Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"

 #include "gc_implementation/shared/gcPolicyCounters.hpp"

 #include "gc_implementation/shared/vmGCOperations.hpp"

 #include "memory/cardTableRS.hpp"

 #include "memory/collectorPolicy.hpp"

 #include "memory/gcLocker.inline.hpp"

 #include "memory/genCollectedHeap.hpp"

 #include "memory/generationSpec.hpp"

 #include "memory/space.hpp"

 #include "memory/universe.hpp"

 #include "runtime/arguments.hpp"

 #include "runtime/globals_extension.hpp"

 #include "runtime/handles.inline.hpp"

 #include "runtime/java.hpp"

 #include "runtime/thread.inline.hpp"

 #include "runtime/vmThread.hpp"

 #include "utilities/macros.hpp"

 #if INCLUDE_ALL_GCS

 #include "gc_implementation/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp"

 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp"

 #endif // INCLUDE_ALL_GCS

 // CollectorPolicy methods.

 CollectorPolicy::CollectorPolicy() :

     _space_alignment(0),

     _heap_alignment(0),

     _initial_heap_byte_size(InitialHeapSize),

     _max_heap_byte_size(MaxHeapSize),

     _min_heap_byte_size(Arguments::min_heap_size()),

     _max_heap_size_cmdline(false),

     _size_policy(NULL),

     _should_clear_all_soft_refs(false),

     _all_soft_refs_clear(false)

 {}

 #ifdef ASSERT

 void CollectorPolicy::assert_flags() {

   assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");

   assert(InitialHeapSize % _heap_alignment == 0, "InitialHeapSize alignment");

   assert(MaxHeapSize % _heap_alignment == 0, "MaxHeapSize alignment");

 }

 void CollectorPolicy::assert_size_info() {

   assert(InitialHeapSize == _initial_heap_byte_size, "Discrepancy between InitialHeapSize flag and local storage");

   assert(MaxHeapSize == _max_heap_byte_size, "Discrepancy between MaxHeapSize flag and local storage");

   assert(_max_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible minimum and maximum heap sizes");

   assert(_initial_heap_byte_size >= _min_heap_byte_size, "Ergonomics decided on incompatible initial and minimum heap sizes");

   assert(_max_heap_byte_size >= _initial_heap_byte_size, "Ergonomics decided on incompatible initial and maximum heap sizes");

   assert(_min_heap_byte_size % _heap_alignment == 0, "min_heap_byte_size alignment");

   assert(_initial_heap_byte_size % _heap_alignment == 0, "initial_heap_byte_size alignment");

   assert(_max_heap_byte_size % _heap_alignment == 0, "max_heap_byte_size alignment");

 }

 #endif // ASSERT

 void CollectorPolicy::initialize_flags() {

   assert(_space_alignment != 0, "Space alignment not set up properly");

   assert(_heap_alignment != 0, "Heap alignment not set up properly");

   assert(_heap_alignment >= _space_alignment,

          err_msg("heap_alignment: " SIZE_FORMAT " less than space_alignment: " SIZE_FORMAT,

                  _heap_alignment, _space_alignment));

   assert(_heap_alignment % _space_alignment == 0,

          err_msg("heap_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,

                  _heap_alignment, _space_alignment));

   if (FLAG_IS_CMDLINE(MaxHeapSize)) {

     if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {

       vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");

     }

     if (_min_heap_byte_size != 0 && MaxHeapSize < _min_heap_byte_size) {

       vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");

     }

     _max_heap_size_cmdline = true;

   }

   // Check heap parameter properties

   if (InitialHeapSize < M) {

     vm_exit_during_initialization("Too small initial heap");

   }

   if (_min_heap_byte_size < M) {

     vm_exit_during_initialization("Too small minimum heap");

   }

   // User inputs from -Xmx and -Xms must be aligned

   _min_heap_byte_size = align_size_up(_min_heap_byte_size, _heap_alignment);

   uintx aligned_initial_heap_size = align_size_up(InitialHeapSize, _heap_alignment);

   uintx aligned_max_heap_size = align_size_up(MaxHeapSize, _heap_alignment);

   // Write back to flags if the values changed

   if (aligned_initial_heap_size != InitialHeapSize) {

     FLAG_SET_ERGO(uintx, InitialHeapSize, aligned_initial_heap_size);

   }

   if (aligned_max_heap_size != MaxHeapSize) {

     FLAG_SET_ERGO(uintx, MaxHeapSize, aligned_max_heap_size);

   }

   if (FLAG_IS_CMDLINE(InitialHeapSize) && _min_heap_byte_size != 0 &&

       InitialHeapSize < _min_heap_byte_size) {

     vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");

   }

   if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {

     FLAG_SET_ERGO(uintx, MaxHeapSize, InitialHeapSize);

   } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {

     FLAG_SET_ERGO(uintx, InitialHeapSize, MaxHeapSize);

     if (InitialHeapSize < _min_heap_byte_size) {

       _min_heap_byte_size = InitialHeapSize;

     }

   }

   _initial_heap_byte_size = InitialHeapSize;

