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comparison src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 0bfd3fb24150 |
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1 /* | |
2 * Copyright 2002-2007 Sun Microsystems, 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 // This class keeps statistical information and computes the | |
26 // optimal free space for both the young and old generation | |
27 // based on current application characteristics (based on gc cost | |
28 // and application footprint). | |
29 // | |
30 // It also computes an optimal tenuring threshold between the young | |
31 // and old generations, so as to equalize the cost of collections | |
32 // of those generations, as well as optimial survivor space sizes | |
33 // for the young generation. | |
34 // | |
35 // While this class is specifically intended for a generational system | |
36 // consisting of a young gen (containing an Eden and two semi-spaces) | |
37 // and a tenured gen, as well as a perm gen for reflective data, it | |
38 // makes NO references to specific generations. | |
39 // | |
40 // 05/02/2003 Update | |
41 // The 1.5 policy makes use of data gathered for the costs of GC on | |
42 // specific generations. That data does reference specific | |
43 // generation. Also diagnostics specific to generations have | |
44 // been added. | |
45 | |
46 // Forward decls | |
47 class elapsedTimer; | |
48 | |
49 class PSAdaptiveSizePolicy : public AdaptiveSizePolicy { | |
50 friend class PSGCAdaptivePolicyCounters; | |
51 private: | |
52 // These values are used to record decisions made during the | |
53 // policy. For example, if the young generation was decreased | |
54 // to decrease the GC cost of minor collections the value | |
55 // decrease_young_gen_for_throughput_true is used. | |
56 | |
57 // Last calculated sizes, in bytes, and aligned | |
58 // NEEDS_CLEANUP should use sizes.hpp, but it works in ints, not size_t's | |
59 | |
60 // Time statistics | |
61 AdaptivePaddedAverage* _avg_major_pause; | |
62 | |
63 // Footprint statistics | |
64 AdaptiveWeightedAverage* _avg_base_footprint; | |
65 | |
66 // Statistical data gathered for GC | |
67 GCStats _gc_stats; | |
68 | |
69 size_t _survivor_size_limit; // Limit in bytes of survivor size | |
70 const double _collection_cost_margin_fraction; | |
71 | |
72 // Variable for estimating the major and minor pause times. | |
73 // These variables represent linear least-squares fits of | |
74 // the data. | |
75 // major pause time vs. old gen size | |
76 LinearLeastSquareFit* _major_pause_old_estimator; | |
77 // major pause time vs. young gen size | |
78 LinearLeastSquareFit* _major_pause_young_estimator; | |
79 | |
80 | |
81 // These record the most recent collection times. They | |
82 // are available as an alternative to using the averages | |
83 // for making ergonomic decisions. | |
84 double _latest_major_mutator_interval_seconds; | |
85 | |
86 const size_t _intra_generation_alignment; // alignment for eden, survivors | |
87 | |
88 const double _gc_minor_pause_goal_sec; // goal for maximum minor gc pause | |
89 | |
90 // The amount of live data in the heap at the last full GC, used | |
91 // as a baseline to help us determine when we need to perform the | |
92 // next full GC. | |
93 size_t _live_at_last_full_gc; | |
94 | |
95 // decrease/increase the old generation for minor pause time | |
96 int _change_old_gen_for_min_pauses; | |
97 | |
98 // increase/decrease the young generation for major pause time | |
99 int _change_young_gen_for_maj_pauses; | |
100 | |
101 | |
102 // Flag indicating that the adaptive policy is ready to use | |
103 bool _old_gen_policy_is_ready; | |
104 | |
105 // Changing the generation sizing depends on the data that is | |
106 // gathered about the effects of changes on the pause times and | |
107 // throughput. These variable count the number of data points | |
108 // gathered. The policy may use these counters as a threshhold | |
109 // for reliable data. | |
110 julong _young_gen_change_for_major_pause_count; | |
111 | |
112 // To facilitate faster growth at start up, supplement the normal | |
113 // growth percentage for the young gen eden and the | |
114 // old gen space for promotion with these value which decay | |
115 // with increasing collections. | |
116 uint _young_gen_size_increment_supplement; | |
117 uint _old_gen_size_increment_supplement; | |
118 | |
119 // The number of bytes absorbed from eden into the old gen by moving the | |
120 // boundary over live data. | |
121 size_t _bytes_absorbed_from_eden; | |
122 | |
123 private: | |
124 | |
125 // Accessors | |
126 AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; } | |
127 double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; } | |
128 | |
129 // Change the young generation size to achieve a minor GC pause time goal | |
130 void adjust_for_minor_pause_time(bool is_full_gc, | |
131 size_t* desired_promo_size_ptr, | |
132 size_t* desired_eden_size_ptr); | |
133 // Change the generation sizes to achieve a GC pause time goal | |
134 // Returned sizes are not necessarily aligned. | |
135 void adjust_for_pause_time(bool is_full_gc, | |
136 size_t* desired_promo_size_ptr, | |
137 size_t* desired_eden_size_ptr); | |
138 // Change the generation sizes to achieve an application throughput goal | |
139 // Returned sizes are not necessarily aligned. | |
140 void adjust_for_throughput(bool is_full_gc, | |
141 size_t* desired_promo_size_ptr, | |
142 size_t* desired_eden_size_ptr); | |
143 // Change the generation sizes to achieve minimum footprint | |
144 // Returned sizes are not aligned. | |
145 size_t adjust_promo_for_footprint(size_t desired_promo_size, | |
146 size_t desired_total); | |
147 size_t adjust_eden_for_footprint(size_t desired_promo_size, | |
148 size_t desired_total); | |
149 | |
150 // Size in bytes for an increment or decrement of eden. | |
151 virtual size_t eden_increment(size_t cur_eden, uint percent_change); | |
152 virtual size_t eden_decrement(size_t cur_eden); | |
153 size_t eden_decrement_aligned_down(size_t cur_eden); | |
154 size_t eden_increment_with_supplement_aligned_up(size_t cur_eden); | |
155 | |
156 // Size in bytes for an increment or decrement of the promotion area | |
157 virtual size_t promo_increment(size_t cur_promo, uint percent_change); | |
158 virtual size_t promo_decrement(size_t cur_promo); | |
159 size_t promo_decrement_aligned_down(size_t cur_promo); | |
160 size_t promo_increment_with_supplement_aligned_up(size_t cur_promo); | |
161 | |
162 // Decay the supplemental growth additive. | |
163 void decay_supplemental_growth(bool is_full_gc); | |
164 | |
165 // Returns a change that has been scaled down. Result | |
166 // is not aligned. (If useful, move to some shared | |
167 // location.) | |
168 size_t scale_down(size_t change, double part, double total); | |
169 | |
170 protected: | |
171 // Time accessors | |
172 | |
173 // Footprint accessors | |
174 size_t live_space() const { | |
175 return (size_t)(avg_base_footprint()->average() + | |
176 avg_young_live()->average() + | |
177 avg_old_live()->average()); | |
178 } | |
179 size_t free_space() const { | |
180 return _eden_size + _promo_size; | |
181 } | |
182 | |
183 void set_promo_size(size_t new_size) { | |
184 _promo_size = new_size; | |
185 } | |
186 void set_survivor_size(size_t new_size) { | |
187 _survivor_size = new_size; | |
188 } | |
189 | |
190 // Update estimators | |
191 void update_minor_pause_old_estimator(double minor_pause_in_ms); | |
192 | |
193 virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; } | |
194 | |
195 public: | |
196 // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving. | |
197 size_t eden_increment_aligned_up(size_t cur_eden); | |
198 size_t eden_increment_aligned_down(size_t cur_eden); | |
199 size_t promo_increment_aligned_up(size_t cur_promo); | |
200 size_t promo_increment_aligned_down(size_t cur_promo); | |
201 | |
202 virtual size_t eden_increment(size_t cur_eden); | |
203 virtual size_t promo_increment(size_t cur_promo); | |
204 | |
205 // Accessors for use by performance counters | |
206 AdaptivePaddedNoZeroDevAverage* avg_promoted() const { | |
207 return _gc_stats.avg_promoted(); | |
208 } | |
209 AdaptiveWeightedAverage* avg_base_footprint() const { | |
210 return _avg_base_footprint; | |
211 } | |
212 | |
213 // Input arguments are initial free space sizes for young and old | |
214 // generations, the initial survivor space size, the | |
215 // alignment values and the pause & throughput goals. | |
216 // | |
217 // NEEDS_CLEANUP this is a singleton object | |
218 PSAdaptiveSizePolicy(size_t init_eden_size, | |
219 size_t init_promo_size, | |
220 size_t init_survivor_size, | |
221 size_t intra_generation_alignment, | |
222 double gc_pause_goal_sec, | |
223 double gc_minor_pause_goal_sec, | |
224 uint gc_time_ratio); | |
225 | |
226 // Methods indicating events of interest to the adaptive size policy, | |
227 // called by GC algorithms. It is the responsibility of users of this | |
228 // policy to call these methods at the correct times! | |
229 void major_collection_begin(); | |
230 void major_collection_end(size_t amount_live, GCCause::Cause gc_cause); | |
231 | |
232 // | |
233 void tenured_allocation(size_t size) { | |
234 _avg_pretenured->sample(size); | |
235 } | |
236 | |
237 // Accessors | |
238 // NEEDS_CLEANUP should use sizes.hpp | |
239 | |
240 size_t calculated_old_free_size_in_bytes() const { | |
241 return (size_t)(_promo_size + avg_promoted()->padded_average()); | |
242 } | |
243 | |
244 size_t average_old_live_in_bytes() const { | |
245 return (size_t) avg_old_live()->average(); | |
246 } | |
247 | |
248 size_t average_promoted_in_bytes() const { | |
249 return (size_t)avg_promoted()->average(); | |
250 } | |
251 | |
252 size_t padded_average_promoted_in_bytes() const { | |
253 return (size_t)avg_promoted()->padded_average(); | |
254 } | |
255 | |
256 int change_young_gen_for_maj_pauses() { | |
257 return _change_young_gen_for_maj_pauses; | |
258 } | |
