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 /*

  * Copyright (c) 2005, 2010, 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/concurrentMarkSweep/cmsAdaptiveSizePolicy.hpp"

 #include "gc_implementation/concurrentMarkSweep/cmsGCAdaptivePolicyCounters.hpp"

 #include "gc_implementation/parNew/asParNewGeneration.hpp"

 #include "gc_implementation/parNew/parNewGeneration.hpp"

 #include "gc_implementation/shared/markSweep.inline.hpp"

 #include "gc_implementation/shared/spaceDecorator.hpp"

 #include "memory/defNewGeneration.inline.hpp"

 #include "memory/referencePolicy.hpp"

 #include "oops/markOop.inline.hpp"

 #include "oops/oop.pcgc.inline.hpp"

 ASParNewGeneration::ASParNewGeneration(ReservedSpace rs,

                                        size_t initial_byte_size,

                                        size_t min_byte_size,

                                        int level) :

   ParNewGeneration(rs, initial_byte_size, level),

   _min_gen_size(min_byte_size) {}

 const char* ASParNewGeneration::name() const {

   return "adaptive size par new generation";

 }

 void ASParNewGeneration::adjust_desired_tenuring_threshold() {

   assert(UseAdaptiveSizePolicy,

     "Should only be used with UseAdaptiveSizePolicy");

 }

 void ASParNewGeneration::resize(size_t eden_size, size_t survivor_size) {

   // Resize the generation if needed. If the generation resize

   // reports false, do not attempt to resize the spaces.

   if (resize_generation(eden_size, survivor_size)) {

     // Then we lay out the spaces inside the generation

     resize_spaces(eden_size, survivor_size);

     space_invariants();

     if (PrintAdaptiveSizePolicy && Verbose) {

       gclog_or_tty->print_cr("Young generation size: "

         "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT

         " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT

         " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,

         eden_size, survivor_size, used(), capacity(),

         max_gen_size(), min_gen_size());

     }

   }

 }

 size_t ASParNewGeneration::available_to_min_gen() {

   assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");

   return virtual_space()->committed_size() - min_gen_size();

 }

 // This method assumes that from-space has live data and that

 // any shrinkage of the young gen is limited by location of

 // from-space.

 size_t ASParNewGeneration::available_to_live() const {

 #undef SHRINKS_AT_END_OF_EDEN

 #ifdef SHRINKS_AT_END_OF_EDEN

   size_t delta_in_survivor = 0;

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

   const size_t space_alignment = heap->intra_heap_alignment();

   const size_t gen_alignment = heap->object_heap_alignment();

   MutableSpace* space_shrinking = NULL;

   if (from_space()->end() > to_space()->end()) {

     space_shrinking = from_space();

   } else {

     space_shrinking = to_space();

   }

   // Include any space that is committed but not included in

   // the survivor spaces.

   assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),

     "Survivor space beyond high end");

   size_t unused_committed = pointer_delta(virtual_space()->high(),

     space_shrinking->end(), sizeof(char));

   if (space_shrinking->is_empty()) {

     // Don't let the space shrink to 0

     assert(space_shrinking->capacity_in_bytes() >= space_alignment,

       "Space is too small");

     delta_in_survivor = space_shrinking->capacity_in_bytes() - space_alignment;

   } else {

     delta_in_survivor = pointer_delta(space_shrinking->end(),

                                       space_shrinking->top(),

                                       sizeof(char));

   }

   size_t delta_in_bytes = unused_committed + delta_in_survivor;

   delta_in_bytes = align_size_down(delta_in_bytes, gen_alignment);

   return delta_in_bytes;

 #else

   // The only space available for shrinking is in to-space if it

   // is above from-space.

   if (to()->bottom() > from()->bottom()) {

     const size_t alignment = os::vm_page_size();

     if (to()->capacity() < alignment) {

       return 0;

     } else {

       return to()->capacity() - alignment;

