1 /*
   2  * Copyright (c) 2001, 2013, 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/shared/adaptiveSizePolicy.hpp"
  27 #include "gc_implementation/shared/gcPolicyCounters.hpp"
  28 #include "gc_implementation/shared/vmGCOperations.hpp"
  29 #include "memory/cardTableRS.hpp"
  30 #include "memory/collectorPolicy.hpp"
  31 #include "memory/gcLocker.inline.hpp"
  32 #include "memory/genCollectedHeap.hpp"
  33 #include "memory/generationSpec.hpp"
  34 #include "memory/space.hpp"
  35 #include "memory/universe.hpp"
  36 #include "runtime/arguments.hpp"
  37 #include "runtime/globals_extension.hpp"
  38 #include "runtime/handles.inline.hpp"
  39 #include "runtime/java.hpp"
  40 #include "runtime/thread.inline.hpp"
  41 #include "runtime/vmThread.hpp"
  42 #include "utilities/macros.hpp"
  43 #if INCLUDE_ALL_GCS
  44 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp"
  45 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp"
  46 #endif // INCLUDE_ALL_GCS
  47 
  48 // CollectorPolicy methods.
  49 
  50 void CollectorPolicy::initialize_flags() {
  51   if (MaxHeapSize < InitialHeapSize) {
  52     vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
  53   }
  54 
  55   if (MetaspaceSize > MaxMetaspaceSize) {
  56     MaxMetaspaceSize = MetaspaceSize;
  57   }
  58   MetaspaceSize = MAX2(min_alignment(), align_size_down_(MetaspaceSize, min_alignment()));
  59   // Don't increase Metaspace size limit above specified.
  60   MaxMetaspaceSize = align_size_down(MaxMetaspaceSize, max_alignment());
  61   if (MetaspaceSize > MaxMetaspaceSize) {
  62     MetaspaceSize = MaxMetaspaceSize;
  63   }
  64 
  65   MinMetaspaceExpansion = MAX2(min_alignment(), align_size_down_(MinMetaspaceExpansion, min_alignment()));
  66   MaxMetaspaceExpansion = MAX2(min_alignment(), align_size_down_(MaxMetaspaceExpansion, min_alignment()));
  67 
  68   MinHeapDeltaBytes = align_size_up(MinHeapDeltaBytes, min_alignment());
  69 
  70   assert(MetaspaceSize    % min_alignment() == 0, "metapace alignment");
  71   assert(MaxMetaspaceSize % max_alignment() == 0, "maximum metaspace alignment");
  72   if (MetaspaceSize < 256*K) {
  73     vm_exit_during_initialization("Too small initial Metaspace size");
  74   }
  75 }
  76 
  77 void CollectorPolicy::initialize_size_info() {
  78   // User inputs from -mx and ms must be aligned
  79   set_min_heap_byte_size(align_size_up(Arguments::min_heap_size(), min_alignment()));
  80   set_initial_heap_byte_size(align_size_up(InitialHeapSize, min_alignment()));
  81   set_max_heap_byte_size(align_size_up(MaxHeapSize, max_alignment()));
  82 
  83   // Check heap parameter properties
  84   if (initial_heap_byte_size() < M) {
  85     vm_exit_during_initialization("Too small initial heap");
  86   }
  87   // Check heap parameter properties
  88   if (min_heap_byte_size() < M) {
  89     vm_exit_during_initialization("Too small minimum heap");
  90   }
  91   if (initial_heap_byte_size() <= NewSize) {
  92      // make sure there is at least some room in old space
  93     vm_exit_during_initialization("Too small initial heap for new size specified");
  94   }
  95   if (max_heap_byte_size() < min_heap_byte_size()) {
  96     vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
  97   }
  98   if (initial_heap_byte_size() < min_heap_byte_size()) {
  99     vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
 100   }
 101   if (max_heap_byte_size() < initial_heap_byte_size()) {
 102     vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
 103   }
 104 
 105   if (PrintGCDetails && Verbose) {
 106     gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT "  Initial heap "
 107       SIZE_FORMAT "  Maximum heap " SIZE_FORMAT,
 108       min_heap_byte_size(), initial_heap_byte_size(), max_heap_byte_size());
 109   }
 110 }
 111 
 112 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
 113   bool result = _should_clear_all_soft_refs;
 114   set_should_clear_all_soft_refs(false);
 115   return result;
 116 }
 117 
 118 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,
 119                                            int max_covered_regions) {
 120   switch (rem_set_name()) {
 121   case GenRemSet::CardTable: {
 122     CardTableRS* res = new CardTableRS(whole_heap, max_covered_regions);
 123     return res;
 124   }
 125   default:
 126     guarantee(false, "unrecognized GenRemSet::Name");
 127     return NULL;
 128   }
 129 }
 130 
 131 void CollectorPolicy::cleared_all_soft_refs() {
 132   // If near gc overhear limit, continue to clear SoftRefs.  SoftRefs may
 133   // have been cleared in the last collection but if the gc overhear
 134   // limit continues to be near, SoftRefs should still be cleared.
