1 /*

     2  * Copyright 2003-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 # include "incls/_precompiled.incl"

    26 # include "incls/_asPSYoungGen.cpp.incl"

    27 

    28 ASPSYoungGen::ASPSYoungGen(size_t init_byte_size,

    29                            size_t minimum_byte_size,

    30                            size_t byte_size_limit) :

    31   PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),

    32   _gen_size_limit(byte_size_limit) {

    33 }

    34 

    35 

    36 ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs,

    37                            size_t init_byte_size,

    38                            size_t minimum_byte_size,

    39                            size_t byte_size_limit) :

    40   //PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),

    41   PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit),

    42   _gen_size_limit(byte_size_limit) {

    43 

    44   assert(vs->committed_size() == init_byte_size, "Cannot replace with");

    45 

    46   _virtual_space = vs;

    47 }

    48 

    49 void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs,

    50                                             size_t alignment) {

    51   assert(_init_gen_size != 0, "Should have a finite size");

    52   _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment);

    53   if (!_virtual_space->expand_by(_init_gen_size)) {

    54     vm_exit_during_initialization("Could not reserve enough space for "

    55                                   "object heap");

    56   }

    57 }

    58 

    59 void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) {

    60   initialize_virtual_space(rs, alignment);

    61   initialize_work();

    62 }

    63 

    64 size_t ASPSYoungGen::available_for_expansion() {

    65 

    66   size_t current_committed_size = virtual_space()->committed_size();

    67   assert((gen_size_limit() >= current_committed_size),

    68     "generation size limit is wrong");

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

    70   size_t result =  gen_size_limit() - current_committed_size;

    71   size_t result_aligned = align_size_down(result, heap->young_gen_alignment());

    72   return result_aligned;

    73 }

    74 

    75 // Return the number of bytes the young gen is willing give up.

    76 //

    77 // Future implementations could check the survivors and if to_space is in the

    78 // right place (below from_space), take a chunk from to_space.

    79 size_t ASPSYoungGen::available_for_contraction() {

    80 

    81   size_t uncommitted_bytes = virtual_space()->uncommitted_size();

    82   if (uncommitted_bytes != 0) {

    83     return uncommitted_bytes;

    84   }

    85 

    86   if (eden_space()->is_empty()) {

    87     // Respect the minimum size for eden and for the young gen as a whole.

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

    89     const size_t eden_alignment = heap->intra_generation_alignment();

    90     const size_t gen_alignment = heap->young_gen_alignment();

    91 

    92     assert(eden_space()->capacity_in_bytes() >= eden_alignment,

    93       "Alignment is wrong");

    94     size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;

    95     eden_avail = align_size_down(eden_avail, gen_alignment);

    96 

    97     assert(virtual_space()->committed_size() >= min_gen_size(),

    98       "minimum gen size is wrong");

    99     size_t gen_avail = virtual_space()->committed_size() - min_gen_size();

   100     assert(virtual_space()->is_aligned(gen_avail), "not aligned");

   101 

   102     const size_t max_contraction = MIN2(eden_avail, gen_avail);

   103     // See comment for ASPSOldGen::available_for_contraction()

   104     // for reasons the "increment" fraction is used.

   105     PSAdaptiveSizePolicy* policy = heap->size_policy();

   106     size_t result = policy->eden_increment_aligned_down(max_contraction);

   107     size_t result_aligned = align_size_down(result, gen_alignment);

   108     if (PrintAdaptiveSizePolicy && Verbose) {

   109       gclog_or_tty->print_cr("ASPSYoungGen::available_for_contraction: %d K",

   110         result_aligned/K);

   111       gclog_or_tty->print_cr("  max_contraction %d K", max_contraction/K);

   112       gclog_or_tty->print_cr("  eden_avail %d K", eden_avail/K);

   113       gclog_or_tty->print_cr("  gen_avail %d K", gen_avail/K);

   114     }

   115     return result_aligned;

   116 

   117   }

   118 

   119   return 0;

   120 }

   121 

   122 // The current implementation only considers to the end of eden.

   123 // If to_space is below from_space, to_space is not considered.

   124 // to_space can be.

   125 size_t ASPSYoungGen::available_to_live() {

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

   127   const size_t alignment = heap->intra_generation_alignment();

   128 

   129   // Include any space that is committed but is not in eden.

   130   size_t available = pointer_delta(eden_space()->bottom(),

   131                                    virtual_space()->low(),

   132                                    sizeof(char));

   133 

   134   const size_t eden_capacity = eden_space()->capacity_in_bytes();

   135   if (eden_space()->is_empty() && eden_capacity > alignment) {

   136     available += eden_capacity - alignment;

   137   }

   138   return available;

   139 }

   140 

   141 // Similar to PSYoungGen::resize_generation() but

   142 //  allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size

   143 //  expands at the low end of the virtual space

   144 //  moves the boundary between the generations in order to expand

   145 //  some additional diagnostics

   146 // If no additional changes are required, this can be deleted

   147 // and the changes factored back into PSYoungGen::resize_generation().

   148 bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {

   149   const size_t alignment = virtual_space()->alignment();

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

   151   bool size_changed = false;

   152 

   153   // There used to be a guarantee here that

   154   //   (eden_size + 2*survivor_size)  <= _max_gen_size

   155   // This requirement is enforced by the calculation of desired_size

   156   // below.  It may not be true on entry since the size of the

   157   // eden_size is no bounded by the generation size.

   158 

   159   assert(max_size() == reserved().byte_size(), "max gen size problem?");

   160   assert(min_gen_size() <= orig_size && orig_size <= max_size(),

   161          "just checking");

   162 

   163   // Adjust new generation size

   164   const size_t eden_plus_survivors =

   165     align_size_up(eden_size + 2 * survivor_size, alignment);

   166   size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),

   167                              min_gen_size());

   168   assert(desired_size <= gen_size_limit(), "just checking");

   169 

   170   if (desired_size > orig_size) {

   171     // Grow the generation

   172     size_t change = desired_size - orig_size;

   173     if (!virtual_space()->expand_by(change)) {

   174       return false;

   175     }

   176     size_changed = true;

   177   } else if (desired_size < orig_size) {

   178     size_t desired_change = orig_size - desired_size;

   179 

   180     // How much is available for shrinking.

   181     size_t available_bytes = limit_gen_shrink(desired_change);

   182     size_t change = MIN2(desired_change, available_bytes);

   183     virtual_space()->shrink_by(change);

   184     size_changed = true;

   185   } else {

   186     if (Verbose && PrintGC) {

   187       if (orig_size == gen_size_limit()) {

   188         gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "

   189           SIZE_FORMAT "K", orig_size/K);

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

   191         gclog_or_tty->print_cr("ASPSYoung generation size at minium: "

   192           SIZE_FORMAT "K", orig_size/K);

   193       }

   194     }

   195   }

   196 

   197   if (size_changed) {

   198     reset_after_change();

   199     if (Verbose && PrintGC) {

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

   201       gclog_or_tty->print_cr("ASPSYoung generation size changed: "

   202         SIZE_FORMAT "K->" SIZE_FORMAT "K",

   203         orig_size/K, current_size/K);

   204     }

   205   }

   206 

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

   208             virtual_space()->committed_size() == max_size(), "Sanity");

   209 

   210   return true;

   211 }

   212 

   213 // Similar to PSYoungGen::resize_spaces() but

   214 //  eden always starts at the low end of the committed virtual space

   215 //  current implementation does not allow holes between the spaces

   216 //  _young_generation_boundary has to be reset because it changes.

   217 //  so additional verification

   218 void ASPSYoungGen::resize_spaces(size_t requested_eden_size,

   219                                  size_t requested_survivor_size) {

   220   assert(requested_eden_size > 0 && requested_survivor_size > 0,

   221          "just checking");

   222 

   223   space_invariants();

   224 

   225   // We require eden and to space to be empty

   226   if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {

   227     return;

   228   }

   229 

   230   if (PrintAdaptiveSizePolicy && Verbose) {

   231     gclog_or_tty->print_cr("PSYoungGen::resize_spaces(requested_eden_size: "

   232                   SIZE_FORMAT

   233                   ", requested_survivor_size: " SIZE_FORMAT ")",

   234                   requested_eden_size, requested_survivor_size);

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

   236                   SIZE_FORMAT,

   237                   eden_space()->bottom(),

   238                   eden_space()->end(),

   239                   pointer_delta(eden_space()->end(),

   240                                 eden_space()->bottom(),

   241                                 sizeof(char)));

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

   243                   SIZE_FORMAT,

   244                   from_space()->bottom(),

   245                   from_space()->end(),

   246                   pointer_delta(from_space()->end(),

   247                                 from_space()->bottom(),

   248                                 sizeof(char)));

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

   250                   SIZE_FORMAT,

   251                   to_space()->bottom(),

   252                   to_space()->end(),

   253                   pointer_delta(  to_space()->end(),

   254                                   to_space()->bottom(),

   255                                   sizeof(char)));

   256   }

   257 

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

   259   if (requested_survivor_size == to_space()->capacity_in_bytes() &&

   260       requested_survivor_size == from_space()->capacity_in_bytes() &&

   261       requested_eden_size == eden_space()->capacity_in_bytes()) {

   262     if (PrintAdaptiveSizePolicy && Verbose) {

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

   264     }

   265     return;

   266   }

   267 

   268   char* eden_start = (char*)virtual_space()->low();

   269   char* eden_end   = (char*)eden_space()->end();

   270   char* from_start = (char*)from_space()->bottom();

   271   char* from_end   = (char*)from_space()->end();

   272   char* to_start   = (char*)to_space()->bottom();

   273   char* to_end     = (char*)to_space()->end();

   274 

   275   assert(eden_start < from_start, "Cannot push into from_space");

   276 

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

   278   const size_t alignment = heap->intra_generation_alignment();

   279 

   280   // Check whether from space is below to space

   281   if (from_start < to_start) {

   282     // Eden, from, to

   283     if (PrintAdaptiveSizePolicy && Verbose) {

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

   285     }

   286 

   287     // Set eden

   288     // Compute how big eden can be, then adjust end.