   _max_heap_byte_size = MaxHeapSize;

   FLAG_SET_ERGO(uintx, MinHeapDeltaBytes, align_size_up(MinHeapDeltaBytes, _space_alignment));

   DEBUG_ONLY(CollectorPolicy::assert_flags();)

 }

 void CollectorPolicy::initialize_size_info() {

   if (PrintGCDetails && Verbose) {

     gclog_or_tty->print_cr("Minimum heap " SIZE_FORMAT "  Initial heap "

       SIZE_FORMAT "  Maximum heap " SIZE_FORMAT,

       _min_heap_byte_size, _initial_heap_byte_size, _max_heap_byte_size);

   }

   DEBUG_ONLY(CollectorPolicy::assert_size_info();)

 }

 bool CollectorPolicy::use_should_clear_all_soft_refs(bool v) {

   bool result = _should_clear_all_soft_refs;

   set_should_clear_all_soft_refs(false);

   return result;

 }

 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,

                                            int max_covered_regions) {

   return new CardTableRS(whole_heap, max_covered_regions);

 }

 void CollectorPolicy::cleared_all_soft_refs() {

   // If near gc overhear limit, continue to clear SoftRefs.  SoftRefs may

   // have been cleared in the last collection but if the gc overhear

   // limit continues to be near, SoftRefs should still be cleared.

   if (size_policy() != NULL) {

     _should_clear_all_soft_refs = size_policy()->gc_overhead_limit_near();

   }

   _all_soft_refs_clear = true;

 }

 size_t CollectorPolicy::compute_heap_alignment() {

   // The card marking array and the offset arrays for old generations are

   // committed in os pages as well. Make sure they are entirely full (to

   // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1

   // byte entry and the os page size is 4096, the maximum heap size should

   // be 512*4096 = 2MB aligned.

   // There is only the GenRemSet in Hotspot and only the GenRemSet::CardTable

   // is supported.

   // Requirements of any new remembered set implementations must be added here.

   size_t alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable);

   // Parallel GC does its own alignment of the generations to avoid requiring a

   // large page (256M on some platforms) for the permanent generation.  The

   // other collectors should also be updated to do their own alignment and then

   // this use of lcm() should be removed.

   if (UseLargePages && !UseParallelGC) {

       // in presence of large pages we have to make sure that our

       // alignment is large page aware

       alignment = lcm(os::large_page_size(), alignment);

   }

   return alignment;

 }

 // GenCollectorPolicy methods.

 GenCollectorPolicy::GenCollectorPolicy() :

     _min_gen0_size(0),

     _initial_gen0_size(0),

     _max_gen0_size(0),

     _gen_alignment(0),

     _generations(NULL)

 {}

 size_t GenCollectorPolicy::scale_by_NewRatio_aligned(size_t base_size) {

   return align_size_down_bounded(base_size / (NewRatio + 1), _gen_alignment);

 }

 size_t GenCollectorPolicy::bound_minus_alignment(size_t desired_size,

                                                  size_t maximum_size) {

   size_t max_minus = maximum_size - _gen_alignment;

   return desired_size < max_minus ? desired_size : max_minus;

 }

 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,

                                                 size_t init_promo_size,

                                                 size_t init_survivor_size) {

   const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;

   _size_policy = new AdaptiveSizePolicy(init_eden_size,

                                         init_promo_size,

                                         init_survivor_size,

                                         max_gc_pause_sec,

                                         GCTimeRatio);

 }

 size_t GenCollectorPolicy::young_gen_size_lower_bound() {

   // The young generation must be aligned and have room for eden + two survivors

   return align_size_up(3 * _space_alignment, _gen_alignment);

 }

 #ifdef ASSERT

 void GenCollectorPolicy::assert_flags() {

   CollectorPolicy::assert_flags();

   assert(NewSize >= _min_gen0_size, "Ergonomics decided on a too small young gen size");

   assert(NewSize <= MaxNewSize, "Ergonomics decided on incompatible initial and maximum young gen sizes");

   assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young gen and heap sizes");

   assert(NewSize % _gen_alignment == 0, "NewSize alignment");

   assert(FLAG_IS_DEFAULT(MaxNewSize) || MaxNewSize % _gen_alignment == 0, "MaxNewSize alignment");

 }

 void TwoGenerationCollectorPolicy::assert_flags() {

   GenCollectorPolicy::assert_flags();

   assert(OldSize + NewSize <= MaxHeapSize, "Ergonomics decided on incompatible generation and heap sizes");

   assert(OldSize % _gen_alignment == 0, "OldSize alignment");

 }

 void GenCollectorPolicy::assert_size_info() {

   CollectorPolicy::assert_size_info();

   // GenCollectorPolicy::initialize_size_info may update the MaxNewSize

   assert(MaxNewSize < MaxHeapSize, "Ergonomics decided on incompatible maximum young and heap sizes");

   assert(NewSize == _initial_gen0_size, "Discrepancy between NewSize flag and local storage");

   assert(MaxNewSize == _max_gen0_size, "Discrepancy between MaxNewSize flag and local storage");

   assert(_min_gen0_size <= _initial_gen0_size, "Ergonomics decided on incompatible minimum and initial young gen sizes");

   assert(_initial_gen0_size <= _max_gen0_size, "Ergonomics decided on incompatible initial and maximum young gen sizes");

   assert(_min_gen0_size % _gen_alignment == 0, "_min_gen0_size alignment");

   assert(_initial_gen0_size % _gen_alignment == 0, "_initial_gen0_size alignment");

   assert(_max_gen0_size % _gen_alignment == 0, "_max_gen0_size alignment");

 }

 void TwoGenerationCollectorPolicy::assert_size_info() {

   GenCollectorPolicy::assert_size_info();

   assert(OldSize == _initial_gen1_size, "Discrepancy between OldSize flag and local storage");

   assert(_min_gen1_size <= _initial_gen1_size, "Ergonomics decided on incompatible minimum and initial old gen sizes");

   assert(_initial_gen1_size <= _max_gen1_size, "Ergonomics decided on incompatible initial and maximum old gen sizes");

   assert(_max_gen1_size % _gen_alignment == 0, "_max_gen1_size alignment");

   assert(_initial_gen1_size % _gen_alignment == 0, "_initial_gen1_size alignment");

   assert(_max_heap_byte_size <= (_max_gen0_size + _max_gen1_size), "Total maximum heap sizes must be sum of generation maximum sizes");

 }

 #endif // ASSERT

 void GenCollectorPolicy::initialize_flags() {

   CollectorPolicy::initialize_flags();

   assert(_gen_alignment != 0, "Generation alignment not set up properly");

   assert(_heap_alignment >= _gen_alignment,

          err_msg("heap_alignment: " SIZE_FORMAT " less than gen_alignment: " SIZE_FORMAT,

                  _heap_alignment, _gen_alignment));

   assert(_gen_alignment % _space_alignment == 0,

          err_msg("gen_alignment: " SIZE_FORMAT " not aligned by space_alignment: " SIZE_FORMAT,

                  _gen_alignment, _space_alignment));

   assert(_heap_alignment % _gen_alignment == 0,

          err_msg("heap_alignment: " SIZE_FORMAT " not aligned by gen_alignment: " SIZE_FORMAT,

                  _heap_alignment, _gen_alignment));

   // All generational heaps have a youngest gen; handle those flags here

   // Make sure the heap is large enough for two generations

   uintx smallest_new_size = young_gen_size_lower_bound();

   uintx smallest_heap_size = align_size_up(smallest_new_size + align_size_up(_space_alignment, _gen_alignment),

                                            _heap_alignment);

   if (MaxHeapSize < smallest_heap_size) {

     FLAG_SET_ERGO(uintx, MaxHeapSize, smallest_heap_size);

     _max_heap_byte_size = MaxHeapSize;

   }

   // If needed, synchronize _min_heap_byte size and _initial_heap_byte_size

   if (_min_heap_byte_size < smallest_heap_size) {

     _min_heap_byte_size = smallest_heap_size;

     if (InitialHeapSize < _min_heap_byte_size) {

       FLAG_SET_ERGO(uintx, InitialHeapSize, smallest_heap_size);

       _initial_heap_byte_size = smallest_heap_size;

     }

   }

   // Now take the actual NewSize into account. We will silently increase NewSize

   // if the user specified a smaller value.

   smallest_new_size = MAX2(smallest_new_size, (uintx)align_size_down(NewSize, _gen_alignment));

   if (smallest_new_size != NewSize) {

     FLAG_SET_ERGO(uintx, NewSize, smallest_new_size);

   }

   _initial_gen0_size = NewSize;

   if (!FLAG_IS_DEFAULT(MaxNewSize)) {

     uintx min_new_size = MAX2(_gen_alignment, _min_gen0_size);

     if (MaxNewSize >= MaxHeapSize) {

       // Make sure there is room for an old generation

       uintx smaller_max_new_size = MaxHeapSize - _gen_alignment;

       if (FLAG_IS_CMDLINE(MaxNewSize)) {

         warning("MaxNewSize (" SIZE_FORMAT "k) is equal to or greater than the entire "

                 "heap (" SIZE_FORMAT "k).  A new max generation size of " SIZE_FORMAT "k will be used.",

                 MaxNewSize/K, MaxHeapSize/K, smaller_max_new_size/K);

       }

       FLAG_SET_ERGO(uintx, MaxNewSize, smaller_max_new_size);

       if (NewSize > MaxNewSize) {

         FLAG_SET_ERGO(uintx, NewSize, MaxNewSize);

         _initial_gen0_size = NewSize;

       }

     } else if (MaxNewSize < min_new_size) {

       FLAG_SET_ERGO(uintx, MaxNewSize, min_new_size);

     } else if (!is_size_aligned(MaxNewSize, _gen_alignment)) {

       FLAG_SET_ERGO(uintx, MaxNewSize, align_size_down(MaxNewSize, _gen_alignment));

     }

     _max_gen0_size = MaxNewSize;

   }

   if (NewSize > MaxNewSize) {

     // At this point this should only happen if the user specifies a large NewSize and/or

     // a small (but not too small) MaxNewSize.

     if (FLAG_IS_CMDLINE(MaxNewSize)) {

       warning("NewSize (" SIZE_FORMAT "k) is greater than the MaxNewSize (" SIZE_FORMAT "k). "

               "A new max generation size of " SIZE_FORMAT "k will be used.",

               NewSize/K, MaxNewSize/K, NewSize/K);

     }

     FLAG_SET_ERGO(uintx, MaxNewSize, NewSize);

     _max_gen0_size = MaxNewSize;

   }

   if (SurvivorRatio < 1 || NewRatio < 1) {

     vm_exit_during_initialization("Invalid young gen ratio specified");

   }

   DEBUG_ONLY(GenCollectorPolicy::assert_flags();)

 }

 void TwoGenerationCollectorPolicy::initialize_flags() {

   GenCollectorPolicy::initialize_flags();

   if (!is_size_aligned(OldSize, _gen_alignment)) {

     FLAG_SET_ERGO(uintx, OldSize, align_size_down(OldSize, _gen_alignment));

   }

   if (FLAG_IS_CMDLINE(OldSize) && FLAG_IS_DEFAULT(MaxHeapSize)) {

     // NewRatio will be used later to set the young generation size so we use

     // it to calculate how big the heap should be based on the requested OldSize

     // and NewRatio.

     assert(NewRatio > 0, "NewRatio should have been set up earlier");

     size_t calculated_heapsize = (OldSize / NewRatio) * (NewRatio + 1);

     calculated_heapsize = align_size_up(calculated_heapsize, _heap_alignment);

     FLAG_SET_ERGO(uintx, MaxHeapSize, calculated_heapsize);

     _max_heap_byte_size = MaxHeapSize;

     FLAG_SET_ERGO(uintx, InitialHeapSize, calculated_heapsize);

     _initial_heap_byte_size = InitialHeapSize;

   }

   // adjust max heap size if necessary

   if (NewSize + OldSize > MaxHeapSize) {

     if (_max_heap_size_cmdline) {

       // somebody set a maximum heap size with the intention that we should not

       // exceed it. Adjust New/OldSize as necessary.

       uintx calculated_size = NewSize + OldSize;

       double shrink_factor = (double) MaxHeapSize / calculated_size;

       uintx smaller_new_size = align_size_down((uintx)(NewSize * shrink_factor), _gen_alignment);

       FLAG_SET_ERGO(uintx, NewSize, MAX2(young_gen_size_lower_bound(), smaller_new_size));

       _initial_gen0_size = NewSize;

       // OldSize is already aligned because above we aligned MaxHeapSize to

       // _heap_alignment, and we just made sure that NewSize is aligned to

       // _gen_alignment. In initialize_flags() we verified that _heap_alignment

       // is a multiple of _gen_alignment.

       FLAG_SET_ERGO(uintx, OldSize, MaxHeapSize - NewSize);

     } else {

       FLAG_SET_ERGO(uintx, MaxHeapSize, align_size_up(NewSize + OldSize, _heap_alignment));

       _max_heap_byte_size = MaxHeapSize;

     }

   }

   always_do_update_barrier = UseConcMarkSweepGC;

   DEBUG_ONLY(TwoGenerationCollectorPolicy::assert_flags();)

 }

 // Values set on the command line win over any ergonomically

 // set command line parameters.

 // Ergonomic choice of parameters are done before this

 // method is called.  Values for command line parameters such as NewSize

 // and MaxNewSize feed those ergonomic choices into this method.

 // This method makes the final generation sizings consistent with

 // themselves and with overall heap sizings.

 // In the absence of explicitly set command line flags, policies

 // such as the use of NewRatio are used to size the generation.

 void GenCollectorPolicy::initialize_size_info() {

   CollectorPolicy::initialize_size_info();

   // _space_alignment is used for alignment within a generation.

   // There is additional alignment done down stream for some

   // collectors that sometimes causes unwanted rounding up of

   // generations sizes.

   // Determine maximum size of gen0

   size_t max_new_size = 0;

   if (!FLAG_IS_DEFAULT(MaxNewSize)) {

     max_new_size = MaxNewSize;

   } else {

     max_new_size = scale_by_NewRatio_aligned(_max_heap_byte_size);

     // Bound the maximum size by NewSize below (since it historically

     // would have been NewSize and because the NewRatio calculation could

     // yield a size that is too small) and bound it by MaxNewSize above.

     // Ergonomics plays here by previously calculating the desired

     // NewSize and MaxNewSize.

     max_new_size = MIN2(MAX2(max_new_size, NewSize), MaxNewSize);

   }

   assert(max_new_size > 0, "All paths should set max_new_size");

   // Given the maximum gen0 size, determine the initial and

   // minimum gen0 sizes.

   if (_max_heap_byte_size == _min_heap_byte_size) {

     // The maximum and minimum heap sizes are the same so

     // the generations minimum and initial must be the

     // same as its maximum.

     _min_gen0_size = max_new_size;

     _initial_gen0_size = max_new_size;

     _max_gen0_size = max_new_size;

   } else {

     size_t desired_new_size = 0;

     if (!FLAG_IS_DEFAULT(NewSize)) {

       // If NewSize is set ergonomically (for example by cms), it

       // would make sense to use it.  If it is used, also use it

       // to set the initial size.  Although there is no reason

       // the minimum size and the initial size have to be the same,

       // the current implementation gets into trouble during the calculation

       // of the tenured generation sizes if they are different.

       // Note that this makes the initial size and the minimum size

       // generally small compared to the NewRatio calculation.

       _min_gen0_size = NewSize;

       desired_new_size = NewSize;

       max_new_size = MAX2(max_new_size, NewSize);

     } else {

       // For the case where NewSize is the default, use NewRatio

       // to size the minimum and initial generation sizes.

       // Use the default NewSize as the floor for these values.  If

       // NewRatio is overly large, the resulting sizes can be too

       // small.

       _min_gen0_size = MAX2(scale_by_NewRatio_aligned(_min_heap_byte_size), NewSize);

       desired_new_size =

         MAX2(scale_by_NewRatio_aligned(_initial_heap_byte_size), NewSize);

     }

     assert(_min_gen0_size > 0, "Sanity check");

     _initial_gen0_size = desired_new_size;

     _max_gen0_size = max_new_size;

     // At this point the desirable initial and minimum sizes have been

     // determined without regard to the maximum sizes.

     // Bound the sizes by the corresponding overall heap sizes.

     _min_gen0_size = bound_minus_alignment(_min_gen0_size, _min_heap_byte_size);

     _initial_gen0_size = bound_minus_alignment(_initial_gen0_size, _initial_heap_byte_size);

     _max_gen0_size = bound_minus_alignment(_max_gen0_size, _max_heap_byte_size);

     // At this point all three sizes have been checked against the

     // maximum sizes but have not been checked for consistency

     // among the three.

     // Final check min <= initial <= max

     _min_gen0_size = MIN2(_min_gen0_size, _max_gen0_size);

     _initial_gen0_size = MAX2(MIN2(_initial_gen0_size, _max_gen0_size), _min_gen0_size);

     _min_gen0_size = MIN2(_min_gen0_size, _initial_gen0_size);

   }

   // Write back to flags if necessary

   if (NewSize != _initial_gen0_size) {

     FLAG_SET_ERGO(uintx, NewSize, _initial_gen0_size);

   }

   if (MaxNewSize != _max_gen0_size) {

     FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size);

   }

   if (PrintGCDetails && Verbose) {

     gclog_or_tty->print_cr("1: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "

       SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,

       _min_gen0_size, _initial_gen0_size, _max_gen0_size);

   }

   DEBUG_ONLY(GenCollectorPolicy::assert_size_info();)

 }

 // Call this method during the sizing of the gen1 to make

 // adjustments to gen0 because of gen1 sizing policy.  gen0 initially has

 // the most freedom in sizing because it is done before the

 // policy for gen1 is applied.  Once gen1 policies have been applied,

 // there may be conflicts in the shape of the heap and this method

 // is used to make the needed adjustments.  The application of the

 // policies could be more sophisticated (iterative for example) but

 // keeping it simple also seems a worthwhile goal.

 bool TwoGenerationCollectorPolicy::adjust_gen0_sizes(size_t* gen0_size_ptr,

                                                      size_t* gen1_size_ptr,

                                                      const size_t heap_size) {

   bool result = false;

   if ((*gen0_size_ptr + *gen1_size_ptr) > heap_size) {

     uintx smallest_new_size = young_gen_size_lower_bound();

     if ((heap_size < (*gen0_size_ptr + _min_gen1_size)) &&

         (heap_size >= _min_gen1_size + smallest_new_size)) {

       // Adjust gen0 down to accommodate _min_gen1_size

       *gen0_size_ptr = align_size_down_bounded(heap_size - _min_gen1_size, _gen_alignment);

       result = true;

     } else {

       *gen1_size_ptr = align_size_down_bounded(heap_size - *gen0_size_ptr, _gen_alignment);

     }

   }

   return result;

 }

 // Minimum sizes of the generations may be different than

 // the initial sizes.  An inconsistently is permitted here

 // in the total size that can be specified explicitly by

 // command line specification of OldSize and NewSize and

 // also a command line specification of -Xms.  Issue a warning

 // but allow the values to pass.

 void TwoGenerationCollectorPolicy::initialize_size_info() {

   GenCollectorPolicy::initialize_size_info();

   // At this point the minimum, initial and maximum sizes

   // of the overall heap and of gen0 have been determined.

   // The maximum gen1 size can be determined from the maximum gen0

   // and maximum heap size since no explicit flags exits

   // for setting the gen1 maximum.

