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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP
27
28 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"
29 #include "gc_implementation/shared/gcStats.hpp"
30 #include "gc_implementation/shared/gcUtil.hpp"
31 #include "gc_interface/gcCause.hpp"
32
33 // This class keeps statistical information and computes the
34 // optimal free space for both the young and old generation
35 // based on current application characteristics (based on gc cost
36 // and application footprint).
37 //
38 // It also computes an optimal tenuring threshold between the young
39 // and old generations, so as to equalize the cost of collections
40 // of those generations, as well as optimial survivor space sizes
41 // for the young generation.
42 //
43 // While this class is specifically intended for a generational system
44 // consisting of a young gen (containing an Eden and two semi-spaces)
45 // and a tenured gen, as well as a perm gen for reflective data, it
46 // makes NO references to specific generations.
47 //
48 // 05/02/2003 Update
49 // The 1.5 policy makes use of data gathered for the costs of GC on
50 // specific generations. That data does reference specific
51 // generation. Also diagnostics specific to generations have
52 // been added.
53
54 // Forward decls
55 class elapsedTimer;
56 class GenerationSizer;
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 _intra_generation_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 threshhold
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 // Change the young generation size to achieve a minor GC pause time goal
139 void adjust_for_minor_pause_time(bool is_full_gc,
140 size_t* desired_promo_size_ptr,
141 size_t* desired_eden_size_ptr);
142 // Change the generation sizes to achieve a GC pause time goal
143 // Returned sizes are not necessarily aligned.
144 void adjust_for_pause_time(bool is_full_gc,
145 size_t* desired_promo_size_ptr,
146 size_t* desired_eden_size_ptr);
147 // Change the generation sizes to achieve an application throughput goal
148 // Returned sizes are not necessarily aligned.
149 void adjust_for_throughput(bool is_full_gc,
150 size_t* desired_promo_size_ptr,
151 size_t* desired_eden_size_ptr);
152 // Change the generation sizes to achieve minimum footprint
153 // Returned sizes are not aligned.
154 size_t adjust_promo_for_footprint(size_t desired_promo_size,
155 size_t desired_total);
156 size_t adjust_eden_for_footprint(size_t desired_promo_size,
157 size_t desired_total);
158
159 // Size in bytes for an increment or decrement of eden.
160 virtual size_t eden_increment(size_t cur_eden, uint percent_change);
161 virtual size_t eden_decrement(size_t cur_eden);
162 size_t eden_decrement_aligned_down(size_t cur_eden);
163 size_t eden_increment_with_supplement_aligned_up(size_t cur_eden);
164
165 // Size in bytes for an increment or decrement of the promotion area
166 virtual size_t promo_increment(size_t cur_promo, uint percent_change);
167 virtual size_t promo_decrement(size_t cur_promo);
168 size_t promo_decrement_aligned_down(size_t cur_promo);
169 size_t promo_increment_with_supplement_aligned_up(size_t cur_promo);
170
171 // Decay the supplemental growth additive.
172 void decay_supplemental_growth(bool is_full_gc);
173
174 // Returns a change that has been scaled down. Result
175 // is not aligned. (If useful, move to some shared
176 // location.)
177 size_t scale_down(size_t change, double part, double total);
178
179 protected:
180 // Time accessors
181
182 // Footprint accessors
183 size_t live_space() const {
184 return (size_t)(avg_base_footprint()->average() +
185 avg_young_live()->average() +
186 avg_old_live()->average());
187 }
188 size_t free_space() const {
189 return _eden_size + _promo_size;
190 }
191
192 void set_promo_size(size_t new_size) {
193 _promo_size = new_size;
194 }
195 void set_survivor_size(size_t new_size) {
196 _survivor_size = new_size;
197 }
198
199 // Update estimators
200 void update_minor_pause_old_estimator(double minor_pause_in_ms);
201
202 virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; }
203
204 public:
205 // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving.
206 size_t eden_increment_aligned_up(size_t cur_eden);
207 size_t eden_increment_aligned_down(size_t cur_eden);
208 size_t promo_increment_aligned_up(size_t cur_promo);
209 size_t promo_increment_aligned_down(size_t cur_promo);
210
211 virtual size_t eden_increment(size_t cur_eden);
212 virtual size_t promo_increment(size_t cur_promo);
213
214 // Accessors for use by performance counters
215 AdaptivePaddedNoZeroDevAverage* avg_promoted() const {
216 return _gc_stats.avg_promoted();
217 }
218 AdaptiveWeightedAverage* avg_base_footprint() const {
219 return _avg_base_footprint;
220 }
221
222 // Input arguments are initial free space sizes for young and old
223 // generations, the initial survivor space size, the
224 // alignment values and the pause & throughput goals.
225 //
226 // NEEDS_CLEANUP this is a singleton object
227 PSAdaptiveSizePolicy(size_t init_eden_size,
228 size_t init_promo_size,
229 size_t init_survivor_size,
230 size_t intra_generation_alignment,
231 double gc_pause_goal_sec,
232 double gc_minor_pause_goal_sec,
233 uint gc_time_ratio);
234
235 // Methods indicating events of interest to the adaptive size policy,
236 // called by GC algorithms. It is the responsibility of users of this
237 // policy to call these methods at the correct times!