   289     // See comment in PSYoungGen::resize_spaces() on

   290     // calculating eden_end.

   291     const size_t eden_size = MIN2(requested_eden_size,

   292                                   pointer_delta(from_start,

   293                                                 eden_start,

   294                                                 sizeof(char)));

   295     eden_end = eden_start + eden_size;

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

   297 

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

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

   300     // extra calculations.

   301 

   302     // First calculate an optimal to-space

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

   304     to_start = (char*)pointer_delta(to_end,

   305                                     (char*)requested_survivor_size,

   306                                     sizeof(char));

   307 

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

   309     if (to_start < (char*)from_space()->end()) {

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

   311 

   312       // Calculate the minimum offset possible for from_end

   313       size_t from_size =

   314         pointer_delta(from_space()->top(), from_start, sizeof(char));

   315 

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

   317       if (from_size == 0) {

   318         from_size = alignment;

   319       } else {

   320         from_size = align_size_up(from_size, alignment);

   321       }

   322 

   323       from_end = from_start + from_size;

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

   325 

   326       guarantee(from_end <= (char*)from_space()->end(),

   327         "from_end moved to the right");

   328 

   329       // Now update to_start with the new from_end

   330       to_start = MAX2(from_end, to_start);

   331     }

   332 

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

   334 

   335     if (PrintAdaptiveSizePolicy && Verbose) {

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

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

   338                     eden_start,

   339                     eden_end,

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

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

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

   343                     from_start,

   344                     from_end,

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

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

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

   348                     to_start,

   349                     to_end,

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

   351     }

   352   } else {

   353     // Eden, to, from

   354     if (PrintAdaptiveSizePolicy && Verbose) {

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

   356     }

   357 

   358     // To space gets priority over eden resizing. Note that we position

   359     // to space as if we were able to resize from space, even though from

   360     // space is not modified.

   361     // Giving eden priority was tried and gave poorer performance.

   362     to_end   = (char*)pointer_delta(virtual_space()->high(),

   363                                     (char*)requested_survivor_size,

   364                                     sizeof(char));

   365     to_end   = MIN2(to_end, from_start);

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

   367                                     sizeof(char));

   368     // if the space sizes are to be increased by several times then

   369     // 'to_start' will point beyond the young generation. In this case

   370     // 'to_start' should be adjusted.

   371     to_start = MAX2(to_start, eden_start + alignment);

   372 

   373     // Compute how big eden can be, then adjust end.

   374     // See comment in PSYoungGen::resize_spaces() on

   375     // calculating eden_end.

   376     const size_t eden_size = MIN2(requested_eden_size,

   377                                   pointer_delta(to_start,

   378                                                 eden_start,

   379                                                 sizeof(char)));

   380     eden_end = eden_start + eden_size;

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

   382 

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

   384     eden_end = MAX2(eden_end, eden_start + alignment);

   385     to_start = MAX2(to_start, eden_end);

   386 

   387     if (PrintAdaptiveSizePolicy && Verbose) {

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

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

   390                     eden_start,

   391                     eden_end,

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

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

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

   395                     to_start,

   396                     to_end,

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

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

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

   400                     from_start,

   401                     from_end,

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

   403     }

   404   }

   405 

   406 

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

   408             "from start moved to the right");

   409   guarantee((HeapWord*)from_end >= from_space()->top(),

   410             "from end moved into live data");

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

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

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

   414 

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

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

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

   418 

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

   420   DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)

   421 

   422   // For PrintAdaptiveSizePolicy block  below

   423   size_t old_from = from_space()->capacity_in_bytes();

   424   size_t old_to   = to_space()->capacity_in_bytes();

   425 

   426   eden_space()->initialize(edenMR, true);

   427     to_space()->initialize(toMR  , true);

   428   from_space()->initialize(fromMR, false);     // Note, not cleared!

   429   PSScavenge::set_young_generation_boundary(eden_space()->bottom());

   430 

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

   432 

   433   if (PrintAdaptiveSizePolicy) {

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

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

   436 

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

   438                   "collection: %d "

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

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

   441                   heap->total_collections(),

   442                   old_from, old_to,

   443                   from_space()->capacity_in_bytes(),

   444                   to_space()->capacity_in_bytes());

   445     gclog_or_tty->cr();

   446   }

   447   space_invariants();

   448 }

   449 

   450 void ASPSYoungGen::reset_after_change() {

   451   assert_locked_or_safepoint(Heap_lock);

   452 

   453   _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),

   454                         (HeapWord*)virtual_space()->high_boundary());

   455   PSScavenge::reference_processor()->set_span(_reserved);

   456 

   457   HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low();

   458   HeapWord* eden_bottom = eden_space()->bottom();

   459   if (new_eden_bottom != eden_bottom) {

   460     MemRegion eden_mr(new_eden_bottom, eden_space()->end());

   461     eden_space()->initialize(eden_mr, true);

   462     PSScavenge::set_young_generation_boundary(eden_space()->bottom());

   463   }

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

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

   466   Universe::heap()->barrier_set()->resize_covered_region(cmr);

   467 

   468   space_invariants();

   469 }