 135   if (size_policy() != NULL) {
 136     _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
 137   }
 138   _all_soft_refs_clear = true;
 139 }
 140 
 141 
 142 // GenCollectorPolicy methods.
 143 
 144 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
 145   size_t x = base_size / (NewRatio+1);
 146   size_t new_gen_size = x > min_alignment() ?
 147                      align_size_down(x, min_alignment()) :
 148                      min_alignment();
 149   return new_gen_size;
 150 }
 151 
 152 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
 153                                                  size_t maximum_size) {
 154   size_t alignment = min_alignment();
 155   size_t max_minus = maximum_size - alignment;
 156   return desired_size < max_minus ? desired_size : max_minus;
 157 }
 158 
 159 
 160 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
 161                                                 size_t init_promo_size,
 162                                                 size_t init_survivor_size) {
 163   const double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;
 164   _size_policy = new AdaptiveSizePolicy(init_eden_size,
 165                                         init_promo_size,
 166                                         init_survivor_size,
 167                                         max_gc_pause_sec,
 168                                         GCTimeRatio);
 169 }
 170 
 171 size_t GenCollectorPolicy::compute_max_alignment() {
 172   // The card marking array and the offset arrays for old generations are
 173   // committed in os pages as well. Make sure they are entirely full (to
 174   // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
 175   // byte entry and the os page size is 4096, the maximum heap size should
 176   // be 512*4096 = 2MB aligned.
 177   size_t alignment = GenRemSet::max_alignment_constraint(rem_set_name());
 178 
 179   // Parallel GC does its own alignment of the generations to avoid requiring a
 180   // large page (256M on some platforms) for the permanent generation.  The
 181   // other collectors should also be updated to do their own alignment and then
 182   // this use of lcm() should be removed.
 183   if (UseLargePages && !UseParallelGC) {
 184       // in presence of large pages we have to make sure that our
 185       // alignment is large page aware
 186       alignment = lcm(os::large_page_size(), alignment);
 187   }
 188 
 189   return alignment;
 190 }
 191 
 192 void GenCollectorPolicy::initialize_flags() {
 193   // All sizes must be multiples of the generation granularity.
 194   set_min_alignment((uintx) Generation::GenGrain);
 195   set_max_alignment(compute_max_alignment());
 196   assert(max_alignment() >= min_alignment() &&
 197          max_alignment() % min_alignment() == 0,
 198          "invalid alignment constraints");
 199 
 200   CollectorPolicy::initialize_flags();
 201 
 202   // All generational heaps have a youngest gen; handle those flags here.
 203 
 204   // Adjust max size parameters
 205   if (NewSize > MaxNewSize) {
 206     MaxNewSize = NewSize;
 207   }
 208   NewSize = align_size_down(NewSize, min_alignment());
 209   MaxNewSize = align_size_down(MaxNewSize, min_alignment());
 210 
 211   // Check validity of heap flags
 212   assert(NewSize     % min_alignment() == 0, "eden space alignment");
 213   assert(MaxNewSize  % min_alignment() == 0, "survivor space alignment");
 214 
 215   if (NewSize < 3*min_alignment()) {
 216      // make sure there room for eden and two survivor spaces
 217     vm_exit_during_initialization("Too small new size specified");
 218   }
 219   if (SurvivorRatio < 1 || NewRatio < 1) {
 220     vm_exit_during_initialization("Invalid heap ratio specified");
 221   }
 222 }
 223 
 224 void TwoGenerationCollectorPolicy::initialize_flags() {
 225   GenCollectorPolicy::initialize_flags();
 226 
 227   OldSize = align_size_down(OldSize, min_alignment());
 228 
 229   if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(NewSize)) {
 230     // NewRatio will be used later to set the young generation size so we use
 231     // it to calculate how big the heap should be based on the requested OldSize
 232     // and NewRatio.
 233     assert(NewRatio > 0, "NewRatio should have been set up earlier");
 234     size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
 235 
 236     calculated_heapsize = align_size_up(calculated_heapsize, max_alignment());
 237     MaxHeapSize = calculated_heapsize;
 238     InitialHeapSize = calculated_heapsize;
 239   }
 240   MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
 241 
 242   // adjust max heap size if necessary
 243   if (NewSize + OldSize > MaxHeapSize) {
 244     if (FLAG_IS_CMDLINE(MaxHeapSize)) {
 245       // somebody set a maximum heap size with the intention that we should not
 246       // exceed it. Adjust New/OldSize as necessary.
 247       uintx calculated_size = NewSize + OldSize;
 248       double shrink_factor = (double) MaxHeapSize / calculated_size;
 249       // align
 250       NewSize = align_size_down((uintx) (NewSize * shrink_factor), min_alignment());
 251       // OldSize is already aligned because above we aligned MaxHeapSize to
 252       // max_alignment(), and we just made sure that NewSize is aligned to
 253       // min_alignment(). In initialize_flags() we verified that max_alignment()
 254       // is a multiple of min_alignment().
 255       OldSize = MaxHeapSize - NewSize;
 256     } else {
 257       MaxHeapSize = NewSize + OldSize;
 258     }
 259   }
 260   // need to do this again
 261   MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
 262 
 263   always_do_update_barrier = UseConcMarkSweepGC;
 264 
 265   // Check validity of heap flags
 266   assert(OldSize     % min_alignment() == 0, "old space alignment");
 267   assert(MaxHeapSize % max_alignment() == 0, "maximum heap alignment");
 268 }
 269 
 270 // Values set on the command line win over any ergonomically
 271 // set command line parameters.
 272 // Ergonomic choice of parameters are done before this
 273 // method is called.  Values for command line parameters such as NewSize
 274 // and MaxNewSize feed those ergonomic choices into this method.
 275 // This method makes the final generation sizings consistent with
 276 // themselves and with overall heap sizings.
 277 // In the absence of explicitly set command line flags, policies
 278 // such as the use of NewRatio are used to size the generation.
 279 void GenCollectorPolicy::initialize_size_info() {
 280   CollectorPolicy::initialize_size_info();
 281 
 282   // min_alignment() is used for alignment within a generation.
 283   // There is additional alignment done down stream for some
 284   // collectors that sometimes causes unwanted rounding up of
 285   // generations sizes.
 286 
 287   // Determine maximum size of gen0
 288 
 289   size_t max_new_size = 0;
 290   if (FLAG_IS_CMDLINE(MaxNewSize) || FLAG_IS_ERGO(MaxNewSize)) {
 291     if (MaxNewSize < min_alignment()) {
 292       max_new_size = min_alignment();
 293     }
 294     if (MaxNewSize >= max_heap_byte_size()) {
 295       max_new_size = align_size_down(max_heap_byte_size() - min_alignment(),
 296                                      min_alignment());
 297       warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or "
 298         "greater than the entire heap (" SIZE_FORMAT "k).  A "
 299         "new generation size of " SIZE_FORMAT "k will be used.",
 300         MaxNewSize/K, max_heap_byte_size()/K, max_new_size/K);
 301     } else {
 302       max_new_size = align_size_down(MaxNewSize, min_alignment());
 303     }
 304 
 305   // The case for FLAG_IS_ERGO(MaxNewSize) could be treated
 306   // specially at this point to just use an ergonomically set
 307   // MaxNewSize to set max_new_size.  For cases with small
 308   // heaps such a policy often did not work because the MaxNewSize
 309   // was larger than the entire heap.  The interpretation given
 310   // to ergonomically set flags is that the flags are set
 311   // by different collectors for their own special needs but
 312   // are not allowed to badly shape the heap.  This allows the
 313   // different collectors to decide what's best for themselves
 314   // without having to factor in the overall heap shape.  It
 315   // can be the case in the future that the collectors would
 316   // only make "wise" ergonomics choices and this policy could
 317   // just accept those choices.  The choices currently made are
 318   // not always "wise".
 319   } else {
 320     max_new_size = scale_by_NewRatio_aligned(max_heap_byte_size());
 321     // Bound the maximum size by NewSize below (since it historically
 322     // would have been NewSize and because the NewRatio calculation could
 323     // yield a size that is too small) and bound it by MaxNewSize above.
 324     // Ergonomics plays here by previously calculating the desired
 325     // NewSize and MaxNewSize.
