1 /*
   2  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp"
  27 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp"
  28 #include "gc_implementation/parNew/asParNewGeneration.hpp"
  29 #include "gc_implementation/parNew/parNewGeneration.hpp"
  30 #include "gc_implementation/shared/markSweep.inline.hpp"
  31 #include "gc_implementation/shared/spaceDecorator.hpp"
  32 #include "memory/defNewGeneration.inline.hpp"
  33 #include "memory/referencePolicy.hpp"
  34 #include "oops/markOop.inline.hpp"
  35 #include "oops/oop.pcgc.inline.hpp"
  36 
  37 ASParNewGeneration::ASParNewGeneration(ReservedSpace rs,
  38                                        size_t initial_byte_size,
  39                                        size_t min_byte_size,
  40                                        int level) :
  41   ParNewGeneration(rs, initial_byte_size, level),
  42   _min_gen_size(min_byte_size) {}
  43 
  44 const char* ASParNewGeneration::name() const {
  45   return "adaptive size par new generation";
  46 }
  47 
  48 void ASParNewGeneration::adjust_desired_tenuring_threshold() {
  49   assert(UseAdaptiveSizePolicy,
  50     "Should only be used with UseAdaptiveSizePolicy");
  51 }
  52 
  53 void ASParNewGeneration::resize(size_t eden_size, size_t survivor_size) {
  54   // Resize the generation if needed. If the generation resize
  55   // reports false, do not attempt to resize the spaces.
  56   if (resize_generation(eden_size, survivor_size)) {
  57     // Then we lay out the spaces inside the generation
  58     resize_spaces(eden_size, survivor_size);
  59 
  60     space_invariants();
  61 
  62     if (PrintAdaptiveSizePolicy && Verbose) {
  63       gclog_or_tty->print_cr("Young generation size: "
  64         "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT
  65         " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT
  66         " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
  67         eden_size, survivor_size, used(), capacity(),
  68         max_gen_size(), min_gen_size());
  69     }
  70   }
  71 }
  72 
  73 size_t ASParNewGeneration::available_to_min_gen() {
  74   assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");
  75   return virtual_space()->committed_size() - min_gen_size();
  76 }
  77 
  78 // This method assumes that from-space has live data and that
  79 // any shrinkage of the young gen is limited by location of
  80 // from-space.
  81 size_t ASParNewGeneration::available_to_live() const {
  82 #undef SHRINKS_AT_END_OF_EDEN
  83 #ifdef SHRINKS_AT_END_OF_EDEN
  84   size_t delta_in_survivor = 0;
  85   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  86   const size_t space_alignment = heap->intra_heap_alignment();
  87   const size_t gen_alignment = heap->object_heap_alignment();
  88 
  89   MutableSpace* space_shrinking = NULL;
  90   if (from_space()->end() > to_space()->end()) {
  91     space_shrinking = from_space();
  92   } else {
  93     space_shrinking = to_space();
  94   }
  95 
  96   // Include any space that is committed but not included in
  97   // the survivor spaces.
  98   assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),
  99     "Survivor space beyond high end");
 100   size_t unused_committed = pointer_delta(virtual_space()->high(),
 101     space_shrinking->end(), sizeof(char));
 102 
 103   if (space_shrinking->is_empty()) {
 104     // Don't let the space shrink to 0
 105     assert(space_shrinking->capacity_in_bytes() >= space_alignment,
 106       "Space is too small");
 107     delta_in_survivor = space_shrinking->capacity_in_bytes() - space_alignment;
 108   } else {
 109     delta_in_survivor = pointer_delta(space_shrinking->end(),
 110                                       space_shrinking->top(),
 111                                       sizeof(char));
 112   }
 113 
 114   size_t delta_in_bytes = unused_committed + delta_in_survivor;
 115   delta_in_bytes = align_size_down(delta_in_bytes, gen_alignment);
 116   return delta_in_bytes;
 117 #else
 118   // The only space available for shrinking is in to-space if it
 119   // is above from-space.
