1 /*
   2  * Copyright (c) 2001, 2015, 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 
  44 // CollectorPolicy methods
  45 
  46 CollectorPolicy::CollectorPolicy() :
  47     _space_alignment(0),
  48     _heap_alignment(0),
  49     _initial_heap_byte_size(InitialHeapSize),
  50     _max_heap_byte_size(MaxHeapSize),
  51     _min_heap_byte_size(Arguments::min_heap_size()),
  52     _max_heap_size_cmdline(false),
  53     _size_policy(NULL),
  54     _should_clear_all_soft_refs(false),
  55     _all_soft_refs_clear(false)
  56 {}
  57 
  58 #ifdef ASSERT
  59 void CollectorPolicy::assert_flags() {
  60   assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");
  61   assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment");
  62   assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment");
  63 }
  64 
  65 void CollectorPolicy::assert_size_info() {
  66   assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage");
  67   assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage");
  68   assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes");
  69   assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes");
  70   assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes");
  71   assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment");
  72   assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment");
  73   assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment");
  74 }
  75 #endif // ASSERT
  76 
  77 void CollectorPolicy::initialize_flags() {
  78   assert(_space_alignment != 0, "Space alignment not set up properly");
  79   assert(_heap_alignment != 0, "Heap alignment not set up properly");
  80   assert(_heap_alignment >= _space_alignment,
  81          err_msg("heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT,
  82                  _heap_alignment, _space_alignment));
  83   assert(_heap_alignment % _space_alignment == 0,
  84          err_msg("heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
  85                  _heap_alignment, _space_alignment));
  86 
  87   if (FLAG_IS_CMDLINE(MaxHeapSize)) {
  88     if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
  89       vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");
  90     }
  91     if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) {
  92       vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
  93     }
  94     _max_heap_size_cmdline = true;
  95   }
  96 
  97   // Check heap parameter properties
  98   if (InitialHeapSize < M) {
  99     vm_exit_during_initialization("Too small initial heap");
 100   }
 101   if (_min_heap_byte_size < M) {
 102     vm_exit_during_initialization("Too small minimum heap");
 103   }
 104 
 105   // User inputs from -Xmx and -Xms must be aligned
 106   _min_heap_byte_size = align_size_up(_min_heap_byte_size, _heap_alignment);
 107   size_t aligned_initial_heap_size = align_size_up(InitialHeapSize, _heap_alignment);
 108   size_t aligned_max_heap_size = align_size_up(MaxHeapSize, _heap_alignment);
 109 
 110   // Write back to flags if the values changed
 111   if (aligned_initial_heap_size != InitialHeapSize) {
 112     FLAG_SET_ERGO(size_t, InitialHeapSize, aligned_initial_heap_size);
 113   }
 114   if (aligned_max_heap_size != MaxHeapSize) {
 115     FLAG_SET_ERGO(size_t, MaxHeapSize, aligned_max_heap_size);
 116   }
 117 
 118   if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 &&
 119       InitialHeapSize < _min_heap_byte_size) {
 120     vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
 121   }
 122   if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
 123     FLAG_SET_ERGO(size_t, MaxHeapSize, InitialHeapSize);
 124   } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {
 125     FLAG_SET_ERGO(size_t, InitialHeapSize, MaxHeapSize);
 126     if (InitialHeapSize < _min_heap_byte_size) {
 127       _min_heap_byte_size = InitialHeapSize;
 128     }
 129   }
 130 
 131   _initial_heap_byte_size = InitialHeapSize;
 132   _max_heap_byte_size = MaxHeapSize;
 133 
 134   FLAG_SET_ERGO(size_t, MinHeapDeltaBytes, align_size_up(MinHeapDeltaBytes, _space_alignment));
 135 
 136   DEBUG_ONLY(CollectorPolicy::assert_flags();)
 137 }
 138 
 139 void CollectorPolicy::initialize_size_info() {
 140   if (PrintGCDetails && Verbose) {
 141     gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT "  Initial heap "
 142       SIZE_FORMAT "  Maximum heap " SIZE_FORMAT,
 143       _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);
 144   }
 145 
 146   DEBUG_ONLY(CollectorPolicy::assert_size_info();)
 147 }
 148 
 149 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {
 150   bool result = _should_clear_all_soft_refs;
 151   set_should_clear_all_soft_refs(false);
 152   return result;
 153 }
 154 
 155 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap) {
 156   return new CardTableRS(whole_heap);
 157 }
 158 
 159 void CollectorPolicy::cleared_all_soft_refs() {
 160   // If near gc overhear limit, continue to clear SoftRefs.  SoftRefs may
 161   // have been cleared in the last collection but if the gc overhear
 162   // limit continues to be near, SoftRefs should still be cleared.
 163   if (size_policy() != NULL) {
 164     _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();
 165   }
 166   _all_soft_refs_clear = true;
 167 }
 168 
 169 size_t CollectorPolicy::compute_heap_alignment() {
 170   // The card marking array and the offset arrays for old generations are
 171   // committed in os pages as well. Make sure they are entirely full (to
 172   // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
 173   // byte entry and the os page size is 4096, the maximum heap size should
 174   // be 512*4096 = 2MB aligned.
 175 
 176   size_t alignment = GenRemSet::max_alignment_constraint();
 177 
 178   if (UseLargePages) {
 179       // In presence of large pages we have to make sure that our
 180       // alignment is large page aware.