 326     max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize);
 327   }
 328   assert(max_new_size > 0, "All paths should set max_new_size");
 329 
 330   // Given the maximum gen0 size, determine the initial and
 331   // minimum gen0 sizes.
 332 
 333   if (max_heap_byte_size() == min_heap_byte_size()) {
 334     // The maximum and minimum heap sizes are the same so
 335     // the generations minimum and initial must be the
 336     // same as its maximum.
 337     set_min_gen0_size(max_new_size);
 338     set_initial_gen0_size(max_new_size);
 339     set_max_gen0_size(max_new_size);
 340   } else {
 341     size_t desired_new_size = 0;
 342     if (!FLAG_IS_DEFAULT(NewSize)) {
 343       // If NewSize is set ergonomically (for example by cms), it
 344       // would make sense to use it.  If it is used, also use it
 345       // to set the initial size.  Although there is no reason
 346       // the minimum size and the initial size have to be the same,
 347       // the current implementation gets into trouble during the calculation
 348       // of the tenured generation sizes if they are different.
 349       // Note that this makes the initial size and the minimum size
 350       // generally small compared to the NewRatio calculation.
 351       _min_gen0_size = NewSize;
 352       desired_new_size = NewSize;
 353       max_new_size = MAX2(max_new_size, NewSize);
 354     } else {
 355       // For the case where NewSize is the default, use NewRatio
 356       // to size the minimum and initial generation sizes.
 357       // Use the default NewSize as the floor for these values.  If
 358       // NewRatio is overly large, the resulting sizes can be too
 359       // small.
 360       _min_gen0_size = MAX2(scale_by_NewRatio_aligned(min_heap_byte_size()),
 361                           NewSize);
 362       desired_new_size =
 363         MAX2(scale_by_NewRatio_aligned(initial_heap_byte_size()),
 364              NewSize);
 365     }
 366 
 367     assert(_min_gen0_size > 0, "Sanity check");
 368     set_initial_gen0_size(desired_new_size);
 369     set_max_gen0_size(max_new_size);
 370 
 371     // At this point the desirable initial and minimum sizes have been
 372     // determined without regard to the maximum sizes.
 373 
 374     // Bound the sizes by the corresponding overall heap sizes.
 375     set_min_gen0_size(
 376       bound_minus_alignment(_min_gen0_size, min_heap_byte_size()));
 377     set_initial_gen0_size(
 378       bound_minus_alignment(_initial_gen0_size, initial_heap_byte_size()));
 379     set_max_gen0_size(
 380       bound_minus_alignment(_max_gen0_size, max_heap_byte_size()));
 381 
 382     // At this point all three sizes have been checked against the
 383     // maximum sizes but have not been checked for consistency
 384     // among the three.
 385 
 386     // Final check min <= initial <= max
 387     set_min_gen0_size(MIN2(_min_gen0_size, _max_gen0_size));
 388     set_initial_gen0_size(
 389       MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size));
 390     set_min_gen0_size(MIN2(_min_gen0_size, _initial_gen0_size));
 391   }
 392 
 393   if (PrintGCDetails && Verbose) {
 394     gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
 395       SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
 396       min_gen0_size(), initial_gen0_size(), max_gen0_size());
 397   }
 398 }
 399 
 400 // Call this method during the sizing of the gen1 to make
 401 // adjustments to gen0 because of gen1 sizing policy.  gen0 initially has
 402 // the most freedom in sizing because it is done before the
 403 // policy for gen1 is applied.  Once gen1 policies have been applied,
 404 // there may be conflicts in the shape of the heap and this method
 405 // is used to make the needed adjustments.  The application of the
 406 // policies could be more sophisticated (iterative for example) but
 407 // keeping it simple also seems a worthwhile goal.
