1 /*
 2  * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.
 3  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
 4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 5  *
 6  * This code is free software; you can redistribute it and/or modify it
 7  * under the terms of the GNU General Public License version 2 only, as
 8  * published by the Free Software Foundation.
 9  *
10  * This code is distributed in the hope that it will be useful, but WITHOUT
11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13  * version 2 for more details (a copy is included in the LICENSE file that
14  * accompanied this code).
15  *
16  * You should have received a copy of the GNU General Public License version
17  * 2 along with this work; if not, write to the Free Software Foundation,
18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19  *
20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21  * or visit www.oracle.com if you need additional information or have any
22  * questions.
23  *
24  */
25 
26 #include "precompiled.hpp"
27 
28 #include "gc/shenandoah/heuristics/shenandoahAggressiveHeuristics.hpp"
29 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
30 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
31 #include "logging/log.hpp"
32 #include "logging/logTag.hpp"
33 #include "runtime/os.hpp"
34 
35 ShenandoahAggressiveHeuristics::ShenandoahAggressiveHeuristics(ShenandoahSpaceInfo* space_info) :
36   ShenandoahHeuristics(space_info) {
37   // Do not shortcut evacuation
38   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold, 100);
39 
40   // Aggressive evacuates everything, so it needs as much evac space as it can get
41   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahEvacReserveOverflow);
42 }
43 
44 void ShenandoahAggressiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
45                                                                            RegionData* data, size_t size,
46                                                                            size_t free) {
47   for (size_t idx = 0; idx < size; idx++) {
48     ShenandoahHeapRegion* r = data[idx]._region;
49     if (r->garbage() > 0) {
50       cset->add_region(r);
51     }
52   }
53 }
54 
55 bool ShenandoahAggressiveHeuristics::should_start_gc() {
56   log_info(gc)("Trigger: Start next cycle immediately");
57   return true;
58 }
59 
60 bool ShenandoahAggressiveHeuristics::should_unload_classes() {
61   if (!can_unload_classes()) return false;
62   if (has_metaspace_oom()) return true;
63   // Randomly unload classes with 50% chance.
64   return (os::random() & 1) == 1;
65 }