1 /*
 2  * Copyright (c) 2018, 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 
27 #include "gc/shenandoah/heuristics/shenandoahStaticHeuristics.hpp"
28 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
29 #include "gc/shenandoah/shenandoahFreeSet.hpp"
30 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
31 #include "gc/shenandoah/shenandoahGeneration.hpp"
32 #include "logging/log.hpp"
33 #include "logging/logTag.hpp"
34 
35 ShenandoahStaticHeuristics::ShenandoahStaticHeuristics(ShenandoahGeneration* generation) :
36   ShenandoahHeuristics(generation) {
37   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
38   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
39 }
40 
41 ShenandoahStaticHeuristics::~ShenandoahStaticHeuristics() {}
42 
43 bool ShenandoahStaticHeuristics::should_start_gc() {
44   size_t max_capacity = _generation->max_capacity();
45   size_t capacity = _generation->soft_max_capacity();
46   size_t available = _generation->available();
47 
48   // Make sure the code below treats available without the soft tail.
49   size_t soft_tail = max_capacity - capacity;
50   available = (available > soft_tail) ? (available - soft_tail) : 0;
51 
52   size_t threshold_available = capacity / 100 * ShenandoahMinFreeThreshold;
53 
54   if (available < threshold_available) {
55     log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
56                  byte_size_in_proper_unit(available),           proper_unit_for_byte_size(available),
57                  byte_size_in_proper_unit(threshold_available), proper_unit_for_byte_size(threshold_available));
58     return true;
59   }
60   return ShenandoahHeuristics::should_start_gc();
61 }
62 
63 void ShenandoahStaticHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
64                                                                        RegionData* data, size_t size,
65                                                                        size_t free) {
66   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
67 
68   for (size_t idx = 0; idx < size; idx++) {
69     ShenandoahHeapRegion* r = data[idx]._region;
70     if (r->garbage() > threshold) {
71       cset->add_region(r);
72     }
73   }
74 }