1 /*
   2  * Copyright (c) 2001, 2016, 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/shared/adaptiveSizePolicy.hpp"
  27 #include "gc/shared/cardTableRS.hpp"
  28 #include "gc/shared/collectorPolicy.hpp"
  29 #include "gc/shared/gcLocker.inline.hpp"
  30 #include "gc/shared/gcPolicyCounters.hpp"
  31 #include "gc/shared/genCollectedHeap.hpp"
  32 #include "gc/shared/generationSpec.hpp"
  33 #include "gc/shared/space.hpp"
  34 #include "gc/shared/vmGCOperations.hpp"
  35 #include "logging/log.hpp"
  36 #include "memory/universe.hpp"
  37 #include "runtime/arguments.hpp"
  38 #include "runtime/globals_extension.hpp"
  39 #include "runtime/handles.inline.hpp"
  40 #include "runtime/java.hpp"
  41 #include "runtime/thread.inline.hpp"
  42 #include "runtime/vmThread.hpp"
  43 #include "utilities/align.hpp"
  44 #include "utilities/macros.hpp"
  45 
  46 // CollectorPolicy methods
  47 
  48 CollectorPolicy::CollectorPolicy() :
  49     _space_alignment(0),
  50     _heap_alignment(0),
  51     _initial_heap_byte_size(InitialHeapSize),
  52     _max_heap_byte_size(MaxHeapSize),
  53     _min_heap_byte_size(Arguments::min_heap_size()),
  54     _size_policy(NULL),
  55     _should_clear_all_soft_refs(false),
  56     _all_soft_refs_clear(false)
  57 {}
  58 
  59 #ifdef ASSERT
  60 void CollectorPolicy::assert_flags() {
  61   assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");
  62   assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment");
  63   assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment");
  64 }
  65 
  66 void CollectorPolicy::assert_size_info() {
  67   assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage");
  68   assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage");
  69   assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes");
  70   assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes");
  71   assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes");
  72   assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment");
  73   assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment");
  74   assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment");
  75 }
  76 #endif // ASSERT
  77 
  78 void CollectorPolicy::initialize_flags() {
  79   assert(_space_alignment != 0, "Space alignment not set up properly");
  80   assert(_heap_alignment != 0, "Heap alignment not set up properly");
  81   assert(_heap_alignment >= _space_alignment,
  82          "heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT,
  83          _heap_alignment, _space_alignment);
  84   assert(_heap_alignment % _space_alignment == 0,
  85          "heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
  86          _heap_alignment, _space_alignment);
  87 
  88   if (FLAG_IS_CMDLINE(MaxHeapSize)) {
  89     if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
  90       vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");
  91     }
  92     if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) {
  93       vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
  94     }
  95   }
  96 
  97   // Check heap parameter properties
  98   if (MaxHeapSize < 2 * M) {
  99     vm_exit_during_initialization("Too small maximum heap");
 100   }
 101   if (InitialHeapSize < M) {
 102     vm_exit_during_initialization("Too small initial heap");
 103   }
 104   if (_min_heap_byte_size < M) {
 105     vm_exit_during_initialization("Too small minimum heap");
 106   }
 107 
 108   // User inputs from -Xmx and -Xms must be aligned
 109   _min_heap_byte_size = align_up(_min_heap_byte_size, _heap_alignment);
 110   size_t aligned_initial_heap_size = align_up(InitialHeapSize, _heap_alignment);
 111   size_t aligned_max_heap_size = align_up(MaxHeapSize, _heap_alignment);
 112 
 113   // Write back to flags if the values changed
 114   if (aligned_initial_heap_size != InitialHeapSize) {
 115     FLAG_SET_ERGO(size_t, InitialHeapSize, aligned_initial_heap_size);
 116   }
 117   if (aligned_max_heap_size != MaxHeapSize) {
 118     FLAG_SET_ERGO(size_t, MaxHeapSize, aligned_max_heap_size);
 119   }
 120 
 121   if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 &&
 122       InitialHeapSize < _min_heap_byte_size) {
 123     vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
 124   }
 125   if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
 126     FLAG_SET_ERGO(size_t, MaxHeapSize, InitialHeapSize);
 127   } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {
 128     FLAG_SET_ERGO(size_t, InitialHeapSize, MaxHeapSize);
 129     if (InitialHeapSize < _min_heap_byte_size) {
 130       _min_heap_byte_size = InitialHeapSize;