     }

   } else {

     return 0;

   }

 #endif

 }

 // Return the number of bytes available for resizing down the young

 // generation.  This is the minimum of

 //      input "bytes"

 //      bytes to the minimum young gen size

 //      bytes to the size currently being used + some small extra

 size_t ASParNewGeneration::limit_gen_shrink (size_t bytes) {

   // Allow shrinkage into the current eden but keep eden large enough

   // to maintain the minimum young gen size

   bytes = MIN3(bytes, available_to_min_gen(), available_to_live());

   return align_size_down(bytes, os::vm_page_size());

 }

 // Note that the the alignment used is the OS page size as

 // opposed to an alignment associated with the virtual space

 // (as is done in the ASPSYoungGen/ASPSOldGen)

 bool ASParNewGeneration::resize_generation(size_t eden_size,

                                            size_t survivor_size) {

   const size_t alignment = os::vm_page_size();

   size_t orig_size = virtual_space()->committed_size();

   bool size_changed = false;

   // There used to be this guarantee there.

   // guarantee ((eden_size + 2*survivor_size)  <= _max_gen_size, "incorrect input arguments");

   // Code below forces this requirement.  In addition the desired eden

   // size and disired survivor sizes are desired goals and may

   // exceed the total generation size.

   assert(min_gen_size() <= orig_size && orig_size <= max_gen_size(),

     "just checking");

   // Adjust new generation size

   const size_t eden_plus_survivors =

           align_size_up(eden_size + 2 * survivor_size, alignment);

   size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_gen_size()),

                              min_gen_size());

   assert(desired_size <= max_gen_size(), "just checking");

   if (desired_size > orig_size) {

     // Grow the generation

     size_t change = desired_size - orig_size;

     assert(change % alignment == 0, "just checking");

     if (expand(change)) {

       return false; // Error if we fail to resize!

     }

     size_changed = true;

   } else if (desired_size < orig_size) {

     size_t desired_change = orig_size - desired_size;

     assert(desired_change % alignment == 0, "just checking");

     desired_change = limit_gen_shrink(desired_change);

     if (desired_change > 0) {

       virtual_space()->shrink_by(desired_change);

       reset_survivors_after_shrink();

       size_changed = true;

     }

   } else {

     if (Verbose && PrintGC) {

       if (orig_size == max_gen_size()) {

         gclog_or_tty->print_cr("ASParNew generation size at maximum: "

           SIZE_FORMAT "K", orig_size/K);

       } else if (orig_size == min_gen_size()) {

         gclog_or_tty->print_cr("ASParNew generation size at minium: "

           SIZE_FORMAT "K", orig_size/K);

       }

     }

   }

   if (size_changed) {

     MemRegion cmr((HeapWord*)virtual_space()->low(),

                   (HeapWord*)virtual_space()->high());

     GenCollectedHeap::heap()->barrier_set()->resize_covered_region(cmr);

     if (Verbose && PrintGC) {

       size_t current_size  = virtual_space()->committed_size();

       gclog_or_tty->print_cr("ASParNew generation size changed: "

                              SIZE_FORMAT "K->" SIZE_FORMAT "K",

                              orig_size/K, current_size/K);

     }

   }

   guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||

             virtual_space()->committed_size() == max_gen_size(), "Sanity");

   return true;

 }

 void ASParNewGeneration::reset_survivors_after_shrink() {

   GenCollectedHeap* gch = GenCollectedHeap::heap();

   HeapWord* new_end = (HeapWord*)virtual_space()->high();

   if (from()->end() > to()->end()) {

     assert(new_end >= from()->end(), "Shrinking past from-space");

   } else {

     assert(new_end >= to()->bottom(), "Shrink was too large");

     // Was there a shrink of the survivor space?

     if (new_end < to()->end()) {

       MemRegion mr(to()->bottom(), new_end);

       to()->initialize(mr,

                        SpaceDecorator::DontClear,

                        SpaceDecorator::DontMangle);

     }

   }

 }

 void ASParNewGeneration::resize_spaces(size_t requested_eden_size,

                                        size_t requested_survivor_size) {

   assert(UseAdaptiveSizePolicy, "sanity check");

   assert(requested_eden_size > 0  && requested_survivor_size > 0,

          "just checking");

   CollectedHeap* heap = Universe::heap();

   assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Sanity");

   // We require eden and to space to be empty

   if ((!eden()->is_empty()) || (!to()->is_empty())) {

     return;

   }

   size_t cur_eden_size = eden()->capacity();

   if (PrintAdaptiveSizePolicy && Verbose) {

     gclog_or_tty->print_cr("ASParNew::resize_spaces(requested_eden_size: "

                   SIZE_FORMAT

                   ", requested_survivor_size: " SIZE_FORMAT ")",

                   requested_eden_size, requested_survivor_size);

     gclog_or_tty->print_cr("    eden: [" PTR_FORMAT ".." PTR_FORMAT ") "

                   SIZE_FORMAT,

                   eden()->bottom(),

                   eden()->end(),

                   pointer_delta(eden()->end(),

                                 eden()->bottom(),

                                 sizeof(char)));

     gclog_or_tty->print_cr("    from: [" PTR_FORMAT ".." PTR_FORMAT ") "

                   SIZE_FORMAT,

                   from()->bottom(),

                   from()->end(),

                   pointer_delta(from()->end(),

                                 from()->bottom(),

                                 sizeof(char)));

     gclog_or_tty->print_cr("      to: [" PTR_FORMAT ".." PTR_FORMAT ") "

                   SIZE_FORMAT,

                   to()->bottom(),

                   to()->end(),

                   pointer_delta(  to()->end(),

                                   to()->bottom(),

                                   sizeof(char)));

   }

   // There's nothing to do if the new sizes are the same as the current

   if (requested_survivor_size == to()->capacity() &&

       requested_survivor_size == from()->capacity() &&

       requested_eden_size == eden()->capacity()) {

     if (PrintAdaptiveSizePolicy && Verbose) {

       gclog_or_tty->print_cr("    capacities are the right sizes, returning");

     }

     return;

   }

   char* eden_start = (char*)eden()->bottom();

   char* eden_end   = (char*)eden()->end();

   char* from_start = (char*)from()->bottom();

   char* from_end   = (char*)from()->end();

   char* to_start   = (char*)to()->bottom();

   char* to_end     = (char*)to()->end();

   const size_t alignment = os::vm_page_size();

   const bool maintain_minimum =

     (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();

   // Check whether from space is below to space

   if (from_start < to_start) {

     // Eden, from, to

     if (PrintAdaptiveSizePolicy && Verbose) {

       gclog_or_tty->print_cr("  Eden, from, to:");

     }

     // Set eden

     // "requested_eden_size" is a goal for the size of eden

     // and may not be attainable.  "eden_size" below is

     // calculated based on the location of from-space and

     // the goal for the size of eden.  from-space is

     // fixed in place because it contains live data.

     // The calculation is done this way to avoid 32bit

     // overflow (i.e., eden_start + requested_eden_size

     // may too large for representation in 32bits).

     size_t eden_size;

     if (maintain_minimum) {

       // Only make eden larger than the requested size if

       // the minimum size of the generation has to be maintained.

       // This could be done in general but policy at a higher

       // level is determining a requested size for eden and that

       // should be honored unless there is a fundamental reason.

       eden_size = pointer_delta(from_start,

                                 eden_start,

                                 sizeof(char));

     } else {

       eden_size = MIN2(requested_eden_size,

                        pointer_delta(from_start, eden_start, sizeof(char)));

     }

     eden_size = align_size_down(eden_size, alignment);

     eden_end = eden_start + eden_size;

     assert(eden_end >= eden_start, "addition overflowed");

     // To may resize into from space as long as it is clear of live data.

     // From space must remain page aligned, though, so we need to do some

     // extra calculations.

     // First calculate an optimal to-space

     to_end   = (char*)virtual_space()->high();

     to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,

                                     sizeof(char));

     // Does the optimal to-space overlap from-space?

     if (to_start < (char*)from()->end()) {

       // Calculate the minimum offset possible for from_end

       size_t from_size = pointer_delta(from()->top(), from_start, sizeof(char));

       // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!

       if (from_size == 0) {

         from_size = alignment;

       } else {

         from_size = align_size_up(from_size, alignment);

       }

       from_end = from_start + from_size;

       assert(from_end > from_start, "addition overflow or from_size problem");

       guarantee(from_end <= (char*)from()->end(), "from_end moved to the right");

       // Now update to_start with the new from_end

       to_start = MAX2(from_end, to_start);

     } else {

       // If shrinking, move to-space down to abut the end of from-space

       // so that shrinking will move to-space down.  If not shrinking

       // to-space is moving up to allow for growth on the next expansion.

       if (requested_eden_size <= cur_eden_size) {

         to_start = from_end;

         if (to_start + requested_survivor_size > to_start) {

           to_end = to_start + requested_survivor_size;

         }

       }

       // else leave to_end pointing to the high end of the virtual space.

     }

     guarantee(to_start != to_end, "to space is zero sized");

     if (PrintAdaptiveSizePolicy && Verbose) {

       gclog_or_tty->print_cr("    [eden_start .. eden_end): "

                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                     eden_start,

                     eden_end,

                     pointer_delta(eden_end, eden_start, sizeof(char)));

       gclog_or_tty->print_cr("    [from_start .. from_end): "

                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                     from_start,

                     from_end,

                     pointer_delta(from_end, from_start, sizeof(char)));

       gclog_or_tty->print_cr("    [  to_start ..   to_end): "

                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                     to_start,

                     to_end,

                     pointer_delta(  to_end,   to_start, sizeof(char)));

     }

   } else {

     // Eden, to, from

     if (PrintAdaptiveSizePolicy && Verbose) {

       gclog_or_tty->print_cr("  Eden, to, from:");

     }

     // Calculate the to-space boundaries based on

     // the start of from-space.

     to_end = from_start;

     to_start = (char*)pointer_delta(from_start,

                                     (char*)requested_survivor_size,

                                     sizeof(char));

     // Calculate the ideal eden boundaries.

     // eden_end is already at the bottom of the generation

     assert(eden_start == virtual_space()->low(),

       "Eden is not starting at the low end of the virtual space");

     if (eden_start + requested_eden_size >= eden_start) {

       eden_end = eden_start + requested_eden_size;

     } else {

       eden_end = to_start;

     }

     // Does eden intrude into to-space?  to-space

     // gets priority but eden is not allowed to shrink

     // to 0.

     if (eden_end > to_start) {

       eden_end = to_start;

     }

     // Don't let eden shrink down to 0 or less.

     eden_end = MAX2(eden_end, eden_start + alignment);

     assert(eden_start + alignment >= eden_start, "Overflow");

     size_t eden_size;

     if (maintain_minimum) {

       // Use all the space available.

       eden_end = MAX2(eden_end, to_start);

       eden_size = pointer_delta(eden_end, eden_start, sizeof(char));

       eden_size = MIN2(eden_size, cur_eden_size);

     } else {

       eden_size = pointer_delta(eden_end, eden_start, sizeof(char));

     }

     eden_size = align_size_down(eden_size, alignment);

     assert(maintain_minimum || eden_size <= requested_eden_size,

       "Eden size is too large");

     assert(eden_size >= alignment, "Eden size is too small");

     eden_end = eden_start + eden_size;

     // Move to-space down to eden.

