1 /*
   2  * Copyright (c) 2019, Red Hat, Inc. 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/shenandoah/shenandoahPassiveMode.hpp"
  27 #include "gc/shenandoah/heuristics/shenandoahPassiveHeuristics.hpp"
  28 #include "logging/log.hpp"
  29 #include "logging/logTag.hpp"
  30 
  31 void ShenandoahPassiveMode::initialize_flags() const {
  32   // Do not allow concurrent cycles.
  33   FLAG_SET_DEFAULT(ExplicitGCInvokesConcurrent, false);
  34   FLAG_SET_DEFAULT(ShenandoahImplicitGCInvokesConcurrent, false);
  35 
  36   // Passive runs with max speed for allocation, because GC is always STW
  37   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahPacing);
  38 
  39   // No need for evacuation reserve with Full GC, only for Degenerated GC.
  40   if (!ShenandoahDegeneratedGC) {
  41     SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahEvacReserve, 0);
  42   }
  43 
  44   // Disable known barriers by default.
  45   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahLoadRefBarrier);
  46   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahSATBBarrier);
  47   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahStoreValEnqueueBarrier);
  48   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCASBarrier);
  49   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCloneBarrier);
  50 
  51   // Final configuration checks
  52   // No barriers are required to run.
  53 }
  54 ShenandoahHeuristics* ShenandoahPassiveMode::initialize_heuristics() const {
  55   if (ShenandoahGCHeuristics != NULL) {
  56     return new ShenandoahPassiveHeuristics();
  57   }
  58   ShouldNotReachHere();
  59   return NULL;
  60 }