rev 59216 : [mq]: cleanup
rev 59217 : [mq]: remove_init_gen_size

   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(ReservedSpace rs, 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   _min_gen_size(min_size),
  45   _max_gen_size(max_size),
  46   _gen_counters(NULL),
  47   _eden_counters(NULL),
  48   _from_counters(NULL),
  49   _to_counters(NULL)
  50 {
  51   initialize(rs, initial_size, GenAlignment);
  52 }
  53 
  54 void PSYoungGen::initialize_virtual_space(ReservedSpace rs,
  55                                           size_t initial_size,
  56                                           size_t alignment) {
  57   assert(initial_size != 0, "Should have a finite size");
  58   _virtual_space = new PSVirtualSpace(rs, alignment);
  59   if (!virtual_space()->expand_by(initial_size)) {
  60     vm_exit_during_initialization("Could not reserve enough space for object heap");

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