1 /*
2 * Copyright (c) 2018, 2020, 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 #include "gc/shared/gcCause.hpp"
27 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
28 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
30 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
31 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
32 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
33 #include "logging/log.hpp"
34 #include "logging/logTag.hpp"
35 #include "runtime/globals_extension.hpp"
36
37 int ShenandoahHeuristics::compare_by_garbage(RegionData a, RegionData b) {
38 if (a._garbage > b._garbage)
39 return -1;
40 else if (a._garbage < b._garbage)
41 return 1;
42 else return 0;
43 }
44
45 ShenandoahHeuristics::ShenandoahHeuristics() :
46 _region_data(nullptr),
47 _degenerated_cycles_in_a_row(0),
48 _successful_cycles_in_a_row(0),
49 _cycle_start(os::elapsedTime()),
50 _last_cycle_end(0),
51 _gc_times_learned(0),
52 _gc_time_penalties(0),
53 _gc_time_history(new TruncatedSeq(10, ShenandoahAdaptiveDecayFactor)),
54 _metaspace_oom()
55 {
56 size_t num_regions = ShenandoahHeap::heap()->num_regions();
57 assert(num_regions > 0, "Sanity");
58
59 _region_data = NEW_C_HEAP_ARRAY(RegionData, num_regions, mtGC);
60 }
61
62 ShenandoahHeuristics::~ShenandoahHeuristics() {
63 FREE_C_HEAP_ARRAY(RegionGarbage, _region_data);
64 }
65
66 void ShenandoahHeuristics::choose_collection_set(ShenandoahCollectionSet* collection_set) {
67 assert(collection_set->count() == 0, "Must be empty");
68
69 ShenandoahHeap* heap = ShenandoahHeap::heap();
70
71 // Check all pinned regions have updated status before choosing the collection set.
72 heap->assert_pinned_region_status();
73
74 // Step 1. Build up the region candidates we care about, rejecting losers and accepting winners right away.
75
76 size_t num_regions = heap->num_regions();
77
78 RegionData* candidates = _region_data;
79
80 size_t cand_idx = 0;
81
82 size_t total_garbage = 0;
83
84 size_t immediate_garbage = 0;
85 size_t immediate_regions = 0;
86
87 size_t free = 0;
90 ShenandoahMarkingContext* const ctx = heap->complete_marking_context();
91
92 for (size_t i = 0; i < num_regions; i++) {
93 ShenandoahHeapRegion* region = heap->get_region(i);
94
95 size_t garbage = region->garbage();
96 total_garbage += garbage;
97
98 if (region->is_empty()) {
99 free_regions++;
100 free += ShenandoahHeapRegion::region_size_bytes();
101 } else if (region->is_regular()) {
102 if (!region->has_live()) {
103 // We can recycle it right away and put it in the free set.
104 immediate_regions++;
105 immediate_garbage += garbage;
106 region->make_trash_immediate();
107 } else {
108 // This is our candidate for later consideration.
109 candidates[cand_idx]._region = region;
110 candidates[cand_idx]._garbage = garbage;
111 cand_idx++;
112 }
113 } else if (region->is_humongous_start()) {
114 // Reclaim humongous regions here, and count them as the immediate garbage
115 #ifdef ASSERT
116 bool reg_live = region->has_live();
117 bool bm_live = ctx->is_marked(cast_to_oop(region->bottom()));
118 assert(reg_live == bm_live,
119 "Humongous liveness and marks should agree. Region live: %s; Bitmap live: %s; Region Live Words: " SIZE_FORMAT,
120 BOOL_TO_STR(reg_live), BOOL_TO_STR(bm_live), region->get_live_data_words());
121 #endif
122 if (!region->has_live()) {
123 heap->trash_humongous_region_at(region);
124
125 // Count only the start. Continuations would be counted on "trash" path
126 immediate_regions++;
127 immediate_garbage += garbage;
128 }
129 } else if (region->is_trash()) {
130 // Count in just trashed collection set, during coalesced CM-with-UR
131 immediate_regions++;
132 immediate_garbage += garbage;
133 }
134 }
135
136 // Step 2. Look back at garbage statistics, and decide if we want to collect anything,
137 // given the amount of immediately reclaimable garbage. If we do, figure out the collection set.
