Mercurial > hg > truffle
diff 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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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,384 @@ +/* + * Copyright 2002-2007 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +// This class keeps statistical information and computes the +// optimal free space for both the young and old generation +// based on current application characteristics (based on gc cost +// and application footprint). +// +// It also computes an optimal tenuring threshold between the young +// and old generations, so as to equalize the cost of collections +// of those generations, as well as optimial survivor space sizes +// for the young generation. +// +// While this class is specifically intended for a generational system +// consisting of a young gen (containing an Eden and two semi-spaces) +// and a tenured gen, as well as a perm gen for reflective data, it +// makes NO references to specific generations. +// +// 05/02/2003 Update +// The 1.5 policy makes use of data gathered for the costs of GC on +// specific generations. That data does reference specific +// generation. Also diagnostics specific to generations have +// been added. + +// Forward decls +class elapsedTimer; + +class PSAdaptiveSizePolicy : public AdaptiveSizePolicy { + friend class PSGCAdaptivePolicyCounters; + private: + // These values are used to record decisions made during the + // policy. For example, if the young generation was decreased + // to decrease the GC cost of minor collections the value + // decrease_young_gen_for_throughput_true is used. + + // Last calculated sizes, in bytes, and aligned + // NEEDS_CLEANUP should use sizes.hpp, but it works in ints, not size_t's + + // Time statistics + AdaptivePaddedAverage* _avg_major_pause; + + // Footprint statistics + AdaptiveWeightedAverage* _avg_base_footprint; + + // Statistical data gathered for GC + GCStats _gc_stats; + + size_t _survivor_size_limit; // Limit in bytes of survivor size + const double _collection_cost_margin_fraction; + + // Variable for estimating the major and minor pause times. + // These variables represent linear least-squares fits of + // the data. + // major pause time vs. old gen size + LinearLeastSquareFit* _major_pause_old_estimator; + // major pause time vs. young gen size + LinearLeastSquareFit* _major_pause_young_estimator; + + + // These record the most recent collection times. They + // are available as an alternative to using the averages + // for making ergonomic decisions. + double _latest_major_mutator_interval_seconds; + + const size_t _intra_generation_alignment; // alignment for eden, survivors + + const double _gc_minor_pause_goal_sec; // goal for maximum minor gc pause + + // The amount of live data in the heap at the last full GC, used + // as a baseline to help us determine when we need to perform the + // next full GC. + size_t _live_at_last_full_gc; + + // decrease/increase the old generation for minor pause time + int _change_old_gen_for_min_pauses; + + // increase/decrease the young generation for major pause time + int _change_young_gen_for_maj_pauses; + + + // Flag indicating that the adaptive policy is ready to use + bool _old_gen_policy_is_ready; + + // Changing the generation sizing depends on the data that is + // gathered about the effects of changes on the pause times and + // throughput. These variable count the number of data points + // gathered. The policy may use these counters as a threshhold + // for reliable data. + julong _young_gen_change_for_major_pause_count; + + // To facilitate faster growth at start up, supplement the normal + // growth percentage for the young gen eden and the + // old gen space for promotion with these value which decay + // with increasing collections. + uint _young_gen_size_increment_supplement; + uint _old_gen_size_increment_supplement; + + // The number of bytes absorbed from eden into the old gen by moving the + // boundary over live data. + size_t _bytes_absorbed_from_eden; + + private: + + // Accessors + AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; } + double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; } + + // Change the young generation size to achieve a minor GC pause time goal + void adjust_for_minor_pause_time(bool