1 /*
   2  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/parallel/generationSizer.hpp"
  27 #include "gc/shared/collectorPolicy.hpp"
  28 #include "runtime/globals_extension.hpp"
  29 #include "utilities/globalDefinitions.hpp"
  30 
  31 void GenerationSizer::initialize_alignments() {
  32   _space_alignment = _gen_alignment = default_gen_alignment();
  33   _heap_alignment = compute_heap_alignment();
  34 }
  35 
  36 void GenerationSizer::initialize_flags() {
  37   // Do basic sizing work
  38   GenCollectorPolicy::initialize_flags();
  39 
  40   // The survivor ratio's are calculated "raw", unlike the
  41   // default gc, which adds 2 to the ratio value. We need to
  42   // make sure the values are valid before using them.
  43   if (MinSurvivorRatio < 3) {
  44     FLAG_SET_ERGO(uintx, MinSurvivorRatio, 3);
  45   }
  46 
  47   if (InitialSurvivorRatio < 3) {
  48     FLAG_SET_ERGO(uintx, InitialSurvivorRatio, 3);
  49   }
  50 }
  51 
  52 void GenerationSizer::initialize_size_info() {
  53   const size_t max_page_sz = os::page_size_for_region_aligned(_max_heap_byte_size, 8);
  54   const size_t min_pages = 4; // 1 for eden + 1 for each survivor + 1 for old
  55   const size_t min_page_sz = os::page_size_for_region_aligned(_min_heap_byte_size, min_pages);
  56   const size_t page_sz = MIN2(max_page_sz, min_page_sz);
  57 
  58   // Can a page size be something else than a power of two?
  59   assert(is_power_of_2((intptr_t)page_sz), "must be a power of 2");
  60   size_t new_alignment = align_up(page_sz, _gen_alignment);
  61   if (new_alignment != _gen_alignment) {
  62     _gen_alignment = new_alignment;
  63     _space_alignment = new_alignment;
  64     // Redo everything from the start
  65     initialize_flags();
  66   }
  67   GenCollectorPolicy::initialize_size_info();
  68 }