1 /*
 2  * Copyright (c) 2019, 2021, 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/heuristics/shenandoahHeuristics.hpp"
27 #include "gc/shenandoah/heuristics/shenandoahPassiveHeuristics.hpp"
28 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
29 #include "logging/log.hpp"
30 #include "logging/logTag.hpp"
31 
32 void ShenandoahPassiveMode::initialize_flags() const {
33   // Do not allow concurrent cycles.
34   FLAG_SET_DEFAULT(ExplicitGCInvokesConcurrent, false);
35   FLAG_SET_DEFAULT(ShenandoahImplicitGCInvokesConcurrent, false);
36 
37   // Passive runs with max speed for allocation, because GC is always STW
38   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahPacing);
39 
40   // No need for evacuation reserve with Full GC, only for Degenerated GC.
41   if (!ShenandoahDegeneratedGC) {
42     SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahEvacReserve, 0);
43   }
44 
45   // Disable known barriers by default.
46   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahLoadRefBarrier);
47   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahSATBBarrier);
48   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahIUBarrier);
49   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCASBarrier);
50   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCloneBarrier);
51   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahNMethodBarrier);
52   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahStackWatermarkBarrier);
53 
54   // Final configuration checks
55   // No barriers are required to run.
56 }
57 ShenandoahHeuristics* ShenandoahPassiveMode::initialize_heuristics(ShenandoahGeneration* generation) const {
58   if (ShenandoahGCHeuristics != NULL) {
59     return new ShenandoahPassiveHeuristics(generation);
60   }
61   ShouldNotReachHere();
62   return NULL;
63 }