 408 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr,
 409                                                      size_t* gen1_size_ptr,
 410                                                      const size_t heap_size,
 411                                                      const size_t min_gen1_size) {
 412   bool result = false;
 413 
 414   if ((*gen1_size_ptr + *gen0_size_ptr) > heap_size) {
 415     if ((heap_size < (*gen0_size_ptr + min_gen1_size)) &&
 416         (heap_size >= min_gen1_size + min_alignment())) {
 417       // Adjust gen0 down to accommodate min_gen1_size
 418       *gen0_size_ptr = heap_size - min_gen1_size;
 419       *gen0_size_ptr =
 420         MAX2((uintx)align_size_down(*gen0_size_ptr, min_alignment()),
 421              min_alignment());
 422       assert(*gen0_size_ptr > 0, "Min gen0 is too large");
 423       result = true;
 424     } else {
 425       *gen1_size_ptr = heap_size - *gen0_size_ptr;
 426       *gen1_size_ptr =
 427         MAX2((uintx)align_size_down(*gen1_size_ptr, min_alignment()),
 428                        min_alignment());
 429     }
 430   }
 431   return result;
 432 }
 433 
 434 // Minimum sizes of the generations may be different than
 435 // the initial sizes.  An inconsistently is permitted here
 436 // in the total size that can be specified explicitly by
 437 // command line specification of OldSize and NewSize and
 438 // also a command line specification of -Xms.  Issue a warning
 439 // but allow the values to pass.
 440 
 441 void TwoGenerationCollectorPolicy::initialize_size_info() {
 442   GenCollectorPolicy::initialize_size_info();
 443 
 444   // At this point the minimum, initial and maximum sizes
 445   // of the overall heap and of gen0 have been determined.
 446   // The maximum gen1 size can be determined from the maximum gen0
 447   // and maximum heap size since no explicit flags exits
 448   // for setting the gen1 maximum.
 449   _max_gen1_size = max_heap_byte_size() - _max_gen0_size;
 450   _max_gen1_size =
 451     MAX2((uintx)align_size_down(_max_gen1_size, min_alignment()),
 452          min_alignment());
 453   // If no explicit command line flag has been set for the
 454   // gen1 size, use what is left for gen1.
 455   if (FLAG_IS_DEFAULT(OldSize) || FLAG_IS_ERGO(OldSize)) {
 456     // The user has not specified any value or ergonomics
 457     // has chosen a value (which may or may not be consistent
 458     // with the overall heap size).  In either case make
 459     // the minimum, maximum and initial sizes consistent
 460     // with the gen0 sizes and the overall heap sizes.
 461     assert(min_heap_byte_size() > _min_gen0_size,
 462       "gen0 has an unexpected minimum size");
 463     set_min_gen1_size(min_heap_byte_size() - min_gen0_size());
 464     set_min_gen1_size(
 465       MAX2((uintx)align_size_down(_min_gen1_size, min_alignment()),
 466            min_alignment()));
 467     set_initial_gen1_size(initial_heap_byte_size() - initial_gen0_size());
 468     set_initial_gen1_size(
 469       MAX2((uintx)align_size_down(_initial_gen1_size, min_alignment()),
 470            min_alignment()));
 471 
 472   } else {
 473     // It's been explicitly set on the command line.  Use the
 474     // OldSize and then determine the consequences.
 475     set_min_gen1_size(OldSize);
 476     set_initial_gen1_size(OldSize);
 477 
 478     // If the user has explicitly set an OldSize that is inconsistent
 479     // with other command line flags, issue a warning.
 480     // The generation minimums and the overall heap mimimum should
 481     // be within one heap alignment.
 482     if ((_min_gen1_size + _min_gen0_size + min_alignment()) <
 483            min_heap_byte_size()) {
 484       warning("Inconsistency between minimum heap size and minimum "
 485           "generation sizes: using minimum heap = " SIZE_FORMAT,
 486           min_heap_byte_size());
 487     }
 488     if ((OldSize > _max_gen1_size)) {
 489       warning("Inconsistency between maximum heap size and maximum "
 490           "generation sizes: using maximum heap = " SIZE_FORMAT
 491           " -XX:OldSize flag is being ignored",
 492           max_heap_byte_size());
 493     }
 494     // If there is an inconsistency between the OldSize and the minimum and/or
 495     // initial size of gen0, since OldSize was explicitly set, OldSize wins.
 496     if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size,
 497                           min_heap_byte_size(), OldSize)) {
 498       if (PrintGCDetails && Verbose) {
 499         gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
 500               SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
 501               min_gen0_size(), initial_gen0_size(), max_gen0_size());
 502       }
 503     }
 504     // Initial size
 505     if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,
 506                          initial_heap_byte_size(), OldSize)) {
 507       if (PrintGCDetails && Verbose) {
 508         gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "
 509           SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,
 510           min_gen0_size(), initial_gen0_size(), max_gen0_size());
 511       }
 512     }
 513   }
 514   // Enforce the maximum gen1 size.