138
139 assert (immediate_garbage <= total_garbage,
140 "Cannot have more immediate garbage than total garbage: " SIZE_FORMAT "%s vs " SIZE_FORMAT "%s",
141 byte_size_in_proper_unit(immediate_garbage), proper_unit_for_byte_size(immediate_garbage),
142 byte_size_in_proper_unit(total_garbage), proper_unit_for_byte_size(total_garbage));
143
144 size_t immediate_percent = (total_garbage == 0) ? 0 : (immediate_garbage * 100 / total_garbage);
145
146 if (immediate_percent <= ShenandoahImmediateThreshold) {
147 choose_collection_set_from_regiondata(collection_set, candidates, cand_idx, immediate_garbage + free);
148 }
149
150 size_t cset_percent = (total_garbage == 0) ? 0 : (collection_set->garbage() * 100 / total_garbage);
151
152 size_t collectable_garbage = collection_set->garbage() + immediate_garbage;
153 size_t collectable_garbage_percent = (total_garbage == 0) ? 0 : (collectable_garbage * 100 / total_garbage);
154
155 log_info(gc, ergo)("Collectable Garbage: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), "
156 "Immediate: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), "
157 "CSet: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%)",
158
159 byte_size_in_proper_unit(collectable_garbage),
160 proper_unit_for_byte_size(collectable_garbage),
161 collectable_garbage_percent,
162
163 byte_size_in_proper_unit(immediate_garbage),
164 proper_unit_for_byte_size(immediate_garbage),
165 immediate_percent,
166
167 byte_size_in_proper_unit(collection_set->garbage()),
168 proper_unit_for_byte_size(collection_set->garbage()),
169 cset_percent);
170 }
171
172 void ShenandoahHeuristics::record_cycle_start() {
173 _cycle_start = os::elapsedTime();
174 }
175
176 void ShenandoahHeuristics::record_cycle_end() {
177 _last_cycle_end = os::elapsedTime();
178 }
179
180 bool ShenandoahHeuristics::should_start_gc() {
181 // Perform GC to cleanup metaspace
182 if (has_metaspace_oom()) {
183 // Some of vmTestbase/metaspace tests depend on following line to count GC cycles
184 log_info(gc)("Trigger: %s", GCCause::to_string(GCCause::_metadata_GC_threshold));
185 return true;
186 }
187
188 if (ShenandoahGuaranteedGCInterval > 0) {
189 double last_time_ms = (os::elapsedTime() - _last_cycle_end) * 1000;
190 if (last_time_ms > ShenandoahGuaranteedGCInterval) {
191 log_info(gc)("Trigger: Time since last GC (%.0f ms) is larger than guaranteed interval (" UINTX_FORMAT " ms)",
192 last_time_ms, ShenandoahGuaranteedGCInterval);
193 return true;
194 }
195 }
196
197 return false;
198 }
199
200 bool ShenandoahHeuristics::should_degenerate_cycle() {
201 return _degenerated_cycles_in_a_row <= ShenandoahFullGCThreshold;
202 }
203
204 void ShenandoahHeuristics::adjust_penalty(intx step) {
205 assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
206 "In range before adjustment: " INTX_FORMAT, _gc_time_penalties);
207
208 intx new_val = _gc_time_penalties + step;
209 if (new_val < 0) {
210 new_val = 0;
211 }
212 if (new_val > 100) {
213 new_val = 100;
214 }
215 _gc_time_penalties = new_val;
216
217 assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
218 "In range after adjustment: " INTX_FORMAT, _gc_time_penalties);
219 }
220
221 void ShenandoahHeuristics::record_success_concurrent() {
222 _degenerated_cycles_in_a_row = 0;
223 _successful_cycles_in_a_row++;
224
225 _gc_time_history->add(time_since_last_gc());
226 _gc_times_learned++;
227
228 adjust_penalty(Concurrent_Adjust);
229 }
230
231 void ShenandoahHeuristics::record_success_degenerated() {
232 _degenerated_cycles_in_a_row++;
233 _successful_cycles_in_a_row = 0;
234
235 adjust_penalty(Degenerated_Penalty);
236 }
237
238 void ShenandoahHeuristics::record_success_full() {
239 _degenerated_cycles_in_a_row = 0;
240 _successful_cycles_in_a_row++;
241
242 adjust_penalty(Full_Penalty);
243 }
244
245 void ShenandoahHeuristics::record_allocation_failure_gc() {
246 // Do nothing.
