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(ShenandoahSpaceInfo* space_info) :
46 _space_info(space_info),
47 _region_data(nullptr),
48 _degenerated_cycles_in_a_row(0),
49 _successful_cycles_in_a_row(0),
50 _cycle_start(os::elapsedTime()),
51 _last_cycle_end(0),
52 _gc_times_learned(0),
53 _gc_time_penalties(0),
54 _gc_time_history(new TruncatedSeq(10, ShenandoahAdaptiveDecayFactor)),
55 _metaspace_oom()
56 {
57 // No unloading during concurrent mark? Communicate that to heuristics
58 if (!ClassUnloadingWithConcurrentMark) {
59 FLAG_SET_DEFAULT(ShenandoahUnloadClassesFrequency, 0);
60 }
61
62 size_t num_regions = ShenandoahHeap::heap()->num_regions();
63 assert(num_regions > 0, "Sanity");
64
65 _region_data = NEW_C_HEAP_ARRAY(RegionData, num_regions, mtGC);
66 }
67
68 ShenandoahHeuristics::~ShenandoahHeuristics() {
69 FREE_C_HEAP_ARRAY(RegionGarbage, _region_data);
70 }
71
72 void ShenandoahHeuristics::choose_collection_set(ShenandoahCollectionSet* collection_set) {
73 assert(collection_set->count() == 0, "Must be empty");
74
75 ShenandoahHeap* heap = ShenandoahHeap::heap();
76
77 // Check all pinned regions have updated status before choosing the collection set.
78 heap->assert_pinned_region_status();
79
80 // Step 1. Build up the region candidates we care about, rejecting losers and accepting winners right away.
81
82 size_t num_regions = heap->num_regions();
83
84 RegionData* candidates = _region_data;
85
86 size_t cand_idx = 0;
87
88 size_t total_garbage = 0;
89
90 size_t immediate_garbage = 0;
91 size_t immediate_regions = 0;
92
93 size_t free = 0;
96 ShenandoahMarkingContext* const ctx = heap->complete_marking_context();
97
98 for (size_t i = 0; i < num_regions; i++) {
99 ShenandoahHeapRegion* region = heap->get_region(i);
100
101 size_t garbage = region->garbage();
102 total_garbage += garbage;
103
104 if (region->is_empty()) {
105 free_regions++;
106 free += ShenandoahHeapRegion::region_size_bytes();
107 } else if (region->is_regular()) {
108 if (!region->has_live()) {
109 // We can recycle it right away and put it in the free set.
110 immediate_regions++;
111 immediate_garbage += garbage;
112 region->make_trash_immediate();
113 } else {
114 // This is our candidate for later consideration.
115 candidates[cand_idx]._region = region;
116 candidates[cand_idx]._garbage = garbage;
117 cand_idx++;
118 }
119 } else if (region->is_humongous_start()) {
120 // Reclaim humongous regions here, and count them as the immediate garbage
121 #ifdef ASSERT
122 bool reg_live = region->has_live();
123 bool bm_live = ctx->is_marked(cast_to_oop(region->bottom()));
124 assert(reg_live == bm_live,
125 "Humongous liveness and marks should agree. Region live: %s; Bitmap live: %s; Region Live Words: " SIZE_FORMAT,
126 BOOL_TO_STR(reg_live), BOOL_TO_STR(bm_live), region->get_live_data_words());
127 #endif
128 if (!region->has_live()) {
129 heap->trash_humongous_region_at(region);
130
131 // Count only the start. Continuations would be counted on "trash" path
132 immediate_regions++;
133 immediate_garbage += garbage;
134 }
135 } else if (region->is_trash()) {
136 // Count in just trashed collection set, during coalesced CM-with-UR
137 immediate_regions++;
138 immediate_garbage += garbage;
139 }
140 }
141
142 // Step 2. Look back at garbage statistics, and decide if we want to collect anything,
143 // given the amount of immediately reclaimable garbage. If we do, figure out the collection set.
