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/shenandoahSpaceInfo.hpp"
28 #include "gc/shenandoah/heuristics/shenandoahPassiveHeuristics.hpp"
29 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
31 #include "logging/log.hpp"
32 #include "logging/logTag.hpp"
33 #include "runtime/java.hpp"
34 
35 void ShenandoahPassiveMode::initialize_flags() const {
36   // Do not allow concurrent cycles.
37   FLAG_SET_DEFAULT(ExplicitGCInvokesConcurrent, false);
38   FLAG_SET_DEFAULT(ShenandoahImplicitGCInvokesConcurrent, false);
39 
40   // Passive runs with max speed for allocation, because GC is always STW
41   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahPacing);
42 
43   // No need for evacuation reserve with Full GC, only for Degenerated GC.
44   if (!ShenandoahDegeneratedGC) {
45     SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahEvacReserve, 0);
46   }
47 
48   // Disable known barriers by default.
49   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahLoadRefBarrier);
50   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahSATBBarrier);
51   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahIUBarrier);
52   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCASBarrier);
53   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCloneBarrier);
54   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahStackWatermarkBarrier);
55   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCardBarrier);
56 
57   // Final configuration checks
58   // Passive mode does not instantiate the machinery to support the card table.
59   // Exit if the flag has been explicitly set.
60   SHENANDOAH_CHECK_FLAG_UNSET(ShenandoahCardBarrier);
61 }
62 
63 ShenandoahHeuristics* ShenandoahPassiveMode::initialize_heuristics(ShenandoahSpaceInfo* space_info) const {
64   if (ShenandoahGCHeuristics == nullptr) {
65     vm_exit_during_initialization("Unknown -XX:ShenandoahGCHeuristics option (null)");
66   }
67   return new ShenandoahPassiveHeuristics(space_info);
68 }