1 /*
2 * Copyright Amazon.com Inc. or its affiliates. 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/shenandoahGlobalHeuristics.hpp"
28 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
29 #include "gc/shenandoah/shenandoahGlobalGeneration.hpp"
30 #include "gc/shenandoah/shenandoahGenerationalHeap.hpp"
31 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
32
33 #include "utilities/quickSort.hpp"
34
35 ShenandoahGlobalHeuristics::ShenandoahGlobalHeuristics(ShenandoahGlobalGeneration* generation)
36 : ShenandoahGenerationalHeuristics(generation) {
37 }
38
39
40 void ShenandoahGlobalHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
41 RegionData* data, size_t size,
42 size_t actual_free) {
43 // Better select garbage-first regions
44 QuickSort::sort<RegionData>(data, (int) size, compare_by_garbage);
45
46 choose_global_collection_set(cset, data, size, actual_free, 0 /* cur_young_garbage */);
47
48 log_cset_composition(cset);
49 }
50
51
52 void ShenandoahGlobalHeuristics::choose_global_collection_set(ShenandoahCollectionSet* cset,
53 const ShenandoahHeuristics::RegionData* data,
54 size_t size, size_t actual_free,
55 size_t cur_young_garbage) const {
56 auto heap = ShenandoahGenerationalHeap::heap();
57 size_t region_size_bytes = ShenandoahHeapRegion::region_size_bytes();
58 size_t capacity = heap->young_generation()->max_capacity();
59 size_t garbage_threshold = region_size_bytes * ShenandoahGarbageThreshold / 100;
60 size_t ignore_threshold = region_size_bytes * ShenandoahIgnoreGarbageThreshold / 100;
61 const uint tenuring_threshold = heap->age_census()->tenuring_threshold();
62
63 size_t young_evac_reserve = heap->young_generation()->get_evacuation_reserve();
64 size_t old_evac_reserve = heap->old_generation()->get_evacuation_reserve();
65 size_t max_young_cset = (size_t) (young_evac_reserve / ShenandoahEvacWaste);
66 size_t young_cur_cset = 0;
67 size_t max_old_cset = (size_t) (old_evac_reserve / ShenandoahOldEvacWaste);
68 size_t old_cur_cset = 0;
69
70 // Figure out how many unaffiliated young regions are dedicated to mutator and to evacuator. Allow the young
71 // collector's unaffiliated regions to be transferred to old-gen if old-gen has more easily reclaimed garbage
72 // than young-gen. At the end of this cycle, any excess regions remaining in old-gen will be transferred back
73 // to young. Do not transfer the mutator's unaffiliated regions to old-gen. Those must remain available
74 // to the mutator as it needs to be able to consume this memory during concurrent GC.
75
76 size_t unaffiliated_young_regions = heap->young_generation()->free_unaffiliated_regions();
77 size_t unaffiliated_young_memory = unaffiliated_young_regions * region_size_bytes;
78
79 if (unaffiliated_young_memory > max_young_cset) {
80 size_t unaffiliated_mutator_memory = unaffiliated_young_memory - max_young_cset;
81 unaffiliated_young_memory -= unaffiliated_mutator_memory;
82 unaffiliated_young_regions = unaffiliated_young_memory / region_size_bytes; // round down
83 unaffiliated_young_memory = unaffiliated_young_regions * region_size_bytes;
84 }
85
86 // We'll affiliate these unaffiliated regions with either old or young, depending on need.
87 max_young_cset -= unaffiliated_young_memory;
88
89 // Keep track of how many regions we plan to transfer from young to old.
90 size_t regions_transferred_to_old = 0;
91
92 size_t free_target = (capacity * ShenandoahMinFreeThreshold) / 100 + max_young_cset;
93 size_t min_garbage = (free_target > actual_free) ? (free_target - actual_free) : 0;
94
95 log_info(gc, ergo)("Adaptive CSet Selection for GLOBAL. Max Young Evacuation: " SIZE_FORMAT
96 "%s, Max Old Evacuation: " SIZE_FORMAT "%s, Actual Free: " SIZE_FORMAT "%s.",
97 byte_size_in_proper_unit(max_young_cset), proper_unit_for_byte_size(max_young_cset),
98 byte_size_in_proper_unit(max_old_cset), proper_unit_for_byte_size(max_old_cset),
99 byte_size_in_proper_unit(actual_free), proper_unit_for_byte_size(actual_free));
100
101 for (size_t idx = 0; idx < size; idx++) {
102 ShenandoahHeapRegion* r = data[idx].get_region();
103 assert(!cset->is_preselected(r->index()), "There should be no preselected regions during GLOBAL GC");
104 bool add_region = false;
105 if (r->is_old() || (r->age() >= tenuring_threshold)) {
106 size_t new_cset = old_cur_cset + r->get_live_data_bytes();
107 if ((r->garbage() > garbage_threshold)) {
108 while ((new_cset > max_old_cset) && (unaffiliated_young_regions > 0)) {
109 unaffiliated_young_regions--;
110 regions_transferred_to_old++;
111 max_old_cset += region_size_bytes / ShenandoahOldEvacWaste;
112 }
113 }
114 if ((new_cset <= max_old_cset) && (r->garbage() > garbage_threshold)) {
115 add_region = true;
116 old_cur_cset = new_cset;
117 }
118 } else {
119 assert(r->is_young() && (r->age() < tenuring_threshold), "DeMorgan's law (assuming r->is_affiliated)");
120 size_t new_cset = young_cur_cset + r->get_live_data_bytes();
121 size_t region_garbage = r->garbage();
122 size_t new_garbage = cur_young_garbage + region_garbage;
123 bool add_regardless = (region_garbage > ignore_threshold) && (new_garbage < min_garbage);
124
125 if (add_regardless || (r->garbage() > garbage_threshold)) {
126 while ((new_cset > max_young_cset) && (unaffiliated_young_regions > 0)) {
127 unaffiliated_young_regions--;
128 max_young_cset += region_size_bytes / ShenandoahEvacWaste;
129 }
130 }
131 if ((new_cset <= max_young_cset) && (add_regardless || (region_garbage > garbage_threshold))) {
132 add_region = true;
133 young_cur_cset = new_cset;
134 cur_young_garbage = new_garbage;
135 }
136 }
137 if (add_region) {
138 cset->add_region(r);
139 }
140 }
141
142 if (regions_transferred_to_old > 0) {
143 heap->generation_sizer()->force_transfer_to_old(regions_transferred_to_old);
144 heap->young_generation()->set_evacuation_reserve(young_evac_reserve - regions_transferred_to_old * region_size_bytes);
145 heap->old_generation()->set_evacuation_reserve(old_evac_reserve + regions_transferred_to_old * region_size_bytes);
146 }
147 }