   _max_gen1_size = MAX2(_max_heap_byte_size - _max_gen0_size, _gen_alignment);

   // If no explicit command line flag has been set for the

   // gen1 size, use what is left for gen1.

   if (!FLAG_IS_CMDLINE(OldSize)) {

     // The user has not specified any value but the ergonomics

     // may have chosen a value (which may or may not be consistent

     // with the overall heap size).  In either case make

     // the minimum, maximum and initial sizes consistent

     // with the gen0 sizes and the overall heap sizes.

     _min_gen1_size = MAX2(_min_heap_byte_size - _min_gen0_size, _gen_alignment);

     _initial_gen1_size = MAX2(_initial_heap_byte_size - _initial_gen0_size, _gen_alignment);

     // _max_gen1_size has already been made consistent above

     FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size);

   } else {

     // It's been explicitly set on the command line.  Use the

     // OldSize and then determine the consequences.

     _min_gen1_size = MIN2(OldSize, _min_heap_byte_size - _min_gen0_size);

     _initial_gen1_size = OldSize;

     // If the user has explicitly set an OldSize that is inconsistent

     // with other command line flags, issue a warning.

     // The generation minimums and the overall heap mimimum should

     // be within one generation alignment.

     if ((_min_gen1_size + _min_gen0_size + _gen_alignment) < _min_heap_byte_size) {

       warning("Inconsistency between minimum heap size and minimum "

               "generation sizes: using minimum heap = " SIZE_FORMAT,

               _min_heap_byte_size);

     }

     if (OldSize > _max_gen1_size) {

       warning("Inconsistency between maximum heap size and maximum "

               "generation sizes: using maximum heap = " SIZE_FORMAT

               " -XX:OldSize flag is being ignored",

               _max_heap_byte_size);

     }

     // If there is an inconsistency between the OldSize and the minimum and/or

     // initial size of gen0, since OldSize was explicitly set, OldSize wins.

     if (adjust_gen0_sizes(&_min_gen0_size, &_min_gen1_size, _min_heap_byte_size)) {

       if (PrintGCDetails && Verbose) {

         gclog_or_tty->print_cr("2: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "

               SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,

               _min_gen0_size, _initial_gen0_size, _max_gen0_size);

       }

     }

     // Initial size

     if (adjust_gen0_sizes(&_initial_gen0_size, &_initial_gen1_size,

                           _initial_heap_byte_size)) {

       if (PrintGCDetails && Verbose) {

         gclog_or_tty->print_cr("3: Minimum gen0 " SIZE_FORMAT "  Initial gen0 "

           SIZE_FORMAT "  Maximum gen0 " SIZE_FORMAT,

           _min_gen0_size, _initial_gen0_size, _max_gen0_size);

       }

     }

   }

   // Enforce the maximum gen1 size.

   _min_gen1_size = MIN2(_min_gen1_size, _max_gen1_size);

   // Check that min gen1 <= initial gen1 <= max gen1

   _initial_gen1_size = MAX2(_initial_gen1_size, _min_gen1_size);

   _initial_gen1_size = MIN2(_initial_gen1_size, _max_gen1_size);

   // Write back to flags if necessary

   if (NewSize != _initial_gen0_size) {

     FLAG_SET_ERGO(uintx, NewSize, _initial_gen0_size);

   }

   if (MaxNewSize != _max_gen0_size) {

     FLAG_SET_ERGO(uintx, MaxNewSize, _max_gen0_size);

   }

   if (OldSize != _initial_gen1_size) {

     FLAG_SET_ERGO(uintx, OldSize, _initial_gen1_size);

   }

   if (PrintGCDetails && Verbose) {

     gclog_or_tty->print_cr("Minimum gen1 " SIZE_FORMAT "  Initial gen1 "

       SIZE_FORMAT "  Maximum gen1 " SIZE_FORMAT,

       _min_gen1_size, _initial_gen1_size, _max_gen1_size);

   }

   DEBUG_ONLY(TwoGenerationCollectorPolicy::assert_size_info();)

 }

 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,

                                         bool is_tlab,

                                         bool* gc_overhead_limit_was_exceeded) {

   GenCollectedHeap *gch = GenCollectedHeap::heap();

   debug_only(gch->check_for_valid_allocation_state());

   assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");

   // In general gc_overhead_limit_was_exceeded should be false so

   // set it so here and reset it to true only if the gc time

   // limit is being exceeded as checked below.

   *gc_overhead_limit_was_exceeded = false;

   HeapWord* result = NULL;

   // Loop until the allocation is satisified,

   // or unsatisfied after GC.

   for (int try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {

     HandleMark hm; // discard any handles allocated in each iteration

     // First allocation attempt is lock-free.

     Generation *gen0 = gch->get_gen(0);

     assert(gen0->supports_inline_contig_alloc(),

       "Otherwise, must do alloc within heap lock");

     if (gen0->should_allocate(size, is_tlab)) {

       result = gen0->par_allocate(size, is_tlab);

       if (result != NULL) {

         assert(gch->is_in_reserved(result), "result not in heap");

         return result;

       }

     }

     unsigned int gc_count_before;  // read inside the Heap_lock locked region

     {

       MutexLocker ml(Heap_lock);

       if (PrintGC && Verbose) {

         gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:"

                       " attempting locked slow path allocation");

       }

       // Note that only large objects get a shot at being

       // allocated in later generations.

       bool first_only = ! should_try_older_generation_allocation(size);

       result = gch->attempt_allocation(size, is_tlab, first_only);

       if (result != NULL) {

         assert(gch->is_in_reserved(result), "result not in heap");

         return result;

       }

       if (GC_locker::is_active_and_needs_gc()) {

         if (is_tlab) {

           return NULL;  // Caller will retry allocating individual object

         }

         if (!gch->is_maximal_no_gc()) {

           // Try and expand heap to satisfy request

           result = expand_heap_and_allocate(size, is_tlab);

           // result could be null if we are out of space

           if (result != NULL) {

             return result;

           }

         }

         if (gclocker_stalled_count > GCLockerRetryAllocationCount) {

           return NULL; // we didn't get to do a GC and we didn't get any memory

         }

         // If this thread is not in a jni critical section, we stall

         // the requestor until the critical section has cleared and

         // GC allowed. When the critical section clears, a GC is

         // initiated by the last thread exiting the critical section; so

         // we retry the allocation sequence from the beginning of the loop,

         // rather than causing more, now probably unnecessary, GC attempts.

         JavaThread* jthr = JavaThread::current();

         if (!jthr->in_critical()) {

           MutexUnlocker mul(Heap_lock);

           // Wait for JNI critical section to be exited

           GC_locker::stall_until_clear();

           gclocker_stalled_count += 1;

           continue;

         } else {

           if (CheckJNICalls) {

             fatal("Possible deadlock due to allocating while"

                   " in jni critical section");

           }

           return NULL;

         }

       }

       // Read the gc count while the heap lock is held.

       gc_count_before = Universe::heap()->total_collections();

     }

     VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);

     VMThread::execute(&op);

     if (op.prologue_succeeded()) {

       result = op.result();

       if (op.gc_locked()) {

          assert(result == NULL, "must be NULL if gc_locked() is true");

          continue;  // retry and/or stall as necessary

       }

       // Allocation has failed and a collection

       // has been done.  If the gc time limit was exceeded the

       // this time, return NULL so that an out-of-memory

       // will be thrown.  Clear gc_overhead_limit_exceeded

       // so that the overhead exceeded does not persist.

       const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();

       const bool softrefs_clear = all_soft_refs_clear();

       if (limit_exceeded && softrefs_clear) {

         *gc_overhead_limit_was_exceeded = true;

         size_policy()->set_gc_overhead_limit_exceeded(false);

         if (op.result() != NULL) {

           CollectedHeap::fill_with_object(op.result(), size);

         }

         return NULL;

       }

       assert(result == NULL || gch->is_in_reserved(result),

              "result not in heap");

       return result;

     }

     // Give a warning if we seem to be looping forever.

     if ((QueuedAllocationWarningCount > 0) &&

         (try_count % QueuedAllocationWarningCount == 0)) {

           warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t"

                   " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : "");

     }

   }

 }

 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,

                                                        bool   is_tlab) {

   GenCollectedHeap *gch = GenCollectedHeap::heap();

   HeapWord* result = NULL;

   for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) {

     Generation *gen = gch->get_gen(i);

     if (gen->should_allocate(size, is_tlab)) {

       result = gen->expand_and_allocate(size, is_tlab);

     }

   }

   assert(result == NULL || gch->is_in_reserved(result), "result not in heap");

   return result;

 }

 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,

                                                         bool   is_tlab) {

   GenCollectedHeap *gch = GenCollectedHeap::heap();

   GCCauseSetter x(gch, GCCause::_allocation_failure);

   HeapWord* result = NULL;

   assert(size != 0, "Precondition violated");

   if (GC_locker::is_active_and_needs_gc()) {

     // GC locker is active; instead of a collection we will attempt

     // to expand the heap, if there's room for expansion.

     if (!gch->is_maximal_no_gc()) {

       result = expand_heap_and_allocate(size, is_tlab);

     }

     return result;   // could be null if we are out of space

   } else if (!gch->incremental_collection_will_fail(false /* don't consult_young */)) {

     // Do an incremental collection.

     gch->do_collection(false            /* full */,

                        false            /* clear_all_soft_refs */,

                        size             /* size */,

                        is_tlab          /* is_tlab */,

                        number_of_generations() - 1 /* max_level */);

   } else {

     if (Verbose && PrintGCDetails) {

       gclog_or_tty->print(" :: Trying full because partial may fail :: ");

     }

     // Try a full collection; see delta for bug id 6266275

     // for the original code and why this has been simplified

     // with from-space allocation criteria modified and

     // such allocation moved out of the safepoint path.

     gch->do_collection(true             /* full */,

                        false            /* clear_all_soft_refs */,

                        size             /* size */,

                        is_tlab          /* is_tlab */,

                        number_of_generations() - 1 /* max_level */);

   }

   result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);

   if (result != NULL) {

     assert(gch->is_in_reserved(result), "result not in heap");

     return result;

   }

   // OK, collection failed, try expansion.

   result = expand_heap_and_allocate(size, is_tlab);

   if (result != NULL) {

     return result;

   }

   // If we reach this point, we're really out of memory. Try every trick

   // we can to reclaim memory. Force collection of soft references. Force

   // a complete compaction of the heap. Any additional methods for finding

   // free memory should be here, especially if they are expensive. If this

   // attempt fails, an OOM exception will be thrown.

   {

     UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted

     gch->do_collection(true             /* full */,

                        true             /* clear_all_soft_refs */,

                        size             /* size */,

                        is_tlab          /* is_tlab */,

                        number_of_generations() - 1 /* max_level */);

   }

   result = gch->attempt_allocation(size, is_tlab, false /* first_only */);

   if (result != NULL) {

     assert(gch->is_in_reserved(result), "result not in heap");

     return result;

   }

   assert(!should_clear_all_soft_refs(),

     "Flag should have been handled and cleared prior to this point");

   // What else?  We might try synchronous finalization later.  If the total

   // space available is large enough for the allocation, then a more

   // complete compaction phase than we've tried so far might be

   // appropriate.

   return NULL;

 }

 MetaWord* CollectorPolicy::satisfy_failed_metadata_allocation(

                                                  ClassLoaderData* loader_data,

                                                  size_t word_size,

                                                  Metaspace::MetadataType mdtype) {

   uint loop_count = 0;

   uint gc_count = 0;

   uint full_gc_count = 0;

   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");

   do {

     MetaWord* result = NULL;

     if (GC_locker::is_active_and_needs_gc()) {

       // If the GC_locker is active, just expand and allocate.

       // If that does not succeed, wait if this thread is not

       // in a critical section itself.

       result =

         loader_data->metaspace_non_null()->expand_and_allocate(word_size,

                                                                mdtype);

       if (result != NULL) {

         return result;

       }

       JavaThread* jthr = JavaThread::current();

       if (!jthr->in_critical()) {

         // Wait for JNI critical section to be exited

         GC_locker::stall_until_clear();

         // The GC invoked by the last thread leaving the critical

         // section will be a young collection and a full collection

         // is (currently) needed for unloading classes so continue

         // to the next iteration to get a full GC.

         continue;

       } else {

         if (CheckJNICalls) {

           fatal("Possible deadlock due to allocating while"

                 " in jni critical section");

         }

         return NULL;

       }

     }

     {  // Need lock to get self consistent gc_count's

       MutexLocker ml(Heap_lock);

       gc_count      = Universe::heap()->total_collections();

       full_gc_count = Universe::heap()->total_full_collections();

     }

     // Generate a VM operation

     VM_CollectForMetadataAllocation op(loader_data,

                                        word_size,

                                        mdtype,

                                        gc_count,

                                        full_gc_count,

                                        GCCause::_metadata_GC_threshold);

     VMThread::execute(&op);

     // If GC was locked out, try again.  Check

     // before checking success because the prologue

     // could have succeeded and the GC still have

     // been locked out.

     if (op.gc_locked()) {

       continue;

     }

     if (op.prologue_succeeded()) {

       return op.result();

     }

     loop_count++;

     if ((QueuedAllocationWarningCount > 0) &&

         (loop_count % QueuedAllocationWarningCount == 0)) {

       warning("satisfy_failed_metadata_allocation() retries %d times \n\t"

               " size=%d", loop_count, word_size);

     }

   } while (true);  // Until a GC is done

 }

 // Return true if any of the following is true:

 // . the allocation won't fit into the current young gen heap

 // . gc locker is occupied (jni critical section)

 // . heap memory is tight -- the most recent previous collection

 //   was a full collection because a partial collection (would

 //   have) failed and is likely to fail again

 bool GenCollectorPolicy::should_try_older_generation_allocation(

         size_t word_size) const {

   GenCollectedHeap* gch = GenCollectedHeap::heap();

   size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();

   return    (word_size > heap_word_size(gen0_capacity))

          || GC_locker::is_active_and_needs_gc()

          || gch->incremental_collection_failed();

 }

 //

 // MarkSweepPolicy methods

 //

 void MarkSweepPolicy::initialize_alignments() {

   _space_alignment = _gen_alignment = (uintx)Generation::GenGrain;

   _heap_alignment = compute_heap_alignment();

 }

 void MarkSweepPolicy::initialize_generations() {

   _generations = NEW_C_HEAP_ARRAY3(GenerationSpecPtr, number_of_generations(), mtGC, 0, AllocFailStrategy::RETURN_NULL);

   if (_generations == NULL) {

     vm_exit_during_initialization("Unable to allocate gen spec");

   }

   if (UseParNewGC) {

     _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);

   } else {

     _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);

   }

   _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);

   if (_generations[0] == NULL || _generations[1] == NULL) {

     vm_exit_during_initialization("Unable to allocate gen spec");

   }

 }

 void MarkSweepPolicy::initialize_gc_policy_counters() {

   // initialize the policy counters - 2 collectors, 3 generations

   if (UseParNewGC) {

     _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3);

   } else {

     _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);

   }

 }