247 }
248
249 void ShenandoahHeuristics::record_requested_gc() {
250 // Assume users call System.gc() when external state changes significantly,
251 // which forces us to re-learn the GC timings and allocation rates.
252 _gc_times_learned = 0;
253 }
254
255 bool ShenandoahHeuristics::can_unload_classes() {
256 if (!ClassUnloading) return false;
257 return true;
258 }
259
260 bool ShenandoahHeuristics::should_unload_classes() {
261 if (!can_unload_classes()) return false;
262 if (has_metaspace_oom()) return true;
263 return ClassUnloadingWithConcurrentMark;
264 }
265
266 void ShenandoahHeuristics::initialize() {
267 // Nothing to do by default.
268 }
269
270 double ShenandoahHeuristics::time_since_last_gc() const {
271 return os::elapsedTime() - _cycle_start;
272 }
|
1 /*
2 * Copyright (c) 2018, 2020, Red Hat, Inc. All rights reserved.
3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "gc/shared/gcCause.hpp"
28 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
29 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
30 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
31 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
32 #include "logging/log.hpp"
33 #include "logging/logTag.hpp"
34 #include "runtime/globals_extension.hpp"
35 #include "utilities/quickSort.hpp"
36
37 // sort by decreasing garbage (so most garbage comes first)
38 int ShenandoahHeuristics::compare_by_garbage(RegionData a, RegionData b) {
39 if (a._u._garbage > b._u._garbage)
40 return -1;
41 else if (a._u._garbage < b._u._garbage)
42 return 1;
43 else return 0;
44 }
45
46 ShenandoahHeuristics::ShenandoahHeuristics(ShenandoahSpaceInfo* space_info) :
47 _space_info(space_info),
48 _region_data(nullptr),
49 _guaranteed_gc_interval(0),
50 _cycle_start(os::elapsedTime()),
51 _last_cycle_end(0),
52 _gc_times_learned(0),
53 _gc_time_penalties(0),
54 _gc_cycle_time_history(new TruncatedSeq(Moving_Average_Samples, ShenandoahAdaptiveDecayFactor)),
55 _metaspace_oom()
56 {
57 size_t num_regions = ShenandoahHeap::heap()->num_regions();
58 assert(num_regions > 0, "Sanity");
59
60 _region_data = NEW_C_HEAP_ARRAY(RegionData, num_regions, mtGC);
61 }
62
63 ShenandoahHeuristics::~ShenandoahHeuristics() {
64 FREE_C_HEAP_ARRAY(RegionGarbage, _region_data);
65 }
66
67 void ShenandoahHeuristics::choose_collection_set(ShenandoahCollectionSet* collection_set) {
68 assert(collection_set->is_empty(), "Must be empty");
69
70 ShenandoahHeap* heap = ShenandoahHeap::heap();
71
72 // Check all pinned regions have updated status before choosing the collection set.
73 heap->assert_pinned_region_status();
74
75 // Step 1. Build up the region candidates we care about, rejecting losers and accepting winners right away.
76
77 size_t num_regions = heap->num_regions();
78
79 RegionData* candidates = _region_data;
80
81 size_t cand_idx = 0;
82
83 size_t total_garbage = 0;
84
85 size_t immediate_garbage = 0;
86 size_t immediate_regions = 0;
87
88 size_t free = 0;
91 ShenandoahMarkingContext* const ctx = heap->complete_marking_context();
92
93 for (size_t i = 0; i < num_regions; i++) {
94 ShenandoahHeapRegion* region = heap->get_region(i);
95
96 size_t garbage = region->garbage();
97 total_garbage += garbage;
98
99 if (region->is_empty()) {
100 free_regions++;
101 free += ShenandoahHeapRegion::region_size_bytes();
102 } else if (region->is_regular()) {
103 if (!region->has_live()) {
104 // We can recycle it right away and put it in the free set.
105 immediate_regions++;
106 immediate_garbage += garbage;
107 region->make_trash_immediate();
108 } else {
109 // This is our candidate for later consideration.
110 candidates[cand_idx]._region = region;
111 candidates[cand_idx]._u._garbage = garbage;
112 cand_idx++;
113 }
114 } else if (region->is_humongous_start()) {
115 // Reclaim humongous regions here, and count them as the immediate garbage
116 #ifdef ASSERT
117 bool reg_live = region->has_live();
118 bool bm_live = ctx->is_marked(cast_to_oop(region->bottom()));
119 assert(reg_live == bm_live,
120 "Humongous liveness and marks should agree. Region live: %s; Bitmap live: %s; Region Live Words: " SIZE_FORMAT,
121 BOOL_TO_STR(reg_live), BOOL_TO_STR(bm_live), region->get_live_data_words());
122 #endif
123 if (!region->has_live()) {
124 heap->trash_humongous_region_at(region);
125
126 // Count only the start. Continuations would be counted on "trash" path
127 immediate_regions++;
128 immediate_garbage += garbage;
129 }
130 } else if (region->is_trash()) {
131 // Count in just trashed collection set, during coalesced CM-with-UR
132 immediate_regions++;
133 immediate_garbage += garbage;
134 }
135 }
136
137 // Step 2. Look back at garbage statistics, and decide if we want to collect anything,
138 // given the amount of immediately reclaimable garbage. If we do, figure out the collection set.
139
140 assert (immediate_garbage <= total_garbage,
141 "Cannot have more immediate garbage than total garbage: " SIZE_FORMAT "%s vs " SIZE_FORMAT "%s",
142 byte_size_in_proper_unit(immediate_garbage), proper_unit_for_byte_size(immediate_garbage),
143 byte_size_in_proper_unit(total_garbage), proper_unit_for_byte_size(total_garbage));
144
145 size_t immediate_percent = (total_garbage == 0) ? 0 : (immediate_garbage * 100 / total_garbage);
146
147 if (immediate_percent <= ShenandoahImmediateThreshold) {
148 choose_collection_set_from_regiondata(collection_set, candidates, cand_idx, immediate_garbage + free);
149 }
150
151 size_t cset_percent = (total_garbage == 0) ? 0 : (collection_set->garbage() * 100 / total_garbage);
152 size_t collectable_garbage = collection_set->garbage() + immediate_garbage;
153 size_t collectable_garbage_percent = (total_garbage == 0) ? 0 : (collectable_garbage * 100 / total_garbage);
154
155 log_info(gc, ergo)("Collectable Garbage: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), "
156 "Immediate: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), " SIZE_FORMAT " regions, "
157 "CSet: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), " SIZE_FORMAT " regions",
158
