Wed, 22 May 2013 11:11:47 -0700
8007762: Rename a bunch of methods in size policy across collectors
Summary: Rename: compute_generations_free_space() = compute_eden_space_size() + compute_old_gen_free_space(); update related logging messages
Reviewed-by: jmasa, johnc, tschatzl, brutisso
Contributed-by: tamao <tao.mao@oracle.com>
1 /*
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP
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"
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.
54 // Forward decls
55 class elapsedTimer;
56 class GenerationSizer;
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.
66 // Last calculated sizes, in bytes, and aligned
67 // NEEDS_CLEANUP should use sizes.hpp, but it works in ints, not size_t's
69 // Time statistics
70 AdaptivePaddedAverage* _avg_major_pause;
72 // Footprint statistics
73 AdaptiveWeightedAverage* _avg_base_footprint;
75 // Statistical data gathered for GC
76 GCStats _gc_stats;
78 size_t _survivor_size_limit; // Limit in bytes of survivor size
79 const double _collection_cost_margin_fraction;
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;
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;
95 const size_t _intra_generation_alignment; // alignment for eden, survivors
97 const double _gc_minor_pause_goal_sec; // goal for maximum minor gc pause
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;
104 // decrease/increase the old generation for minor pause time
105 int _change_old_gen_for_min_pauses;
107 // increase/decrease the young generation for major pause time
108 int _change_young_gen_for_maj_pauses;
111 // Flag indicating that the adaptive policy is ready to use
112 bool _old_gen_policy_is_ready;
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;
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;
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;
132 private:
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; }
138 // Change the young generation size to achieve a minor GC pause time goal
139 void adjust_promo_for_minor_pause_time(bool is_full_gc,
140 size_t* desired_promo_size_ptr,
141 size_t* desired_eden_size_ptr);
142 void adjust_eden_for_minor_pause_time(bool is_full_gc,
143 size_t* desired_eden_size_ptr);
144 // Change the generation sizes to achieve a GC pause time goal
145 // Returned sizes are not necessarily aligned.
146 void adjust_promo_for_pause_time(bool is_full_gc,
147 size_t* desired_promo_size_ptr,
148 size_t* desired_eden_size_ptr);
149 void adjust_eden_for_pause_time(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 an application throughput goal
153 // Returned sizes are not necessarily aligned.
154 void adjust_promo_for_throughput(bool is_full_gc,
155 size_t* desired_promo_size_ptr);
156 void adjust_eden_for_throughput(bool is_full_gc,
157 size_t* desired_eden_size_ptr);
158 // Change the generation sizes to achieve minimum footprint
159 // Returned sizes are not aligned.
160 size_t adjust_promo_for_footprint(size_t desired_promo_size,
161 size_t desired_total);
162 size_t adjust_eden_for_footprint(size_t desired_promo_size,
163 size_t desired_total);
165 // Size in bytes for an increment or decrement of eden.
166 virtual size_t eden_increment(size_t cur_eden, uint percent_change);
167 virtual size_t eden_decrement(size_t cur_eden);
168 size_t eden_decrement_aligned_down(size_t cur_eden);
169 size_t eden_increment_with_supplement_aligned_up(size_t cur_eden);
171 // Size in bytes for an increment or decrement of the promotion area
172 virtual size_t promo_increment(size_t cur_promo, uint percent_change);
173 virtual size_t promo_decrement(size_t cur_promo);
174 size_t promo_decrement_aligned_down(size_t cur_promo);
175 size_t promo_increment_with_supplement_aligned_up(size_t cur_promo);
177 // Returns a change that has been scaled down. Result
178 // is not aligned. (If useful, move to some shared
179 // location.)
180 size_t scale_down(size_t change, double part, double total);
182 protected:
183 // Time accessors
185 // Footprint accessors
186 size_t live_space() const {
187 return (size_t)(avg_base_footprint()->average() +
188 avg_young_live()->average() +
189 avg_old_live()->average());
190 }
191 size_t free_space() const {
192 return _eden_size + _promo_size;
193 }
195 void set_promo_size(size_t new_size) {
196 _promo_size = new_size;
197 }
198 void set_survivor_size(size_t new_size) {
199 _survivor_size = new_size;
200 }
202 // Update estimators
203 void update_minor_pause_old_estimator(double minor_pause_in_ms);
205 virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; }
207 public:
208 // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving.
209 size_t eden_increment_aligned_up(size_t cur_eden);
210 size_t eden_increment_aligned_down(size_t cur_eden);
211 size_t promo_increment_aligned_up(size_t cur_promo);
212 size_t promo_increment_aligned_down(size_t cur_promo);
214 virtual size_t eden_increment(size_t cur_eden);
215 virtual size_t promo_increment(size_t cur_promo);
217 // Accessors for use by performance counters
218 AdaptivePaddedNoZeroDevAverage* avg_promoted() const {
219 return _gc_stats.avg_promoted();
220 }
221 AdaptiveWeightedAverage* avg_base_footprint() const {
222 return _avg_base_footprint;
223 }
225 // Input arguments are initial free space sizes for young and old
226 // generations, the initial survivor space size, the
227 // alignment values and the pause & throughput goals.
228 //
229 // NEEDS_CLEANUP this is a singleton object
230 PSAdaptiveSizePolicy(size_t init_eden_size,
231 size_t init_promo_size,
232 size_t init_survivor_size,
233 size_t intra_generation_alignment,
234 double gc_pause_goal_sec,
235 double gc_minor_pause_goal_sec,
236 uint gc_time_ratio);
238 // Methods indicating events of interest to the adaptive size policy,
239 // called by GC algorithms. It is the responsibility of users of this
240 // policy to call these methods at the correct times!