 181       alignment = lcm(os::large_page_size(), alignment);
 182   }
 183 
 184   return alignment;
 185 }
 186 
 187 // GenCollectorPolicy methods
 188 
 189 GenCollectorPolicy::GenCollectorPolicy() :
 190     _min_young_size(0),
 191     _initial_young_size(0),
 192     _max_young_size(0),
 193     _gen_alignment(0),
 194     _min_old_size(0),
 195     _initial_old_size(0),
 196     _max_old_size(0),
 197     _generations(NULL)
 198 {}
 199 
 200 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
 201   return align_size_down_bounded(base_size / (NewRatio + 1), _gen_alignment);
 202 }
 203 
 204 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
 205                                                  size_t maximum_size) {
 206   size_t max_minus = maximum_size - _gen_alignment;
 207   return desired_size < max_minus ? desired_size : max_minus;
 208 }
 209 
 210 
 211 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
 212                                                 size_t init_promo_size,
 213                                                 size_t init_survivor_size) {
 214   const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
 215   _size_policy = new AdaptiveSizePolicy(init_eden_size,
 216                                         init_promo_size,
 217                                         init_survivor_size,
 218                                         max_gc_pause_sec,
 219                                         GCTimeRatio);
 220 }
 221 
 222 size_t GenCollectorPolicy::young_gen_size_lower_bound() {
 223   // The young generation must be aligned and have room for eden + two survivors
 224   return align_size_up(3 * _space_alignment, _gen_alignment);
 225 }
 226 
 227 #ifdef ASSERT
 228 void GenCollectorPolicy::assert_flags() {
 229   CollectorPolicy::assert_flags();
 230   assert(NewSize >= _min_young_size, "Ergonomics decided on a too small young gen size");
 231   assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes");
 232   assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes");
 233   assert(NewSize % _gen_alignment == 0, "NewSize alignment");
 234   assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment");
 235   assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");
 236   assert(OldSize % _gen_alignment == 0, "OldSize alignment");
 237 }
 238 
 239 void GenCollectorPolicy::assert_size_info() {
 240   CollectorPolicy::assert_size_info();
 241   // GenCollectorPolicy::initialize_size_info may update the MaxNewSize
 242   assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");
 243   assert(NewSize == _initial_young_size, "Discrepancy between NewSize flag and local storage");
 244   assert(MaxNewSize == _max_young_size, "Discrepancy between MaxNewSize flag and local storage");
 245   assert(OldSize == _initial_old_size, "Discrepancy between OldSize flag and local storage");
 246   assert(_min_young_size <= _initial_young_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");
 247   assert(_initial_young_size <= _max_young_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");
 248   assert(_min_young_size % _gen_alignment == 0, "_min_young_size alignment");
 249   assert(_initial_young_size % _gen_alignment == 0, "_initial_young_size alignment");
 250   assert(_max_young_size % _gen_alignment == 0, "_max_young_size alignment");
 251   assert(_min_young_size <= bound_minus_alignment(_min_young_size, _min_heap_byte_size),
 252       "Ergonomics made minimum young generation larger than minimum heap");
 253   assert(_initial_young_size <=  bound_minus_alignment(_initial_young_size, _initial_heap_byte_size),
 254       "Ergonomics made initial young generation larger than initial heap");
 255   assert(_max_young_size <= bound_minus_alignment(_max_young_size, _max_heap_byte_size),
 256       "Ergonomics made maximum young generation lager than maximum heap");
 257   assert(_min_old_size <= _initial_old_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");
 258   assert(_initial_old_size <= _max_old_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");
 259   assert(_max_old_size % _gen_alignment == 0, "_max_old_size alignment");
 260   assert(_initial_old_size % _gen_alignment == 0, "_initial_old_size alignment");
 261   assert(_max_heap_byte_size <= (_max_young_size + _max_old_size), "Total maximum heap sizes must be sum of generation maximum sizes");
 262   assert(_min_young_size + _min_old_size <= _min_heap_byte_size, "Minimum generation sizes exceed minimum heap size");
 263   assert(_initial_young_size + _initial_old_size == _initial_heap_byte_size, "Initial generation sizes should match initial heap size");
 264   assert(_max_young_size + _max_old_size == _max_heap_byte_size, "Maximum generation sizes should match maximum heap size");
 265 }
 266 #endif // ASSERT
 267 
 268 void GenCollectorPolicy::initialize_flags() {
 269   CollectorPolicy::initialize_flags();
 270 
 271   assert(_gen_alignment != 0, "Generation alignment not set up properly");
 272   assert(_heap_alignment >= _gen_alignment,
 273          err_msg("heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,
 274                  _heap_alignment, _gen_alignment));
 275   assert(_gen_alignment % _space_alignment == 0,
 276          err_msg("gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
 277                  _gen_alignment, _space_alignment));
 278   assert(_heap_alignment % _gen_alignment == 0,
 279          err_msg("heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT,
 280                  _heap_alignment, _gen_alignment));
 281 
 282   // All generational heaps have a youngest gen; handle those flags here
 283 
 284   // Make sure the heap is large enough for two generations
 285   size_t smallest_new_size = young_gen_size_lower_bound();
 286   size_t smallest_heap_size = align_size_up(smallest_new_size + align_size_up(_space_alignment, _gen_alignment),
 287                                            _heap_alignment);
 288   if (MaxHeapSize < smallest_heap_size) {
 289     FLAG_SET_ERGO(size_t, MaxHeapSize, smallest_heap_size);
 290     _max_heap_byte_size = MaxHeapSize;
 291   }
 292   // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size
 293   if (_min_heap_byte_size < smallest_heap_size) {
 294     _min_heap_byte_size = smallest_heap_size;
 295     if (InitialHeapSize < _min_heap_byte_size) {
 296       FLAG_SET_ERGO(size_t, InitialHeapSize, smallest_heap_size);
 297       _initial_heap_byte_size = smallest_heap_size;
 298     }
 299   }
 300 
 301   // Make sure NewSize allows an old generation to fit even if set on the command line
 302   if (FLAG_IS_CMDLINE(NewSize) && NewSize >= _initial_heap_byte_size) {
 303     warning("NewSize was set larger than initial heap size, will use initial heap size.");
 304     NewSize = bound_minus_alignment(NewSize, _initial_heap_byte_size);
 305   }
 306 
 307   // Now take the actual NewSize into account. We will silently increase NewSize
 308   // if the user specified a smaller or unaligned value.
