1 /*
2 * Copyright (c) 2015, Oracle and/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 #include "gc/g1/g1CollectedHeap.inline.hpp"
27 #include "gc/g1/g1IHOPControl.hpp"
28 #include "gc/g1/g1Predictions.hpp"
29 #include "gc/shared/gcTrace.hpp"
30 #include "logging/log.hpp"
31
32 G1IHOPControl::G1IHOPControl(double initial_ihop_percent, size_t target_occupancy) :
33 _initial_ihop_percent(initial_ihop_percent),
34 _target_occupancy(target_occupancy),
35 _last_allocated_bytes(0),
36 _last_allocation_time_s(0.0)
37 {
38 assert(_initial_ihop_percent >= 0.0 && _initial_ihop_percent <= 100.0, "Initial IHOP value must be between 0 and 100 but is %.3f", initial_ihop_percent);
39 }
40
41 void G1IHOPControl::update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size) {
42 assert(allocation_time_s >= 0.0, "Allocation time must be positive but is %.3f", allocation_time_s);
43
44 _last_allocation_time_s = allocation_time_s;
45 _last_allocated_bytes = allocated_bytes;
46 }
47
48 void G1IHOPControl::print() {
49 size_t cur_conc_mark_start_threshold = get_conc_mark_start_threshold();
50 log_debug(gc, ihop)("Basic information (value update), threshold: " SIZE_FORMAT "B (%1.2f), target occupancy: " SIZE_FORMAT "B, current occupancy: " SIZE_FORMAT "B,"
51 " recent old gen allocation rate: %1.2f, recent marking phase length: %1.2f",
52 cur_conc_mark_start_threshold,
53 cur_conc_mark_start_threshold * 100.0 / _target_occupancy,
54 _target_occupancy,
55 G1CollectedHeap::heap()->used(),
56 _last_allocation_time_s > 0.0 ? _last_allocated_bytes / _last_allocation_time_s : 0.0,
57 last_marking_length_s());
58 }
59
60 void G1IHOPControl::send_trace_event(G1NewTracer* tracer) {
61 tracer->report_basic_ihop_statistics(get_conc_mark_start_threshold(),
62 _target_occupancy,
63 G1CollectedHeap::heap()->used(),
64 _last_allocated_bytes,
65 _last_allocation_time_s,
66 last_marking_length_s());
67 }
68
69 G1StaticIHOPControl::G1StaticIHOPControl(double ihop_percent, size_t target_occupancy) :
70 G1IHOPControl(ihop_percent, target_occupancy),
71 _last_marking_length_s(0.0) {
72 assert(_target_occupancy > 0, "Target occupancy must be larger than zero.");
73 }
74
75 #ifndef PRODUCT
76 static void test_update(G1IHOPControl* ctrl, double alloc_time, size_t alloc_amount, size_t young_size, double mark_time) {
77 for (int i = 0; i < 100; i++) {
78 ctrl->update_allocation_info(alloc_time, alloc_amount, young_size);
79 ctrl->update_marking_length(mark_time);
80 }
81 }
82
83 void G1StaticIHOPControl::test() {
84 size_t const initial_ihop = 45;
85
86 G1StaticIHOPControl ctrl(initial_ihop, 100);
87
88 size_t threshold = ctrl.get_conc_mark_start_threshold();
89 assert(threshold == initial_ihop,
90 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
91
92 ctrl.update_allocation_info(100.0, 100, 100);
93 threshold = ctrl.get_conc_mark_start_threshold();
94 assert(threshold == initial_ihop,
95 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
96
97 ctrl.update_marking_length(1000.0);
98 threshold = ctrl.get_conc_mark_start_threshold();
99 assert(threshold == initial_ihop,
100 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
101
102 // Whatever we pass, the IHOP value must stay the same.