159 byte_size_in_proper_unit(collectable_garbage),
160 proper_unit_for_byte_size(collectable_garbage),
161 collectable_garbage_percent,
162
163 byte_size_in_proper_unit(immediate_garbage),
164 proper_unit_for_byte_size(immediate_garbage),
165 immediate_percent,
166 immediate_regions,
167
168 byte_size_in_proper_unit(collection_set->garbage()),
169 proper_unit_for_byte_size(collection_set->garbage()),
170 cset_percent,
171 collection_set->count());
172 }
173
174 void ShenandoahHeuristics::record_cycle_start() {
175 _cycle_start = os::elapsedTime();
176 }
177
178 void ShenandoahHeuristics::record_cycle_end() {
179 _last_cycle_end = os::elapsedTime();
180 }
181
182 bool ShenandoahHeuristics::should_start_gc() {
183 // Perform GC to cleanup metaspace
184 if (has_metaspace_oom()) {
185 // Some of vmTestbase/metaspace tests depend on following line to count GC cycles
186 log_info(gc)("Trigger: %s", GCCause::to_string(GCCause::_metadata_GC_threshold));
187 return true;
188 }
189
190 if (_guaranteed_gc_interval > 0) {
191 double last_time_ms = (os::elapsedTime() - _last_cycle_end) * 1000;
192 if (last_time_ms > _guaranteed_gc_interval) {
193 log_info(gc)("Trigger (%s): Time since last GC (%.0f ms) is larger than guaranteed interval (" UINTX_FORMAT " ms)",
194 _space_info->name(), last_time_ms, _guaranteed_gc_interval);
195 return true;
196 }
197 }
198
199 return false;
200 }
201
202 bool ShenandoahHeuristics::should_degenerate_cycle() {
203 return ShenandoahHeap::heap()->shenandoah_policy()->consecutive_degenerated_gc_count() <= ShenandoahFullGCThreshold;
204 }
205
206 void ShenandoahHeuristics::adjust_penalty(intx step) {
207 assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
208 "In range before adjustment: " INTX_FORMAT, _gc_time_penalties);
209
210 intx new_val = _gc_time_penalties + step;
211 if (new_val < 0) {
212 new_val = 0;
213 }
214 if (new_val > 100) {
215 new_val = 100;
216 }
217 _gc_time_penalties = new_val;
218
219 assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
220 "In range after adjustment: " INTX_FORMAT, _gc_time_penalties);
221 }
222
223 void ShenandoahHeuristics::record_success_concurrent(bool abbreviated) {
224 _gc_times_learned++;
225
226 adjust_penalty(Concurrent_Adjust);
227
228 if (_gc_times_learned <= ShenandoahLearningSteps || !(abbreviated && ShenandoahAdaptiveIgnoreShortCycles)) {
229 _gc_cycle_time_history->add(elapsed_cycle_time());
230 }
231 }
232
233 void ShenandoahHeuristics::record_success_degenerated() {
234 adjust_penalty(Degenerated_Penalty);
235 }
236
237 void ShenandoahHeuristics::record_success_full() {
238 adjust_penalty(Full_Penalty);
239 }
240
241 void ShenandoahHeuristics::record_allocation_failure_gc() {
242 // Do nothing.
243 }
244
245 void ShenandoahHeuristics::record_requested_gc() {
246 // Assume users call System.gc() when external state changes significantly,
247 // which forces us to re-learn the GC timings and allocation rates.
248 _gc_times_learned = 0;
249 }
250
251 bool ShenandoahHeuristics::can_unload_classes() {
252 return ClassUnloading;
253 }
254
255 bool ShenandoahHeuristics::should_unload_classes() {
256 if (!can_unload_classes()) return false;
257 if (has_metaspace_oom()) return true;
258 return ClassUnloadingWithConcurrentMark;
259 }
260
261 void ShenandoahHeuristics::initialize() {
262 // Nothing to do by default.
263 }
264
265 double ShenandoahHeuristics::elapsed_cycle_time() const {
266 return os::elapsedTime() - _cycle_start;
267 }
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