 309   size_t bounded_new_size = bound_minus_alignment(NewSize, MaxHeapSize);
 310   bounded_new_size = MAX2(smallest_new_size, (size_t)align_size_down(bounded_new_size, _gen_alignment));
 311   if (bounded_new_size != NewSize) {
 312     // Do not use FLAG_SET_ERGO to update NewSize here, since this will override
 313     // if NewSize was set on the command line or not. This information is needed
 314     // later when setting the initial and minimum young generation size.
 315     NewSize = bounded_new_size;
 316   }
 317   _min_young_size = smallest_new_size;
 318   _initial_young_size = NewSize;
 319 
 320   if (!FLAG_IS_DEFAULT(MaxNewSize)) {
 321     if (MaxNewSize >= MaxHeapSize) {
 322       // Make sure there is room for an old generation
 323       size_t smaller_max_new_size = MaxHeapSize - _gen_alignment;
 324       if (FLAG_IS_CMDLINE(MaxNewSize)) {
 325         warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "
 326                 "heap (" SIZE_FORMAT "k).  A new max generation size of " SIZE_FORMAT "k will be used.",
 327                 MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K);
 328       }
 329       FLAG_SET_ERGO(size_t, MaxNewSize, smaller_max_new_size);
 330       if (NewSize > MaxNewSize) {
 331         FLAG_SET_ERGO(size_t, NewSize, MaxNewSize);
 332         _initial_young_size = NewSize;
 333       }
 334     } else if (MaxNewSize < _initial_young_size) {
 335       FLAG_SET_ERGO(size_t, MaxNewSize, _initial_young_size);
 336     } else if (!is_size_aligned(MaxNewSize, _gen_alignment)) {
 337       FLAG_SET_ERGO(size_t, MaxNewSize, align_size_down(MaxNewSize, _gen_alignment));
 338     }
 339     _max_young_size = MaxNewSize;
 340   }
 341 
 342   if (NewSize > MaxNewSize) {
 343     // At this point this should only happen if the user specifies a large NewSize and/or
 344     // a small (but not too small) MaxNewSize.
 345     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 346       warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
 347               "A new max generation size of " SIZE_FORMAT "k will be used.",
 348               NewSize/K, MaxNewSize/K, NewSize/K);
 349     }
 350     FLAG_SET_ERGO(size_t, MaxNewSize, NewSize);
 351     _max_young_size = MaxNewSize;
 352   }
 353 
 354   if (SurvivorRatio < 1 || NewRatio < 1) {
 355     vm_exit_during_initialization("Invalid young gen ratio specified");
 356   }
 357 
 358   if (!is_size_aligned(OldSize, _gen_alignment)) {
 359     // Setting OldSize directly to preserve information about the possible
 360     // setting of OldSize on the command line.
 361     OldSize = align_size_down(OldSize, _gen_alignment);
 362   }
 363 
 364   if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {
 365     // NewRatio will be used later to set the young generation size so we use
 366     // it to calculate how big the heap should be based on the requested OldSize
 367     // and NewRatio.
 368     assert(NewRatio > 0, "NewRatio should have been set up earlier");
 369     size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
 370 
 371     calculated_heapsize = align_size_up(calculated_heapsize, _heap_alignment);
 372     FLAG_SET_ERGO(size_t, MaxHeapSize, calculated_heapsize);
 373     _max_heap_byte_size = MaxHeapSize;
 374     FLAG_SET_ERGO(size_t, InitialHeapSize, calculated_heapsize);
 375     _initial_heap_byte_size = InitialHeapSize;
 376   }
 377 
 378   // Adjust NewSize and OldSize or MaxHeapSize to match each other
 379   if (NewSize + OldSize > MaxHeapSize) {
 380     if (_max_heap_size_cmdline) {
 381       // Somebody has set a maximum heap size with the intention that we should not
 382       // exceed it. Adjust New/OldSize as necessary.
 383       size_t calculated_size = NewSize + OldSize;
 384       double shrink_factor = (double) MaxHeapSize / calculated_size;
 385       size_t smaller_new_size = align_size_down((size_t)(NewSize * shrink_factor), _gen_alignment);
 386       FLAG_SET_ERGO(size_t, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size));
 387       _initial_young_size = NewSize;
 388 
 389       // OldSize is already aligned because above we aligned MaxHeapSize to
 390       // _heap_alignment, and we just made sure that NewSize is aligned to
 391       // _gen_alignment. In initialize_flags() we verified that _heap_alignment
 392       // is a multiple of _gen_alignment.
 393       FLAG_SET_ERGO(size_t, OldSize, MaxHeapSize - NewSize);
 394     } else {
 395       FLAG_SET_ERGO(size_t, MaxHeapSize, align_size_up(NewSize + OldSize, _heap_alignment));
 396       _max_heap_byte_size = MaxHeapSize;
 397     }
 398   }
 399 
 400   // Update NewSize, if possible, to avoid sizing the young gen too small when only
 401   // OldSize is set on the command line.
 402   if (FLAG_IS_CMDLINE(OldSize) && !FLAG_IS_CMDLINE(NewSize)) {
 403     if (OldSize < _initial_heap_byte_size) {
 404       size_t new_size = _initial_heap_byte_size - OldSize;
 405       // Need to compare against the flag value for max since _max_young_size
 406       // might not have been set yet.
 407       if (new_size >= _min_young_size && new_size <= MaxNewSize) {
 408         FLAG_SET_ERGO(size_t, NewSize, new_size);
 409         _initial_young_size = NewSize;
 410       }
 411     }
 412   }
 413 
 414   always_do_update_barrier = UseConcMarkSweepGC;
 415 
 416   DEBUG_ONLY(GenCollectorPolicy::assert_flags();)
 417 }
 418 
 419 // Values set on the command line win over any ergonomically
 420 // set command line parameters.
 421 // Ergonomic choice of parameters are done before this
 422 // method is called.  Values for command line parameters such as NewSize
 423 // and MaxNewSize feed those ergonomic choices into this method.
 424 // This method makes the final generation sizings consistent with
 425 // themselves and with overall heap sizings.
 426 // In the absence of explicitly set command line flags, policies
 427 // such as the use of NewRatio are used to size the generation.
 428 
 429 // Minimum sizes of the generations may be different than
 430 // the initial sizes.  An inconsistency is permitted here
 431 // in the total size that can be specified explicitly by
 432 // command line specification of OldSize and NewSize and
 433 // also a command line specification of -Xms.  Issue a warning
 434 // but allow the values to pass.
 435 void GenCollectorPolicy::initialize_size_info() {
 436   CollectorPolicy::initialize_size_info();
 437 
 438   _initial_young_size = NewSize;
 439   _max_young_size = MaxNewSize;
 440   _initial_old_size = OldSize;
 441 
 442   // Determine maximum size of the young generation.
 443 
 444   if (FLAG_IS_DEFAULT(MaxNewSize)) {
 445     _max_young_size = scale_by_NewRatio_aligned(_max_heap_byte_size);
 446     // Bound the maximum size by NewSize below (since it historically
 447     // would have been NewSize and because the NewRatio calculation could
 448     // yield a size that is too small) and bound it by MaxNewSize above.
 449     // Ergonomics plays here by previously calculating the desired
 450     // NewSize and MaxNewSize.
 451     _max_young_size = MIN2(MAX2(_max_young_size, _initial_young_size), MaxNewSize);
 452   }
 453 
 454   // Given the maximum young size, determine the initial and
 455   // minimum young sizes.
 456 
 457   if (_max_heap_byte_size == _initial_heap_byte_size) {
 458     // The maximum and initial heap sizes are the same so the generation's
 459     // initial size must be the same as it maximum size. Use NewSize as the
 460     // size if set on command line.
 461     _max_young_size = FLAG_IS_CMDLINE(NewSize) ? NewSize : _max_young_size;
 462     _initial_young_size = _max_young_size;
 463 
 464     // Also update the minimum size if min == initial == max.
 465     if (_max_heap_byte_size == _min_heap_byte_size) {
 466       _min_young_size = _max_young_size;
 467     }
 468   } else {
 469     if (FLAG_IS_CMDLINE(NewSize)) {
 470       // If NewSize is set on the command line, we should use it as
 471       // the initial size, but make sure it is within the heap bounds.
 472       _initial_young_size =
 473         MIN2(_max_young_size, bound_minus_alignment(NewSize, _initial_heap_byte_size));
 474       _min_young_size = bound_minus_alignment(_initial_young_size, _min_heap_byte_size);
 475     } else {
 476       // For the case where NewSize is not set on the command line, use
 477       // NewRatio to size the initial generation size. Use the current
 478       // NewSize as the floor, because if NewRatio is overly large, the resulting
 479       // size can be too small.
 480       _initial_young_size =
 481         MIN2(_max_young_size, MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize));
 482     }
 483   }
 484 
 485   if (PrintGCDetails && Verbose) {
 486     gclog_or_tty->print_cr("1: Minimum young " SIZE_FORMAT "  Initial young "
 487       SIZE_FORMAT "  Maximum young " SIZE_FORMAT,
 488       _min_young_size, _initial_young_size, _max_young_size);
 489   }
 490 
 491   // At this point the minimum, initial and maximum sizes
 492   // of the overall heap and of the young generation have been determined.
 493   // The maximum old size can be determined from the maximum young
 494   // and maximum heap size since no explicit flags exist
 495   // for setting the old generation maximum.
 496   _max_old_size = MAX2(_max_heap_byte_size - _max_young_size, _gen_alignment);
 497 
 498   // If no explicit command line flag has been set for the
 499   // old generation size, use what is left.
 500   if (!FLAG_IS_CMDLINE(OldSize)) {
 501     // The user has not specified any value but the ergonomics
 502     // may have chosen a value (which may or may not be consistent
 503     // with the overall heap size).  In either case make
 504     // the minimum, maximum and initial sizes consistent
 505     // with the young sizes and the overall heap sizes.
 506     _min_old_size = _gen_alignment;
 507     _initial_old_size = MIN2(_max_old_size, MAX2(_initial_heap_byte_size - _initial_young_size, _min_old_size));
 508     // _max_old_size has already been made consistent above.
 509   } else {
 510     // OldSize has been explicitly set on the command line. Use it
 511     // for the initial size but make sure the minimum allow a young
 512     // generation to fit as well.
 513     // If the user has explicitly set an OldSize that is inconsistent
 514     // with other command line flags, issue a warning.
 515     // The generation minimums and the overall heap minimum should
 516     // be within one generation alignment.
 517     if (_initial_old_size > _max_old_size) {
 518       warning("Inconsistency between maximum heap size and maximum "
 519           "generation sizes: using maximum heap = " SIZE_FORMAT
 520           " -XX:OldSize flag is being ignored",
 521           _max_heap_byte_size);
 522       _initial_old_size = _max_old_size;
 523     }
 524 
 525     _min_old_size = MIN2(_initial_old_size, _min_heap_byte_size - _min_young_size);
 526   }
 527 
 528   // The initial generation sizes should match the initial heap size,
 529   // if not issue a warning and resize the generations. This behavior
 530   // differs from JDK8 where the generation sizes have higher priority
 531   // than the initial heap size.
 532   if ((_initial_old_size + _initial_young_size) != _initial_heap_byte_size) {
 533     warning("Inconsistency between generation sizes and heap size, resizing "
 534             "the generations to fit the heap.");
 535 
 536     size_t desired_young_size = _initial_heap_byte_size - _initial_old_size;
 537     if (_initial_heap_byte_size < _initial_old_size) {
 538       // Old want all memory, use minimum for young and rest for old
 539       _initial_young_size = _min_young_size;
 540       _initial_old_size = _initial_heap_byte_size - _min_young_size;
 541     } else if (desired_young_size > _max_young_size) {
 542       // Need to increase both young and old generation
 543       _initial_young_size = _max_young_size;
 544       _initial_old_size = _initial_heap_byte_size - _max_young_size;
 545     } else if (desired_young_size < _min_young_size) {
 546       // Need to decrease both young and old generation
 547       _initial_young_size = _min_young_size;
 548       _initial_old_size = _initial_heap_byte_size - _min_young_size;
 549     } else {
 550       // The young generation boundaries allow us to only update the
 551       // young generation.
 552       _initial_young_size = desired_young_size;
 553     }
 554 
 555     if (PrintGCDetails && Verbose) {
 556       gclog_or_tty->print_cr("2: Minimum young " SIZE_FORMAT "  Initial young "
 557         SIZE_FORMAT "  Maximum young " SIZE_FORMAT,
 558         _min_young_size, _initial_young_size, _max_young_size);
 559     }
 560   }
 561 
 562   // Write back to flags if necessary.
 563   if (NewSize != _initial_young_size) {
 564     FLAG_SET_ERGO(size_t, NewSize, _initial_young_size);
 565   }
 566 
 567   if (MaxNewSize != _max_young_size) {
 568     FLAG_SET_ERGO(size_t, MaxNewSize, _max_young_size);
 569   }
 570 
 571   if (OldSize != _initial_old_size) {
 572     FLAG_SET_ERGO(size_t, OldSize, _initial_old_size);
 573   }
 574 
 575   if (PrintGCDetails && Verbose) {
 576     gclog_or_tty->print_cr("Minimum old " SIZE_FORMAT "  Initial old "
 577       SIZE_FORMAT "  Maximum old " SIZE_FORMAT,
 578       _min_old_size, _initial_old_size, _max_old_size);
 579   }
 580 
 581   DEBUG_ONLY(GenCollectorPolicy::assert_size_info();)
 582 }
 583 
 584 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
 585                                         bool is_tlab,
 586                                         bool* gc_overhead_limit_was_exceeded) {
 587   GenCollectedHeap *gch = GenCollectedHeap::heap();
 588 
 589   debug_only(gch->check_for_valid_allocation_state());
 590   assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
 591 
 592   // In general gc_overhead_limit_was_exceeded should be false so
 593   // set it so here and reset it to true only if the gc time
 594   // limit is being exceeded as checked below.
 595   *gc_overhead_limit_was_exceeded = false;
 596 
 597   HeapWord* result = NULL;
 598 
 599   // Loop until the allocation is satisfied, or unsatisfied after GC.
 600   for (uint try_count = 1, gclocker_stalled_count = 0, gc_attempt = 1; /* return or throw */; try_count += 1) {
 601     HandleMark hm; // Discard any handles allocated in each iteration.
 602 
 603     // First allocation attempt is lock-free.
 604     Generation *young = gch->young_gen();
 605     assert(young->supports_inline_contig_alloc(),
 606       "Otherwise, must do alloc within heap lock");
 607     if (young->should_allocate(size, is_tlab)) {
 608       result = young->par_allocate(size, is_tlab);
 609       if (result != NULL) {
 610         assert(gch->is_in_reserved(result), "result not in heap");
 611         return result;
 612       }
 613     }
 614     uint gc_count_before;  // Read inside the Heap_lock locked region.
 615     {
 616       MutexLocker ml(Heap_lock);
 617       if (PrintGC && Verbose) {
 618         gclog_or_tty->print_cr("GenCollectorPolicy::mem_allocate_work:"
 619                                " attempting locked slow path allocation");
 620       }
 621       // Note that only large objects get a shot at being
 622       // allocated in later generations.
 623       bool first_only = ! should_try_older_generation_allocation(size);
 624 
 625       result = gch->attempt_allocation(size, is_tlab, first_only);
 626       if (result != NULL) {
 627         assert(gch->is_in_reserved(result), "result not in heap");
 628         return result;
 629       }
 630 
 631       if (GC_locker::is_active_and_needs_gc()) {
 632         if (is_tlab) {
 633           return NULL;  // Caller will retry allocating individual object.
 634         }
 635         if (!gch->is_maximal_no_gc()) {
 636           // Try and expand heap to satisfy request.
 637           result = expand_heap_and_allocate(size, is_tlab);
 638           // Result could be null if we are out of space.
 639           if (result != NULL) {
 640             return result;
 641           }
 642         }
 643 
 644         if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
 645           return NULL; // We didn't get to do a GC and we didn't get any memory.
 646         }
 647 
 648         // If this thread is not in a jni critical section, we stall
 649         // the requestor until the critical section has cleared and
 650         // GC allowed. When the critical section clears, a GC is
 651         // initiated by the last thread exiting the critical section; so
 652         // we retry the allocation sequence from the beginning of the loop,
 653         // rather than causing more, now probably unnecessary, GC attempts.
 654         JavaThread* jthr = JavaThread::current();
 655         if (!jthr->in_critical()) {
 656           MutexUnlocker mul(Heap_lock);
 657           // Wait for JNI critical section to be exited
 658           GC_locker::stall_until_clear();
 659           gclocker_stalled_count += 1;
 660           continue;
 661         } else {
 662           if (CheckJNICalls) {
 663             fatal("Possible deadlock due to allocating while"
 664                   " in jni critical section");
 665           }
 666           return NULL;
 667         }
 668       }
 669 
 670       // Read the gc count while the heap lock is held.
 671       gc_count_before = Universe::heap()->total_collections();
 672     }
 673 
 674     VM_GenCollectForAllocation op(size, is_tlab, gc_count_before, gc_attempt++);
 675     VMThread::execute(&op);
 676     if (op.prologue_succeeded()) {
 677       result = op.result();
 678       if (op.gc_locked()) {
 679          assert(result == NULL, "must be NULL if gc_locked() is true");
 680          continue;  // Retry and/or stall as necessary.
 681       }
 682 
 683       // Allocation has failed and a collection
 684       // has been done.  If the gc time limit was exceeded the
 685       // this time, return NULL so that an out-of-memory
 686       // will be thrown.  Clear gc_overhead_limit_exceeded
 687       // so that the overhead exceeded does not persist.
 688 
 689       const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
 690       const bool softrefs_clear = all_soft_refs_clear();
 691 
 692       if (limit_exceeded && softrefs_clear) {
 693         *gc_overhead_limit_was_exceeded = true;
 694         size_policy()->set_gc_overhead_limit_exceeded(false);
 695         if (op.result() != NULL) {
 696           CollectedHeap::fill_with_object(op.result(), size);
 697         }
 698         return NULL;
 699       }
 700       assert(result == NULL || gch->is_in_reserved(result),
 701              "result not in heap");
 702       return result;
 703     }
 704 
 705     // Give a warning if we seem to be looping forever.
 706     if ((QueuedAllocationWarningCount > 0) &&
 707         (try_count % QueuedAllocationWarningCount == 0)) {
 708           warning("GenCollectorPolicy::mem_allocate_work retries %d times \n\t"
 709                   " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
 710     }
 711   }
 712 }
 713 
 714 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
 715                                                        bool   is_tlab) {
 716   GenCollectedHeap *gch = GenCollectedHeap::heap();
 717   HeapWord* result = NULL;
 718   Generation *old = gch->old_gen();
 719   if (old->should_allocate(size, is_tlab)) {
 720     result = old->expand_and_allocate(size, is_tlab);
 721   }
 722   if (result == NULL) {
 723     Generation *young = gch->young_gen();
 724     if (young->should_allocate(size, is_tlab)) {
 725       result = young->expand_and_allocate(size, is_tlab);
 726     }
 727   }
 728   assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
 729   return result;
 730 }
 731 
 732 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
 733                                                         bool   is_tlab) {
 734   GenCollectedHeap *gch = GenCollectedHeap::heap();
 735   GCCauseSetter x(gch, GCCause::_allocation_failure);
 736   HeapWord* result = NULL;
 737 
 738   assert(size != 0, "Precondition violated");
 739   if (GC_locker::is_active_and_needs_gc()) {
 740     // GC locker is active; instead of a collection we will attempt
 741     // to expand the heap, if there's room for expansion.
 742     if (!gch->is_maximal_no_gc()) {
 743       result = expand_heap_and_allocate(size, is_tlab);
 744     }
 745     return result;   // Could be null if we are out of space.
 746   } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {
 747     // Do an incremental collection.
 748     gch->do_collection(false            /* full */,
 749                        false            /* clear_all_soft_refs */,
 750                        size             /* size */,
 751                        is_tlab          /* is_tlab */,
 752                        number_of_generations() - 1 /* max_level */);
 753   } else {
 754     if (Verbose && PrintGCDetails) {
 755       gclog_or_tty->print(" :: Trying full because partial may fail :: ");
 756     }
 757     // Try a full collection; see delta for bug id 6266275
 758     // for the original code and why this has been simplified
 759     // with from-space allocation criteria modified and
 760     // such allocation moved out of the safepoint path.
 761     gch->do_collection(true             /* full */,
 762                        false            /* clear_all_soft_refs */,
 763                        size             /* size */,
 764                        is_tlab          /* is_tlab */,
 765                        number_of_generations() - 1 /* max_level */);
 766   }
 767 
 768   result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
 769 
 770   if (result != NULL) {
 771     assert(gch->is_in_reserved(result), "result not in heap");
 772     return result;
 773   }
 774 
 775   // OK, collection failed, try expansion.
 776   result = expand_heap_and_allocate(size, is_tlab);
 777   if (result != NULL) {
 778     return result;
 779   }
 780 
 781   // If we reach this point, we're really out of memory. Try every trick
 782   // we can to reclaim memory. Force collection of soft references. Force
 783   // a complete compaction of the heap. Any additional methods for finding
 784   // free memory should be here, especially if they are expensive. If this
 785   // attempt fails, an OOM exception will be thrown.
 786   {
 787     UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
 788 
 789     gch->do_collection(true             /* full */,
 790                        true             /* clear_all_soft_refs */,
 791                        size             /* size */,
 792                        is_tlab          /* is_tlab */,
 793                        number_of_generations() - 1 /* max_level */);
 794   }
 795 
 796   result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
 797   if (result != NULL) {
 798     assert(gch->is_in_reserved(result), "result not in heap");
 799     return result;
 800   }
 801 
 802   assert(!should_clear_all_soft_refs(),
 803     "Flag should have been handled and cleared prior to this point");
 804 
 805   // What else?  We might try synchronous finalization later.  If the total
 806   // space available is large enough for the allocation, then a more
 807   // complete compaction phase than we've tried so far might be
 808   // appropriate.
 809   return NULL;
 810 }
 811 
 812 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(
 813                                                  ClassLoaderData* loader_data,
 814                                                  size_t word_size,
 815                                                  Metaspace::MetadataType mdtype) {
 816   uint loop_count = 0;
 817   uint gc_count = 0;
 818   uint full_gc_count = 0;
 819   uint gc_attempt = 1;
 820 
 821   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
 822 
 823   do {
 824     MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
 825     if (result != NULL) {
 826       return result;
 827     }
 828 
 829     if (GC_locker::is_active_and_needs_gc()) {
 830       // If the GC_locker is active, just expand and allocate.
 831       // If that does not succeed, wait if this thread is not
 832       // in a critical section itself.
 833       result =
 834         loader_data->metaspace_non_null()->expand_and_allocate(word_size,
 835                                                                mdtype);
 836       if (result != NULL) {
 837         return result;
 838       }
 839       JavaThread* jthr = JavaThread::current();
 840       if (!jthr->in_critical()) {
 841         // Wait for JNI critical section to be exited
 842         GC_locker::stall_until_clear();
 843         // The GC invoked by the last thread leaving the critical
 844         // section will be a young collection and a full collection
 845         // is (currently) needed for unloading classes so continue
 846         // to the next iteration to get a full GC.
 847         continue;
 848       } else {
 849         if (CheckJNICalls) {
 850           fatal("Possible deadlock due to allocating while"
 851                 " in jni critical section");
 852         }
 853         return NULL;
 854       }
 855     }
 856 
 857     {  // Need lock to get self consistent gc_count's
 858       MutexLocker ml(Heap_lock);
 859       gc_count      = Universe::heap()->total_collections();
 860       full_gc_count = Universe::heap()->total_full_collections();
 861     }
 862 
 863     // Generate a VM operation
 864     VM_CollectForMetadataAllocation op(loader_data,
 865                                        word_size,
 866                                        mdtype,
 867                                        gc_count,
 868                                        full_gc_count,
 869                                        GCCause::_metadata_GC_threshold,
 870                                        gc_attempt++);
 871     VMThread::execute(&op);
 872 
 873     // If GC was locked out, try again. Check before checking success because the
 874     // prologue could have succeeded and the GC still have been locked out.
 875     if (op.gc_locked()) {
 876       continue;
 877     }
 878 
 879     if (op.prologue_succeeded()) {
 880       return op.result();
 881     }
 882     loop_count++;
 883     if ((QueuedAllocationWarningCount > 0) &&
 884         (loop_count % QueuedAllocationWarningCount == 0)) {
 885       warning("satisfy_failed_metadata_allocation() retries %d times \n\t"
 886               " size=" SIZE_FORMAT, loop_count, word_size);
 887     }
 888   } while (true);  // Until a GC is done
 889 }
 890 
 891 // Return true if any of the following is true:
 892 // . the allocation won't fit into the current young gen heap
 893 // . gc locker is occupied (jni critical section)
 894 // . heap memory is tight -- the most recent previous collection
 895 //   was a full collection because a partial collection (would
 896 //   have) failed and is likely to fail again
 897 bool GenCollectorPolicy::should_try_older_generation_allocation(
 898         size_t word_size) const {
 899   GenCollectedHeap* gch = GenCollectedHeap::heap();
 900   size_t young_capacity = gch->young_gen()->capacity_before_gc();
 901   return    (word_size > heap_word_size(young_capacity))
 902          || GC_locker::is_active_and_needs_gc()
 903          || gch->incremental_collection_failed();
 904 }
 905 
 906 
 907 //
 908 // MarkSweepPolicy methods
 909 //
 910 
 911 void MarkSweepPolicy::initialize_alignments() {
 912   _space_alignment = _gen_alignment = (size_t)Generation::GenGrain;
 913   _heap_alignment = compute_heap_alignment();
 914 }
 915 
 916 void MarkSweepPolicy::initialize_generations() {
 917   _generations = NEW_C_HEAP_ARRAY(GenerationSpecPtr, number_of_generations(), mtGC);
 918   _generations[0] = new GenerationSpec(Generation::DefNew, _initial_young_size, _max_young_size);
 919   _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_old_size, _max_old_size);
 920 }
 921 
 922 void MarkSweepPolicy::initialize_gc_policy_counters() {
 923   // Initialize the policy counters - 2 collectors, 3 generations.
 924   _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
 925 }
 926 
 927 /////////////// Unit tests ///////////////
 928 
 929 #ifndef PRODUCT
 930 // Testing that the NewSize flag is handled correct is hard because it
 931 // depends on so many other configurable variables. This test only tries to
 932 // verify that there are some basic rules for NewSize honored by the policies.
 933 class TestGenCollectorPolicy {
 934 public:
 935   static void test_new_size() {
 936     size_t flag_value;
 937 
 938     save_flags();
 939 
 940     // If NewSize is set on the command line, it should be used
 941     // for both min and initial young size if less than min heap.
 942     flag_value = 20 * M;
 943     set_basic_flag_values();
 944     FLAG_SET_CMDLINE(size_t, NewSize, flag_value);
 945     verify_young_min(flag_value);
 946 
 947     set_basic_flag_values();
 948     FLAG_SET_CMDLINE(size_t, NewSize, flag_value);
 949     verify_young_initial(flag_value);
 950 
 951     // If NewSize is set on command line, but is larger than the min
 952     // heap size, it should only be used for initial young size.
 953     flag_value = 80 * M;
 954     set_basic_flag_values();
 955     FLAG_SET_CMDLINE(size_t, NewSize, flag_value);
 956     verify_young_initial(flag_value);
 957 
 958     // If NewSize has been ergonomically set, the collector policy
 959     // should use it for min but calculate the initial young size
 960     // using NewRatio.
 961     flag_value = 20 * M;
 962     set_basic_flag_values();
 963     FLAG_SET_ERGO(size_t, NewSize, flag_value);
 964     verify_young_min(flag_value);
 965 
 966     set_basic_flag_values();
 967     FLAG_SET_ERGO(size_t, NewSize, flag_value);
 968     verify_scaled_young_initial(InitialHeapSize);
 969 
 970     restore_flags();
 971   }
 972 
 973   static void test_old_size() {
 974     size_t flag_value;
 975     size_t heap_alignment = CollectorPolicy::compute_heap_alignment();
 976 
 977     save_flags();
 978 
 979     // If OldSize is set on the command line, it should be used
 980     // for both min and initial old size if less than min heap.
 981     flag_value = 20 * M;
 982     set_basic_flag_values();
 983     FLAG_SET_CMDLINE(size_t, OldSize, flag_value);
 984     verify_old_min(flag_value);
 985 
 986     set_basic_flag_values();
 987     FLAG_SET_CMDLINE(size_t, OldSize, flag_value);
 988     // Calculate what we expect the flag to be.
 989     size_t expected_old_initial = align_size_up(InitialHeapSize, heap_alignment) - MaxNewSize;
 990     verify_old_initial(expected_old_initial);
 991 
 992     // If MaxNewSize is large, the maximum OldSize will be less than
 993     // what's requested on the command line and it should be reset
 994     // ergonomically.
 995     // We intentionally set MaxNewSize + OldSize > MaxHeapSize (see over_size).
 996     flag_value = 30 * M;
 997     set_basic_flag_values();
 998     FLAG_SET_CMDLINE(size_t, OldSize, flag_value);
 999     size_t over_size = 20*M;
1000     size_t new_size_value = align_size_up(MaxHeapSize, heap_alignment) - flag_value + over_size;
1001     FLAG_SET_CMDLINE(size_t, MaxNewSize, new_size_value);
1002     // Calculate what we expect the flag to be.
1003     expected_old_initial = align_size_up(MaxHeapSize, heap_alignment) - MaxNewSize;
1004     verify_old_initial(expected_old_initial);
1005     restore_flags();
1006   }
1007 
1008   static void verify_young_min(size_t expected) {
1009     MarkSweepPolicy msp;
1010     msp.initialize_all();
1011 
1012     assert(msp.min_young_size() <= expected, err_msg("%zu  > %zu", msp.min_young_size(), expected));
1013   }
1014 
1015   static void verify_young_initial(size_t expected) {
1016     MarkSweepPolicy msp;
1017     msp.initialize_all();
1018 
1019     assert(msp.initial_young_size() == expected, err_msg("%zu != %zu", msp.initial_young_size(), expected));
1020   }
1021 
1022   static void verify_scaled_young_initial(size_t initial_heap_size) {
1023     MarkSweepPolicy msp;
1024     msp.initialize_all();
1025 
1026     if (InitialHeapSize > initial_heap_size) {
1027       // InitialHeapSize was adapted by msp.initialize_all, e.g. due to alignment
1028       // caused by 64K page size.
1029       initial_heap_size = InitialHeapSize;
1030     }
1031 
1032     size_t expected = msp.scale_by_NewRatio_aligned(initial_heap_size);
1033     assert(msp.initial_young_size() == expected, err_msg("%zu != %zu", msp.initial_young_size(), expected));
1034     assert(FLAG_IS_ERGO(NewSize) && NewSize == expected,
1035         err_msg("NewSize should have been set ergonomically to %zu, but was %zu", expected, NewSize));
1036   }
1037 
1038   static void verify_old_min(size_t expected) {
1039     MarkSweepPolicy msp;
1040     msp.initialize_all();
1041 
1042     assert(msp.min_old_size() <= expected, err_msg("%zu  > %zu", msp.min_old_size(), expected));
1043   }
1044 
1045   static void verify_old_initial(size_t expected) {
1046     MarkSweepPolicy msp;
1047     msp.initialize_all();
1048 
1049     assert(msp.initial_old_size() == expected, err_msg("%zu != %zu", msp.initial_old_size(), expected));
1050   }
1051 
1052 
1053 private:
1054   static size_t original_InitialHeapSize;
1055   static size_t original_MaxHeapSize;
1056   static size_t original_MaxNewSize;
1057   static size_t original_MinHeapDeltaBytes;
1058   static size_t original_NewSize;
1059   static size_t original_OldSize;
1060 
1061   static void set_basic_flag_values() {
1062     FLAG_SET_ERGO(size_t, MaxHeapSize, 180 * M);
1063     FLAG_SET_ERGO(size_t, InitialHeapSize, 100 * M);
1064     FLAG_SET_ERGO(size_t, OldSize, 4 * M);
1065     FLAG_SET_ERGO(size_t, NewSize, 1 * M);
1066     FLAG_SET_ERGO(size_t, MaxNewSize, 80 * M);
1067     Arguments::set_min_heap_size(40 * M);
1068   }
1069 
1070   static void save_flags() {
1071     original_InitialHeapSize   = InitialHeapSize;
1072     original_MaxHeapSize       = MaxHeapSize;
1073     original_MaxNewSize        = MaxNewSize;
1074     original_MinHeapDeltaBytes = MinHeapDeltaBytes;
1075     original_NewSize           = NewSize;
1076     original_OldSize           = OldSize;
1077   }
1078 
1079   static void restore_flags() {
1080     InitialHeapSize   = original_InitialHeapSize;
1081     MaxHeapSize       = original_MaxHeapSize;
1082     MaxNewSize        = original_MaxNewSize;
1083     MinHeapDeltaBytes = original_MinHeapDeltaBytes;
1084     NewSize           = original_NewSize;
1085     OldSize           = original_OldSize;
1086   }
1087 };
1088 
1089 size_t TestGenCollectorPolicy::original_InitialHeapSize   = 0;
1090 size_t TestGenCollectorPolicy::original_MaxHeapSize       = 0;
1091 size_t TestGenCollectorPolicy::original_MaxNewSize        = 0;
1092 size_t TestGenCollectorPolicy::original_MinHeapDeltaBytes = 0;
1093 size_t TestGenCollectorPolicy::original_NewSize           = 0;
1094 size_t TestGenCollectorPolicy::original_OldSize           = 0;
1095 
1096 void TestNewSize_test() {
1097   TestGenCollectorPolicy::test_new_size();
1098 }
1099 
1100 void TestOldSize_test() {
1101   TestGenCollectorPolicy::test_old_size();
1102 }
1103 
1104 #endif