src/hotspot/share/gc/shared/gcArguments.cpp

/*
 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
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 */

#include "precompiled.hpp"
#include "gc/shared/gcArguments.hpp"
#include "runtime/arguments.hpp"
#include "runtime/globals.hpp"
#include "runtime/globals_extension.hpp"
#include "utilities/macros.hpp"

void GCArguments::initialize() {
  if (FullGCALot && FLAG_IS_DEFAULT(MarkSweepAlwaysCompactCount)) {
    MarkSweepAlwaysCompactCount = 1;  // Move objects every gc.
  }

  if (!(UseParallelGC || UseParallelOldGC) && FLAG_IS_DEFAULT(ScavengeBeforeFullGC)) {
    FLAG_SET_DEFAULT(ScavengeBeforeFullGC, false);
  }

  if (GCTimeLimit == 100) {
    // Turn off gc-overhead-limit-exceeded checks
    FLAG_SET_DEFAULT(UseGCOverheadLimit, false);
  }

  if (MinHeapFreeRatio == 100) {
    // Keeping the heap 100% free is hard ;-) so limit it to 99%.
    FLAG_SET_ERGO(uintx, MinHeapFreeRatio, 99);
  }

  if (!ClassUnloading) {
    // If class unloading is disabled, also disable concurrent class unloading.
    FLAG_SET_CMDLINE(bool, ClassUnloadingWithConcurrentMark, false);
  }
}