 120   if (to()->bottom() > from()->bottom()) {
 121     const size_t alignment = os::vm_page_size();
 122     if (to()->capacity() < alignment) {
 123       return 0;
 124     } else {
 125       return to()->capacity() - alignment;
 126     }
 127   } else {
 128     return 0;
 129   }
 130 #endif
 131 }
 132 
 133 // Return the number of bytes available for resizing down the young
 134 // generation.  This is the minimum of
 135 //      input "bytes"
 136 //      bytes to the minimum young gen size
 137 //      bytes to the size currently being used + some small extra
 138 size_t ASParNewGeneration::limit_gen_shrink (size_t bytes) {
 139   // Allow shrinkage into the current eden but keep eden large enough
 140   // to maintain the minimum young gen size
 141   bytes = MIN3(bytes, available_to_min_gen(), available_to_live());
 142   return align_size_down(bytes, os::vm_page_size());
 143 }
 144 
 145 // Note that the the alignment used is the OS page size as
 146 // opposed to an alignment associated with the virtual space
 147 // (as is done in the ASPSYoungGen/ASPSOldGen)
 148 bool ASParNewGeneration::resize_generation(size_t eden_size,
 149                                            size_t survivor_size) {
 150   const size_t alignment = os::vm_page_size();
 151   size_t orig_size = virtual_space()->committed_size();
 152   bool size_changed = false;
 153 
 154   // There used to be this guarantee there.
 155   // guarantee ((eden_size + 2*survivor_size)  <= _max_gen_size, "incorrect input arguments");
 156   // Code below forces this requirement.  In addition the desired eden
 157   // size and disired survivor sizes are desired goals and may
 158   // exceed the total generation size.
 159 
 160   assert(min_gen_size() <= orig_size && orig_size <= max_gen_size(),
 161     "just checking");
 162 
 163   // Adjust new generation size
 164   const size_t eden_plus_survivors =
 165           align_size_up(eden_size + 2 * survivor_size, alignment);
 166   size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_gen_size()),
 167                              min_gen_size());
 168   assert(desired_size <= max_gen_size(), "just checking");
 169 
 170   if (desired_size > orig_size) {
 171     // Grow the generation
 172     size_t change = desired_size - orig_size;
 173     assert(change % alignment == 0, "just checking");
 174     if (expand(change)) {
 175       return false; // Error if we fail to resize!
 176     }
 177     size_changed = true;
 178   } else if (desired_size < orig_size) {
 179     size_t desired_change = orig_size - desired_size;
 180     assert(desired_change % alignment == 0, "just checking");
 181 
 182     desired_change = limit_gen_shrink(desired_change);
 183 
 184     if (desired_change > 0) {
 185       virtual_space()->shrink_by(desired_change);
 186       reset_survivors_after_shrink();
 187 
 188       size_changed = true;
 189     }
 190   } else {
 191     if (Verbose && PrintGC) {
 192       if (orig_size == max_gen_size()) {
 193         gclog_or_tty->print_cr("ASParNew generation size at maximum: "
 194           SIZE_FORMAT "K", orig_size/K);
 195       } else if (orig_size == min_gen_size()) {
 196         gclog_or_tty->print_cr("ASParNew generation size at minium: "
 197           SIZE_FORMAT "K", orig_size/K);
 198       }
 199     }
 200   }
 201 
 202   if (size_changed) {
 203     MemRegion cmr((HeapWord*)virtual_space()->low(),
 204                   (HeapWord*)virtual_space()->high());
 205     GenCollectedHeap::heap()->barrier_set()->resize_covered_region(cmr);
 206 
 207     if (Verbose && PrintGC) {
 208       size_t current_size  = virtual_space()->committed_size();
 209       gclog_or_tty->print_cr("ASParNew generation size changed: "
 210                              SIZE_FORMAT "K->" SIZE_FORMAT "K",
 211                              orig_size/K, current_size/K);
 212     }
 213   }
 214 
 215   guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
 216             virtual_space()->committed_size() == max_gen_size(), "Sanity");
 217 
 218   return true;
 219 }
 220 
 221 void ASParNewGeneration::reset_survivors_after_shrink() {
 222 
 223   GenCollectedHeap* gch = GenCollectedHeap::heap();
 224   HeapWord* new_end = (HeapWord*)virtual_space()->high();
 225 
 226   if (from()->end() > to()->end()) {
 227     assert(new_end >= from()->end(), "Shrinking past from-space");
 228   } else {
 229     assert(new_end >= to()->bottom(), "Shrink was too large");
 230     // Was there a shrink of the survivor space?