259 void set_change_young_gen_for_maj_pauses(int v) { | |
260 _change_young_gen_for_maj_pauses = v; | |
261 } | |
262 | |
263 int change_old_gen_for_min_pauses() { | |
264 return _change_old_gen_for_min_pauses; | |
265 } | |
266 void set_change_old_gen_for_min_pauses(int v) { | |
267 _change_old_gen_for_min_pauses = v; | |
268 } | |
269 | |
270 // Return true if the old generation size was changed | |
271 // to try to reach a pause time goal. | |
272 bool old_gen_changed_for_pauses() { | |
273 bool result = _change_old_gen_for_maj_pauses != 0 || | |
274 _change_old_gen_for_min_pauses != 0; | |
275 return result; | |
276 } | |
277 | |
278 // Return true if the young generation size was changed | |
279 // to try to reach a pause time goal. | |
280 bool young_gen_changed_for_pauses() { | |
281 bool result = _change_young_gen_for_min_pauses != 0 || | |
282 _change_young_gen_for_maj_pauses != 0; | |
283 return result; | |
284 } | |
285 // end flags for pause goal | |
286 | |
287 // Return true if the old generation size was changed | |
288 // to try to reach a throughput goal. | |
289 bool old_gen_changed_for_throughput() { | |
290 bool result = _change_old_gen_for_throughput != 0; | |
291 return result; | |
292 } | |
293 | |
294 // Return true if the young generation size was changed | |
295 // to try to reach a throughput goal. | |
296 bool young_gen_changed_for_throughput() { | |
297 bool result = _change_young_gen_for_throughput != 0; | |
298 return result; | |
299 } | |
300 | |
301 int decrease_for_footprint() { return _decrease_for_footprint; } | |
302 | |
303 | |
304 // Accessors for estimators. The slope of the linear fit is | |
305 // currently all that is used for making decisions. | |
306 | |
307 LinearLeastSquareFit* major_pause_old_estimator() { | |
308 return _major_pause_old_estimator; | |
309 } | |
310 | |
311 LinearLeastSquareFit* major_pause_young_estimator() { | |
312 return _major_pause_young_estimator; | |
313 } | |
314 | |
315 | |
316 virtual void clear_generation_free_space_flags(); | |
317 | |
318 float major_pause_old_slope() { return _major_pause_old_estimator->slope(); } | |
319 float major_pause_young_slope() { | |
320 return _major_pause_young_estimator->slope(); | |
321 } | |
322 float major_collection_slope() { return _major_collection_estimator->slope();} | |
323 | |
324 bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; } | |
325 | |
326 // Given the amount of live data in the heap, should we | |
327 // perform a Full GC? | |
328 bool should_full_GC(size_t live_in_old_gen); | |
329 | |
330 // Calculates optimial free space sizes for both the old and young | |
331 // generations. Stores results in _eden_size and _promo_size. | |
332 // Takes current used space in all generations as input, as well | |
333 // as an indication if a full gc has just been performed, for use | |
334 // in deciding if an OOM error should be thrown. | |
335 void compute_generation_free_space(size_t young_live, | |
336 size_t eden_live, | |
337 size_t old_live, | |
338 size_t perm_live, | |
339 size_t cur_eden, // current eden in bytes | |
340 size_t max_old_gen_size, | |
341 size_t max_eden_size, | |
342 bool is_full_gc, | |
343 GCCause::Cause gc_cause); | |
344 | |
345 // Calculates new survivor space size; returns a new tenuring threshold | |
346 // value. Stores new survivor size in _survivor_size. | |
347 int compute_survivor_space_size_and_threshold(bool is_survivor_overflow, | |
348 int tenuring_threshold, | |
349 size_t survivor_limit); | |
350 | |
351 // Return the maximum size of a survivor space if the young generation were of | |
352 // size gen_size. | |
353 size_t max_survivor_size(size_t gen_size) { | |
354 // Never allow the target survivor size to grow more than MinSurvivorRatio | |
355 // of the young generation size. We cannot grow into a two semi-space | |
356 // system, with Eden zero sized. Even if the survivor space grows, from() | |
357 // might grow by moving the bottom boundary "down" -- so from space will | |
358 // remain almost full anyway (top() will be near end(), but there will be a | |
359 // large filler object at the bottom). | |
360 const size_t sz = gen_size / MinSurvivorRatio; | |
361 const size_t alignment = _intra_generation_alignment; | |
362 return sz > alignment ? align_size_down(sz, alignment) : alignment; | |
363 } | |
364 | |
365 size_t live_at_last_full_gc() { | |
366 return _live_at_last_full_gc; | |
367 } | |
368 | |
369 size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; } | |
370 void reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; } | |
371 | |
372 void set_bytes_absorbed_from_eden(size_t val) { | |
373 _bytes_absorbed_from_eden = val; | |
374 } | |
375 | |
376 // Update averages that are always used (even | |
377 // if adaptive sizing is turned off). | |
378 void update_averages(bool is_survivor_overflow, | |
379 size_t survived, | |
380 size_t promoted); | |
381 | |
382 // Printing support | |
383 virtual bool print_adaptive_size_policy_on(outputStream* st) const; | |
384 }; |