1 /* 2 * Copyright (c) 2001, 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 #include "precompiled.hpp" 26 #include "gc/parallel/mutableNUMASpace.hpp" 27 #include "gc/parallel/parallelScavengeHeap.hpp" 28 #include "gc/parallel/psMarkSweepDecorator.hpp" 29 #include "gc/parallel/psScavenge.hpp" 30 #include "gc/parallel/psYoungGen.hpp" 31 #include "gc/shared/gcUtil.hpp" 32 #include "gc/shared/genArguments.hpp" 33 #include "gc/shared/spaceDecorator.inline.hpp" 34 #include "logging/log.hpp" 35 #include "oops/oop.inline.hpp" 36 #include "runtime/java.hpp" 37 #include "utilities/align.hpp" 38 39 PSYoungGen::PSYoungGen(size_t initial_size, size_t min_size, size_t max_size) : 40 _reserved(), 41 _virtual_space(NULL), 42 _eden_space(NULL), 43 _from_space(NULL), 44 _to_space(NULL), 45 _eden_mark_sweep(NULL), 46 _from_mark_sweep(NULL), 47 _to_mark_sweep(NULL), 48 _init_gen_size(initial_size), 49 _min_gen_size(min_size), 50 _max_gen_size(max_size), 51 _gen_counters(NULL), 52 _eden_counters(NULL), 53 _from_counters(NULL), 54 _to_counters(NULL) 55 {} 56 57 void PSYoungGen::initialize_virtual_space(ReservedSpace rs, size_t alignment) { 58 assert(_init_gen_size != 0, "Should have a finite size"); 59 _virtual_space = new PSVirtualSpace(rs, alignment); 60 if (!virtual_space()->expand_by(_init_gen_size)) { 61 vm_exit_during_initialization("Could not reserve enough space for " 62 "object heap"); 63 } 64 } 65 66 void PSYoungGen::initialize(ReservedSpace rs, size_t alignment) { 67 initialize_virtual_space(rs, alignment); 68 initialize_work(); 69 } 70 71 void PSYoungGen::initialize_work() { 72 73 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(), 74 (HeapWord*)virtual_space()->high_boundary()); 75 76 MemRegion cmr((HeapWord*)virtual_space()->low(), 77 (HeapWord*)virtual_space()->high()); 78 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr); 79 80 if (ZapUnusedHeapArea) { 81 // Mangle newly committed space immediately because it 82 // can be done here more simply that after the new 83 // spaces have been computed. 84 SpaceMangler::mangle_region(cmr); 85 } 86 87 if (UseNUMA) { 88 _eden_space = new MutableNUMASpace(virtual_space()->alignment()); 89 } else { 90 _eden_space = new MutableSpace(virtual_space()->alignment()); 91 } 92 _from_space = new MutableSpace(virtual_space()->alignment()); 93 _to_space = new MutableSpace(virtual_space()->alignment()); 94 95 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL) { 96 vm_exit_during_initialization("Could not allocate a young gen space"); 97 } 98 99 // Allocate the mark sweep views of spaces 100 _eden_mark_sweep = 101 new PSMarkSweepDecorator(_eden_space, NULL, MarkSweepDeadRatio); 102 _from_mark_sweep = 103 new PSMarkSweepDecorator(_from_space, NULL, MarkSweepDeadRatio); 104 _to_mark_sweep = 105 new PSMarkSweepDecorator(_to_space, NULL, MarkSweepDeadRatio); 106 107 if (_eden_mark_sweep == NULL || 108 _from_mark_sweep == NULL || 109 _to_mark_sweep == NULL) { 110 vm_exit_during_initialization("Could not complete allocation" 111 " of the young generation"); 112 } 113 114 // Generation Counters - generation 0, 3 subspaces 115 _gen_counters = new PSGenerationCounters("new", 0, 3, _min_gen_size, 116 _max_gen_size, _virtual_space); 117 118 // Compute maximum space sizes for performance counters 119 size_t alignment = SpaceAlignment; 120 size_t size = virtual_space()->reserved_size(); 121 122 size_t max_survivor_size; 123 size_t max_eden_size; 124 125 if (UseAdaptiveSizePolicy) { 126 max_survivor_size = size / MinSurvivorRatio; 127 128 // round the survivor space size down to the nearest alignment 129 // and make sure its size is greater than 0. 130 max_survivor_size = align_down(max_survivor_size, alignment); 131 max_survivor_size = MAX2(max_survivor_size, alignment); 132 133 // set the maximum size of eden to be the size of the young gen 134 // less two times the minimum survivor size. The minimum survivor 135 // size for UseAdaptiveSizePolicy is one alignment. 136 max_eden_size = size - 2 * alignment; 137 } else { 138 max_survivor_size = size / InitialSurvivorRatio; 139 140 // round the survivor space size down to the nearest alignment 141 // and make sure its size is greater than 0. 