 231     if (new_end < to()->end()) {
 232       MemRegion mr(to()->bottom(), new_end);
 233       to()->initialize(mr,
 234                        SpaceDecorator::DontClear,
 235                        SpaceDecorator::DontMangle);
 236     }
 237   }
 238 }
 239 void ASParNewGeneration::resize_spaces(size_t requested_eden_size,
 240                                        size_t requested_survivor_size) {
 241   assert(UseAdaptiveSizePolicy, "sanity check");
 242   assert(requested_eden_size > 0  && requested_survivor_size > 0,
 243          "just checking");
 244   CollectedHeap* heap = Universe::heap();
 245   assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Sanity");
 246 
 247 
 248   // We require eden and to space to be empty
 249   if ((!eden()->is_empty()) || (!to()->is_empty())) {
 250     return;
 251   }
 252 
 253   size_t cur_eden_size = eden()->capacity();
 254 
 255   if (PrintAdaptiveSizePolicy && Verbose) {
 256     gclog_or_tty->print_cr("ASParNew::resize_spaces(requested_eden_size: "
 257                   SIZE_FORMAT
 258                   ", requested_survivor_size: " SIZE_FORMAT ")",
 259                   requested_eden_size, requested_survivor_size);
 260     gclog_or_tty->print_cr("    eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
 261                   SIZE_FORMAT,
 262                   eden()->bottom(),
 263                   eden()->end(),
 264                   pointer_delta(eden()->end(),
 265                                 eden()->bottom(),
 266                                 sizeof(char)));
 267     gclog_or_tty->print_cr("    from: [" PTR_FORMAT ".." PTR_FORMAT ") "
 268                   SIZE_FORMAT,
 269                   from()->bottom(),
 270                   from()->end(),
 271                   pointer_delta(from()->end(),
 272                                 from()->bottom(),
 273                                 sizeof(char)));
 274     gclog_or_tty->print_cr("      to: [" PTR_FORMAT ".." PTR_FORMAT ") "
 275                   SIZE_FORMAT,
 276                   to()->bottom(),
 277                   to()->end(),
 278                   pointer_delta(  to()->end(),
 279                                   to()->bottom(),
 280                                   sizeof(char)));
 281   }
 282 
 283   // There's nothing to do if the new sizes are the same as the current
 284   if (requested_survivor_size == to()->capacity() &&
 285       requested_survivor_size == from()->capacity() &&
 286       requested_eden_size == eden()->capacity()) {
 287     if (PrintAdaptiveSizePolicy && Verbose) {
 288       gclog_or_tty->print_cr("    capacities are the right sizes, returning");
 289     }
 290     return;
 291   }
 292 
 293   char* eden_start = (char*)eden()->bottom();
 294   char* eden_end   = (char*)eden()->end();
 295   char* from_start = (char*)from()->bottom();
 296   char* from_end   = (char*)from()->end();
 297   char* to_start   = (char*)to()->bottom();
 298   char* to_end     = (char*)to()->end();
 299 
 300   const size_t alignment = os::vm_page_size();
 301   const bool maintain_minimum =
 302     (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
 303 
 304   // Check whether from space is below to space
 305   if (from_start < to_start) {
 306     // Eden, from, to
 307     if (PrintAdaptiveSizePolicy && Verbose) {
 308       gclog_or_tty->print_cr("  Eden, from, to:");
 309     }
 310 
 311     // Set eden
 312     // "requested_eden_size" is a goal for the size of eden
 313     // and may not be attainable.  "eden_size" below is
 314     // calculated based on the location of from-space and
 315     // the goal for the size of eden.  from-space is
 316     // fixed in place because it contains live data.
 317     // The calculation is done this way to avoid 32bit
 318     // overflow (i.e., eden_start + requested_eden_size
 319     // may too large for representation in 32bits).
 320     size_t eden_size;
 321     if (maintain_minimum) {
 322       // Only make eden larger than the requested size if
 323       // the minimum size of the generation has to be maintained.
 324       // This could be done in general but policy at a higher
 325       // level is determining a requested size for eden and that
 326       // should be honored unless there is a fundamental reason.
 327       eden_size = pointer_delta(from_start,
 328                                 eden_start,
 329                                 sizeof(char));
 330     } else {
 331       eden_size = MIN2(requested_eden_size,
 332                        pointer_delta(from_start, eden_start, sizeof(char)));
 333     }
 334 
 335     eden_size = align_size_down(eden_size, alignment);
 336     eden_end = eden_start + eden_size;
 337     assert(eden_end >= eden_start, "addition overflowed");
 338 
 339     // To may resize into from space as long as it is clear of live data.
