--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/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;
+};