103 test_update(&ctrl, 2, 10, 10, 3);
104 threshold = ctrl.get_conc_mark_start_threshold();
105 assert(threshold == initial_ihop,
106 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
107
108 test_update(&ctrl, 12, 10, 10, 3);
109 threshold = ctrl.get_conc_mark_start_threshold();
110 assert(threshold == initial_ihop,
111 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
112 }
113 #endif
114
115 G1AdaptiveIHOPControl::G1AdaptiveIHOPControl(double ihop_percent,
116 size_t initial_target_occupancy,
117 G1Predictions const* predictor,
118 size_t heap_reserve_percent,
119 size_t heap_waste_percent) :
120 G1IHOPControl(ihop_percent, initial_target_occupancy),
121 _predictor(predictor),
122 _marking_times_s(10, 0.95),
123 _allocation_rate_s(10, 0.95),
124 _last_unrestrained_young_size(0),
125 _heap_reserve_percent(heap_reserve_percent),
126 _heap_waste_percent(heap_waste_percent)
127 {
128 }
129
130 size_t G1AdaptiveIHOPControl::actual_target_threshold() const {
131 // The actual target threshold takes the heap reserve and the expected waste in
132 // free space into account.
133 // _heap_reserve is that part of the total heap capacity that is reserved for
134 // eventual promotion failure.
135 // _heap_waste is the amount of space will never be reclaimed in any
136 // heap, so can not be used for allocation during marking and must always be
137 // considered.
138
139 double safe_total_heap_percentage = MIN2((double)(_heap_reserve_percent + _heap_waste_percent), 100.0);
140
141 return (size_t)MIN2(
142 G1CollectedHeap::heap()->max_capacity() * (100.0 - safe_total_heap_percentage) / 100.0,
143 _target_occupancy * (100.0 - _heap_waste_percent) / 100.0
144 );
145 }
146
147 bool G1AdaptiveIHOPControl::have_enough_data_for_prediction() const {
148 return ((size_t)_marking_times_s.num() >= G1AdaptiveIHOPNumInitialSamples) &&
149 ((size_t)_allocation_rate_s.num() >= G1AdaptiveIHOPNumInitialSamples);
150 }
151
152 size_t G1AdaptiveIHOPControl::get_conc_mark_start_threshold() {
153 if (have_enough_data_for_prediction()) {
154 double pred_marking_time = _predictor->get_new_prediction(&_marking_times_s);
155 double pred_promotion_rate = _predictor->get_new_prediction(&_allocation_rate_s);
156 size_t pred_promotion_size = (size_t)(pred_marking_time * pred_promotion_rate);
157
158 // In reality we would need the maximum size of the young gen during
159 // marking. This is a conservative estimate.
160 size_t predicted_needed_bytes_during_marking =
161 pred_promotion_size + _last_unrestrained_young_size;
162
163 size_t internal_threshold = actual_target_threshold();
164 size_t predicted_initiating_threshold = predicted_needed_bytes_during_marking < internal_threshold ?
165 internal_threshold - predicted_needed_bytes_during_marking :
166 0;
167 return predicted_initiating_threshold;
168 } else {
169 // Use the initial value.
170 return (size_t)(_initial_ihop_percent * _target_occupancy / 100.0);
171 }
172 }
173
174 void G1AdaptiveIHOPControl::update_allocation_info(double allocation_time_s,
175 size_t allocated_bytes,
176 size_t additional_buffer_size) {
177 G1IHOPControl::update_allocation_info(allocation_time_s, allocated_bytes, additional_buffer_size);
178
179 double allocation_rate = (double) allocated_bytes / allocation_time_s;
180 _allocation_rate_s.add(allocation_rate);
181
182 _last_unrestrained_young_size = additional_buffer_size;
183 }
184
185 void G1AdaptiveIHOPControl::update_marking_length(double marking_length_s) {
186 assert(marking_length_s >= 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s);
187 _marking_times_s.add(marking_length_s);
188 }
189
190 void G1AdaptiveIHOPControl::print() {
191 G1IHOPControl::print();
192 size_t actual_target = actual_target_threshold();
193 log_debug(gc, ihop)("Adaptive IHOP information (value update), threshold: " SIZE_FORMAT "B (%1.2f), internal target occupancy: " SIZE_FORMAT "B,"
194 " predicted old gen allocation rate: %1.2f, predicted marking phase length: %1.2f, prediction active: %s",
195 get_conc_mark_start_threshold(),
196 percent_of(get_conc_mark_start_threshold(), actual_target),
197 actual_target,
198 _predictor->get_new_prediction(&_allocation_rate_s),
199 _predictor->get_new_prediction(&_marking_times_s),
200 have_enough_data_for_prediction() ? "true" : "false");
201 }
202
203 void G1AdaptiveIHOPControl::send_trace_event(G1NewTracer* tracer) {
204 G1IHOPControl::send_trace_event(tracer);
205 tracer->report_adaptive_ihop_statistics(get_conc_mark_start_threshold(),
206 actual_target_threshold(),
207 G1CollectedHeap::heap()->used(),
208 _last_unrestrained_young_size,
209 _predictor->get_new_prediction(&_allocation_rate_s),
210 _predictor->get_new_prediction(&_marking_times_s),
211 have_enough_data_for_prediction());
212 }
213
214 #ifndef PRODUCT
215 void G1AdaptiveIHOPControl::test() {
216 size_t const initial_threshold = 45;
217 size_t const young_size = 10;
218 size_t const target_size = 100;
219
220 // The final IHOP value is always
221 // target_size - (young_size + alloc_amount/alloc_time * marking_time)
222
223 G1Predictions pred(0.95);
224 G1AdaptiveIHOPControl ctrl(initial_threshold, target_size, &pred, 0, 0);
225
226 // First "load".
227 size_t const alloc_time1 = 2;
228 size_t const alloc_amount1 = 10;
229 size_t const marking_time1 = 2;
230 size_t const settled_ihop1 = target_size - (young_size + alloc_amount1/alloc_time1 * marking_time1);
231
232 size_t threshold;
233 threshold = ctrl.get_conc_mark_start_threshold();
234 assert(threshold == initial_threshold,
235 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_threshold, threshold);
236 for (size_t i = 0; i < G1AdaptiveIHOPNumInitialSamples - 1; i++) {
237 ctrl.update_allocation_info(alloc_time1, alloc_amount1, young_size);
238 ctrl.update_marking_length(marking_time1);
239 // Not enough data yet.
240 threshold = ctrl.get_conc_mark_start_threshold();
241 assert(threshold == initial_threshold,
242 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_threshold, threshold);
243 }
244
245 test_update(&ctrl, alloc_time1, alloc_amount1, young_size, marking_time1);
246
247 threshold = ctrl.get_conc_mark_start_threshold();
248 assert(threshold == settled_ihop1,
249 "Expected IHOP threshold to settle at " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop1, threshold);
250
251 // Second "load". A bit higher allocation rate.
252 size_t const alloc_time2 = 2;
253 size_t const alloc_amount2 = 30;
254 size_t const marking_time2 = 2;
255 size_t const settled_ihop2 = target_size - (young_size + alloc_amount2/alloc_time2 * marking_time2);
256
257 test_update(&ctrl, alloc_time2, alloc_amount2, young_size, marking_time2);
258
259 threshold = ctrl.get_conc_mark_start_threshold();
260 assert(threshold < settled_ihop1,
261 "Expected IHOP threshold to settle at a value lower than " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop1, threshold);
262
263 // Third "load". Very high (impossible) allocation rate.
264 size_t const alloc_time3 = 1;
265 size_t const alloc_amount3 = 50;
266 size_t const marking_time3 = 2;
267 size_t const settled_ihop3 = 0;
268
269 test_update(&ctrl, alloc_time3, alloc_amount3, young_size, marking_time3);
270 threshold = ctrl.get_conc_mark_start_threshold();
271
272 assert(threshold == settled_ihop3,
273 "Expected IHOP threshold to settle at " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop3, threshold);
274
275 // And back to some arbitrary value.
276 test_update(&ctrl, alloc_time2, alloc_amount2, young_size, marking_time2);
277
278 threshold = ctrl.get_conc_mark_start_threshold();
279 assert(threshold > settled_ihop3,
280 "Expected IHOP threshold to settle at value larger than " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop3, threshold);
281 }
282
283 void IHOP_test() {
284 G1StaticIHOPControl::test();
285 }
286 #endif