238 void major_collection_begin();
239 void major_collection_end(size_t amount_live, GCCause::Cause gc_cause);
240
241 //
242 void tenured_allocation(size_t size) {
243 _avg_pretenured->sample(size);
244 }
245
246 // Accessors
247 // NEEDS_CLEANUP should use sizes.hpp
248
249 size_t calculated_old_free_size_in_bytes() const {
250 return (size_t)(_promo_size + avg_promoted()->padded_average());
251 }
252
253 size_t average_old_live_in_bytes() const {
254 return (size_t) avg_old_live()->average();
255 }
256
257 size_t average_promoted_in_bytes() const {
258 return (size_t)avg_promoted()->average();
259 }
260
261 size_t padded_average_promoted_in_bytes() const {
262 return (size_t)avg_promoted()->padded_average();
263 }
264
265 int change_young_gen_for_maj_pauses() {
266 return _change_young_gen_for_maj_pauses;
267 }
268 void set_change_young_gen_for_maj_pauses(int v) {
269 _change_young_gen_for_maj_pauses = v;
270 }
271
272 int change_old_gen_for_min_pauses() {
273 return _change_old_gen_for_min_pauses;
274 }
275 void set_change_old_gen_for_min_pauses(int v) {
276 _change_old_gen_for_min_pauses = v;
277 }
278
279 // Return true if the old generation size was changed
280 // to try to reach a pause time goal.
281 bool old_gen_changed_for_pauses() {
282 bool result = _change_old_gen_for_maj_pauses != 0 ||
283 _change_old_gen_for_min_pauses != 0;
284 return result;
285 }
286
287 // Return true if the young generation size was changed
288 // to try to reach a pause time goal.
289 bool young_gen_changed_for_pauses() {
290 bool result = _change_young_gen_for_min_pauses != 0 ||
291 _change_young_gen_for_maj_pauses != 0;
292 return result;
293 }
294 // end flags for pause goal
295
296 // Return true if the old generation size was changed
297 // to try to reach a throughput goal.
298 bool old_gen_changed_for_throughput() {
299 bool result = _change_old_gen_for_throughput != 0;
300 return result;
301 }
302
303 // Return true if the young generation size was changed
304 // to try to reach a throughput goal.
305 bool young_gen_changed_for_throughput() {
306 bool result = _change_young_gen_for_throughput != 0;
307 return result;
308 }
309
310 int decrease_for_footprint() { return _decrease_for_footprint; }
311
312
313 // Accessors for estimators. The slope of the linear fit is
314 // currently all that is used for making decisions.
315
316 LinearLeastSquareFit* major_pause_old_estimator() {
317 return _major_pause_old_estimator;
318 }
319
320 LinearLeastSquareFit* major_pause_young_estimator() {
321 return _major_pause_young_estimator;
322 }
323
324
325 virtual void clear_generation_free_space_flags();
326
327 float major_pause_old_slope() { return _major_pause_old_estimator->slope(); }
328 float major_pause_young_slope() {
329 return _major_pause_young_estimator->slope();
330 }
331 float major_collection_slope() { return _major_collection_estimator->slope();}
332
333 bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; }
334
335 // Given the amount of live data in the heap, should we
336 // perform a Full GC?
337 bool should_full_GC(size_t live_in_old_gen);
338
339 // Calculates optimial free space sizes for both the old and young
340 // generations. Stores results in _eden_size and _promo_size.
341 // Takes current used space in all generations as input, as well
342 // as an indication if a full gc has just been performed, for use
343 // in deciding if an OOM error should be thrown.
344 void compute_generation_free_space(size_t young_live,
345 size_t eden_live,
346 size_t old_live,
347 size_t perm_live,
348 size_t cur_eden, // current eden in bytes
349 size_t max_old_gen_size,
350 size_t max_eden_size,
351 bool is_full_gc,
352 GCCause::Cause gc_cause,
353 CollectorPolicy* collector_policy);
354
355 // Calculates new survivor space size; returns a new tenuring threshold
356 // value. Stores new survivor size in _survivor_size.
357 int compute_survivor_space_size_and_threshold(bool is_survivor_overflow,
358 int tenuring_threshold,
359 size_t survivor_limit);
360
361 // Return the maximum size of a survivor space if the young generation were of
362 // size gen_size.
363 size_t max_survivor_size(size_t gen_size) {
364 // Never allow the target survivor size to grow more than MinSurvivorRatio
365 // of the young generation size. We cannot grow into a two semi-space
366 // system, with Eden zero sized. Even if the survivor space grows, from()
367 // might grow by moving the bottom boundary "down" -- so from space will
368 // remain almost full anyway (top() will be near end(), but there will be a
369 // large filler object at the bottom).
370 const size_t sz = gen_size / MinSurvivorRatio;
371 const size_t alignment = _intra_generation_alignment;
372 return sz > alignment ? align_size_down(sz, alignment) : alignment;
373 }
374
375 size_t live_at_last_full_gc() {
376 return _live_at_last_full_gc;
377 }
378
379 size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; }
380 void reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; }
381
382 void set_bytes_absorbed_from_eden(size_t val) {
383 _bytes_absorbed_from_eden = val;
384 }
385
386 // Update averages that are always used (even
387 // if adaptive sizing is turned off).
388 void update_averages(bool is_survivor_overflow,
389 size_t survived,
390 size_t promoted);
391
392 // Printing support
393 virtual bool print_adaptive_size_policy_on(outputStream* st) const;
394 };
395
396 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP