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 #include "gc/shared/gcTrace.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 ergo_verbose6(ErgoIHOP,
51 "basic information",
52 ergo_format_reason("value update")
53 ergo_format_byte_perc("threshold")
54 ergo_format_byte("target occupancy")
55 ergo_format_byte("current occupancy")
56 ergo_format_double("recent old gen allocation rate")
57 ergo_format_double("recent marking phase length"),
58 cur_conc_mark_start_threshold,
59 cur_conc_mark_start_threshold * 100.0 / _target_occupancy,
60 _target_occupancy,
61 G1CollectedHeap::heap()->used(),
62 _last_allocation_time_s > 0.0 ? _last_allocated_bytes / _last_allocation_time_s : 0.0,
63 last_marking_length_s());
64 }
65
66 void G1IHOPControl::send_trace_event(G1NewTracer* tracer) {
67 tracer->report_basic_ihop_statistics(get_conc_mark_start_threshold(),
68 _target_occupancy,
69 G1CollectedHeap::heap()->used(),
70 _last_allocated_bytes,
71 _last_allocation_time_s,
72 last_marking_length_s());
73 }
74
75 G1StaticIHOPControl::G1StaticIHOPControl(double ihop_percent, size_t target_occupancy) :
76 G1IHOPControl(ihop_percent, target_occupancy),
77 _last_marking_length_s(0.0) {
78 assert(_target_occupancy > 0, "Target occupancy must be larger than zero.");
79 }
80
81 #ifndef PRODUCT
82 static void test_update(G1IHOPControl* ctrl, double alloc_time, size_t alloc_amount, size_t young_size, double mark_time) {
83 for (int i = 0; i < 100; i++) {
84 ctrl->update_allocation_info(alloc_time, alloc_amount, young_size);
85 ctrl->update_marking_length(mark_time);
86 }
87 }
88
89 void G1StaticIHOPControl::test() {
90 size_t const initial_ihop = 45;
91
92 G1StaticIHOPControl ctrl(initial_ihop, 100);
93
94 size_t 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 ctrl.update_allocation_info(100.0, 100, 100);
99 threshold = ctrl.get_conc_mark_start_threshold();
100 assert(threshold == initial_ihop,
101 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
102
103 ctrl.update_marking_length(1000.0);
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 // Whatever we pass, the IHOP value must stay the same.
109 test_update(&ctrl, 2, 10, 10, 3);
110 threshold = ctrl.get_conc_mark_start_threshold();
111 assert(threshold == initial_ihop,
112 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
113
114 test_update(&ctrl, 12, 10, 10, 3);
115 threshold = ctrl.get_conc_mark_start_threshold();
116 assert(threshold == initial_ihop,
117 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_ihop, threshold);
118 }
119 #endif
120
121 G1AdaptiveIHOPControl::G1AdaptiveIHOPControl(double ihop_percent,
122 size_t initial_target_occupancy,
123 G1Predictions const* predictor,
124 size_t heap_reserve_percent,
125 size_t heap_waste_percent) :
126 G1IHOPControl(ihop_percent, initial_target_occupancy),
127 _predictor(predictor),
128 _marking_times_s(10, 0.95),
129 _allocation_rate_s(10, 0.95),
130 _last_unrestrained_young_size(0),
131 _heap_reserve_percent(heap_reserve_percent),
132 _heap_waste_percent(heap_waste_percent)
133 {
134 }
135
136 size_t G1AdaptiveIHOPControl::actual_target_threshold() const {
137 // The actual target threshold takes the heap reserve and the expected waste in
138 // free space into account.
139 // _heap_reserve is that part of the total heap capacity that is reserved for
140 // eventual promotion failure.
141 // _heap_waste is the amount of space will never be reclaimed in any
142 // heap, so can not be used for allocation during marking and must always be
143 // considered.
144
145 double safe_total_heap_percentage = MIN2((double)(_heap_reserve_percent + _heap_waste_percent), 100.0);
146
147 return MIN2(
148 G1CollectedHeap::heap()->max_capacity() * (100.0 - safe_total_heap_percentage) / 100.0,
149 _target_occupancy * (100.0 - _heap_waste_percent) / 100.0
150 );
151 }
152
153 bool G1AdaptiveIHOPControl::have_enough_data_for_prediction() const {
154 return ((size_t)_marking_times_s.num() >= G1AdaptiveIHOPNumInitialSamples) &&
155 ((size_t)_allocation_rate_s.num() >= G1AdaptiveIHOPNumInitialSamples);
156 }
157
158 size_t G1AdaptiveIHOPControl::get_conc_mark_start_threshold() {
159 if (have_enough_data_for_prediction()) {
160 double pred_marking_time = _predictor->get_new_prediction(&_marking_times_s);
161 double pred_promotion_rate = _predictor->get_new_prediction(&_allocation_rate_s);
162
163 size_t predicted_needed_bytes_during_marking =
164 (pred_marking_time * pred_promotion_rate +
165 _last_unrestrained_young_size); // In reality we would need the maximum size of the young gen during marking. This is a conservative estimate.
166
167 size_t internal_threshold = actual_target_threshold();
168 size_t predicted_initiating_threshold = predicted_needed_bytes_during_marking < internal_threshold ?
169 internal_threshold - predicted_needed_bytes_during_marking :
170 0;
171 return predicted_initiating_threshold;
172 } else {
173 // Use the initial value.
