1 /*
2 * Copyright (c) 2002, 2019, 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 #ifndef SHARE_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP
26 #define SHARE_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP
27
28 #include "gc/shared/adaptiveSizePolicy.hpp"
29 #include "gc/shared/gcCause.hpp"
30 #include "gc/shared/gcStats.hpp"
31 #include "gc/shared/gcUtil.hpp"
32 #include "utilities/align.hpp"
33
34 // This class keeps statistical information and computes the
35 // optimal free space for both the young and old generation
36 // based on current application characteristics (based on gc cost
37 // and application footprint).
38 //
39 // It also computes an optimal tenuring threshold between the young
40 // and old generations, so as to equalize the cost of collections
41 // of those generations, as well as optimal survivor space sizes
42 // for the young generation.
43 //
44 // While this class is specifically intended for a generational system
45 // consisting of a young gen (containing an Eden and two semi-spaces)
46 // and a tenured gen, as well as a perm gen for reflective data, it
47 // makes NO references to specific generations.
48 //
49 // 05/02/2003 Update
50 // The 1.5 policy makes use of data gathered for the costs of GC on
51 // specific generations. That data does reference specific
52 // generation. Also diagnostics specific to generations have
53 // been added.
54
55 // Forward decls
56 class elapsedTimer;
57
58 class PSAdaptiveSizePolicy : public AdaptiveSizePolicy {
59 friend class PSGCAdaptivePolicyCounters;
60 private:
61 // These values are used to record decisions made during the
62 // policy. For example, if the young generation was decreased
63 // to decrease the GC cost of minor collections the value
64 // decrease_young_gen_for_throughput_true is used.
65
66 // Last calculated sizes, in bytes, and aligned
67 // NEEDS_CLEANUP should use sizes.hpp, but it works in ints, not size_t's
68
69 // Time statistics
70 AdaptivePaddedAverage* _avg_major_pause;
71
72 // Footprint statistics
73 AdaptiveWeightedAverage* _avg_base_footprint;
74
75 // Statistical data gathered for GC
76 GCStats _gc_stats;
77
78 size_t _survivor_size_limit; // Limit in bytes of survivor size
79 const double _collection_cost_margin_fraction;
80
81 // Variable for estimating the major and minor pause times.
82 // These variables represent linear least-squares fits of
83 // the data.
84 // major pause time vs. old gen size
85 LinearLeastSquareFit* _major_pause_old_estimator;
86 // major pause time vs. young gen size
87 LinearLeastSquareFit* _major_pause_young_estimator;
88
89
90 // These record the most recent collection times. They
91 // are available as an alternative to using the averages
92 // for making ergonomic decisions.
93 double _latest_major_mutator_interval_seconds;
94
95 const size_t _space_alignment; // alignment for eden, survivors
96
97 const double _gc_minor_pause_goal_sec; // goal for maximum minor gc pause
98
99 // The amount of live data in the heap at the last full GC, used
100 // as a baseline to help us determine when we need to perform the
101 // next full GC.
102 size_t _live_at_last_full_gc;
103
104 // decrease/increase the old generation for minor pause time
105 int _change_old_gen_for_min_pauses;
106
107 // increase/decrease the young generation for major pause time
108 int _change_young_gen_for_maj_pauses;
109
110
111 // Flag indicating that the adaptive policy is ready to use
112 bool _old_gen_policy_is_ready;
113
114 // Changing the generation sizing depends on the data that is
115 // gathered about the effects of changes on the pause times and
116 // throughput. These variable count the number of data points
117 // gathered. The policy may use these counters as a threshold
118 // for reliable data.
119 julong _young_gen_change_for_major_pause_count;
120
121 // To facilitate faster growth at start up, supplement the normal
122 // growth percentage for the young gen eden and the
123 // old gen space for promotion with these value which decay
124 // with increasing collections.
125 uint _young_gen_size_increment_supplement;
126 uint _old_gen_size_increment_supplement;
127
128 // The number of bytes absorbed from eden into the old gen by moving the
129 // boundary over live data.
130 size_t _bytes_absorbed_from_eden;
131
132 private:
133
134 // Accessors
135 AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; }
136 double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; }
137
138 void adjust_eden_for_minor_pause_time(bool is_full_gc,
139 size_t* desired_eden_size_ptr);
140 // Change the generation sizes to achieve a GC pause time goal
141 // Returned sizes are not necessarily aligned.
142 void adjust_promo_for_pause_time(bool is_full_gc,
143 size_t* desired_promo_size_ptr,
144 size_t* desired_eden_size_ptr);
145 void adjust_eden_for_pause_time(bool is_full_gc,
146 size_t* desired_promo_size_ptr,
147 size_t* desired_eden_size_ptr);
148 // Change the generation sizes to achieve an application throughput goal
149 // Returned sizes are not necessarily aligned.