 131     }
 132   }
 133 
 134   _initial_heap_byte_size = InitialHeapSize;
 135   _max_heap_byte_size = MaxHeapSize;
 136 
 137   FLAG_SET_ERGO(size_t, MinHeapDeltaBytes, align_up(MinHeapDeltaBytes, _space_alignment));
 138 
 139   DEBUG_ONLY(CollectorPolicy::assert_flags();)
 140 }
 141 
 142 void CollectorPolicy::initialize_size_info() {
 143   log_debug(gc, heap)("Minimum heap " SIZE_FORMAT "  Initial heap " SIZE_FORMAT "  Maximum heap " SIZE_FORMAT,
 144                       _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);
 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 CardTableRS* 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 = CardTableRS::ct_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     _min_old_size(0),
 194     _initial_old_size(0),
 195     _max_old_size(0),
 196     _gen_alignment(0),
 197     _young_gen_spec(NULL),
 198     _old_gen_spec(NULL)
 199 {}
 200 
 201 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {
 202   return align_down_bounded(base_size / (NewRatio + 1), _gen_alignment);
 203 }
 204 
 205 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,
 206                                                  size_t maximum_size) {
 207   size_t max_minus = maximum_size - _gen_alignment;
 208   return desired_size < max_minus ? desired_size : max_minus;
 209 }
 210 
 211 
 212 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
 213                                                 size_t init_promo_size,
 214                                                 size_t init_survivor_size) {
 215   const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
 216   _size_policy = new AdaptiveSizePolicy(init_eden_size,
 217                                         init_promo_size,
 218                                         init_survivor_size,
 219                                         max_gc_pause_sec,
 220                                         GCTimeRatio);
 221 }
 222 
 223 size_t GenCollectorPolicy::young_gen_size_lower_bound() {
 224   // The young generation must be aligned and have room for eden + two survivors
 225   return align_up(3 * _space_alignment, _gen_alignment);
 226 }
 227 
 228 size_t GenCollectorPolicy::old_gen_size_lower_bound() {
 229   return align_up(_space_alignment, _gen_alignment);
 230 }
 231 
 232 #ifdef ASSERT
 233 void GenCollectorPolicy::assert_flags() {
 234   CollectorPolicy::assert_flags();
 235   assert(NewSize >= _min_young_size, "Ergonomics decided on a too small young gen size");
 236   assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes");
 237   assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes");
 238   assert(NewSize % _gen_alignment == 0, "NewSize alignment");
 239   assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment");
 240   assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");
 241   assert(OldSize % _gen_alignment == 0, "OldSize alignment");
 242 }
 243 
 244 void GenCollectorPolicy::assert_size_info() {
 245   CollectorPolicy::assert_size_info();
 246   // GenCollectorPolicy::initialize_size_info may update the MaxNewSize
 247   assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");
 248   assert(NewSize == _initial_young_size, "Discrepancy between NewSize flag and local storage");
 249   assert(MaxNewSize == _max_young_size, "Discrepancy between MaxNewSize flag and local storage");
 250   assert(OldSize == _initial_old_size, "Discrepancy between OldSize flag and local storage");
 251   assert(_min_young_size <= _initial_young_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");
 252   assert(_initial_young_size <= _max_young_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");
 253   assert(_min_young_size % _gen_alignment == 0, "_min_young_size alignment");
 254   assert(_initial_young_size % _gen_alignment == 0, "_initial_young_size alignment");
 255   assert(_max_young_size % _gen_alignment == 0, "_max_young_size alignment");
 256   assert(_min_young_size <= bound_minus_alignment(_min_young_size, _min_heap_byte_size),
 257       "Ergonomics made minimum young generation larger than minimum heap");
 258   assert(_initial_young_size <=  bound_minus_alignment(_initial_young_size, _initial_heap_byte_size),
 259       "Ergonomics made initial young generation larger than initial heap");
 260   assert(_max_young_size <= bound_minus_alignment(_max_young_size, _max_heap_byte_size),
 261       "Ergonomics made maximum young generation lager than maximum heap");
 262   assert(_min_old_size <= _initial_old_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");
 263   assert(_initial_old_size <= _max_old_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");
 264   assert(_max_old_size % _gen_alignment == 0, "_max_old_size alignment");
 265   assert(_initial_old_size % _gen_alignment == 0, "_initial_old_size alignment");
 266   assert(_max_heap_byte_size <= (_max_young_size + _max_old_size), "Total maximum heap sizes must be sum of generation maximum sizes");
 267   assert(_min_young_size + _min_old_size <= _min_heap_byte_size, "Minimum generation sizes exceed minimum heap size");
 268   assert(_initial_young_size + _initial_old_size == _initial_heap_byte_size, "Initial generation sizes should match initial heap size");
 269   assert(_max_young_size + _max_old_size == _max_heap_byte_size, "Maximum generation sizes should match maximum heap size");
 270 }
 271 #endif // ASSERT
 272 
 273 void GenCollectorPolicy::initialize_flags() {
 274   CollectorPolicy::initialize_flags();
 275 
 276   assert(_gen_alignment != 0, "Generation alignment not set up properly");
 277   assert(_heap_alignment >= _gen_alignment,
 278          "heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,
 279          _heap_alignment, _gen_alignment);
 280   assert(_gen_alignment % _space_alignment == 0,
 281          "gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,
 282          _gen_alignment, _space_alignment);
 283   assert(_heap_alignment % _gen_alignment == 0,
 284          "heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT,
 285          _heap_alignment, _gen_alignment);
 286 
 287   // All generational heaps have a young gen; handle those flags here
 288 
 289   // Make sure the heap is large enough for two generations
 290   size_t smallest_new_size = young_gen_size_lower_bound();
 291   size_t smallest_heap_size = align_up(smallest_new_size + old_gen_size_lower_bound(),
 292                                            _heap_alignment);
 293   if (MaxHeapSize < smallest_heap_size) {
 294     FLAG_SET_ERGO(size_t, MaxHeapSize, smallest_heap_size);
 295     _max_heap_byte_size = MaxHeapSize;
 296   }
 297   // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size
 298   if (_min_heap_byte_size < smallest_heap_size) {
 299     _min_heap_byte_size = smallest_heap_size;
 300     if (InitialHeapSize < _min_heap_byte_size) {
 301       FLAG_SET_ERGO(size_t, InitialHeapSize, smallest_heap_size);
 302       _initial_heap_byte_size = smallest_heap_size;
 303     }
 304   }
 305 
 306   // Make sure NewSize allows an old generation to fit even if set on the command line
 307   if (FLAG_IS_CMDLINE(NewSize) && NewSize >= _initial_heap_byte_size) {
 308     log_warning(gc, ergo)("NewSize was set larger than initial heap size, will use initial heap size.");
 309     FLAG_SET_ERGO(size_t, NewSize, bound_minus_alignment(NewSize, _initial_heap_byte_size));
 310   }
 311 
 312   // Now take the actual NewSize into account. We will silently increase NewSize
 313   // if the user specified a smaller or unaligned value.
 314   size_t bounded_new_size = bound_minus_alignment(NewSize, MaxHeapSize);
 315   bounded_new_size = MAX2(smallest_new_size, align_down(bounded_new_size, _gen_alignment));
 316   if (bounded_new_size != NewSize) {
 317     FLAG_SET_ERGO(size_t, NewSize, bounded_new_size);
 318   }
 319   _min_young_size = smallest_new_size;
 320   _initial_young_size = NewSize;
 321 
 322   if (!FLAG_IS_DEFAULT(MaxNewSize)) {
 323     if (MaxNewSize >= MaxHeapSize) {
 324       // Make sure there is room for an old generation
 325       size_t smaller_max_new_size = MaxHeapSize - _gen_alignment;
 326       if (FLAG_IS_CMDLINE(MaxNewSize)) {
 327         log_warning(gc, ergo)("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "
 328                               "heap (" SIZE_FORMAT "k).  A new max generation size of " SIZE_FORMAT "k will be used.",
 329                               MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K);
 330       }
 331       FLAG_SET_ERGO(size_t, MaxNewSize, smaller_max_new_size);
 332       if (NewSize > MaxNewSize) {
 333         FLAG_SET_ERGO(size_t, NewSize, MaxNewSize);
 334         _initial_young_size = NewSize;
 335       }
 336     } else if (MaxNewSize < _initial_young_size) {
 337       FLAG_SET_ERGO(size_t, MaxNewSize, _initial_young_size);
 338     } else if (!is_aligned(MaxNewSize, _gen_alignment)) {
 339       FLAG_SET_ERGO(size_t, MaxNewSize, align_down(MaxNewSize, _gen_alignment));
 340     }
 341     _max_young_size = MaxNewSize;
 342   }
 343 
 344   if (NewSize > MaxNewSize) {
 345     // At this point this should only happen if the user specifies a large NewSize and/or
 346     // a small (but not too small) MaxNewSize.
 347     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 348       log_warning(gc, ergo)("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "
 349                             "A new max generation size of " SIZE_FORMAT "k will be used.",
 350                             NewSize/K, MaxNewSize/K, NewSize/K);
 351     }
 352     FLAG_SET_ERGO(size_t, MaxNewSize, NewSize);
 353     _max_young_size = MaxNewSize;
 354   }
 355 
 356   if (SurvivorRatio < 1 || NewRatio < 1) {
 357     vm_exit_during_initialization("Invalid young gen ratio specified");
 358   }
 359 
 360   if (OldSize < old_gen_size_lower_bound()) {
 361     FLAG_SET_ERGO(size_t, OldSize, old_gen_size_lower_bound());
 362   }
 363   if (!is_aligned(OldSize, _gen_alignment)) {
 364     FLAG_SET_ERGO(size_t, OldSize, align_down(OldSize, _gen_alignment));
 365   }
 366 
 367   if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {
 368     // NewRatio will be used later to set the young generation size so we use
 369     // it to calculate how big the heap should be based on the requested OldSize
 370     // and NewRatio.
 371     assert(NewRatio > 0, "NewRatio should have been set up earlier");
 372     size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);
 373 
 374     calculated_heapsize = align_up(calculated_heapsize, _heap_alignment);
 375     FLAG_SET_ERGO(size_t, MaxHeapSize, calculated_heapsize);
 376     _max_heap_byte_size = MaxHeapSize;
 377     FLAG_SET_ERGO(size_t, InitialHeapSize, calculated_heapsize);
 378     _initial_heap_byte_size = InitialHeapSize;
 379   }
 380 
 381   // Adjust NewSize and OldSize or MaxHeapSize to match each other
 382   if (NewSize + OldSize > MaxHeapSize) {
 383     if (FLAG_IS_CMDLINE(MaxHeapSize)) {
 384       // Somebody has set a maximum heap size with the intention that we should not
 385       // exceed it. Adjust New/OldSize as necessary.
 386       size_t calculated_size = NewSize + OldSize;
 387       double shrink_factor = (double) MaxHeapSize / calculated_size;
 388       size_t smaller_new_size = align_down((size_t)(NewSize * shrink_factor), _gen_alignment);
 389       FLAG_SET_ERGO(size_t, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size));
 390       _initial_young_size = NewSize;
 391 
 392       // OldSize is already aligned because above we aligned MaxHeapSize to
 393       // _heap_alignment, and we just made sure that NewSize is aligned to
 394       // _gen_alignment. In initialize_flags() we verified that _heap_alignment
 395       // is a multiple of _gen_alignment.
 396       FLAG_SET_ERGO(size_t, OldSize, MaxHeapSize - NewSize);
 397     } else {
 398       FLAG_SET_ERGO(size_t, MaxHeapSize, align_up(NewSize + OldSize, _heap_alignment));
 399       _max_heap_byte_size = MaxHeapSize;
 400     }
 401   }
 402 
 403   // Update NewSize, if possible, to avoid sizing the young gen too small when only
 404   // OldSize is set on the command line.
 405   if (FLAG_IS_CMDLINE(OldSize) && !FLAG_IS_CMDLINE(NewSize)) {
 406     if (OldSize < _initial_heap_byte_size) {
 407       size_t new_size = _initial_heap_byte_size - OldSize;
 408       // Need to compare against the flag value for max since _max_young_size
 409       // might not have been set yet.
 410       if (new_size >= _min_young_size && new_size <= MaxNewSize) {
 411         FLAG_SET_ERGO(size_t, NewSize, new_size);
 412         _initial_young_size = NewSize;
 413       }
 414     }
 415   }
 416 
 417   always_do_update_barrier = UseConcMarkSweepGC;
 418 
 419   DEBUG_ONLY(GenCollectorPolicy::assert_flags();)
 420 }
 421 
 422 // Values set on the command line win over any ergonomically
 423 // set command line parameters.
 424 // Ergonomic choice of parameters are done before this
 425 // method is called.  Values for command line parameters such as NewSize
 426 // and MaxNewSize feed those ergonomic choices into this method.
 427 // This method makes the final generation sizings consistent with
 428 // themselves and with overall heap sizings.
 429 // In the absence of explicitly set command line flags, policies
 430 // such as the use of NewRatio are used to size the generation.
 431 
 432 // Minimum sizes of the generations may be different than
 433 // the initial sizes.  An inconsistency is permitted here
 434 // in the total size that can be specified explicitly by
 435 // command line specification of OldSize and NewSize and
 436 // also a command line specification of -Xms.  Issue a warning
 437 // but allow the values to pass.
 438 void GenCollectorPolicy::initialize_size_info() {
 439   CollectorPolicy::initialize_size_info();
 440 
 441   _initial_young_size = NewSize;
 442   _max_young_size = MaxNewSize;
 443   _initial_old_size = OldSize;
 444 
 445   // Determine maximum size of the young generation.
 446 
 447   if (FLAG_IS_DEFAULT(MaxNewSize)) {
 448     _max_young_size = scale_by_NewRatio_aligned(_max_heap_byte_size);
 449     // Bound the maximum size by NewSize below (since it historically
 450     // would have been NewSize and because the NewRatio calculation could
 451     // yield a size that is too small) and bound it by MaxNewSize above.
 452     // Ergonomics plays here by previously calculating the desired
 453     // NewSize and MaxNewSize.
 454     _max_young_size = MIN2(MAX2(_max_young_size, _initial_young_size), MaxNewSize);
 455   }
 456 
 457   // Given the maximum young size, determine the initial and
 458   // minimum young sizes.
 459 
 460   if (_max_heap_byte_size == _initial_heap_byte_size) {
 461     // The maximum and initial heap sizes are the same so the generation's
 462     // initial size must be the same as it maximum size. Use NewSize as the
 463     // size if set on command line.
 464     _max_young_size = FLAG_IS_CMDLINE(NewSize) ? NewSize : _max_young_size;
 465     _initial_young_size = _max_young_size;
 466 
 467     // Also update the minimum size if min == initial == max.
 468     if (_max_heap_byte_size == _min_heap_byte_size) {
 469       _min_young_size = _max_young_size;
 470     }
 471   } else {
 472     if (FLAG_IS_CMDLINE(NewSize)) {
 473       // If NewSize is set on the command line, we should use it as
 474       // the initial size, but make sure it is within the heap bounds.
 475       _initial_young_size =
 476         MIN2(_max_young_size, bound_minus_alignment(NewSize, _initial_heap_byte_size));
 477       _min_young_size = bound_minus_alignment(_initial_young_size, _min_heap_byte_size);
 478     } else {
 479       // For the case where NewSize is not set on the command line, use
 480       // NewRatio to size the initial generation size. Use the current
 481       // NewSize as the floor, because if NewRatio is overly large, the resulting
 482       // size can be too small.
 483       _initial_young_size =
 484         MIN2(_max_young_size, MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize));
 485     }
 486   }
 487 
 488   log_trace(gc, heap)("1: Minimum young " SIZE_FORMAT "  Initial young " SIZE_FORMAT "  Maximum young " SIZE_FORMAT,
 489                       _min_young_size, _initial_young_size, _max_young_size);
 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       log_warning(gc, ergo)("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     log_warning(gc, ergo)("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     log_trace(gc, heap)("2: Minimum young " SIZE_FORMAT "  Initial young " SIZE_FORMAT "  Maximum young " SIZE_FORMAT,
 556                     _min_young_size, _initial_young_size, _max_young_size);
 557   }
 558 
 559   // Write back to flags if necessary.
 560   if (NewSize != _initial_young_size) {
 561     FLAG_SET_ERGO(size_t, NewSize, _initial_young_size);
 562   }
 563 
 564   if (MaxNewSize != _max_young_size) {
 565     FLAG_SET_ERGO(size_t, MaxNewSize, _max_young_size);
 566   }
 567 
 568   if (OldSize != _initial_old_size) {
 569     FLAG_SET_ERGO(size_t, OldSize, _initial_old_size);
 570   }
 571 
 572   log_trace(gc, heap)("Minimum old " SIZE_FORMAT "  Initial old " SIZE_FORMAT "  Maximum old " SIZE_FORMAT,
 573                   _min_old_size, _initial_old_size, _max_old_size);
 574 
 575   DEBUG_ONLY(GenCollectorPolicy::assert_size_info();)
 576 }
 577 
 578 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
 579                                         bool is_tlab,
 580                                         bool* gc_overhead_limit_was_exceeded) {
 581   GenCollectedHeap *gch = GenCollectedHeap::heap();
 582 
 583   debug_only(gch->check_for_valid_allocation_state());
 584   assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
 585 
 586   // In general gc_overhead_limit_was_exceeded should be false so
 587   // set it so here and reset it to true only if the gc time
 588   // limit is being exceeded as checked below.
 589   *gc_overhead_limit_was_exceeded = false;
 590 
 591   HeapWord* result = NULL;
 592 
 593   // Loop until the allocation is satisfied, or unsatisfied after GC.
 594   for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
 595     HandleMark hm; // Discard any handles allocated in each iteration.
 596 
 597     // First allocation attempt is lock-free.
 598     Generation *young = gch->young_gen();
 599     assert(young->supports_inline_contig_alloc(),
 600       "Otherwise, must do alloc within heap lock");
 601     if (young->should_allocate(size, is_tlab)) {
 602       result = young->par_allocate(size, is_tlab);
 603       if (result != NULL) {
 604         assert(gch->is_in_reserved(result), "result not in heap");
 605         return result;
 606       }
 607     }
 608     uint gc_count_before;  // Read inside the Heap_lock locked region.
 609     {
 610       MutexLocker ml(Heap_lock);
 611       log_trace(gc, alloc)("GenCollectorPolicy::mem_allocate_work: attempting locked slow path allocation");
 612       // Note that only large objects get a shot at being
 613       // allocated in later generations.
 614       bool first_only = ! should_try_older_generation_allocation(size);
 615 
 616       result = gch->attempt_allocation(size, is_tlab, first_only);
 617       if (result != NULL) {
 618         assert(gch->is_in_reserved(result), "result not in heap");
 619         return result;
 620       }
 621 
 622       if (GCLocker::is_active_and_needs_gc()) {
 623         if (is_tlab) {
 624           return NULL;  // Caller will retry allocating individual object.
 625         }
 626         if (!gch->is_maximal_no_gc()) {
 627           // Try and expand heap to satisfy request.
 628           result = expand_heap_and_allocate(size, is_tlab);
 629           // Result could be null if we are out of space.
 630           if (result != NULL) {
 631             return result;
 632           }
 633         }
 634 
 635         if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
 636           return NULL; // We didn't get to do a GC and we didn't get any memory.
 637         }
 638 
 639         // If this thread is not in a jni critical section, we stall
 640         // the requestor until the critical section has cleared and
 641         // GC allowed. When the critical section clears, a GC is
 642         // initiated by the last thread exiting the critical section; so
 643         // we retry the allocation sequence from the beginning of the loop,
 644         // rather than causing more, now probably unnecessary, GC attempts.
 645         JavaThread* jthr = JavaThread::current();
 646         if (!jthr->in_critical()) {
 647           MutexUnlocker mul(Heap_lock);
 648           // Wait for JNI critical section to be exited
 649           GCLocker::stall_until_clear();
 650           gclocker_stalled_count += 1;
 651           continue;
 652         } else {
 653           if (CheckJNICalls) {
 654             fatal("Possible deadlock due to allocating while"
 655                   " in jni critical section");
 656           }
 657           return NULL;
 658         }
 659       }
 660 
 661       // Read the gc count while the heap lock is held.
 662       gc_count_before = gch->total_collections();
 663     }
 664 
 665     VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
 666     VMThread::execute(&op);
 667     if (op.prologue_succeeded()) {
 668       result = op.result();
 669       if (op.gc_locked()) {
 670          assert(result == NULL, "must be NULL if gc_locked() is true");
 671          continue;  // Retry and/or stall as necessary.
 672       }
 673 
 674       // Allocation has failed and a collection
 675       // has been done.  If the gc time limit was exceeded the
 676       // this time, return NULL so that an out-of-memory
 677       // will be thrown.  Clear gc_overhead_limit_exceeded
 678       // so that the overhead exceeded does not persist.
 679 
 680       const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
 681       const bool softrefs_clear = all_soft_refs_clear();
 682 
 683       if (limit_exceeded && softrefs_clear) {
 684         *gc_overhead_limit_was_exceeded = true;
 685         size_policy()->set_gc_overhead_limit_exceeded(false);
 686         if (op.result() != NULL) {
 687           CollectedHeap::fill_with_object(op.result(), size);
 688         }
 689         return NULL;
 690       }
 691       assert(result == NULL || gch->is_in_reserved(result),
 692              "result not in heap");
 693       return result;
 694     }
 695 
 696     // Give a warning if we seem to be looping forever.
 697     if ((QueuedAllocationWarningCount > 0) &&
 698         (try_count % QueuedAllocationWarningCount == 0)) {
 699           log_warning(gc, ergo)("GenCollectorPolicy::mem_allocate_work retries %d times,"
 700                                 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
 701     }
 702   }
 703 }
 704 
 705 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
 706                                                        bool   is_tlab) {
 707   GenCollectedHeap *gch = GenCollectedHeap::heap();
 708   HeapWord* result = NULL;
 709   Generation *old = gch->old_gen();
 710   if (old->should_allocate(size, is_tlab)) {
 711     result = old->expand_and_allocate(size, is_tlab);
 712   }
 713   if (result == NULL) {
 714     Generation *young = gch->young_gen();
 715     if (young->should_allocate(size, is_tlab)) {
 716       result = young->expand_and_allocate(size, is_tlab);
 717     }
 718   }
 719   assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
 720   return result;
 721 }
 722 
 723 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
 724                                                         bool   is_tlab) {
 725   GenCollectedHeap *gch = GenCollectedHeap::heap();
 726   GCCauseSetter x(gch, GCCause::_allocation_failure);
 727   HeapWord* result = NULL;
 728 
 729   assert(size != 0, "Precondition violated");
 730   if (GCLocker::is_active_and_needs_gc()) {
 731     // GC locker is active; instead of a collection we will attempt
 732     // to expand the heap, if there's room for expansion.
 733     if (!gch->is_maximal_no_gc()) {
 734       result = expand_heap_and_allocate(size, is_tlab);
 735     }
 736     return result;   // Could be null if we are out of space.
 737   } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {
 738     // Do an incremental collection.
 739     gch->do_collection(false,                     // full
 740                        false,                     // clear_all_soft_refs
 741                        size,                      // size
 742                        is_tlab,                   // is_tlab
 743                        GenCollectedHeap::OldGen); // max_generation
 744   } else {
 745     log_trace(gc)(" :: Trying full because partial may fail :: ");
 746     // Try a full collection; see delta for bug id 6266275
 747     // for the original code and why this has been simplified
 748     // with from-space allocation criteria modified and
 749     // such allocation moved out of the safepoint path.
 750     gch->do_collection(true,                      // full
 751                        false,                     // clear_all_soft_refs
 752                        size,                      // size
 753                        is_tlab,                   // is_tlab
 754                        GenCollectedHeap::OldGen); // max_generation
 755   }
 756 
 757   result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
 758 
 759   if (result != NULL) {
 760     assert(gch->is_in_reserved(result), "result not in heap");
 761     return result;
 762   }
 763 
 764   // OK, collection failed, try expansion.
 765   result = expand_heap_and_allocate(size, is_tlab);
 766   if (result != NULL) {
 767     return result;
 768   }
 769 
 770   // If we reach this point, we're really out of memory. Try every trick
 771   // we can to reclaim memory. Force collection of soft references. Force
 772   // a complete compaction of the heap. Any additional methods for finding
 773   // free memory should be here, especially if they are expensive. If this
 774   // attempt fails, an OOM exception will be thrown.
 775   {
 776     UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
 777 
 778     gch->do_collection(true,                      // full
 779                        true,                      // clear_all_soft_refs
 780                        size,                      // size
 781                        is_tlab,                   // is_tlab
 782                        GenCollectedHeap::OldGen); // max_generation
 783   }
 784 
 785   result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
 786   if (result != NULL) {
 787     assert(gch->is_in_reserved(result), "result not in heap");
 788     return result;
 789   }
 790 
 791   assert(!should_clear_all_soft_refs(),
 792     "Flag should have been handled and cleared prior to this point");
 793 
 794   // What else?  We might try synchronous finalization later.  If the total
 795   // space available is large enough for the allocation, then a more
 796   // complete compaction phase than we've tried so far might be
 797   // appropriate.
 798   return NULL;
 799 }
 800 
 801 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(
 802                                                  ClassLoaderData* loader_data,
 803                                                  size_t word_size,
 804                                                  Metaspace::MetadataType mdtype) {
 805   uint loop_count = 0;
 806   uint gc_count = 0;
 807   uint full_gc_count = 0;
 808 
 809   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
 810 
 811   do {
 812     MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
 813     if (result != NULL) {
 814       return result;
 815     }
 816 
 817     if (GCLocker::is_active_and_needs_gc()) {
 818       // If the GCLocker is active, just expand and allocate.
 819       // If that does not succeed, wait if this thread is not
 820       // in a critical section itself.
 821       result =
 822         loader_data->metaspace_non_null()->expand_and_allocate(word_size,
 823                                                                mdtype);
 824       if (result != NULL) {
 825         return result;
 826       }
 827       JavaThread* jthr = JavaThread::current();
 828       if (!jthr->in_critical()) {
 829         // Wait for JNI critical section to be exited
 830         GCLocker::stall_until_clear();
 831         // The GC invoked by the last thread leaving the critical
 832         // section will be a young collection and a full collection
 833         // is (currently) needed for unloading classes so continue
 834         // to the next iteration to get a full GC.
 835         continue;
 836       } else {
 837         if (CheckJNICalls) {
 838           fatal("Possible deadlock due to allocating while"
 839                 " in jni critical section");
 840         }
 841         return NULL;
 842       }
 843     }
 844 
 845     {  // Need lock to get self consistent gc_count's
 846       MutexLocker ml(Heap_lock);
 847       gc_count      = Universe::heap()->total_collections();
 848       full_gc_count = Universe::heap()->total_full_collections();
 849     }
 850 
 851     // Generate a VM operation
 852     VM_CollectForMetadataAllocation op(loader_data,
 853                                        word_size,
 854                                        mdtype,
 855                                        gc_count,
 856                                        full_gc_count,
 857                                        GCCause::_metadata_GC_threshold);
 858     VMThread::execute(&op);
 859 
 860     // If GC was locked out, try again. Check before checking success because the
 861     // prologue could have succeeded and the GC still have been locked out.
 862     if (op.gc_locked()) {
 863       continue;
 864     }
 865 
 866     if (op.prologue_succeeded()) {
 867       return op.result();
 868     }
 869     loop_count++;
 870     if ((QueuedAllocationWarningCount > 0) &&
 871         (loop_count % QueuedAllocationWarningCount == 0)) {
 872       log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
 873                             " size=" SIZE_FORMAT, loop_count, word_size);
 874     }
 875   } while (true);  // Until a GC is done
 876 }
 877 
 878 // Return true if any of the following is true:
 879 // . the allocation won't fit into the current young gen heap
 880 // . gc locker is occupied (jni critical section)
 881 // . heap memory is tight -- the most recent previous collection
 882 //   was a full collection because a partial collection (would
 883 //   have) failed and is likely to fail again
 884 bool GenCollectorPolicy::should_try_older_generation_allocation(
 885         size_t word_size) const {
 886   GenCollectedHeap* gch = GenCollectedHeap::heap();
 887   size_t young_capacity = gch->young_gen()->capacity_before_gc();
 888   return    (word_size > heap_word_size(young_capacity))
 889          || GCLocker::is_active_and_needs_gc()
 890          || gch->incremental_collection_failed();
 891 }
 892 
 893 
 894 //
 895 // MarkSweepPolicy methods
 896 //
 897 
 898 void MarkSweepPolicy::initialize_alignments() {
 899   _space_alignment = _gen_alignment = (size_t)Generation::GenGrain;
 900   _heap_alignment = compute_heap_alignment();
 901 }
 902 
 903 void MarkSweepPolicy::initialize_generations() {
 904   _young_gen_spec = new GenerationSpec(Generation::DefNew, _initial_young_size, _max_young_size, _gen_alignment);
 905   _old_gen_spec   = new GenerationSpec(Generation::MarkSweepCompact, _initial_old_size, _max_old_size, _gen_alignment);
 906 }
 907 
 908 void MarkSweepPolicy::initialize_gc_policy_counters() {
 909   // Initialize the policy counters - 2 collectors, 3 generations.
 910   _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
 911 }
 912