174 return _initial_ihop_percent * _target_occupancy / 100.0;
175 }
176 }
177
178 void G1AdaptiveIHOPControl::update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size) {
179 G1IHOPControl::update_allocation_info(allocation_time_s, allocated_bytes, additional_buffer_size);
180
181 double allocation_rate = (double) allocated_bytes / allocation_time_s;
182 _allocation_rate_s.add(allocation_rate);
183
184 _last_unrestrained_young_size = additional_buffer_size;
185 }
186
187 void G1AdaptiveIHOPControl::update_marking_length(double marking_length_s) {
188 assert(marking_length_s >= 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s);
189 _marking_times_s.add(marking_length_s);
190 }
191
192 void G1AdaptiveIHOPControl::print() {
193 G1IHOPControl::print();
194 size_t actual_target = actual_target_threshold();
195 ergo_verbose6(ErgoIHOP,
196 "adaptive IHOP information",
197 ergo_format_reason("value update")
198 ergo_format_byte_perc("threshold")
199 ergo_format_byte("internal target occupancy")
200 ergo_format_double("predicted old gen allocation rate")
201 ergo_format_double("predicted marking phase length")
202 ergo_format_str("prediction active"),
203 get_conc_mark_start_threshold(),
204 percent_of(get_conc_mark_start_threshold(), actual_target),
205 actual_target,
206 _predictor->get_new_prediction(&_allocation_rate_s),
207 _predictor->get_new_prediction(&_marking_times_s),
208 have_enough_data_for_prediction() ? "true" : "false"
209 );
210 }
211
212 void G1AdaptiveIHOPControl::send_trace_event(G1NewTracer* tracer) {
213 G1IHOPControl::send_trace_event(tracer);
214 tracer->report_adaptive_ihop_statistics(get_conc_mark_start_threshold(),
215 actual_target_threshold(),
216 G1CollectedHeap::heap()->used(),
217 _last_unrestrained_young_size,
218 _predictor->get_new_prediction(&_allocation_rate_s),
219 _predictor->get_new_prediction(&_marking_times_s),
220 have_enough_data_for_prediction());
221 }
222
223 #ifndef PRODUCT
224 void G1AdaptiveIHOPControl::test() {
225 size_t const initial_threshold = 45;
226 size_t const young_size = 10;
227 size_t const target_size = 100;
228
229 // The final IHOP value is always
230 // target_size - (young_size + alloc_amount/alloc_time * marking_time)
231
232 G1Predictions pred(0.95);
233 G1AdaptiveIHOPControl ctrl(initial_threshold, target_size, &pred, 0, 0);
234
235 // First "load".
236 size_t const alloc_time1 = 2;
237 size_t const alloc_amount1 = 10;
238 size_t const marking_time1 = 2;
239 size_t const settled_ihop1 = target_size - (young_size + alloc_amount1/alloc_time1 * marking_time1);
240
241 size_t threshold;
242 threshold = ctrl.get_conc_mark_start_threshold();
243 assert(threshold == initial_threshold,
244 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_threshold, threshold);
245 for (size_t i = 0; i < G1AdaptiveIHOPNumInitialSamples - 1; i++) {
246 ctrl.update_allocation_info(alloc_time1, alloc_amount1, young_size);
247 ctrl.update_marking_length(marking_time1);
248 // Not enough data yet.
249 threshold = ctrl.get_conc_mark_start_threshold();
250 assert(threshold == initial_threshold,
251 "Expected IHOP threshold of " SIZE_FORMAT " but is " SIZE_FORMAT, initial_threshold, threshold);
252 }
253
254 test_update(&ctrl, alloc_time1, alloc_amount1, young_size, marking_time1);
255
256 threshold = ctrl.get_conc_mark_start_threshold();
257 assert(threshold == settled_ihop1,
258 "Expected IHOP threshold to settle at " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop1, threshold);
259
260 // Second "load". A bit higher allocation rate.
261 size_t const alloc_time2 = 2;
262 size_t const alloc_amount2 = 30;
263 size_t const marking_time2 = 2;
264 size_t const settled_ihop2 = target_size - (young_size + alloc_amount2/alloc_time2 * marking_time2);
265
266 test_update(&ctrl, alloc_time2, alloc_amount2, young_size, marking_time2);
267
268 threshold = ctrl.get_conc_mark_start_threshold();
269 assert(threshold < settled_ihop1,
270 "Expected IHOP threshold to settle at a value lower than " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop1, threshold);
271
272 // Third "load". Very high (impossible) allocation rate.
273 size_t const alloc_time3 = 1;
274 size_t const alloc_amount3 = 50;
275 size_t const marking_time3 = 2;
276 size_t const settled_ihop3 = 0;
277
278 test_update(&ctrl, alloc_time3, alloc_amount3, young_size, marking_time3);
279 threshold = ctrl.get_conc_mark_start_threshold();
280
281 assert(threshold == settled_ihop3,
282 "Expected IHOP threshold to settle at " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop3, threshold);
283
284 // And back to some arbitrary value.
285 test_update(&ctrl, alloc_time2, alloc_amount2, young_size, marking_time2);
286
287 threshold = ctrl.get_conc_mark_start_threshold();
288 assert(threshold > settled_ihop3,
289 "Expected IHOP threshold to settle at value larger than " SIZE_FORMAT " but is " SIZE_FORMAT, settled_ihop3, threshold);
290 }
291
292 void IHOP_test() {
293 G1StaticIHOPControl::test();
294 }
295 #endif