144
145 assert (immediate_garbage <= total_garbage,
146 "Cannot have more immediate garbage than total garbage: " SIZE_FORMAT "%s vs " SIZE_FORMAT "%s",
147 byte_size_in_proper_unit(immediate_garbage), proper_unit_for_byte_size(immediate_garbage),
148 byte_size_in_proper_unit(total_garbage), proper_unit_for_byte_size(total_garbage));
149
150 size_t immediate_percent = (total_garbage == 0) ? 0 : (immediate_garbage * 100 / total_garbage);
151
152 if (immediate_percent <= ShenandoahImmediateThreshold) {
153 choose_collection_set_from_regiondata(collection_set, candidates, cand_idx, immediate_garbage + free);
154 }
155
156 size_t cset_percent = (total_garbage == 0) ? 0 : (collection_set->garbage() * 100 / total_garbage);
157
158 size_t collectable_garbage = collection_set->garbage() + immediate_garbage;
159 size_t collectable_garbage_percent = (total_garbage == 0) ? 0 : (collectable_garbage * 100 / total_garbage);
160
161 log_info(gc, ergo)("Collectable Garbage: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), "
162 "Immediate: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), "
163 "CSet: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%)",
164
165 byte_size_in_proper_unit(collectable_garbage),
166 proper_unit_for_byte_size(collectable_garbage),
167 collectable_garbage_percent,
168
169 byte_size_in_proper_unit(immediate_garbage),
170 proper_unit_for_byte_size(immediate_garbage),
171 immediate_percent,
172
173 byte_size_in_proper_unit(collection_set->garbage()),
174 proper_unit_for_byte_size(collection_set->garbage()),
175 cset_percent);
176 }
177
178 void ShenandoahHeuristics::record_cycle_start() {
179 _cycle_start = os::elapsedTime();
180 }
181
182 void ShenandoahHeuristics::record_cycle_end() {
183 _last_cycle_end = os::elapsedTime();
184 }
185
186 bool ShenandoahHeuristics::should_start_gc() {
187 // Perform GC to cleanup metaspace
188 if (has_metaspace_oom()) {
189 // Some of vmTestbase/metaspace tests depend on following line to count GC cycles
190 log_info(gc)("Trigger: %s", GCCause::to_string(GCCause::_metadata_GC_threshold));
191 return true;
192 }
193
194 if (ShenandoahGuaranteedGCInterval > 0) {
195 double last_time_ms = (os::elapsedTime() - _last_cycle_end) * 1000;
196 if (last_time_ms > ShenandoahGuaranteedGCInterval) {
197 log_info(gc)("Trigger: Time since last GC (%.0f ms) is larger than guaranteed interval (" UINTX_FORMAT " ms)",
198 last_time_ms, ShenandoahGuaranteedGCInterval);
199 return true;
200 }
201 }
202
203 return false;
204 }
205
206 bool ShenandoahHeuristics::should_degenerate_cycle() {
207 return _degenerated_cycles_in_a_row <= ShenandoahFullGCThreshold;
208 }
209
210 void ShenandoahHeuristics::adjust_penalty(intx step) {
211 assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
212 "In range before adjustment: " INTX_FORMAT, _gc_time_penalties);
213
214 intx new_val = _gc_time_penalties + step;
215 if (new_val < 0) {
216 new_val = 0;
217 }
218 if (new_val > 100) {
219 new_val = 100;
220 }
221 _gc_time_penalties = new_val;
222
223 assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
224 "In range after adjustment: " INTX_FORMAT, _gc_time_penalties);
225 }
226
227 void ShenandoahHeuristics::record_success_concurrent() {
228 _degenerated_cycles_in_a_row = 0;
229 _successful_cycles_in_a_row++;
230
231 _gc_time_history->add(time_since_last_gc());
232 _gc_times_learned++;
233
234 adjust_penalty(Concurrent_Adjust);
235 }
236
237 void ShenandoahHeuristics::record_success_degenerated() {
238 _degenerated_cycles_in_a_row++;
239 _successful_cycles_in_a_row = 0;
240
241 adjust_penalty(Degenerated_Penalty);
242 }
243
244 void ShenandoahHeuristics::record_success_full() {
245 _degenerated_cycles_in_a_row = 0;
246 _successful_cycles_in_a_row++;
247
248 adjust_penalty(Full_Penalty);
249 }
250
251 void ShenandoahHeuristics::record_allocation_failure_gc() {
252 // Do nothing.
