truffle: src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp comparison

comparison src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
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children	0bfd3fb24150

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+/*
+* 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;
+};

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comparison src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp @ 0:a61af66fc99e jdk7-b24