is_full_gc, + size_t* desired_promo_size_ptr, + size_t* desired_eden_size_ptr); + // Change the generation sizes to achieve a GC pause time goal + // Returned sizes are not necessarily aligned. + void adjust_for_pause_time(bool is_full_gc, + size_t* desired_promo_size_ptr, + size_t* desired_eden_size_ptr); + // Change the generation sizes to achieve an application throughput goal + // Returned sizes are not necessarily aligned. + void adjust_for_throughput(bool is_full_gc, + size_t* desired_promo_size_ptr, + size_t* desired_eden_size_ptr); + // Change the generation sizes to achieve minimum footprint + // Returned sizes are not aligned. + size_t adjust_promo_for_footprint(size_t desired_promo_size, + size_t desired_total); + size_t adjust_eden_for_footprint(size_t desired_promo_size, + size_t desired_total); + + // Size in bytes for an increment or decrement of eden. + virtual size_t eden_increment(size_t cur_eden, uint percent_change); + virtual size_t eden_decrement(size_t cur_eden); + size_t eden_decrement_aligned_down(size_t cur_eden); + size_t eden_increment_with_supplement_aligned_up(size_t cur_eden); + + // Size in bytes for an increment or decrement of the promotion area + virtual size_t promo_increment(size_t cur_promo, uint percent_change); + virtual size_t promo_decrement(size_t cur_promo); + size_t promo_decrement_aligned_down(size_t cur_promo); + size_t promo_increment_with_supplement_aligned_up(size_t cur_promo); + + // Decay the supplemental growth additive. + void decay_supplemental_growth(bool is_full_gc); + + // Returns a change that has been scaled down. Result + // is not aligned. (If useful, move to some shared + // location.) + size_t scale_down(size_t change, double part, double total); + + protected: + // Time accessors + + // Footprint accessors + size_t live_space() const { + return (size_t)(avg_base_footprint()->average() + + avg_young_live()->average() + + avg_old_live()->average()); + } + size_t free_space() const { + return _eden_size + _promo_size; + } + + void set_promo_size(size_t new_size) { + _promo_size = new_size; + } + void set_survivor_size(size_t new_size) { + _survivor_size = new_size; + } + + // Update estimators + void update_minor_pause_old_estimator(double minor_pause_in_ms); + + virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; } + + public: + // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving. + size_t eden_increment_aligned_up(size_t cur_eden); + size_t eden_increment_aligned_down(size_t cur_eden); + size_t promo_increment_aligned_up(size_t cur_promo); + size_t promo_increment_aligned_down(size_t cur_promo); + + virtual size_t eden_increment(size_t cur_eden); + virtual size_t promo_increment(size_t cur_promo); + + // Accessors for use by performance counters + AdaptivePaddedNoZeroDevAverage* avg_promoted() const { + return _gc_stats.avg_promoted(); + } + AdaptiveWeightedAverage* avg_base_footprint() const { + return _avg_base_footprint; + } + + // Input arguments are initial free space sizes for young and old + // generations, the initial survivor space size, the + // alignment values and the pause & throughput goals. + // + // NEEDS_CLEANUP this is a singleton object + PSAdaptiveSizePolicy(size_t init_eden_size, + size_t init_promo_size, + size_t init_survivor_size, + size_t intra_generation_alignment, + double gc_pause_goal_sec, + double gc_minor_pause_goal_sec, + uint gc_time_ratio); + + // Methods indicating events of interest to the adaptive size policy, + // called by GC algorithms. It is the responsibility of users of this + // policy to call these methods at the correct times! + void major_collection_begin(); + void major_collection_end(size_t amount_live, GCCause::Cause gc_cause); + + // + void tenured_allocation(size_t size) { + _avg_pretenured->sample(size); + } + + // Accessors + // NEEDS_CLEANUP should use sizes.hpp + + size_t calculated_old_free_size_in_bytes() const { + return (size_t)(_promo_size + avg_promoted()->padded_average()); + } + + size_t average_old_live_in_bytes() const { + return (size_t) avg_old_live()->average(); + } + + size_t average_promoted_in_bytes() const { + return (size_t)avg_promoted()->average(); + } + + size_t padded_average_promoted_in_bytes() const { + return (size_t)avg_promoted()->padded_average(); + } + + int change_young_gen_for_maj_pauses() { + return _change_young_gen_for_maj_pauses; + } + void set_change_young_gen_for_maj_pauses(int v) { + _change_young_gen_for_maj_pauses = v; + } + + int change_old_gen_for_min_pauses() { + return _change_old_gen_for_min_pauses; + } + void set_change_old_gen_for_min_pauses(int v) { + _change_old_gen_for_min_pauses = v; + } + + // Return true if the old generation size was changed + // to try to reach a pause time goal. + bool old_gen_changed_for_pauses() { + bool result = _change_old_gen_for_maj_pauses != 0 || + _change_old_gen_for_min_pauses != 0; + return result; + } + + // Return true if the young generation size was changed + // to try to reach a pause time goal. + bool young_gen_changed_for_pauses() { + bool result = _change_young_gen_for_min_pauses != 0 || + _change_young_gen_for_maj_pauses != 0; + return result; + } + // end flags for pause goal + + // Return true if the old generation size was changed + // to try to reach a throughput goal. + bool old_gen_changed_for_throughput() { + bool result = _change_old_gen_for_throughput != 0; + return result; + } + + // Return true if the young generation size was changed + // to try to reach a throughput goal. + bool young_gen_changed_for_throughput() { + bool result = _change_young_gen_for_throughput != 0; + return result; + } + + int decrease_for_footprint() { return _decrease_for_footprint; } + + + // Accessors for estimators. The slope of the linear fit is + // currently all that is used for making decisions. + + LinearLeastSquareFit* major_pause_old_estimator() { + return _major_pause_old_estimator; + } + + LinearLeastSquareFit* major_pause_young_estimator() { + return _major_pause_young_estimator; + } + + + virtual void clear_generation_free_space_flags(); + + float major_pause_old_slope() { return _major_pause_old_estimator->slope(); } + float major_pause_young_slope() { + return _major_pause_young_estimator->slope(); + } + float major_collection_slope() { return _major_collection_estimator->slope();} + + bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; } + + // Given the amount of live data in the heap, should we + // perform a Full GC? + bool should_full_GC(size_t live_in_old_gen); + + // Calculates optimial free space sizes for both the old and young + // generations. Stores results in _eden_size and _promo_size. + // Takes current used space in all generations as input, as well + // as an indication if a full gc has just been performed, for use + // in deciding if an OOM error should be thrown. + void compute_generation_free_space(size_t young_live, + size_t eden_live, + size_t old_live, + size_t perm_live, + size_t cur_eden, // current eden in bytes + size_t max_old_gen_size, + size_t max_eden_size, + bool is_full_gc, + GCCause::Cause gc_cause); + + // Calculates new survivor space size; returns a new tenuring threshold + // value. Stores new survivor size in _survivor_size. + int compute_survivor_space_size_and_threshold(bool is_survivor_overflow, + int tenuring_threshold, + size_t survivor_limit); + + // Return the maximum size of a survivor space if the young generation were of + // size gen_size. + size_t max_survivor_size(size_t gen_size) { + // Never allow the target survivor size to grow more than MinSurvivorRatio + // of the young generation size. We cannot grow into a two semi-space + // system, with Eden zero sized. Even if the survivor space grows, from() + // might grow by moving the bottom boundary "down" -- so from space will + // remain almost full anyway (top() will be near end(), but there will be a + // large filler object at the bottom). + const size_t sz = gen_size / MinSurvivorRatio; + const size_t alignment = _intra_generation_alignment; + return sz > alignment ? align_size_down(sz, alignment) : alignment; + } + + size_t live_at_last_full_gc() { + return _live_at_last_full_gc; + } + + size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; } + void reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; } + + void set_bytes_absorbed_from_eden(size_t val) { + _bytes_absorbed_from_eden = val; + } + + // Update averages that are always used (even + // if adaptive sizing is turned off). + void update_averages(bool is_survivor_overflow, + size_t survived, + size_t promoted); + + // Printing support + virtual bool print_adaptive_size_policy_on(outputStream* st) const; +};