142 max_survivor_size = align_down(max_survivor_size, alignment); 143 max_survivor_size = MAX2(max_survivor_size, alignment); 144 145 // set the maximum size of eden to be the size of the young gen 146 // less two times the survivor size when the generation is 100% 147 // committed. The minimum survivor size for -UseAdaptiveSizePolicy 148 // is dependent on the committed portion (current capacity) of the 149 // generation - the less space committed, the smaller the survivor 150 // space, possibly as small as an alignment. However, we are interested 151 // in the case where the young generation is 100% committed, as this 152 // is the point where eden reaches its maximum size. At this point, 153 // the size of a survivor space is max_survivor_size. 154 max_eden_size = size - 2 * max_survivor_size; 155 } 156 157 _eden_counters = new SpaceCounters("eden", 0, max_eden_size, _eden_space, 158 _gen_counters); 159 _from_counters = new SpaceCounters("s0", 1, max_survivor_size, _from_space, 160 _gen_counters); 161 _to_counters = new SpaceCounters("s1", 2, max_survivor_size, _to_space, 162 _gen_counters); 163 164 compute_initial_space_boundaries(); 165 } 166 167 void PSYoungGen::compute_initial_space_boundaries() { 168 // Compute sizes 169 size_t size = virtual_space()->committed_size(); 170 assert(size >= 3 * SpaceAlignment, "Young space is not large enough for eden + 2 survivors"); 171 172 size_t survivor_size = size / InitialSurvivorRatio; 173 survivor_size = align_down(survivor_size, SpaceAlignment); 174 // ... but never less than an alignment 175 survivor_size = MAX2(survivor_size, SpaceAlignment); 176 177 // Young generation is eden + 2 survivor spaces 178 size_t eden_size = size - (2 * survivor_size); 179 180 // Now go ahead and set 'em. 181 set_space_boundaries(eden_size, survivor_size); 182 space_invariants(); 183 184 if (UsePerfData) { 185 _eden_counters->update_capacity(); 186 _from_counters->update_capacity(); 187 _to_counters->update_capacity(); 188 } 189 } 190 191 void PSYoungGen::set_space_boundaries(size_t eden_size, size_t survivor_size) { 192 assert(eden_size < virtual_space()->committed_size(), "just checking"); 193 assert(eden_size > 0 && survivor_size > 0, "just checking"); 194 195 // Initial layout is Eden, to, from. After swapping survivor spaces, 196 // that leaves us with Eden, from, to, which is step one in our two 197 // step resize-with-live-data procedure. 198 char *eden_start = virtual_space()->low(); 199 char *to_start = eden_start + eden_size; 200 char *from_start = to_start + survivor_size; 201 char *from_end = from_start + survivor_size; 202 203 assert(from_end == virtual_space()->high(), "just checking"); 204 assert(is_object_aligned(eden_start), "checking alignment"); 205 assert(is_object_aligned(to_start), "checking alignment"); 206 assert(is_object_aligned(from_start), "checking alignment"); 207 208 MemRegion eden_mr((HeapWord*)eden_start, (HeapWord*)to_start); 209 MemRegion to_mr ((HeapWord*)to_start, (HeapWord*)from_start); 210 MemRegion from_mr((HeapWord*)from_start, (HeapWord*)from_end); 211 212 eden_space()->initialize(eden_mr, true, ZapUnusedHeapArea); 213 to_space()->initialize(to_mr , true, ZapUnusedHeapArea); 214 from_space()->initialize(from_mr, true, ZapUnusedHeapArea); 215 } 216 217 #ifndef PRODUCT 218 void PSYoungGen::space_invariants() { 219 // Currently, our eden size cannot shrink to zero 220 guarantee(eden_space()->capacity_in_bytes() >= SpaceAlignment, "eden too small"); 221 guarantee(from_space()->capacity_in_bytes() >= SpaceAlignment, "from too small"); 222 guarantee(to_space()->capacity_in_bytes() >= SpaceAlignment, "to too small"); 223 224 // Relationship of spaces to each other 225 char* eden_start = (char*)eden_space()->bottom(); 226 char* eden_end = (char*)eden_space()->end(); 227 char* from_start = (char*)from_space()->bottom(); 228 char* from_end = (char*)from_space()->end(); 229 char* to_start = (char*)to_space()->bottom(); 230 char* to_end = (char*)to_space()->end(); 231 232 guarantee(eden_start >= virtual_space()->low(), "eden bottom"); 233 guarantee(eden_start < eden_end, "eden space consistency"); 234 guarantee(from_start < from_end, "from space consistency"); 235 guarantee(to_start < to_end, "to space consistency"); 236 237 // Check whether from space is below to space 238 if (from_start < to_start) { 239 // Eden, from, to 240 guarantee(eden_end <= from_start, "eden/from boundary"); 241 guarantee(from_end <= to_start, "from/to boundary"); 242 guarantee(to_end <= virtual_space()->high(), "to end"); 243 } else { 244 // Eden, to, from 245 guarantee(eden_end <= to_start, "eden/to boundary"); 246 guarantee(to_end <= from_start, "to/from boundary"); 247 guarantee(from_end <= virtual_space()->high(), "from end"); 248 } 249 250 // More checks that the virtual space is consistent with the spaces 251 assert(virtual_space()->committed_size() >= 252 (eden_space()->capacity_in_bytes() + 253 to_space()->capacity_in_bytes() + 254 from_space()->capacity_in_bytes()), "Committed size is inconsistent"); 255 assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(), 256 "Space invariant"); 257 char* eden_top = (char*)eden_space()->top(); 258 char* from_top = (char*)from_space()->top(); 259 char* to_top = (char*)to_space()->top(); 260 assert(eden_top <= virtual_space()->high(), "eden top"); 261 assert(from_top <= virtual_space()->high(), "from top"); 262 assert(to_top <= virtual_space()->high(), "to top"); 263 264 virtual_space()->verify(); 265 } 266 #endif 267 268 void PSYoungGen::resize(size_t eden_size, size_t survivor_size) { 269 // Resize the generation if needed. If the generation resize 270 // reports false, do not attempt to resize the spaces. 271 if (resize_generation(eden_size, survivor_size)) { 272 // Then we lay out the spaces inside the generation 273 resize_spaces(eden_size, survivor_size); 274 275 space_invariants(); 276 277 log_trace(gc, ergo)("Young generation size: " 278 "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT 279 " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT 280 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT, 281 eden_size, survivor_size, used_in_bytes(), capacity_in_bytes(), 282 _max_gen_size, min_gen_size()); 283 } 284 } 285 286 287 bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) { 288 const size_t alignment = virtual_space()->alignment(); 289 size_t orig_size = virtual_space()->committed_size(); 290 bool size_changed = false; 291 292 // There used to be this guarantee there. 293 // guarantee ((eden_size + 2*survivor_size) <= _max_gen_size, "incorrect input arguments"); 294 // Code below forces this requirement. In addition the desired eden 295 // size and desired survivor sizes are desired goals and may 296 // exceed the total generation size. 297 298 assert(min_gen_size() <= orig_size && orig_size <= max_size(), "just checking"); 299 300 // Adjust new generation size 301 const size_t eden_plus_survivors = 302 align_up(eden_size + 2 * survivor_size, alignment); 303 size_t desired_size = clamp(eden_plus_survivors, min_gen_size(), max_size()); 304 assert(desired_size <= max_size(), "just checking"); 305 306 if (desired_size > orig_size) { 307 // Grow the generation 308 size_t change = desired_size - orig_size; 309 assert(change % alignment == 0, "just checking"); 310 HeapWord* prev_high = (HeapWord*) virtual_space()->high(); 311 if (!virtual_space()->expand_by(change)) { 312 return false; // Error if we fail to resize! 313 } 314 if (ZapUnusedHeapArea) { 315 // Mangle newly committed space immediately because it 316 // can be done here more simply that after the new 317 // spaces have been computed. 318 HeapWord* new_high = (HeapWord*) virtual_space()->high(); 319 MemRegion mangle_region(prev_high, new_high); 320 SpaceMangler::mangle_region(mangle_region); 321 } 322 size_changed = true; 323 } else if (desired_size < orig_size) { 324 size_t desired_change = orig_size - desired_size; 325 assert(desired_change % alignment == 0, "just checking"); 326 327 desired_change = limit_gen_shrink(desired_change); 328 329 if (desired_change > 0) { 330 virtual_space()->shrink_by(desired_change); 331 reset_survivors_after_shrink(); 332 333 size_changed = true; 334 } 335 } else { 336 if (orig_size == gen_size_limit()) { 337 log_trace(gc)("PSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K); 338 } else if (orig_size == min_gen_size()) { 339 log_trace(gc)("PSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K); 340 } 341 } 342 343 if (size_changed) { 344 post_resize(); 345 log_trace(gc)("PSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K", 346 orig_size/K, virtual_space()->committed_size()/K); 347 } 348 349 guarantee(eden_plus_survivors <= virtual_space()->committed_size() || 350 virtual_space()->committed_size() == max_size(), "Sanity"); 351 352 return true; 353 } 354 355 #ifndef PRODUCT 356 // In the numa case eden is not mangled so a survivor space 357 // moving into a region previously occupied by a survivor 358 // may find an unmangled region. Also in the PS case eden 359 // to-space and from-space may not touch (i.e., there may be 360 // gaps between them due to movement while resizing the 361 // spaces). Those gaps must be mangled. 362 void PSYoungGen::mangle_survivors(MutableSpace* s1, 363 MemRegion s1MR, 364 MutableSpace* s2, 365 MemRegion s2MR) { 366 // Check eden and gap between eden and from-space, in deciding 367 // what to mangle in from-space. Check the gap between from-space 368 // and to-space when deciding what to mangle. 369 // 370 // +--------+ +----+ +---+ 371 // | eden | |s1 | |s2 | 372 // +--------+ +----+ +---+ 373 // +-------+ +-----+ 374 // |s1MR | |s2MR | 375 // +-------+ +-----+ 376 // All of survivor-space is properly mangled so find the 377 // upper bound on the mangling for any portion above current s1. 378 HeapWord* delta_end = MIN2(s1->bottom(), s1MR.end()); 379 MemRegion delta1_left; 380 if (s1MR.start() < delta_end) { 381 delta1_left = MemRegion(s1MR.start(), delta_end); 382 s1->mangle_region(delta1_left); 383 } 384 // Find any portion to the right of the current s1. 385 HeapWord* delta_start = MAX2(s1->end(), s1MR.start()); 386 MemRegion delta1_right; 387 if (delta_start < s1MR.end()) { 388 delta1_right = MemRegion(delta_start, s1MR.end()); 389 s1->mangle_region(delta1_right); 390 } 391 392 // Similarly for the second survivor space except that 393 // any of the new region that overlaps with the current 394 // region of the first survivor space has already been 395 // mangled. 396 delta_end = MIN2(s2->bottom(), s2MR.end()); 397 delta_start = MAX2(s2MR.start(), s1->end()); 398 MemRegion delta2_left; 399 if (s2MR.start() < delta_end) { 400 delta2_left = MemRegion(s2MR.start(), delta_end); 401 s2->mangle_region(delta2_left); 402 } 403 delta_start = MAX2(s2->end(), s2MR.start()); 404 MemRegion delta2_right; 405 if (delta_start < s2MR.end()) { 406 s2->mangle_region(delta2_right); 407 } 408 409 // s1 410 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") " 411 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")", 412 p2i(s1->bottom()), p2i(s1->end()), 413 p2i(s1MR.start()), p2i(s1MR.end())); 414 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", " 415 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")", 416 p2i(delta1_left.start()), p2i(delta1_left.end()), 417 p2i(delta1_right.start()), p2i(delta1_right.end())); 418 419 // s2 420 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") " 421 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")", 422 p2i(s2->bottom()), p2i(s2->end()), 423 p2i(s2MR.start()), p2i(s2MR.end())); 424 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", " 425 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")", 426 p2i(delta2_left.start()), p2i(delta2_left.end()), 427 p2i(delta2_right.start()), p2i(delta2_right.end())); 428 } 429 #endif // NOT PRODUCT 430 431 void PSYoungGen::resize_spaces(size_t requested_eden_size, 432 size_t requested_survivor_size) { 433 assert(UseAdaptiveSizePolicy, "sanity check"); 434 assert(requested_eden_size > 0 && requested_survivor_size > 0, 435 "just checking"); 436 437 // We require eden and to space to be empty 438 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) { 439 return; 440 } 441 442 log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: " SIZE_FORMAT ", requested_survivor_size: " SIZE_FORMAT ")", 443 requested_eden_size, requested_survivor_size); 444 log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, 445 p2i(eden_space()->bottom()), 446 p2i(eden_space()->end()), 447 pointer_delta(eden_space()->end(), 448 eden_space()->bottom(), 449 sizeof(char))); 450 log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, 451 p2i(from_space()->bottom()), 452 p2i(from_space()->end()), 453 pointer_delta(from_space()->end(), 454 from_space()->bottom(), 455 sizeof(char))); 456 log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, 457 p2i(to_space()->bottom()), 458 p2i(to_space()->end()), 459 pointer_delta( to_space()->end(), 460 to_space()->bottom(), 461 sizeof(char))); 462 463 // There's nothing to do if the new sizes are the same as the current 464 if (requested_survivor_size == to_space()->capacity_in_bytes() && 465 requested_survivor_size == from_space()->capacity_in_bytes() && 466 requested_eden_size == eden_space()->capacity_in_bytes()) { 467 log_trace(gc, ergo)(" capacities are the right sizes, returning"); 468 return; 469 } 470 471 char* eden_start = (char*)eden_space()->bottom(); 472 char* eden_end = (char*)eden_space()->end(); 473 char* from_start = (char*)from_space()->bottom(); 474 char* from_end = (char*)from_space()->end(); 475 char* to_start = (char*)to_space()->bottom(); 476 char* to_end = (char*)to_space()->end(); 477 478 const bool maintain_minimum = 479 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size(); 480 481 bool eden_from_to_order = from_start < to_start; 482 // Check whether from space is below to space 483 if (eden_from_to_order) { 484 // Eden, from, to 485 eden_from_to_order = true; 486 log_trace(gc, ergo)(" Eden, from, to:"); 487 488 // Set eden 489 // "requested_eden_size" is a goal for the size of eden 490 // and may not be attainable. "eden_size" below is 491 // calculated based on the location of from-space and 492 // the goal for the size of eden. from-space is 493 // fixed in place because it contains live data. 494 // The calculation is done this way to avoid 32bit 495 // overflow (i.e., eden_start + requested_eden_size 496 // may too large for representation in 32bits). 497 size_t eden_size; 498 if (maintain_minimum) { 499 // Only make eden larger than the requested size if 500 // the minimum size of the generation has to be maintained. 501 // This could be done in general but policy at a higher 502 // level is determining a requested size for eden and that 503 // should be honored unless there is a fundamental reason. 504 eden_size = pointer_delta(from_start, 505 eden_start, 506 sizeof(char)); 507 } else { 508 eden_size = MIN2(requested_eden_size, 509 pointer_delta(from_start, eden_start, sizeof(char))); 510 } 511 512 eden_end = eden_start + eden_size; 513 assert(eden_end >= eden_start, "addition overflowed"); 514 515 // To may resize into from space as long as it is clear of live data. 516 // From space must remain page aligned, though, so we need to do some 517 // extra calculations. 518 519 // First calculate an optimal to-space 520 to_end = (char*)virtual_space()->high(); 521 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size, 522 sizeof(char)); 523 524 // Does the optimal to-space overlap from-space? 525 if (to_start < (char*)from_space()->end()) { 526 // Calculate the minimum offset possible for from_end 527 size_t from_size = pointer_delta(from_space()->top(), from_start, sizeof(char)); 528 529 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME! 530 if (from_size == 0) { 531 from_size = SpaceAlignment; 532 } else { 533 from_size = align_up(from_size, SpaceAlignment); 534 } 535 536 from_end = from_start + from_size; 537 assert(from_end > from_start, "addition overflow or from_size problem"); 538 539 guarantee(from_end <= (char*)from_space()->end(), "from_end moved to the right"); 540 541 // Now update to_start with the new from_end 542 to_start = MAX2(from_end, to_start); 543 } 544 545 guarantee(to_start != to_end, "to space is zero sized"); 546 547 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 548 p2i(eden_start), 549 p2i(eden_end), 550 pointer_delta(eden_end, eden_start, sizeof(char))); 551 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 552 p2i(from_start), 553 p2i(from_end), 554 pointer_delta(from_end, from_start, sizeof(char))); 555 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 556 p2i(to_start), 557 p2i(to_end), 558 pointer_delta( to_end, to_start, sizeof(char))); 559 } else { 560 // Eden, to, from 561 log_trace(gc, ergo)(" Eden, to, from:"); 562 563 // To space gets priority over eden resizing. Note that we position 564 // to space as if we were able to resize from space, even though from 565 // space is not modified. 566 // Giving eden priority was tried and gave poorer performance. 567 to_end = (char*)pointer_delta(virtual_space()->high(), 568 (char*)requested_survivor_size, 569 sizeof(char)); 570 to_end = MIN2(to_end, from_start); 571 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size, 572 sizeof(char)); 573 // if the space sizes are to be increased by several times then 574 // 'to_start' will point beyond the young generation. In this case 575 // 'to_start' should be adjusted. 576 to_start = MAX2(to_start, eden_start + SpaceAlignment); 577 578 // Compute how big eden can be, then adjust end. 579 // See comments above on calculating eden_end. 580 size_t eden_size; 581 if (maintain_minimum) { 582 eden_size = pointer_delta(to_start, eden_start, sizeof(char)); 583 } else { 584 eden_size = MIN2(requested_eden_size, 585 pointer_delta(to_start, eden_start, sizeof(char))); 586 } 587 eden_end = eden_start + eden_size; 588 assert(eden_end >= eden_start, "addition overflowed"); 589 590 // Could choose to not let eden shrink 591 // to_start = MAX2(to_start, eden_end); 592 593 // Don't let eden shrink down to 0 or less. 594 eden_end = MAX2(eden_end, eden_start + SpaceAlignment); 595 to_start = MAX2(to_start, eden_end); 596 597 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 598 p2i(eden_start), 599 p2i(eden_end), 600 pointer_delta(eden_end, eden_start, sizeof(char))); 601 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 602 p2i(to_start), 603 p2i(to_end), 604 pointer_delta( to_end, to_start, sizeof(char))); 605 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, 606 p2i(from_start), 607 p2i(from_end), 608 pointer_delta(from_end, from_start, sizeof(char))); 609 } 610 611 612 guarantee((HeapWord*)from_start <= from_space()->bottom(), 613 "from start moved to the right"); 614 guarantee((HeapWord*)from_end >= from_space()->top(), 615 "from end moved into live data"); 616 assert(is_object_aligned(eden_start), "checking alignment"); 617 assert(is_object_aligned(from_start), "checking alignment"); 618 assert(is_object_aligned(to_start), "checking alignment"); 619 620 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end); 621 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end); 622 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end); 623 624 // Let's make sure the call to initialize doesn't reset "top"! 625 HeapWord* old_from_top = from_space()->top(); 626 627 // For logging block below 628 size_t old_from = from_space()->capacity_in_bytes(); 629 size_t old_to = to_space()->capacity_in_bytes(); 630 631 if (ZapUnusedHeapArea) { 632 // NUMA is a special case because a numa space is not mangled 633 // in order to not prematurely bind its address to memory to 634 // the wrong memory (i.e., don't want the GC thread to first 635 // touch the memory). The survivor spaces are not numa 636 // spaces and are mangled. 637 if (UseNUMA) { 638 if (eden_from_to_order) { 639 mangle_survivors(from_space(), fromMR, to_space(), toMR); 640 } else { 641 mangle_survivors(to_space(), toMR, from_space(), fromMR); 642 } 643 } 644 645 // If not mangling the spaces, do some checking to verify that 646 // the spaces are already mangled. 647 // The spaces should be correctly mangled at this point so 648 // do some checking here. Note that they are not being mangled 649 // in the calls to initialize(). 650 // Must check mangling before the spaces are reshaped. Otherwise, 651 // the bottom or end of one space may have moved into an area 652 // covered by another space and a failure of the check may 653 // not correctly indicate which space is not properly mangled. 