 340     // From space must remain page aligned, though, so we need to do some
 341     // extra calculations.
 342 
 343     // First calculate an optimal to-space
 344     to_end   = (char*)virtual_space()->high();
 345     to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
 346                                     sizeof(char));
 347 
 348     // Does the optimal to-space overlap from-space?
 349     if (to_start < (char*)from()->end()) {
 350       // Calculate the minimum offset possible for from_end
 351       size_t from_size = pointer_delta(from()->top(), from_start, sizeof(char));
 352 
 353       // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
 354       if (from_size == 0) {
 355         from_size = alignment;
 356       } else {
 357         from_size = align_size_up(from_size, alignment);
 358       }
 359 
 360       from_end = from_start + from_size;
 361       assert(from_end > from_start, "addition overflow or from_size problem");
 362 
 363       guarantee(from_end <= (char*)from()->end(), "from_end moved to the right");
 364 
 365       // Now update to_start with the new from_end
 366       to_start = MAX2(from_end, to_start);
 367     } else {
 368       // If shrinking, move to-space down to abut the end of from-space
 369       // so that shrinking will move to-space down.  If not shrinking
 370       // to-space is moving up to allow for growth on the next expansion.
 371       if (requested_eden_size <= cur_eden_size) {
 372         to_start = from_end;
 373         if (to_start + requested_survivor_size > to_start) {
 374           to_end = to_start + requested_survivor_size;
 375         }
 376       }
 377       // else leave to_end pointing to the high end of the virtual space.
 378     }
 379 
 380     guarantee(to_start != to_end, "to space is zero sized");
 381 
 382     if (PrintAdaptiveSizePolicy && Verbose) {
 383       gclog_or_tty->print_cr("    [eden_start .. eden_end): "
 384                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 385                     eden_start,
 386                     eden_end,
 387                     pointer_delta(eden_end, eden_start, sizeof(char)));
 388       gclog_or_tty->print_cr("    [from_start .. from_end): "
 389                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 390                     from_start,
 391                     from_end,
 392                     pointer_delta(from_end, from_start, sizeof(char)));
 393       gclog_or_tty->print_cr("    [  to_start ..   to_end): "
 394                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 395                     to_start,
 396                     to_end,
 397                     pointer_delta(  to_end,   to_start, sizeof(char)));
 398     }
 399   } else {
 400     // Eden, to, from
 401     if (PrintAdaptiveSizePolicy && Verbose) {
 402       gclog_or_tty->print_cr("  Eden, to, from:");
 403     }
 404 
 405     // Calculate the to-space boundaries based on
 406     // the start of from-space.
 407     to_end = from_start;
 408     to_start = (char*)pointer_delta(from_start,
 409                                     (char*)requested_survivor_size,
 410                                     sizeof(char));
 411     // Calculate the ideal eden boundaries.
 412     // eden_end is already at the bottom of the generation
 413     assert(eden_start == virtual_space()->low(),
 414       "Eden is not starting at the low end of the virtual space");
 415     if (eden_start + requested_eden_size >= eden_start) {
 416       eden_end = eden_start + requested_eden_size;
 417     } else {
 418       eden_end = to_start;
 419     }
 420 
 421     // Does eden intrude into to-space?  to-space
 422     // gets priority but eden is not allowed to shrink
 423     // to 0.
 424     if (eden_end > to_start) {
 425       eden_end = to_start;
 426     }
 427 
 428     // Don't let eden shrink down to 0 or less.
 429     eden_end = MAX2(eden_end, eden_start + alignment);
 430     assert(eden_start + alignment >= eden_start, "Overflow");
 431 
 432     size_t eden_size;
 433     if (maintain_minimum) {
 434       // Use all the space available.
 435       eden_end = MAX2(eden_end, to_start);
 436       eden_size = pointer_delta(eden_end, eden_start, sizeof(char));
 437       eden_size = MIN2(eden_size, cur_eden_size);
 438     } else {
 439       eden_size = pointer_delta(eden_end, eden_start, sizeof(char));
 440     }
 441     eden_size = align_size_down(eden_size, alignment);
 442     assert(maintain_minimum || eden_size <= requested_eden_size,
 443       "Eden size is too large");
 444     assert(eden_size >= alignment, "Eden size is too small");
 445     eden_end = eden_start + eden_size;
 446 
 447     // Move to-space down to eden.
 448     if (requested_eden_size < cur_eden_size) {
 449       to_start = eden_end;
 450       if (to_start + requested_survivor_size > to_start) {
 451         to_end = MIN2(from_start, to_start + requested_survivor_size);
 452       } else {
 453         to_end = from_start;
 454       }
 455     }
 456 
 457     // eden_end may have moved so again make sure
 458     // the to-space and eden don't overlap.
 459     to_start = MAX2(eden_end, to_start);
 460 
 461     // from-space
 462     size_t from_used = from()->used();
 463     if (requested_survivor_size > from_used) {
 464       if (from_start + requested_survivor_size >= from_start) {
 465         from_end = from_start + requested_survivor_size;
 466       }
 467       if (from_end > virtual_space()->high()) {
 468         from_end = virtual_space()->high();
 469       }
 470     }
 471 
 472     assert(to_start >= eden_end, "to-space should be above eden");
 473     if (PrintAdaptiveSizePolicy && Verbose) {
 474       gclog_or_tty->print_cr("    [eden_start .. eden_end): "
 475                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 476                     eden_start,
 477                     eden_end,
 478                     pointer_delta(eden_end, eden_start, sizeof(char)));
 479       gclog_or_tty->print_cr("    [  to_start ..   to_end): "
 480                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 481                     to_start,
 482                     to_end,
 483                     pointer_delta(  to_end,   to_start, sizeof(char)));
 484       gclog_or_tty->print_cr("    [from_start .. from_end): "
 485                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 486                     from_start,
 487                     from_end,
 488                     pointer_delta(from_end, from_start, sizeof(char)));
 489     }
 490   }
 491 
 492 
 493   guarantee((HeapWord*)from_start <= from()->bottom(),
 494             "from start moved to the right");
 495   guarantee((HeapWord*)from_end >= from()->top(),
 496             "from end moved into live data");
 497   assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
 498   assert(is_object_aligned((intptr_t)from_start), "checking alignment");
 499   assert(is_object_aligned((intptr_t)to_start), "checking alignment");
 500 
 501   MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
 502   MemRegion toMR  ((HeapWord*)to_start,   (HeapWord*)to_end);
 503   MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
 504 
 505   // Let's make sure the call to initialize doesn't reset "top"!
 506   HeapWord* old_from_top = from()->top();
 507 
 508   // For PrintAdaptiveSizePolicy block  below
 509   size_t old_from = from()->capacity();
 510   size_t old_to   = to()->capacity();
 511 
 512   // If not clearing the spaces, do some checking to verify that
 513   // the spaces are already mangled.
 514 
 515   // Must check mangling before the spaces are reshaped.  Otherwise,
 516   // the bottom or end of one space may have moved into another
 517   // a failure of the check may not correctly indicate which space
 518   // is not properly mangled.
 519   if (ZapUnusedHeapArea) {
 520     HeapWord* limit = (HeapWord*) virtual_space()->high();
 521     eden()->check_mangled_unused_area(limit);
 522     from()->check_mangled_unused_area(limit);
 523       to()->check_mangled_unused_area(limit);
 524   }
 525 
 526   // The call to initialize NULL's the next compaction space
 527   eden()->initialize(edenMR,
 528                      SpaceDecorator::Clear,
 529                      SpaceDecorator::DontMangle);
 530   eden()->set_next_compaction_space(from());
 531     to()->initialize(toMR  ,
 532                      SpaceDecorator::Clear,
 533                      SpaceDecorator::DontMangle);
 534   from()->initialize(fromMR,
 535                      SpaceDecorator::DontClear,
 536                      SpaceDecorator::DontMangle);
 537 
 538   assert(from()->top() == old_from_top, "from top changed!");
 539 
 540   if (PrintAdaptiveSizePolicy) {
 541     GenCollectedHeap* gch = GenCollectedHeap::heap();
 542     assert(gch->kind() == CollectedHeap::GenCollectedHeap, "Sanity");
 543 
 544     gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "
 545                   "collection: %d "
 546                   "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
 547                   "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
 548                   gch->total_collections(),
 549                   old_from, old_to,
 550                   from()->capacity(),
 551                   to()->capacity());
 552     gclog_or_tty->cr();
 553   }
 554 }
 555 
 556 void ASParNewGeneration::compute_new_size() {
 557   GenCollectedHeap* gch = GenCollectedHeap::heap();
 558   assert(gch->kind() == CollectedHeap::GenCollectedHeap,
 559     "not a CMS generational heap");
 560 
 561 
 562   CMSAdaptiveSizePolicy* size_policy =
 563     (CMSAdaptiveSizePolicy*)gch->gen_policy()->size_policy();
 564   assert(size_policy->is_gc_cms_adaptive_size_policy(),
 565     "Wrong type of size policy");
 566 
 567   size_t survived = from()->used();
 568   if (!survivor_overflow()) {
 569     // Keep running averages on how much survived
 570     size_policy->avg_survived()->sample(survived);
 571   } else {
 572     size_t promoted =
 573       (size_t) next_gen()->gc_stats()->avg_promoted()->last_sample();
 574     assert(promoted < gch->capacity(), "Conversion problem?");
 575     size_t survived_guess = survived + promoted;
 576     size_policy->avg_survived()->sample(survived_guess);
 577   }
 578 
 579   size_t survivor_limit = max_survivor_size();
 580   _tenuring_threshold =
 581     size_policy->compute_survivor_space_size_and_threshold(
 582                                                      _survivor_overflow,
 583                                                      _tenuring_threshold,
 584                                                      survivor_limit);
 585   size_policy->avg_young_live()->sample(used());
 586   size_policy->avg_eden_live()->sample(eden()->used());
 587 
 588   size_policy->compute_young_generation_free_space(eden()->capacity(),
 589                                                    max_gen_size());
 590 
 591   resize(size_policy->calculated_eden_size_in_bytes(),
 592          size_policy->calculated_survivor_size_in_bytes());
 593 
 594   if (UsePerfData) {
 595     CMSGCAdaptivePolicyCounters* counters =
 596       (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters();
 597     assert(counters->kind() ==
 598            GCPolicyCounters::CMSGCAdaptivePolicyCountersKind,
 599       "Wrong kind of counters");
 600     counters->update_tenuring_threshold(_tenuring_threshold);
 601     counters->update_survivor_overflowed(_survivor_overflow);
 602     counters->update_young_capacity(capacity());
 603   }
 604 }
 605 
 606 
 607 #ifndef PRODUCT
 608 // Changes from PSYoungGen version
 609 //      value of "alignment"
 610 void ASParNewGeneration::space_invariants() {
 611   const size_t alignment = os::vm_page_size();
 612 
 613   // Currently, our eden size cannot shrink to zero
 614   guarantee(eden()->capacity() >= alignment, "eden too small");
 615   guarantee(from()->capacity() >= alignment, "from too small");
 616   guarantee(to()->capacity() >= alignment, "to too small");
 617 
 618   // Relationship of spaces to each other
 619   char* eden_start = (char*)eden()->bottom();
 620   char* eden_end   = (char*)eden()->end();
 621   char* from_start = (char*)from()->bottom();
 622   char* from_end   = (char*)from()->end();
 623   char* to_start   = (char*)to()->bottom();
 624   char* to_end     = (char*)to()->end();
 625 
 626   guarantee(eden_start >= virtual_space()->low(), "eden bottom");
 627   guarantee(eden_start < eden_end, "eden space consistency");
 628   guarantee(from_start < from_end, "from space consistency");
 629   guarantee(to_start < to_end, "to space consistency");
 630 
 631   // Check whether from space is below to space
 632   if (from_start < to_start) {
 633     // Eden, from, to
 634     guarantee(eden_end <= from_start, "eden/from boundary");
 635     guarantee(from_end <= to_start,   "from/to boundary");
 636     guarantee(to_end <= virtual_space()->high(), "to end");
 637   } else {
 638     // Eden, to, from
 639     guarantee(eden_end <= to_start, "eden/to boundary");
 640     guarantee(to_end <= from_start, "to/from boundary");
 641     guarantee(from_end <= virtual_space()->high(), "from end");
 642   }
 643 
 644   // More checks that the virtual space is consistent with the spaces
 645   assert(virtual_space()->committed_size() >=
 646     (eden()->capacity() +
 647      to()->capacity() +
 648      from()->capacity()), "Committed size is inconsistent");
 649   assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(),
 650     "Space invariant");
 651   char* eden_top = (char*)eden()->top();
 652   char* from_top = (char*)from()->top();
 653   char* to_top = (char*)to()->top();
 654   assert(eden_top <= virtual_space()->high(), "eden top");
 655   assert(from_top <= virtual_space()->high(), "from top");
 656   assert(to_top <= virtual_space()->high(), "to top");
 657 }
 658 #endif
--- EOF ---