253 }
254
269 if (!ClassUnloadingWithConcurrentMark) return false;
270 if (ShenandoahUnloadClassesFrequency == 0) return false;
271 return true;
272 }
273
274 bool ShenandoahHeuristics::should_unload_classes() {
275 if (!can_unload_classes_normal()) return false;
276 if (has_metaspace_oom()) return true;
277 size_t cycle = ShenandoahHeap::heap()->shenandoah_policy()->cycle_counter();
278 // Unload classes every Nth GC cycle.
279 // This should not happen in the same cycle as process_references to amortize costs.
280 // Offsetting by one is enough to break the rendezvous when periods are equal.
281 // When periods are not equal, offsetting by one is just as good as any other guess.
282 return (cycle + 1) % ShenandoahUnloadClassesFrequency == 0;
283 }
284
285 void ShenandoahHeuristics::initialize() {
286 // Nothing to do by default.
287 }
288
289 double ShenandoahHeuristics::time_since_last_gc() const {
290 return os::elapsedTime() - _cycle_start;
291 }
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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 _degenerated_cycles_in_a_row(0),
50 _successful_cycles_in_a_row(0),
51 _guaranteed_gc_interval(0),
52 _cycle_start(os::elapsedTime()),
53 _last_cycle_end(0),
54 _gc_times_learned(0),
55 _gc_time_penalties(0),
56 _gc_cycle_time_history(new TruncatedSeq(Moving_Average_Samples, ShenandoahAdaptiveDecayFactor)),
57 _metaspace_oom()
58 {
59 // No unloading during concurrent mark? Communicate that to heuristics
60 if (!ClassUnloadingWithConcurrentMark) {
61 FLAG_SET_DEFAULT(ShenandoahUnloadClassesFrequency, 0);
62 }
63
64 size_t num_regions = ShenandoahHeap::heap()->num_regions();
65 assert(num_regions > 0, "Sanity");
66
67 _region_data = NEW_C_HEAP_ARRAY(RegionData, num_regions, mtGC);
68 }
69
70 ShenandoahHeuristics::~ShenandoahHeuristics() {
71 FREE_C_HEAP_ARRAY(RegionGarbage, _region_data);
72 }
73
74 void ShenandoahHeuristics::choose_collection_set(ShenandoahCollectionSet* collection_set) {
75 assert(collection_set->is_empty(), "Must be empty");
76
77 ShenandoahHeap* heap = ShenandoahHeap::heap();
78
79 // Check all pinned regions have updated status before choosing the collection set.
80 heap->assert_pinned_region_status();
81
82 // Step 1. Build up the region candidates we care about, rejecting losers and accepting winners right away.
83
84 size_t num_regions = heap->num_regions();
85
86 RegionData* candidates = _region_data;
87
88 size_t cand_idx = 0;
89
90 size_t total_garbage = 0;
91
92 size_t immediate_garbage = 0;
93 size_t immediate_regions = 0;
94
95 size_t free = 0;
98 ShenandoahMarkingContext* const ctx = heap->complete_marking_context();
99
100 for (size_t i = 0; i < num_regions; i++) {
101 ShenandoahHeapRegion* region = heap->get_region(i);
102
103 size_t garbage = region->garbage();
104 total_garbage += garbage;
105
106 if (region->is_empty()) {
107 free_regions++;
108 free += ShenandoahHeapRegion::region_size_bytes();
109 } else if (region->is_regular()) {
110 if (!region->has_live()) {
111 // We can recycle it right away and put it in the free set.
112 immediate_regions++;
113 immediate_garbage += garbage;
114 region->make_trash_immediate();
115 } else {
116 // This is our candidate for later consideration.
117 candidates[cand_idx]._region = region;
118 candidates[cand_idx]._u._garbage = garbage;
119 cand_idx++;
120 }
121 } else if (region->is_humongous_start()) {
122 // Reclaim humongous regions here, and count them as the immediate garbage
123 #ifdef ASSERT
124 bool reg_live = region->has_live();
125 bool bm_live = ctx->is_marked(cast_to_oop(region->bottom()));
126 assert(reg_live == bm_live,
127 "Humongous liveness and marks should agree. Region live: %s; Bitmap live: %s; Region Live Words: " SIZE_FORMAT,
128 BOOL_TO_STR(reg_live), BOOL_TO_STR(bm_live), region->get_live_data_words());
129 #endif
130 if (!region->has_live()) {
131 heap->trash_humongous_region_at(region);
132
133 // Count only the start. Continuations would be counted on "trash" path
134 immediate_regions++;
135 immediate_garbage += garbage;
136 }
137 } else if (region->is_trash()) {
138 // Count in just trashed collection set, during coalesced CM-with-UR
139 immediate_regions++;
140 immediate_garbage += garbage;
141 }
142 }
143
144 // Step 2. Look back at garbage statistics, and decide if we want to collect anything,
145 // given the amount of immediately reclaimable garbage. If we do, figure out the collection set.
146
147 assert (immediate_garbage <= total_garbage,
148 "Cannot have more immediate garbage than total garbage: " SIZE_FORMAT "%s vs " SIZE_FORMAT "%s",
149 byte_size_in_proper_unit(immediate_garbage), proper_unit_for_byte_size(immediate_garbage),
150 byte_size_in_proper_unit(total_garbage), proper_unit_for_byte_size(total_garbage));
151
152 size_t immediate_percent = (total_garbage == 0) ? 0 : (immediate_garbage * 100 / total_garbage);
153
154 if (immediate_percent <= ShenandoahImmediateThreshold) {
155 choose_collection_set_from_regiondata(collection_set, candidates, cand_idx, immediate_garbage + free);
156 } else {
157 // We are going to skip evacuation and update refs because we reclaimed
158 // sufficient amounts of immediate garbage.
159 heap->shenandoah_policy()->record_abbreviated_cycle();
160 }
161
162 size_t cset_percent = (total_garbage == 0) ? 0 : (collection_set->garbage() * 100 / total_garbage);
163 size_t collectable_garbage = collection_set->garbage() + immediate_garbage;
164 size_t collectable_garbage_percent = (total_garbage == 0) ? 0 : (collectable_garbage * 100 / total_garbage);
165
166 log_info(gc, ergo)("Collectable Garbage: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), "
167 "Immediate: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), " SIZE_FORMAT " regions, "
168 "CSet: " SIZE_FORMAT "%s (" SIZE_FORMAT "%%), " SIZE_FORMAT " regions",
169
170 byte_size_in_proper_unit(collectable_garbage),
171 proper_unit_for_byte_size(collectable_garbage),
172 collectable_garbage_percent,
173
174 byte_size_in_proper_unit(immediate_garbage),
175 proper_unit_for_byte_size(immediate_garbage),
176 immediate_percent,
177 immediate_regions,
178
179 byte_size_in_proper_unit(collection_set->garbage()),
180 proper_unit_for_byte_size(collection_set->garbage()),
181 cset_percent,
182 collection_set->count());
183 }
184
185 void ShenandoahHeuristics::record_cycle_start() {
186 _cycle_start = os::elapsedTime();
187 }
188
189 void ShenandoahHeuristics::record_cycle_end() {
190 _last_cycle_end = os::elapsedTime();
191 }
192
193 bool ShenandoahHeuristics::should_start_gc() {
194 // Perform GC to cleanup metaspace
195 if (has_metaspace_oom()) {
196 // Some of vmTestbase/metaspace tests depend on following line to count GC cycles
197 log_info(gc)("Trigger: %s", GCCause::to_string(GCCause::_metadata_GC_threshold));
198 return true;
199 }
200
201 if (_guaranteed_gc_interval > 0) {
202 double last_time_ms = (os::elapsedTime() - _last_cycle_end) * 1000;
203 if (last_time_ms > _guaranteed_gc_interval) {
204 log_info(gc)("Trigger (%s): Time since last GC (%.0f ms) is larger than guaranteed interval (" UINTX_FORMAT " ms)",
205 _space_info->name(), last_time_ms, _guaranteed_gc_interval);
206 return true;
207 }
208 }
209
210 return false;
211 }
212
213 bool ShenandoahHeuristics::should_degenerate_cycle() {
214 return _degenerated_cycles_in_a_row <= ShenandoahFullGCThreshold;
215 }
216
217 void ShenandoahHeuristics::adjust_penalty(intx step) {
218 assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
219 "In range before adjustment: " INTX_FORMAT, _gc_time_penalties);
220
221 intx new_val = _gc_time_penalties + step;
222 if (new_val < 0) {
223 new_val = 0;
224 }
225 if (new_val > 100) {
226 new_val = 100;
227 }
228 _gc_time_penalties = new_val;
229
230 assert(0 <= _gc_time_penalties && _gc_time_penalties <= 100,
231 "In range after adjustment: " INTX_FORMAT, _gc_time_penalties);
232 }
233
234 void ShenandoahHeuristics::record_success_concurrent(bool abbreviated) {
235 _degenerated_cycles_in_a_row = 0;
236 _successful_cycles_in_a_row++;
237 _gc_times_learned++;
238
239 adjust_penalty(Concurrent_Adjust);
240
241 if (_gc_times_learned <= ShenandoahLearningSteps || !(abbreviated && ShenandoahAdaptiveIgnoreShortCycles)) {
242 _gc_cycle_time_history->add(elapsed_cycle_time());
243 }
244 }
245
246 void ShenandoahHeuristics::record_success_degenerated() {
247 _degenerated_cycles_in_a_row++;
248 _successful_cycles_in_a_row = 0;
249
250 adjust_penalty(Degenerated_Penalty);
251 }
252
253 void ShenandoahHeuristics::record_success_full() {
254 _degenerated_cycles_in_a_row = 0;
255 _successful_cycles_in_a_row++;
256
257 adjust_penalty(Full_Penalty);
258 }
259
260 void ShenandoahHeuristics::record_allocation_failure_gc() {
261 // Do nothing.
262 }
263
278 if (!ClassUnloadingWithConcurrentMark) return false;
279 if (ShenandoahUnloadClassesFrequency == 0) return false;
280 return true;
281 }
282
283 bool ShenandoahHeuristics::should_unload_classes() {
284 if (!can_unload_classes_normal()) return false;
285 if (has_metaspace_oom()) return true;
286 size_t cycle = ShenandoahHeap::heap()->shenandoah_policy()->cycle_counter();
287 // Unload classes every Nth GC cycle.
288 // This should not happen in the same cycle as process_references to amortize costs.
289 // Offsetting by one is enough to break the rendezvous when periods are equal.
290 // When periods are not equal, offsetting by one is just as good as any other guess.
291 return (cycle + 1) % ShenandoahUnloadClassesFrequency == 0;
292 }
293
294 void ShenandoahHeuristics::initialize() {
295 // Nothing to do by default.
296 }
297
298 double ShenandoahHeuristics::elapsed_cycle_time() const {
299 return os::elapsedTime() - _cycle_start;
300 }
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