150 void adjust_promo_for_throughput(bool is_full_gc,
151 size_t* desired_promo_size_ptr);
152 void adjust_eden_for_throughput(bool is_full_gc,
153 size_t* desired_eden_size_ptr);
154 // Change the generation sizes to achieve minimum footprint
155 // Returned sizes are not aligned.
156 size_t adjust_promo_for_footprint(size_t desired_promo_size,
157 size_t desired_total);
158 size_t adjust_eden_for_footprint(size_t desired_promo_size,
159 size_t desired_total);
160
161 // Size in bytes for an increment or decrement of eden.
162 virtual size_t eden_increment(size_t cur_eden, uint percent_change);
163 virtual size_t eden_decrement(size_t cur_eden);
164 size_t eden_decrement_aligned_down(size_t cur_eden);
165 size_t eden_increment_with_supplement_aligned_up(size_t cur_eden);
166
167 // Size in bytes for an increment or decrement of the promotion area
168 virtual size_t promo_increment(size_t cur_promo, uint percent_change);
169 virtual size_t promo_decrement(size_t cur_promo);
170 size_t promo_decrement_aligned_down(size_t cur_promo);
171 size_t promo_increment_with_supplement_aligned_up(size_t cur_promo);
172
173 // Returns a change that has been scaled down. Result
174 // is not aligned. (If useful, move to some shared
175 // location.)
176 size_t scale_down(size_t change, double part, double total);
177
178 protected:
179 // Time accessors
180
181 // Footprint accessors
182 size_t live_space() const {
183 return (size_t)(avg_base_footprint()->average() +
184 avg_young_live()->average() +
185 avg_old_live()->average());
186 }
187 size_t free_space() const {
188 return _eden_size + _promo_size;
189 }
190
191 void set_promo_size(size_t new_size) {
192 _promo_size = new_size;
193 }
194 void set_survivor_size(size_t new_size) {
195 _survivor_size = new_size;
196 }
197
198 // Update estimators
199 void update_minor_pause_old_estimator(double minor_pause_in_ms);
200
201 virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; }
202
203 public:
204 // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving.
205 size_t eden_increment_aligned_up(size_t cur_eden);
206 size_t eden_increment_aligned_down(size_t cur_eden);
207 size_t promo_increment_aligned_up(size_t cur_promo);
208 size_t promo_increment_aligned_down(size_t cur_promo);
209
210 virtual size_t eden_increment(size_t cur_eden);
211 virtual size_t promo_increment(size_t cur_promo);
212
213 // Accessors for use by performance counters
214 AdaptivePaddedNoZeroDevAverage* avg_promoted() const {
215 return _gc_stats.avg_promoted();
216 }
217 AdaptiveWeightedAverage* avg_base_footprint() const {
218 return _avg_base_footprint;
219 }
220
221 // Input arguments are initial free space sizes for young and old
222 // generations, the initial survivor space size, the
223 // alignment values and the pause & throughput goals.
224 //
225 // NEEDS_CLEANUP this is a singleton object
226 PSAdaptiveSizePolicy(size_t init_eden_size,
227 size_t init_promo_size,
228 size_t init_survivor_size,
229 size_t space_alignment,
230 double gc_pause_goal_sec,
231 double gc_minor_pause_goal_sec,
232 uint gc_time_ratio);
233
234 // Methods indicating events of interest to the adaptive size policy,
235 // called by GC algorithms. It is the responsibility of users of this
236 // policy to call these methods at the correct times!
237 void major_collection_begin();
238 void major_collection_end(size_t amount_live, GCCause::Cause gc_cause);
239
240 void tenured_allocation(size_t size) {
241 _avg_pretenured->sample(size);
242 }
243
244 // Accessors
245 // NEEDS_CLEANUP should use sizes.hpp
246
247 static size_t calculate_free_based_on_live(size_t live, uintx ratio_as_percentage);
248
249 size_t calculated_old_free_size_in_bytes() const;
250
251 size_t average_old_live_in_bytes() const {
252 return (size_t) avg_old_live()->average();
253 }
254
255 size_t average_promoted_in_bytes() const {
256 return (size_t)avg_promoted()->average();
257 }
258
259 size_t padded_average_promoted_in_bytes() const {
260 return (size_t)avg_promoted()->padded_average();
261 }
262
263 int change_young_gen_for_maj_pauses() {
264 return _change_young_gen_for_maj_pauses;
265 }
266 void set_change_young_gen_for_maj_pauses(int v) {
267 _change_young_gen_for_maj_pauses = v;
268 }
269
270 int change_old_gen_for_min_pauses() {
271 return _change_old_gen_for_min_pauses;
272 }
273 void set_change_old_gen_for_min_pauses(int v) {
274 _change_old_gen_for_min_pauses = v;
275 }
276
277 // Return true if the old generation size was changed
278 // to try to reach a pause time goal.
279 bool old_gen_changed_for_pauses() {
280 bool result = _change_old_gen_for_maj_pauses != 0 ||
281 _change_old_gen_for_min_pauses != 0;
282 return result;
283 }
284
285 // Return true if the young generation size was changed
286 // to try to reach a pause time goal.
287 bool young_gen_changed_for_pauses() {
288 bool result = _change_young_gen_for_min_pauses != 0 ||
289 _change_young_gen_for_maj_pauses != 0;
290 return result;
291 }
292 // end flags for pause goal
293
294 // Return true if the old generation size was changed
295 // to try to reach a throughput goal.
296 bool old_gen_changed_for_throughput() {
297 bool result = _change_old_gen_for_throughput != 0;
298 return result;
299 }
300
301 // Return true if the young generation size was changed
302 // to try to reach a throughput goal.
303 bool young_gen_changed_for_throughput() {
304 bool result = _change_young_gen_for_throughput != 0;
305 return result;
306 }
307
308 int decrease_for_footprint() { return _decrease_for_footprint; }
309
310
311 // Accessors for estimators. The slope of the linear fit is
312 // currently all that is used for making decisions.
313
314 LinearLeastSquareFit* major_pause_old_estimator() {
315 return _major_pause_old_estimator;
316 }
317
318 LinearLeastSquareFit* major_pause_young_estimator() {
319 return _major_pause_young_estimator;
320 }
321
322
323 virtual void clear_generation_free_space_flags();
324
325 float major_pause_old_slope() { return _major_pause_old_estimator->slope(); }
326 float major_pause_young_slope() {
327 return _major_pause_young_estimator->slope();
328 }
329 float major_collection_slope() { return _major_collection_estimator->slope();}
330
331 bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; }
332
333 // Given the amount of live data in the heap, should we
334 // perform a Full GC?
335 bool should_full_GC(size_t live_in_old_gen);
336
337 // Calculates optimal (free) space sizes for both the young and old
338 // generations. Stores results in _eden_size and _promo_size.
339 // Takes current used space in all generations as input, as well
340 // as an indication if a full gc has just been performed, for use
341 // in deciding if an OOM error should be thrown.
342 void compute_generations_free_space(size_t young_live,
343 size_t eden_live,
344 size_t old_live,
345 size_t cur_eden, // current eden in bytes
346 size_t max_old_gen_size,
347 size_t max_eden_size,
348 bool is_full_gc);
349
350 void compute_eden_space_size(size_t young_live,
351 size_t eden_live,
352 size_t cur_eden, // current eden in bytes
353 size_t max_eden_size,
354 bool is_full_gc);
355
356 void compute_old_gen_free_space(size_t old_live,
357 size_t cur_eden, // current eden in bytes
358 size_t max_old_gen_size,
359 bool is_full_gc);
360
361 // Calculates new survivor space size; returns a new tenuring threshold
362 // value. Stores new survivor size in _survivor_size.
363 uint compute_survivor_space_size_and_threshold(bool is_survivor_overflow,
364 uint tenuring_threshold,
365 size_t survivor_limit);
366
367 // Return the maximum size of a survivor space if the young generation were of
368 // size gen_size.
369 size_t max_survivor_size(size_t gen_size) {
370 // Never allow the target survivor size to grow more than MinSurvivorRatio
371 // of the young generation size. We cannot grow into a two semi-space
372 // system, with Eden zero sized. Even if the survivor space grows, from()
373 // might grow by moving the bottom boundary "down" -- so from space will
374 // remain almost full anyway (top() will be near end(), but there will be a
375 // large filler object at the bottom).
376 const size_t sz = gen_size / MinSurvivorRatio;
377 const size_t alignment = _space_alignment;
378 return sz > alignment ? align_down(sz, alignment) : alignment;
379 }
380
381 size_t live_at_last_full_gc() {
382 return _live_at_last_full_gc;
383 }
384
385 size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; }
386 void reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; }
387
388 void set_bytes_absorbed_from_eden(size_t val) {
389 _bytes_absorbed_from_eden = val;
390 }
391
392 // Update averages that are always used (even
393 // if adaptive sizing is turned off).
394 void update_averages(bool is_survivor_overflow,
395 size_t survived,
396 size_t promoted);
397
398 // Printing support
399 virtual bool print() const;
400
401 // Decay the supplemental growth additive.
402 void decay_supplemental_growth(bool is_full_gc);
403 };
404
405 #endif // SHARE_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP