1 /*
2 * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25
26 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
27 #include "gc_implementation/shenandoah/heuristics/shenandoahCompactHeuristics.hpp"
28 #include "gc_implementation/shenandoah/shenandoahFreeSet.hpp"
29 #include "gc_implementation/shenandoah/shenandoahHeapRegion.hpp"
30 #include "gc_implementation/shenandoah/shenandoahLogging.hpp"
31
32 ShenandoahCompactHeuristics::ShenandoahCompactHeuristics() : ShenandoahHeuristics() {
33 SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
34 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
35 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahUncommit);
36 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahAlwaysClearSoftRefs);
37 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold, 10);
38 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold, 100);
39 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay, 1000);
40 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000);
41 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold, 10);
42
43 // Final configuration checks
44 SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
45 SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);
46 SHENANDOAH_CHECK_FLAG_SET(ShenandoahKeepAliveBarrier);
47 SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
48 SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
49 }
50
51 bool ShenandoahCompactHeuristics::should_start_gc() const {
52 ShenandoahHeap* heap = ShenandoahHeap::heap();
53
54 size_t capacity = heap->max_capacity();
55 size_t available = heap->free_set()->available();
56
57 size_t threshold_bytes_allocated = capacity / 100 * ShenandoahAllocationThreshold;
58 size_t min_threshold = capacity / 100 * ShenandoahMinFreeThreshold;
59
60 if (available < min_threshold) {
61 log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
62 byte_size_in_proper_unit(available), proper_unit_for_byte_size(available),
63 byte_size_in_proper_unit(min_threshold), proper_unit_for_byte_size(min_threshold));
64 return true;
65 }
66
67 if (available < threshold_bytes_allocated) {
68 log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is lower than allocated recently (" SIZE_FORMAT "%s)",
69 byte_size_in_proper_unit(available), proper_unit_for_byte_size(available),
70 byte_size_in_proper_unit(threshold_bytes_allocated), proper_unit_for_byte_size(threshold_bytes_allocated));
71 return true;
72 }
73
74 size_t bytes_allocated = heap->bytes_allocated_since_gc_start();
75 if (bytes_allocated > threshold_bytes_allocated) {
76 log_info(gc)("Trigger: Allocated since last cycle (" SIZE_FORMAT "%s) is larger than allocation threshold (" SIZE_FORMAT "%s)",
77 byte_size_in_proper_unit(bytes_allocated), proper_unit_for_byte_size(bytes_allocated),
78 byte_size_in_proper_unit(threshold_bytes_allocated), proper_unit_for_byte_size(threshold_bytes_allocated));
79 return true;
80 }
81
82 return ShenandoahHeuristics::should_start_gc();
83 }
84
85 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
86 RegionData* data, size_t size,
87 size_t actual_free) {
88 // Do not select too large CSet that would overflow the available free space
89 size_t max_cset = actual_free * 3 / 4;
90
91 log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "%s, Max CSet: " SIZE_FORMAT "%s",
92 byte_size_in_proper_unit(actual_free), proper_unit_for_byte_size(actual_free),
93 byte_size_in_proper_unit(max_cset), proper_unit_for_byte_size(max_cset));
94
95 size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
96
97 size_t live_cset = 0;
98 for (size_t idx = 0; idx < size; idx++) {
99 ShenandoahHeapRegion* r = data[idx]._region;
100 size_t new_cset = live_cset + r->get_live_data_bytes();
101 if (new_cset < max_cset && r->garbage() > threshold) {
102 live_cset = new_cset;
103 cset->add_region(r);
104 }
105 }
106 }
107
108 const char* ShenandoahCompactHeuristics::name() {
109 return "compact";
110 }
111
112 bool ShenandoahCompactHeuristics::is_diagnostic() {
113 return false;
114 }
115
116 bool ShenandoahCompactHeuristics::is_experimental() {
117 return false;
118 }