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/shenandoahCollectionSet.hpp"
28 #include "gc/shenandoah/heuristics/shenandoahCompactHeuristics.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 ShenandoahCompactHeuristics::ShenandoahCompactHeuristics() : ShenandoahHeuristics() {
36 SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
37 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
38 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahUncommit);
39 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahAlwaysClearSoftRefs);
40 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold, 10);
41 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold, 100);
42 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay, 1000);
43 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000);
44 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold, 10);
45 }
46
47 bool ShenandoahCompactHeuristics::should_start_gc() {
48 ShenandoahHeap* heap = ShenandoahHeap::heap();
49
50 size_t max_capacity = heap->max_capacity();
51 size_t capacity = heap->soft_max_capacity();
52 size_t available = heap->free_set()->available();
53
54 // Make sure the code below treats available without the soft tail.
55 size_t soft_tail = max_capacity - capacity;
56 available = (available > soft_tail) ? (available - soft_tail) : 0;
57
58 size_t threshold_bytes_allocated = capacity / 100 * ShenandoahAllocationThreshold;
59 size_t min_threshold = capacity / 100 * ShenandoahMinFreeThreshold;
60
61 if (available < min_threshold) {
62 log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
63 byte_size_in_proper_unit(available), proper_unit_for_byte_size(available),
64 byte_size_in_proper_unit(min_threshold), proper_unit_for_byte_size(min_threshold));
65 return true;
66 }
67
68 size_t bytes_allocated = heap->bytes_allocated_since_gc_start();
69 if (bytes_allocated > threshold_bytes_allocated) {
70 log_info(gc)("Trigger: Allocated since last cycle (" SIZE_FORMAT "%s) is larger than allocation threshold (" SIZE_FORMAT "%s)",
71 byte_size_in_proper_unit(bytes_allocated), proper_unit_for_byte_size(bytes_allocated),
72 byte_size_in_proper_unit(threshold_bytes_allocated), proper_unit_for_byte_size(threshold_bytes_allocated));
73 return true;
74 }
75
76 return ShenandoahHeuristics::should_start_gc();
77 }
78
79 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
80 RegionData* data, size_t size,
81 size_t actual_free) {
82 // Do not select too large CSet that would overflow the available free space
83 size_t max_cset = actual_free * 3 / 4;
84
85 log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "%s, Max CSet: " SIZE_FORMAT "%s",
86 byte_size_in_proper_unit(actual_free), proper_unit_for_byte_size(actual_free),
87 byte_size_in_proper_unit(max_cset), proper_unit_for_byte_size(max_cset));
88
89 size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
90
91 size_t live_cset = 0;
92 for (size_t idx = 0; idx < size; idx++) {
93 ShenandoahHeapRegion* r = data[idx]._region;
94 size_t new_cset = live_cset + r->get_live_data_bytes();
95 if (new_cset < max_cset && r->garbage() > threshold) {
96 live_cset = new_cset;
97 cset->add_region(r);
98 }
99 }
100 }