 515   set_min_gen1_size(MIN2(_min_gen1_size, _max_gen1_size));
 516 
 517   // Check that min gen1 <= initial gen1 <= max gen1
 518   set_initial_gen1_size(MAX2(_initial_gen1_size, _min_gen1_size));
 519   set_initial_gen1_size(MIN2(_initial_gen1_size, _max_gen1_size));
 520 
 521   if (PrintGCDetails && Verbose) {
 522     gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT "  Initial gen1 "
 523       SIZE_FORMAT "  Maximum gen1 " SIZE_FORMAT,
 524       min_gen1_size(), initial_gen1_size(), max_gen1_size());
 525   }
 526 }
 527 
 528 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
 529                                         bool is_tlab,
 530                                         bool* gc_overhead_limit_was_exceeded) {
 531   GenCollectedHeap *gch = GenCollectedHeap::heap();
 532 
 533   debug_only(gch->check_for_valid_allocation_state());
 534   assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
 535 
 536   // In general gc_overhead_limit_was_exceeded should be false so
 537   // set it so here and reset it to true only if the gc time
 538   // limit is being exceeded as checked below.
 539   *gc_overhead_limit_was_exceeded = false;
 540 
 541   HeapWord* result = NULL;
 542 
 543   // Loop until the allocation is satisified,
 544   // or unsatisfied after GC.
 545   for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
 546     HandleMark hm; // discard any handles allocated in each iteration
 547 
 548     // First allocation attempt is lock-free.
 549     Generation *gen0 = gch->get_gen(0);
 550     assert(gen0->supports_inline_contig_alloc(),
 551       "Otherwise, must do alloc within heap lock");
 552     if (gen0->should_allocate(size, is_tlab)) {
 553       result = gen0->par_allocate(size, is_tlab);
 554       if (result != NULL) {
 555         assert(gch->is_in_reserved(result), "result not in heap");
 556         return result;
 557       }
 558     }
 559     unsigned int gc_count_before;  // read inside the Heap_lock locked region
 560     {
 561       MutexLocker ml(Heap_lock);
 562       if (PrintGC && Verbose) {
 563         gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:"
 564                       " attempting locked slow path allocation");
 565       }
 566       // Note that only large objects get a shot at being
 567       // allocated in later generations.
 568       bool first_only = ! should_try_older_generation_allocation(size);
 569 
 570       result = gch->attempt_allocation(size, is_tlab, first_only);
 571       if (result != NULL) {
 572         assert(gch->is_in_reserved(result), "result not in heap");
 573         return result;
 574       }
 575 
 576       if (GC_locker::is_active_and_needs_gc()) {
 577         if (is_tlab) {
 578           return NULL;  // Caller will retry allocating individual object
 579         }
 580         if (!gch->is_maximal_no_gc()) {
 581           // Try and expand heap to satisfy request
 582           result = expand_heap_and_allocate(size, is_tlab);
 583           // result could be null if we are out of space
 584           if (result != NULL) {
 585             return result;
 586           }
 587         }
 588 
 589         if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
 590           return NULL; // we didn't get to do a GC and we didn't get any memory
 591         }
 592 
 593         // If this thread is not in a jni critical section, we stall
 594         // the requestor until the critical section has cleared and
 595         // GC allowed. When the critical section clears, a GC is
 596         // initiated by the last thread exiting the critical section; so
 597         // we retry the allocation sequence from the beginning of the loop,
 598         // rather than causing more, now probably unnecessary, GC attempts.
 599         JavaThread* jthr = JavaThread::current();
 600         if (!jthr->in_critical()) {
 601           MutexUnlocker mul(Heap_lock);
 602           // Wait for JNI critical section to be exited
 603           GC_locker::stall_until_clear();
 604           gclocker_stalled_count += 1;
 605           continue;
 606         } else {
 607           if (CheckJNICalls) {
 608             fatal("Possible deadlock due to allocating while"
 609                   " in jni critical section");
 610           }
 611           return NULL;
 612         }
 613       }
 614 
 615       // Read the gc count while the heap lock is held.
 616       gc_count_before = Universe::heap()->total_collections();
 617     }
 618 
 619     VM_GenCollectForAllocation op(size,
 620                                   is_tlab,
 621                                   gc_count_before);
 622     VMThread::execute(&op);
 623     if (op.prologue_succeeded()) {
 624       result = op.result();
 625       if (op.gc_locked()) {
 626          assert(result == NULL, "must be NULL if gc_locked() is true");
 627          continue;  // retry and/or stall as necessary
 628       }
 629 
 630       // Allocation has failed and a collection
 631       // has been done.  If the gc time limit was exceeded the
 632       // this time, return NULL so that an out-of-memory
 633       // will be thrown.  Clear gc_overhead_limit_exceeded
 634       // so that the overhead exceeded does not persist.