241 void major_collection_begin();
242 void major_collection_end(size_t amount_live, GCCause::Cause gc_cause);
244 //
245 void tenured_allocation(size_t size) {
246 _avg_pretenured->sample(size);
247 }
249 // Accessors
250 // NEEDS_CLEANUP should use sizes.hpp
252 size_t calculated_old_free_size_in_bytes() const {
253 return (size_t)(_promo_size + avg_promoted()->padded_average());
254 }
256 size_t average_old_live_in_bytes() const {
257 return (size_t) avg_old_live()->average();
258 }
260 size_t average_promoted_in_bytes() const {
261 return (size_t)avg_promoted()->average();
262 }
264 size_t padded_average_promoted_in_bytes() const {
265 return (size_t)avg_promoted()->padded_average();
266 }
268 int change_young_gen_for_maj_pauses() {
269 return _change_young_gen_for_maj_pauses;
270 }
271 void set_change_young_gen_for_maj_pauses(int v) {
272 _change_young_gen_for_maj_pauses = v;
273 }
275 int change_old_gen_for_min_pauses() {
276 return _change_old_gen_for_min_pauses;
277 }
278 void set_change_old_gen_for_min_pauses(int v) {
279 _change_old_gen_for_min_pauses = v;
280 }
282 // Return true if the old generation size was changed
283 // to try to reach a pause time goal.
284 bool old_gen_changed_for_pauses() {
285 bool result = _change_old_gen_for_maj_pauses != 0 ||
286 _change_old_gen_for_min_pauses != 0;
287 return result;
288 }
290 // Return true if the young generation size was changed
291 // to try to reach a pause time goal.
292 bool young_gen_changed_for_pauses() {
293 bool result = _change_young_gen_for_min_pauses != 0 ||
294 _change_young_gen_for_maj_pauses != 0;
295 return result;
296 }
297 // end flags for pause goal
299 // Return true if the old generation size was changed
300 // to try to reach a throughput goal.
301 bool old_gen_changed_for_throughput() {
302 bool result = _change_old_gen_for_throughput != 0;
303 return result;
304 }
306 // Return true if the young generation size was changed
307 // to try to reach a throughput goal.
308 bool young_gen_changed_for_throughput() {
309 bool result = _change_young_gen_for_throughput != 0;
310 return result;
311 }
313 int decrease_for_footprint() { return _decrease_for_footprint; }
316 // Accessors for estimators. The slope of the linear fit is
317 // currently all that is used for making decisions.
319 LinearLeastSquareFit* major_pause_old_estimator() {
320 return _major_pause_old_estimator;
321 }
323 LinearLeastSquareFit* major_pause_young_estimator() {
324 return _major_pause_young_estimator;
325 }
328 virtual void clear_generation_free_space_flags();
330 float major_pause_old_slope() { return _major_pause_old_estimator->slope(); }
331 float major_pause_young_slope() {
332 return _major_pause_young_estimator->slope();
333 }
334 float major_collection_slope() { return _major_collection_estimator->slope();}
336 bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; }
338 // Given the amount of live data in the heap, should we
339 // perform a Full GC?
340 bool should_full_GC(size_t live_in_old_gen);
342 // Calculates optimal (free) space sizes for both the young and old
343 // generations. Stores results in _eden_size and _promo_size.
344 // Takes current used space in all generations as input, as well
345 // as an indication if a full gc has just been performed, for use
346 // in deciding if an OOM error should be thrown.
347 void compute_generations_free_space(size_t young_live,
348 size_t eden_live,
349 size_t old_live,
350 size_t cur_eden, // current eden in bytes
351 size_t max_old_gen_size,
352 size_t max_eden_size,
353 bool is_full_gc);
355 void compute_eden_space_size(size_t young_live,
356 size_t eden_live,
357 size_t cur_eden, // current eden in bytes
358 size_t max_eden_size,
359 bool is_full_gc);
361 void compute_old_gen_free_space(size_t old_live,
362 size_t cur_eden, // current eden in bytes
363 size_t max_old_gen_size,
364 bool is_full_gc);
366 // Calculates new survivor space size; returns a new tenuring threshold
367 // value. Stores new survivor size in _survivor_size.
368 uint compute_survivor_space_size_and_threshold(bool is_survivor_overflow,
369 uint tenuring_threshold,
370 size_t survivor_limit);
372 // Return the maximum size of a survivor space if the young generation were of
373 // size gen_size.
374 size_t max_survivor_size(size_t gen_size) {
375 // Never allow the target survivor size to grow more than MinSurvivorRatio
376 // of the young generation size. We cannot grow into a two semi-space
377 // system, with Eden zero sized. Even if the survivor space grows, from()
378 // might grow by moving the bottom boundary "down" -- so from space will
379 // remain almost full anyway (top() will be near end(), but there will be a
380 // large filler object at the bottom).
381 const size_t sz = gen_size / MinSurvivorRatio;
382 const size_t alignment = _intra_generation_alignment;
383 return sz > alignment ? align_size_down(sz, alignment) : alignment;
384 }
386 size_t live_at_last_full_gc() {
387 return _live_at_last_full_gc;
388 }
390 size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; }
391 void reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; }
393 void set_bytes_absorbed_from_eden(size_t val) {
394 _bytes_absorbed_from_eden = val;
395 }
397 // Update averages that are always used (even
398 // if adaptive sizing is turned off).
399 void update_averages(bool is_survivor_overflow,
400 size_t survived,
401 size_t promoted);
403 // Printing support
404 virtual bool print_adaptive_size_policy_on(outputStream* st) const;
406 // Decay the supplemental growth additive.
407 void decay_supplemental_growth(bool is_full_gc);
408 };
410 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP