1 /*
   2  * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #include "precompiled.hpp"
  25 #include "gc_implementation/shenandoah/heuristics/shenandoahPassiveHeuristics.hpp"
  26 #include "gc_implementation/shenandoah/mode/shenandoahPassiveMode.hpp"
  27 #include "gc_implementation/shenandoah/shenandoahLogging.hpp"
  28 
  29 void ShenandoahPassiveMode::initialize_flags() const {
  30   // Do not allow concurrent cycles.
  31   FLAG_SET_DEFAULT(ExplicitGCInvokesConcurrent, false);
  32   FLAG_SET_DEFAULT(ShenandoahImplicitGCInvokesConcurrent, false);
  33 
  34   // Passive runs with max speed for allocation, because GC is always STW
  35   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahPacing);
  36 
  37   // No need for evacuation reserve with Full GC, only for Degenerated GC.
  38   if (!ShenandoahDegeneratedGC) {
  39     SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahEvacReserve, 0);
  40   }
  41 
  42   // Disable known barriers by default.
  43   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahLoadRefBarrier);
  44   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahSATBBarrier);
  45   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahStoreValEnqueueBarrier);
  46   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCASBarrier);
  47   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCloneBarrier);
  48 
  49   // Final configuration checks
  50   // No barriers are required to run.
  51 }
  52 ShenandoahHeuristics* ShenandoahPassiveMode::initialize_heuristics() const {
  53   if (ShenandoahGCHeuristics != NULL) {
  54     return new ShenandoahPassiveHeuristics();
  55   }
  56   ShouldNotReachHere();
  57   return NULL;
  58 }