 635 
 636       const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
 637       const bool softrefs_clear = all_soft_refs_clear();
 638 
 639       if (limit_exceeded && softrefs_clear) {
 640         *gc_overhead_limit_was_exceeded = true;
 641         size_policy()->set_gc_overhead_limit_exceeded(false);
 642         if (op.result() != NULL) {
 643           CollectedHeap::fill_with_object(op.result(), size);
 644         }
 645         return NULL;
 646       }
 647       assert(result == NULL || gch->is_in_reserved(result),
 648              "result not in heap");
 649       return result;
 650     }
 651 
 652     // Give a warning if we seem to be looping forever.
 653     if ((QueuedAllocationWarningCount > 0) &&
 654         (try_count % QueuedAllocationWarningCount == 0)) {
 655           warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t"
 656                   " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : "");
 657     }
 658   }
 659 }
 660 
 661 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
 662                                                        bool   is_tlab) {
 663   GenCollectedHeap *gch = GenCollectedHeap::heap();
 664   HeapWord* result = NULL;
 665   for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) {
 666     Generation *gen = gch->get_gen(i);
 667     if (gen->should_allocate(size, is_tlab)) {
 668       result = gen->expand_and_allocate(size, is_tlab);
 669     }
 670   }
 671   assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
 672   return result;
 673 }
 674 
 675 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
 676                                                         bool   is_tlab) {
 677   GenCollectedHeap *gch = GenCollectedHeap::heap();
 678   GCCauseSetter x(gch, GCCause::_allocation_failure);
 679   HeapWord* result = NULL;
 680 
 681   assert(size != 0, "Precondition violated");
 682   if (GC_locker::is_active_and_needs_gc()) {
 683     // GC locker is active; instead of a collection we will attempt
 684     // to expand the heap, if there's room for expansion.
 685     if (!gch->is_maximal_no_gc()) {
 686       result = expand_heap_and_allocate(size, is_tlab);
 687     }
 688     return result;   // could be null if we are out of space
 689   } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {
 690     // Do an incremental collection.
 691     gch->do_collection(false            /* full */,
 692                        false            /* clear_all_soft_refs */,
 693                        size             /* size */,
 694                        is_tlab          /* is_tlab */,
 695                        number_of_generations() - 1 /* max_level */);
 696   } else {
 697     if (Verbose && PrintGCDetails) {
 698       gclog_or_tty->print(" :: Trying full because partial may fail :: ");
 699     }
 700     // Try a full collection; see delta for bug id 6266275
 701     // for the original code and why this has been simplified
 702     // with from-space allocation criteria modified and
 703     // such allocation moved out of the safepoint path.
 704     gch->do_collection(true             /* full */,
 705                        false            /* clear_all_soft_refs */,
 706                        size             /* size */,
 707                        is_tlab          /* is_tlab */,
 708                        number_of_generations() - 1 /* max_level */);
 709   }
 710 
 711   result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
 712 
 713   if (result != NULL) {
 714     assert(gch->is_in_reserved(result), "result not in heap");
 715     return result;
 716   }
 717 
 718   // OK, collection failed, try expansion.
 719   result = expand_heap_and_allocate(size, is_tlab);
 720   if (result != NULL) {
 721     return result;
 722   }
 723 
 724   // If we reach this point, we're really out of memory. Try every trick
 725   // we can to reclaim memory. Force collection of soft references. Force
 726   // a complete compaction of the heap. Any additional methods for finding
 727   // free memory should be here, especially if they are expensive. If this
 728   // attempt fails, an OOM exception will be thrown.
 729   {
 730     IntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
 731 
 732     gch->do_collection(true             /* full */,
 733                        true             /* clear_all_soft_refs */,
 734                        size             /* size */,
 735                        is_tlab          /* is_tlab */,
 736                        number_of_generations() - 1 /* max_level */);
 737   }
 738 
 739   result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
 740   if (result != NULL) {
 741     assert(gch->is_in_reserved(result), "result not in heap");
 742     return result;
 743   }
 744 
 745   assert(!should_clear_all_soft_refs(),
 746     "Flag should have been handled and cleared prior to this point");
 747 
 748   // What else?  We might try synchronous finalization later.  If the total
 749   // space available is large enough for the allocation, then a more
 750   // complete compaction phase than we've tried so far might be
 751   // appropriate.
 752   return NULL;
 753 }
 754 
 755 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(
 756                                                  ClassLoaderData* loader_data,
 757                                                  size_t word_size,
 758                                                  Metaspace::MetadataType mdtype) {
 759   uint loop_count = 0;
 760   uint gc_count = 0;
 761   uint full_gc_count = 0;
 762 
 763   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
 764 
 765   do {
 766     MetaWord* result = NULL;
 767     if (GC_locker::is_active_and_needs_gc()) {
 768       // If the GC_locker is active, just expand and allocate.
 769       // If that does not succeed, wait if this thread is not
 770       // in a critical section itself.
 771       result =
 772         loader_data->metaspace_non_null()->expand_and_allocate(word_size,
 773                                                                mdtype);
 774       if (result != NULL) {
 775         return result;
 776       }
 777       JavaThread* jthr = JavaThread::current();
 778       if (!jthr->in_critical()) {
 779         // Wait for JNI critical section to be exited
 780         GC_locker::stall_until_clear();
 781         // The GC invoked by the last thread leaving the critical
 782         // section will be a young collection and a full collection
 783         // is (currently) needed for unloading classes so continue
 784         // to the next iteration to get a full GC.
 785         continue;
 786       } else {
 787         if (CheckJNICalls) {
 788           fatal("Possible deadlock due to allocating while"
 789                 " in jni critical section");
 790         }
 791         return NULL;
 792       }
 793     }
 794 
 795     {  // Need lock to get self consistent gc_count's
 796       MutexLocker ml(Heap_lock);
 797       gc_count      = Universe::heap()->total_collections();
 798       full_gc_count = Universe::heap()->total_full_collections();
 799     }
 800 
 801     // Generate a VM operation
 802     VM_CollectForMetadataAllocation op(loader_data,
 803                                        word_size,
 804                                        mdtype,
 805                                        gc_count,
 806                                        full_gc_count,
 807                                        GCCause::_metadata_GC_threshold);
 808     VMThread::execute(&op);
 809 
 810     // If GC was locked out, try again.  Check
 811     // before checking success because the prologue
 812     // could have succeeded and the GC still have
 813     // been locked out.
 814     if (op.gc_locked()) {
 815       continue;
 816     }
 817 
 818     if (op.prologue_succeeded()) {
 819       return op.result();
 820     }
 821     loop_count++;
 822     if ((QueuedAllocationWarningCount > 0) &&
 823         (loop_count % QueuedAllocationWarningCount == 0)) {
 824       warning("satisfy_failed_metadata_allocation() retries %d times \n\t"
 825               " size=%d", loop_count, word_size);
 826     }
 827   } while (true);  // Until a GC is done
 828 }
 829 
 830 // Return true if any of the following is true:
 831 // . the allocation won't fit into the current young gen heap
 832 // . gc locker is occupied (jni critical section)
 833 // . heap memory is tight -- the most recent previous collection
 834 //   was a full collection because a partial collection (would
 835 //   have) failed and is likely to fail again
 836 bool GenCollectorPolicy::should_try_older_generation_allocation(
 837         size_t word_size) const {
 838   GenCollectedHeap* gch = GenCollectedHeap::heap();
 839   size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
 840   return    (word_size > heap_word_size(gen0_capacity))
 841          || GC_locker::is_active_and_needs_gc()
 842          || gch->incremental_collection_failed();
 843 }
 844 
 845 
 846 //
 847 // MarkSweepPolicy methods
 848 //
 849 
 850 MarkSweepPolicy::MarkSweepPolicy() {
 851   initialize_all();
 852 }
 853 
 854 void MarkSweepPolicy::initialize_generations() {
 855   _generations = new GenerationSpecPtr[number_of_generations()];
 856   if (_generations == NULL)
 857     vm_exit_during_initialization("Unable to allocate gen spec");
 858 
 859   if (UseParNewGC) {
 860     _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);
 861   } else {
 862     _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);
 863   }
 864   _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);
 865 
 866   if (_generations[0] == NULL || _generations[1] == NULL)
 867     vm_exit_during_initialization("Unable to allocate gen spec");
 868 }
 869 
 870 void MarkSweepPolicy::initialize_gc_policy_counters() {
 871   // initialize the policy counters - 2 collectors, 3 generations
 872   if (UseParNewGC) {
 873     _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3);
 874   } else {
 875     _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
 876   }
 877 }