654 HeapWord* limit = (HeapWord*) virtual_space()->high(); 655 eden_space()->check_mangled_unused_area(limit); 656 from_space()->check_mangled_unused_area(limit); 657 to_space()->check_mangled_unused_area(limit); 658 } 659 // When an existing space is being initialized, it is not 660 // mangled because the space has been previously mangled. 661 eden_space()->initialize(edenMR, 662 SpaceDecorator::Clear, 663 SpaceDecorator::DontMangle); 664 to_space()->initialize(toMR, 665 SpaceDecorator::Clear, 666 SpaceDecorator::DontMangle); 667 from_space()->initialize(fromMR, 668 SpaceDecorator::DontClear, 669 SpaceDecorator::DontMangle); 670 671 assert(from_space()->top() == old_from_top, "from top changed!"); 672 673 log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: collection: %d (" SIZE_FORMAT ", " SIZE_FORMAT ") -> (" SIZE_FORMAT ", " SIZE_FORMAT ") ", 674 ParallelScavengeHeap::heap()->total_collections(), 675 old_from, old_to, 676 from_space()->capacity_in_bytes(), 677 to_space()->capacity_in_bytes()); 678 } 679 680 void PSYoungGen::swap_spaces() { 681 MutableSpace* s = from_space(); 682 _from_space = to_space(); 683 _to_space = s; 684 685 // Now update the decorators. 686 PSMarkSweepDecorator* md = from_mark_sweep(); 687 _from_mark_sweep = to_mark_sweep(); 688 _to_mark_sweep = md; 689 690 assert(from_mark_sweep()->space() == from_space(), "Sanity"); 691 assert(to_mark_sweep()->space() == to_space(), "Sanity"); 692 } 693 694 size_t PSYoungGen::capacity_in_bytes() const { 695 return eden_space()->capacity_in_bytes() 696 + from_space()->capacity_in_bytes(); // to_space() is only used during scavenge 697 } 698 699 700 size_t PSYoungGen::used_in_bytes() const { 701 return eden_space()->used_in_bytes() 702 + from_space()->used_in_bytes(); // to_space() is only used during scavenge 703 } 704 705 706 size_t PSYoungGen::free_in_bytes() const { 707 return eden_space()->free_in_bytes() 708 + from_space()->free_in_bytes(); // to_space() is only used during scavenge 709 } 710 711 size_t PSYoungGen::capacity_in_words() const { 712 return eden_space()->capacity_in_words() 713 + from_space()->capacity_in_words(); // to_space() is only used during scavenge 714 } 715 716 717 size_t PSYoungGen::used_in_words() const { 718 return eden_space()->used_in_words() 719 + from_space()->used_in_words(); // to_space() is only used during scavenge 720 } 721 722 723 size_t PSYoungGen::free_in_words() const { 724 return eden_space()->free_in_words() 725 + from_space()->free_in_words(); // to_space() is only used during scavenge 726 } 727 728 void PSYoungGen::object_iterate(ObjectClosure* blk) { 729 eden_space()->object_iterate(blk); 730 from_space()->object_iterate(blk); 731 to_space()->object_iterate(blk); 732 } 733 734 #if INCLUDE_SERIALGC 735 736 void PSYoungGen::precompact() { 737 eden_mark_sweep()->precompact(); 738 from_mark_sweep()->precompact(); 739 to_mark_sweep()->precompact(); 740 } 741 742 void PSYoungGen::adjust_pointers() { 743 eden_mark_sweep()->adjust_pointers(); 744 from_mark_sweep()->adjust_pointers(); 745 to_mark_sweep()->adjust_pointers(); 746 } 747 748 void PSYoungGen::compact() { 749 eden_mark_sweep()->compact(ZapUnusedHeapArea); 750 from_mark_sweep()->compact(ZapUnusedHeapArea); 751 // Mark sweep stores preserved markWords in to space, don't disturb! 752 to_mark_sweep()->compact(false); 753 } 754 755 #endif // INCLUDE_SERIALGC 756 757 void PSYoungGen::print() const { print_on(tty); } 758 void PSYoungGen::print_on(outputStream* st) const { 759 st->print(" %-15s", "PSYoungGen"); 760 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 761 capacity_in_bytes()/K, used_in_bytes()/K); 762 virtual_space()->print_space_boundaries_on(st); 763 st->print(" eden"); eden_space()->print_on(st); 764 st->print(" from"); from_space()->print_on(st); 765 st->print(" to "); to_space()->print_on(st); 766 } 767 768 size_t PSYoungGen::available_for_expansion() { 769 ShouldNotReachHere(); 770 return 0; 771 } 772 773 size_t PSYoungGen::available_for_contraction() { 774 ShouldNotReachHere(); 775 return 0; 776 } 777 778 size_t PSYoungGen::available_to_min_gen() { 779 assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant"); 780 return virtual_space()->committed_size() - min_gen_size(); 781 } 782 783 // This method assumes that from-space has live data and that 784 // any shrinkage of the young gen is limited by location of 785 // from-space. 