1 /*
   2  * Copyright (c) 2018, 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/g1/g1HeterogeneousCollectorPolicy.hpp"
  27 #include "logging/log.hpp"
  28 #include "runtime/globals_extension.hpp"
  29 #include "runtime/os.hpp"
  30 #include "utilities/formatBuffer.hpp"
  31 
  32 const double G1HeterogeneousCollectorPolicy::MaxRamFractionForYoung = 0.8;
  33 size_t G1HeterogeneousCollectorPolicy::MaxMemoryForYoung;
  34 
  35 static size_t calculate_reasonable_max_memory_for_young(FormatBuffer<100> &calc_str, double max_ram_fraction_for_young) {
  36   julong phys_mem;
  37   // If MaxRam is specified, we use that as maximum physical memory available.
  38   if (FLAG_IS_DEFAULT(MaxRAM)) {
  39     phys_mem = os::physical_memory();
  40     calc_str.append("Physical_Memory");
  41   } else {
  42     phys_mem = (julong)MaxRAM;
  43     calc_str.append("MaxRAM");
  44   }
  45 
  46   julong reasonable_max = phys_mem;
  47 
  48   // If either MaxRAMFraction or MaxRAMPercentage is specified, we use them to calculate
  49   // reasonable max size of young generation.
  50   if (!FLAG_IS_DEFAULT(MaxRAMFraction)) {
  51     reasonable_max = (julong)(phys_mem / MaxRAMFraction);
  52     calc_str.append(" / MaxRAMFraction");
  53   }  else if (!FLAG_IS_DEFAULT(MaxRAMPercentage)) {
  54     reasonable_max = (julong)((phys_mem * MaxRAMPercentage) / 100);
  55     calc_str.append(" * MaxRAMPercentage / 100");
  56   }  else {
  57     // We use our own fraction to calculate max size of young generation.
  58     reasonable_max = phys_mem * max_ram_fraction_for_young;
  59     calc_str.append(" * %0.2f", max_ram_fraction_for_young);
  60   }
  61 
  62   return (size_t)reasonable_max;
  63 }
  64 
  65 void G1HeterogeneousCollectorPolicy::initialize_flags() {
  66 
  67   FormatBuffer<100> calc_str("");
  68 
  69   MaxMemoryForYoung = calculate_reasonable_max_memory_for_young(calc_str, MaxRamFractionForYoung);
  70 
  71   if (MaxNewSize > MaxMemoryForYoung) {
  72     if (FLAG_IS_CMDLINE(MaxNewSize)) {
  73       log_warning(gc, ergo)("Setting MaxNewSize to " SIZE_FORMAT " based on dram available (calculation = align(%s))",
  74                             MaxMemoryForYoung, calc_str.buffer());
  75     } else {
  76       log_info(gc, ergo)("Setting MaxNewSize to " SIZE_FORMAT " based on dram available (calculation = align(%s)). "
  77                          "Dram usage can be lowered by setting MaxNewSize to a lower value", MaxMemoryForYoung, calc_str.buffer());
  78     }
  79     MaxNewSize = MaxMemoryForYoung;
  80   }
  81   if (NewSize > MaxMemoryForYoung) {
  82     if (FLAG_IS_CMDLINE(NewSize)) {
  83       log_warning(gc, ergo)("Setting NewSize to " SIZE_FORMAT " based on dram available (calculation = align(%s))",
  84                             MaxMemoryForYoung, calc_str.buffer());
  85     }
  86     NewSize = MaxMemoryForYoung;
  87   }
  88 
  89   // After setting new size flags, call base class initialize_flags()
  90   G1CollectorPolicy::initialize_flags();
  91 }
  92 
  93 size_t G1HeterogeneousCollectorPolicy::reasonable_max_memory_for_young() {
  94   return MaxMemoryForYoung;
  95 }
  96 
  97 size_t G1HeterogeneousCollectorPolicy::heap_reserved_size_bytes() const {
  98     return 2 * _max_heap_byte_size;
  99 }
 100 
 101 bool G1HeterogeneousCollectorPolicy::is_hetero_heap() const {
 102   return true;
 103 }