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/shenandoahHeap.inline.hpp"
31 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
32 #include "logging/log.hpp"
33 #include "logging/logTag.hpp"
34 
35 ShenandoahStaticHeuristics::ShenandoahStaticHeuristics() : ShenandoahHeuristics() {
36   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
37   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
38 }
39 
40 ShenandoahStaticHeuristics::~ShenandoahStaticHeuristics() {}
41 
42 bool ShenandoahStaticHeuristics::should_start_gc() {
43   ShenandoahHeap* heap = ShenandoahHeap::heap();
44 
45   size_t max_capacity = heap->max_capacity();
46   size_t capacity = heap->soft_max_capacity();
47   size_t available = heap->free_set()->available();
48 
49   // Make sure the code below treats available without the soft tail.
50   size_t soft_tail = max_capacity - capacity;
51   available = (available > soft_tail) ? (available - soft_tail) : 0;
52 
53   size_t threshold_available = capacity / 100 * ShenandoahMinFreeThreshold;
54 
55   if (available < threshold_available) {
56     log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
57                  byte_size_in_proper_unit(available),           proper_unit_for_byte_size(available),
58                  byte_size_in_proper_unit(threshold_available), proper_unit_for_byte_size(threshold_available));
59     return true;
60   }
61   return ShenandoahHeuristics::should_start_gc();
62 }
63 
64 void ShenandoahStaticHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
65                                                                        RegionData* data, size_t size,
66                                                                        size_t free) {
67   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
68 
69   for (size_t idx = 0; idx < size; idx++) {
70     ShenandoahHeapRegion* r = data[idx]._region;
71     if (r->garbage() > threshold) {
72       cset->add_region(r);
73     }
74   }
75 }