786 size_t PSYoungGen::available_to_live() { 787 size_t delta_in_survivor = 0; 788 MutableSpace* space_shrinking = NULL; 789 if (from_space()->end() > to_space()->end()) { 790 space_shrinking = from_space(); 791 } else { 792 space_shrinking = to_space(); 793 } 794 795 // Include any space that is committed but not included in 796 // the survivor spaces. 797 assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(), 798 "Survivor space beyond high end"); 799 size_t unused_committed = pointer_delta(virtual_space()->high(), 800 space_shrinking->end(), sizeof(char)); 801 802 if (space_shrinking->is_empty()) { 803 // Don't let the space shrink to 0 804 assert(space_shrinking->capacity_in_bytes() >= SpaceAlignment, 805 "Space is too small"); 806 delta_in_survivor = space_shrinking->capacity_in_bytes() - SpaceAlignment; 807 } else { 808 delta_in_survivor = pointer_delta(space_shrinking->end(), 809 space_shrinking->top(), 810 sizeof(char)); 811 } 812 813 size_t delta_in_bytes = unused_committed + delta_in_survivor; 814 delta_in_bytes = align_down(delta_in_bytes, GenAlignment); 815 return delta_in_bytes; 816 } 817 818 // Return the number of bytes available for resizing down the young 819 // generation. This is the minimum of 820 // input "bytes" 821 // bytes to the minimum young gen size 822 // bytes to the size currently being used + some small extra 823 size_t PSYoungGen::limit_gen_shrink(size_t bytes) { 824 // Allow shrinkage into the current eden but keep eden large enough 825 // to maintain the minimum young gen size 826 bytes = MIN3(bytes, available_to_min_gen(), available_to_live()); 827 return align_down(bytes, virtual_space()->alignment()); 828 } 829 830 void PSYoungGen::reset_after_change() { 831 ShouldNotReachHere(); 832 } 833 834 void PSYoungGen::reset_survivors_after_shrink() { 835 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(), 836 (HeapWord*)virtual_space()->high_boundary()); 837 PSScavenge::set_subject_to_discovery_span(_reserved); 838 839 MutableSpace* space_shrinking = NULL; 840 if (from_space()->end() > to_space()->end()) { 841 space_shrinking = from_space(); 842 } else { 843 space_shrinking = to_space(); 844 } 845 846 HeapWord* new_end = (HeapWord*)virtual_space()->high(); 847 assert(new_end >= space_shrinking->bottom(), "Shrink was too large"); 848 // Was there a shrink of the survivor space? 849 if (new_end < space_shrinking->end()) { 850 MemRegion mr(space_shrinking->bottom(), new_end); 851 space_shrinking->initialize(mr, 852 SpaceDecorator::DontClear, 853 SpaceDecorator::Mangle); 854 } 855 } 856 857 // This method currently does not expect to expand into eden (i.e., 858 // the virtual space boundaries is expected to be consistent 859 // with the eden boundaries.. 860 void PSYoungGen::post_resize() { 861 assert_locked_or_safepoint(Heap_lock); 862 assert((eden_space()->bottom() < to_space()->bottom()) && 863 (eden_space()->bottom() < from_space()->bottom()), 864 "Eden is assumed to be below the survivor spaces"); 865 866 MemRegion cmr((HeapWord*)virtual_space()->low(), 867 (HeapWord*)virtual_space()->high()); 868 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr); 869 space_invariants(); 870 } 871 872 873 874 void PSYoungGen::update_counters() { 875 if (UsePerfData) { 876 _eden_counters->update_all(); 877 _from_counters->update_all(); 878 _to_counters->update_all(); 879 _gen_counters->update_all(); 880 } 881 } 882 883 void PSYoungGen::verify() { 884 eden_space()->verify(); 885 from_space()->verify(); 886 to_space()->verify(); 887 } 888 889 #ifndef PRODUCT 890 void PSYoungGen::record_spaces_top() { 891 assert(ZapUnusedHeapArea, "Not mangling unused space"); 892 eden_space()->set_top_for_allocations(); 893 from_space()->set_top_for_allocations(); 894 to_space()->set_top_for_allocations(); 895 } 896 #endif