, 755 "Space is too small"); 756 delta_in_survivor = space_shrinking->capacity_in_bytes() - SpaceAlignment; 757 } else { 758 delta_in_survivor = pointer_delta(space_shrinking->end(), 759 space_shrinking->top(), 760 sizeof(char)); 761 } 762 763 size_t delta_in_bytes = unused_committed + delta_in_survivor; 764 delta_in_bytes = align_down(delta_in_bytes, GenAlignment); 765 return delta_in_bytes; 766 } 767 768 // Return the number of bytes available for resizing down the young 769 // generation. This is the minimum of 770 // input "bytes" 771 // bytes to the minimum young gen size 772 // bytes to the size currently being used + some small extra 773 size_t PSYoungGen::limit_gen_shrink(size_t bytes) { 774 // Allow shrinkage into the current eden but keep eden large enough 775 // to maintain the minimum young gen size 776 bytes = MIN3(bytes, available_to_min_gen(), available_to_live()); 777 return align_down(bytes, virtual_space()->alignment()); 778 } 779 780 void PSYoungGen::reset_after_change() { 781 ShouldNotReachHere(); 782 } 783 784 void PSYoungGen::reset_survivors_after_shrink() { 785 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(), 786 (HeapWord*)virtual_space()->high_boundary()); 787 PSScavenge::set_subject_to_discovery_span(_reserved); 788 789 MutableSpace* space_shrinking = NULL; 790 if (from_space()->end() > to_space()->end()) { 791 space_shrinking = from_space(); 792 } else { 793 space_shrinking = to_space(); 794 } 795 796 HeapWord* new_end = (HeapWord*)virtual_space()->high(); 797 assert(new_end >= space_shrinking->bottom(), "Shrink was too large"); 798 // Was there a shrink of the survivor space? 799 if (new_end < space_shrinking->end()) { 800 MemRegion mr(space_shrinking->bottom(), new_end); 801 space_shrinking->initialize(mr, 802 SpaceDecorator::DontClear, 803 SpaceDecorator::Mangle); 804 } 805 } 806 807 // This method currently does not expect to expand into eden (i.e., 808 // the virtual space boundaries is expected to be consistent 809 // with the eden boundaries.. 810 void PSYoungGen::post_resize() { 811 assert_locked_or_safepoint(Heap_lock); 812 assert((eden_space()->bottom() < to_space()->bottom()) && 813 (eden_space()->bottom() < from_space()->bottom()), 814 "Eden is assumed to be below the survivor spaces"); 815 816 MemRegion cmr((HeapWord*)virtual_space()->low(), 817 (HeapWord*)virtual_space()->high()); 818 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr); 819 space_invariants(); 820 } 821 822 823 824 void PSYoungGen::update_counters() { 825 if (UsePerfData) { 826 _eden_counters->update_all(); 827 _from_counters->update_all(); 828 _to_counters->update_all(); 829 _gen_counters->update_all(); 830 } 831 } 832 833 void PSYoungGen::verify() { 834 eden_space()->verify(); 835 from_space()->verify(); 836 to_space()->verify(); 837 } 838 839 #ifndef PRODUCT 840 void PSYoungGen::record_spaces_top() { 841 assert(ZapUnusedHeapArea, "Not mangling unused space"); 842 eden_space()->set_top_for_allocations(); 843 from_space()->set_top_for_allocations(); 844 to_space()->set_top_for_allocations(); 845 } 846 #endif