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 
  29 void GenerationSizer::initialize_alignments() {
  30   _space_alignment = _gen_alignment = default_gen_alignment();
  31   _heap_alignment = compute_heap_alignment();
  32 }
  33 
  34 void GenerationSizer::initialize_flags() {
  35   // Do basic sizing work
  36   GenCollectorPolicy::initialize_flags();
  37 
  38   // The survivor ratio's are calculated "raw", unlike the
  39   // default gc, which adds 2 to the ratio value. We need to
  40   // make sure the values are valid before using them.
  41   if (MinSurvivorRatio < 3) {
  42     FLAG_SET_ERGO(uintx, MinSurvivorRatio, 3);
  43   }
  44 
  45   if (InitialSurvivorRatio < 3) {
  46     FLAG_SET_ERGO(uintx, InitialSurvivorRatio, 3);
  47   }
  48 }
  49 
  50 void GenerationSizer::initialize_size_info() {
  51   const size_t max_page_sz = os::page_size_for_region_aligned(_max_heap_byte_size, 8);
  52   const size_t min_pages = 4; // 1 for eden + 1 for each survivor + 1 for old
  53   const size_t min_page_sz = os::page_size_for_region_aligned(_min_heap_byte_size, min_pages);
  54   const size_t page_sz = MIN2(max_page_sz, min_page_sz);
  55 
  56   // Can a page size be something else than a power of two?
  57   assert(is_power_of_2((intptr_t)page_sz), "must be a power of 2");
  58   size_t new_alignment = round_to(page_sz, _gen_alignment);
  59   if (new_alignment != _gen_alignment) {
  60     _gen_alignment = new_alignment;
  61     _space_alignment = new_alignment;
  62     // Redo everything from the start
  63     initialize_flags();
  64   }
  65   GenCollectorPolicy::initialize_size_info();
  66 }