1 /*
   2  * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_GENERATIONSIZER_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_GENERATIONSIZER_HPP
  27 
  28 #include "memory/collectorPolicy.hpp"
  29 
  30 // There is a nice batch of tested generation sizing code in
  31 // TwoGenerationCollectorPolicy. Lets reuse it!
  32 
  33 class GenerationSizer : public TwoGenerationCollectorPolicy {
  34 private:
  35 
  36   void trace_gen_sizes(const char* const str) {
  37     if (TracePageSizes) {
  38       tty->print_cr("%s:  " SIZE_FORMAT "," SIZE_FORMAT " "
  39                     SIZE_FORMAT "," SIZE_FORMAT " "
  40                     SIZE_FORMAT,
  41                     str,
  42                     _min_gen1_size / K, _max_gen1_size / K,
  43                     _min_gen0_size / K, _max_gen0_size / K,
  44                     _max_heap_byte_size / K);
  45     }
  46   }
  47 
  48   void initialize_alignments() {
  49     _space_alignment = _gen_alignment = default_gen_alignment();
  50     _heap_alignment = compute_heap_alignment();
  51   }
  52 
  53   void initialize_flags() {
  54     // Do basic sizing work
  55     TwoGenerationCollectorPolicy::initialize_flags();
  56 
  57     assert(UseSerialGC ||
  58            !FLAG_IS_DEFAULT(ParallelGCThreads) ||
  59            (ParallelGCThreads > 0),
  60            "ParallelGCThreads should be set before flag initialization");
  61 
  62     // The survivor ratio's are calculated "raw", unlike the
  63     // default gc, which adds 2 to the ratio value. We need to
  64     // make sure the values are valid before using them.
  65     if (MinSurvivorRatio < 3) {
  66       FLAG_SET_ERGO(uintx, MinSurvivorRatio, 3);
  67     }
  68 
  69     if (InitialSurvivorRatio < 3) {
  70       FLAG_SET_ERGO(uintx, InitialSurvivorRatio, 3);
  71     }
  72   }
  73 
  74   void initialize_size_info() {
  75     trace_gen_sizes("ps heap raw");
  76     const size_t page_sz = os::page_size_for_region(_min_heap_byte_size,
  77                                                     _max_heap_byte_size,
  78                                                     8);
  79 
  80     // Can a page size be something else than a power of two?
  81     assert(is_power_of_2((intptr_t)page_sz), "must be a power of 2");
  82     size_t new_alignment = round_to(page_sz, _gen_alignment);
  83     if (new_alignment != _gen_alignment) {
  84       _gen_alignment = new_alignment;
  85       // Redo everything from the start
  86       initialize_flags();
  87     }
  88     TwoGenerationCollectorPolicy::initialize_size_info();
  89 
  90     trace_gen_sizes("ps heap rnd");
  91   }
  92 };
  93 
  94 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_GENERATIONSIZER_HPP