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/g1ErgoVerbose.hpp"
28 #include "gc/g1/g1IHOPControl.hpp"
29 #include "gc/g1/g1Predictions.hpp"
30
31 G1IHOPControl::G1IHOPControl(double initial_ihop_percent, size_t target_occupancy) :
32 _initial_ihop_percent(initial_ihop_percent),
33 _target_occupancy(target_occupancy),
34 _last_allocated_bytes(0),
35 _last_allocation_time_s(0.0)
36 {
37 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);
38 }
39
40 void G1IHOPControl::update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size) {
41 assert(allocation_time_s >= 0.0, "Allocation time must be positive but is %.3f", allocation_time_s);
42
43 _last_allocation_time_s = allocation_time_s;
44 _last_allocated_bytes = allocated_bytes;
45 }
46
47 void G1IHOPControl::print() {
48 size_t cur_conc_mark_start_threshold = get_conc_mark_start_threshold();
49 ergo_verbose6(ErgoIHOP,
50 "basic information",
51 ergo_format_reason("value update")
52 ergo_format_byte_perc("threshold")
53 ergo_format_byte("target occupancy")
54 ergo_format_byte("current occupancy")
55 ergo_format_double("recent old gen allocation rate")
56 ergo_format_double("recent marking phase length"),
57 cur_conc_mark_start_threshold,
58 cur_conc_mark_start_threshold * 100.0 / _target_occupancy,
59 _target_occupancy,
60 G1CollectedHeap::heap()->used(),
61 _last_allocation_time_s > 0.0 ? _last_allocated_bytes / _last_allocation_time_s : 0.0,
62 last_marking_length_s());
63 }
64
65 G1StaticIHOPControl::G1StaticIHOPControl(double ihop_percent, size_t target_occupancy) :
66 G1IHOPControl(ihop_percent, target_occupancy),
67 _last_marking_length_s(0.0) {
68 assert(_target_occupancy > 0, "Target occupancy must be larger than zero.");
69 }
70
71 #ifndef PRODUCT
72 static void test_update(G1IHOPControl* ctrl, double alloc_time, size_t alloc_amount, size_t young_size, double mark_time) {
73 for (int i = 0; i < 100; i++) {
74 ctrl->update_allocation_info(alloc_time, alloc_amount, young_size);
75 ctrl->update_marking_length(mark_time);
76 }
77 }
78
79 void G1StaticIHOPControl::test() {
80 size_t const initial_ihop = 45;
81
82 G1StaticIHOPControl ctrl(initial_ihop, 100);
83
84 size_t threshold = ctrl.get_conc_mark_start_threshold();
85 assert(threshold == initial_ihop,
86 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
87
88 ctrl.update_allocation_info(100.0, 100, 100);
89 threshold = ctrl.get_conc_mark_start_threshold();
90 assert(threshold == initial_ihop,
91 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
92
93 ctrl.update_marking_length(1000.0);
94 threshold = ctrl.get_conc_mark_start_threshold();
95 assert(threshold == initial_ihop,
96 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
97
98 // Whatever we pass, the IHOP value must stay the same.
99 test_update(&ctrl, 2, 10, 10, 3);
100 threshold = ctrl.get_conc_mark_start_threshold();
101 assert(threshold == initial_ihop,
102 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
103
104 test_update(&ctrl, 12, 10, 10, 3);
105 threshold = ctrl.get_conc_mark_start_threshold();
106 assert(threshold == initial_ihop,
107 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
108 }
109 #endif
110
111 G1AdaptiveIHOPControl::G1AdaptiveIHOPControl(double ihop_percent,
112 size_t initial_target_occupancy,
113 G1Predictions const* predictor,
114 size_t heap_reserve_percent,
115 size_t heap_waste_percent) :
116 G1IHOPControl(ihop_percent, initial_target_occupancy),
117 _predictor(predictor),
118 _marking_times_s(10, 0.95),
119 _allocation_rate_s(10, 0.95),
120 _last_unrestrained_young_size(0),
121 _heap_reserve_percent(heap_reserve_percent),
122 _heap_waste_percent(heap_waste_percent)
123 {
124 }
125
126 size_t G1AdaptiveIHOPControl::actual_target_threshold() const {
127 // The actual target threshold takes the heap reserve and the expected waste in
128 // free space into account.
129 // _heap_reserve is that part of the total heap capacity that is reserved for
130 // eventual promotion failure.
131 // _heap_waste is the amount of space will never be reclaimed in any
132 // heap, so can not be used for allocation during marking and must always be
133 // considered.
134
135 double safe_total_heap_percentage = MIN2((double)(_heap_reserve_percent + _heap_waste_percent), 100.0);
136
137 return MIN2(
138 G1CollectedHeap::heap()->max_capacity() * (100.0 - safe_total_heap_percentage) / 100.0,
139 _target_occupancy * (100.0 - _heap_waste_percent) / 100.0
140 );
141 }
142
143 bool G1AdaptiveIHOPControl::have_enough_data_for_prediction() const {
144 return ((size_t)_marking_times_s.num() >= G1AdaptiveIHOPNumInitialSamples) &&
145 ((size_t)_allocation_rate_s.num() >= G1AdaptiveIHOPNumInitialSamples);
146 }
147
148 void G1AdaptiveIHOPControl::set_target_occupancy(size_t target_occupancy) {
149 _target_occupancy = target_occupancy;
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
157 size_t predicted_needed_bytes_during_marking =
158 (pred_marking_time * pred_promotion_rate +
159 _last_unrestrained_young_size); // In reality we would need the maximum size of the young gen during marking. This is a conservative estimate.
160
161 size_t internal_threshold = actual_target_threshold();
162 size_t predicted_initiating_threshold = predicted_needed_bytes_during_marking < internal_threshold ?
163 internal_threshold - predicted_needed_bytes_during_marking :
164 0;
165 return predicted_initiating_threshold;
166 } else {
167 // Use the initial value.
168 return _initial_ihop_percent * _target_occupancy / 100.0;
169 }
170 }
171
172 void G1AdaptiveIHOPControl::update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size) {
173 assert(allocation_time_s >= 0.0, "Allocation time must be positive but is %.3f", allocation_time_s);
174 double allocation_rate = (double) allocated_bytes / allocation_time_s;
175 _allocation_rate_s.add(allocation_rate);
176
177 _last_allocation_bytes = allocated_bytes;
178 _last_unrestrained_young_size = additional_buffer_size;
179 }
180
181 void G1AdaptiveIHOPControl::update_marking_length(double marking_length_s) {
182 assert(marking_length_s >= 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s);
183 _marking_times_s.add(marking_length_s);
184 }
185
186 void G1AdaptiveIHOPControl::print() {
187 ergo_verbose6(ErgoIHOP,
188 "basic information",
189 ergo_format_reason("value update")
190 ergo_format_byte_perc("threshold")
191 ergo_format_byte("target occupancy")
192 ergo_format_byte("current occupancy")
193 ergo_format_double("recent old gen allocation rate")
194 ergo_format_double("recent marking phase length"),
195 get_conc_mark_start_threshold(),
196 percent_of(get_conc_mark_start_threshold(), _target_occupancy),
197 _target_occupancy,
198 G1CollectedHeap::heap()->used(),
199 _allocation_rate_s.last(),
200 _marking_times_s.last()
201 );
202 size_t actual_target = actual_target_threshold();
203 ergo_verbose6(ErgoIHOP,
204 "adaptive IHOP information",
205 ergo_format_reason("value update")
206 ergo_format_byte_perc("threshold")
207 ergo_format_byte("internal target occupancy")
208 ergo_format_double("predicted old gen allocation rate")
209 ergo_format_double("predicted marking phase length")
210 ergo_format_str("prediction active"),
211 get_conc_mark_start_threshold(),
212 percent_of(get_conc_mark_start_threshold(), actual_target),
213 actual_target,
214 _predictor->get_new_prediction(&_allocation_rate_s),
215 _predictor->get_new_prediction(&_marking_times_s),
216 have_enough_data_for_prediction() ? "true" : "false"
217 );
218 }
219
220 #ifndef PRODUCT
221 void G1AdaptiveIHOPControl::test() {
222 size_t const initial_threshold = 45;
223 size_t const young_size = 10;
224 size_t const target_size = 100;
225
226 // The final IHOP value is always
227 // target_size - (young_size + alloc_amount/alloc_time * marking_time)
228
229 G1Predictions pred(0.95);
230 G1AdaptiveIHOPControl ctrl(initial_threshold, target_size, &pred, 0, 0);
231
232 // First "load".
233 size_t const alloc_time1 = 2;
234 size_t const alloc_amount1 = 10;
235 size_t const marking_time1 = 2;
236 size_t const settled_ihop1 = target_size - (young_size + alloc_amount1/alloc_time1 * marking_time1);
237
238 size_t threshold;
239 threshold = ctrl.get_conc_mark_start_threshold();
240 assert(threshold == initial_threshold,
241 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_threshold, threshold);
242 for (size_t i = 0; i < G1AdaptiveIHOPNumInitialSamples - 1; i++) {
243 ctrl.update_allocation_info(alloc_time1, alloc_amount1, young_size);
244 ctrl.update_marking_length(marking_time1);
245 // Not enough data yet.
246 threshold = ctrl.get_conc_mark_start_threshold();
247 assert(threshold == initial_threshold,
248 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_threshold, threshold);
249 }
250
251 test_update(&ctrl, alloc_time1, alloc_amount1, young_size, marking_time1);
252
253 threshold = ctrl.get_conc_mark_start_threshold();
254 assert(threshold == settled_ihop1,
255 "Expected IHOP threshold to settle at " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop1, threshold);
256
257 // Second "load". A bit higher allocation rate.
258 size_t const alloc_time2 = 2;
259 size_t const alloc_amount2 = 30;
260 size_t const marking_time2 = 2;
261 size_t const settled_ihop2 = target_size - (young_size + alloc_amount2/alloc_time2 * marking_time2);
262
263 test_update(&ctrl, alloc_time2, alloc_amount2, young_size, marking_time2);
264
265 threshold = ctrl.get_conc_mark_start_threshold();
266 assert(threshold < settled_ihop1,
267 "Expected IHOP threshold to settle at a value lower than " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop1, threshold);
268
269 // Third "load". Very high (impossible) allocation rate.
270 size_t const alloc_time3 = 1;
271 size_t const alloc_amount3 = 50;
272 size_t const marking_time3 = 2;
273 size_t const settled_ihop3 = 0;
274
275 test_update(&ctrl, alloc_time3, alloc_amount3, young_size, marking_time3);
276 threshold = ctrl.get_conc_mark_start_threshold();
277
278 assert(threshold == settled_ihop3,
279 "Expected IHOP threshold to settle at " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop3, threshold);
280
281 // And back to some arbitrary value.
282 test_update(&ctrl, alloc_time2, alloc_amount2, young_size, marking_time2);
283
284 threshold = ctrl.get_conc_mark_start_threshold();
285 assert(threshold > settled_ihop3,
286 "Expected IHOP threshold to settle at value larger than " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop3, threshold);
287 }
288
289 void IHOP_test() {
290 G1StaticIHOPControl::test();
291 }
292 #endif