     if (requested_eden_size < cur_eden_size) {

       to_start = eden_end;

       if (to_start + requested_survivor_size > to_start) {

         to_end = MIN2(from_start, to_start + requested_survivor_size);

       } else {

         to_end = from_start;

       }

     }

     // eden_end may have moved so again make sure

     // the to-space and eden don't overlap.

     to_start = MAX2(eden_end, to_start);

     // from-space

     size_t from_used = from()->used();

     if (requested_survivor_size > from_used) {

       if (from_start + requested_survivor_size >= from_start) {

         from_end = from_start + requested_survivor_size;

       }

       if (from_end > virtual_space()->high()) {

         from_end = virtual_space()->high();

       }

     }

     assert(to_start >= eden_end, "to-space should be above eden");

     if (PrintAdaptiveSizePolicy && Verbose) {

       gclog_or_tty->print_cr("    [eden_start .. eden_end): "

                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                     eden_start,

                     eden_end,

                     pointer_delta(eden_end, eden_start, sizeof(char)));

       gclog_or_tty->print_cr("    [  to_start ..   to_end): "

                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                     to_start,

                     to_end,

                     pointer_delta(  to_end,   to_start, sizeof(char)));

       gclog_or_tty->print_cr("    [from_start .. from_end): "

                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,

                     from_start,

                     from_end,

                     pointer_delta(from_end, from_start, sizeof(char)));

     }

   }

   guarantee((HeapWord*)from_start <= from()->bottom(),

             "from start moved to the right");

   guarantee((HeapWord*)from_end >= from()->top(),

             "from end moved into live data");

   assert(is_object_aligned((intptr_t)eden_start), "checking alignment");

   assert(is_object_aligned((intptr_t)from_start), "checking alignment");

   assert(is_object_aligned((intptr_t)to_start), "checking alignment");

   MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);

   MemRegion toMR  ((HeapWord*)to_start,   (HeapWord*)to_end);

   MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);

   // Let's make sure the call to initialize doesn't reset "top"!

   HeapWord* old_from_top = from()->top();

   // For PrintAdaptiveSizePolicy block  below

   size_t old_from = from()->capacity();

   size_t old_to   = to()->capacity();

   // If not clearing the spaces, do some checking to verify that

   // the spaces are already mangled.

   // Must check mangling before the spaces are reshaped.  Otherwise,

   // the bottom or end of one space may have moved into another

   // a failure of the check may not correctly indicate which space

   // is not properly mangled.

   if (ZapUnusedHeapArea) {

     HeapWord* limit = (HeapWord*) virtual_space()->high();

     eden()->check_mangled_unused_area(limit);

     from()->check_mangled_unused_area(limit);

       to()->check_mangled_unused_area(limit);

   }

   // The call to initialize NULL's the next compaction space

   eden()->initialize(edenMR,

                      SpaceDecorator::Clear,

                      SpaceDecorator::DontMangle);

   eden()->set_next_compaction_space(from());

     to()->initialize(toMR  ,

                      SpaceDecorator::Clear,

                      SpaceDecorator::DontMangle);

   from()->initialize(fromMR,

                      SpaceDecorator::DontClear,

                      SpaceDecorator::DontMangle);

   assert(from()->top() == old_from_top, "from top changed!");

   if (PrintAdaptiveSizePolicy) {

     GenCollectedHeap* gch = GenCollectedHeap::heap();

     assert(gch->kind() == CollectedHeap::GenCollectedHeap, "Sanity");

     gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "

                   "collection: %d "

                   "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "

                   "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",

                   gch->total_collections(),

                   old_from, old_to,

                   from()->capacity(),

                   to()->capacity());

     gclog_or_tty->cr();

   }

 }

 void ASParNewGeneration::compute_new_size() {

   GenCollectedHeap* gch = GenCollectedHeap::heap();

   assert(gch->kind() == CollectedHeap::GenCollectedHeap,

     "not a CMS generational heap");

