rev 58017 : [mq]: 8238854-remove-superfluous-alloc-checks

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