   CMSAdaptiveSizePolicy* size_policy =

     (CMSAdaptiveSizePolicy*)gch->gen_policy()->size_policy();

   assert(size_policy->is_gc_cms_adaptive_size_policy(),

     "Wrong type of size policy");

   size_t survived = from()->used();

   if (!survivor_overflow()) {

     // Keep running averages on how much survived

     size_policy->avg_survived()->sample(survived);

   } else {

     size_t promoted =

       (size_t) next_gen()->gc_stats()->avg_promoted()->last_sample();

     assert(promoted < gch->capacity(), "Conversion problem?");

     size_t survived_guess = survived + promoted;

     size_policy->avg_survived()->sample(survived_guess);

   }

   size_t survivor_limit = max_survivor_size();

   _tenuring_threshold =

     size_policy->compute_survivor_space_size_and_threshold(

                                                      _survivor_overflow,

                                                      _tenuring_threshold,

                                                      survivor_limit);

   size_policy->avg_young_live()->sample(used());

   size_policy->avg_eden_live()->sample(eden()->used());

   size_policy->compute_young_generation_free_space(eden()->capacity(),

                                                    max_gen_size());

   resize(size_policy->calculated_eden_size_in_bytes(),

          size_policy->calculated_survivor_size_in_bytes());

   if (UsePerfData) {

     CMSGCAdaptivePolicyCounters* counters =

       (CMSGCAdaptivePolicyCounters*) gch->collector_policy()->counters();

     assert(counters->kind() ==

            GCPolicyCounters::CMSGCAdaptivePolicyCountersKind,

       "Wrong kind of counters");

     counters->update_tenuring_threshold(_tenuring_threshold);

     counters->update_survivor_overflowed(_survivor_overflow);

     counters->update_young_capacity(capacity());

   }

 }

 #ifndef PRODUCT

 // Changes from PSYoungGen version

 //      value of "alignment"

 void ASParNewGeneration::space_invariants() {

   const size_t alignment = os::vm_page_size();

   // Currently, our eden size cannot shrink to zero

   guarantee(eden()->capacity() >= alignment, "eden too small");

   guarantee(from()->capacity() >= alignment, "from too small");

   guarantee(to()->capacity() >= alignment, "to too small");

   // Relationship of spaces to each other

   char* eden_start = (char*)eden()->bottom();

   char* eden_end   = (char*)eden()->end();

   char* from_start = (char*)from()->bottom();

   char* from_end   = (char*)from()->end();

   char* to_start   = (char*)to()->bottom();

   char* to_end     = (char*)to()->end();

   guarantee(eden_start >= virtual_space()->low(), "eden bottom");

   guarantee(eden_start < eden_end, "eden space consistency");

   guarantee(from_start < from_end, "from space consistency");

   guarantee(to_start < to_end, "to space consistency");

   // Check whether from space is below to space

   if (from_start < to_start) {

     // Eden, from, to

     guarantee(eden_end <= from_start, "eden/from boundary");

     guarantee(from_end <= to_start,   "from/to boundary");

     guarantee(to_end <= virtual_space()->high(), "to end");

   } else {

     // Eden, to, from

     guarantee(eden_end <= to_start, "eden/to boundary");

     guarantee(to_end <= from_start, "to/from boundary");

     guarantee(from_end <= virtual_space()->high(), "from end");

   }

   // More checks that the virtual space is consistent with the spaces

   assert(virtual_space()->committed_size() >=

     (eden()->capacity() +

      to()->capacity() +

      from()->capacity()), "Committed size is inconsistent");

   assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(),

     "Space invariant");

   char* eden_top = (char*)eden()->top();

   char* from_top = (char*)from()->top();

   char* to_top = (char*)to()->top();

   assert(eden_top <= virtual_space()->high(), "eden top");

   assert(from_top <= virtual_space()->high(), "from top");

   assert(to_top <= virtual_space()->high(), "to top");

 }

 #endif