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 /*

  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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  */

 #include "precompiled.hpp"

 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"

 #include "gc_interface/gcCause.hpp"

 #include "memory/collectorPolicy.hpp"

 #include "runtime/timer.hpp"

 #include "utilities/ostream.hpp"

 elapsedTimer AdaptiveSizePolicy::_minor_timer;

 elapsedTimer AdaptiveSizePolicy::_major_timer;

 // The throughput goal is implemented as

 //      _throughput_goal = 1 - ( 1 / (1 + gc_cost_ratio))

 // gc_cost_ratio is the ratio

 //      application cost / gc cost

 // For example a gc_cost_ratio of 4 translates into a

 // throughput goal of .80

 AdaptiveSizePolicy::AdaptiveSizePolicy(size_t init_eden_size,

                                        size_t init_promo_size,

                                        size_t init_survivor_size,

                                        double gc_pause_goal_sec,

                                        uint gc_cost_ratio) :

     _eden_size(init_eden_size),

     _promo_size(init_promo_size),

     _survivor_size(init_survivor_size),

     _gc_pause_goal_sec(gc_pause_goal_sec),

     _throughput_goal(1.0 - double(1.0 / (1.0 + (double) gc_cost_ratio))),

     _gc_overhead_limit_exceeded(false),

     _print_gc_overhead_limit_would_be_exceeded(false),

     _gc_overhead_limit_count(0),

     _latest_minor_mutator_interval_seconds(0),

     _threshold_tolerance_percent(1.0 + ThresholdTolerance/100.0),

     _young_gen_change_for_minor_throughput(0),

     _old_gen_change_for_major_throughput(0) {

   assert(AdaptiveSizePolicyGCTimeLimitThreshold > 0,

     "No opportunity to clear SoftReferences before GC overhead limit");

   _avg_minor_pause    =

     new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);

   _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);

   _avg_minor_gc_cost  = new AdaptiveWeightedAverage(AdaptiveTimeWeight);

   _avg_major_gc_cost  = new AdaptiveWeightedAverage(AdaptiveTimeWeight);

   _avg_young_live     = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);

   _avg_old_live       = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);

   _avg_eden_live      = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);

   _avg_survived       = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight,

                                                   SurvivorPadding);

   _avg_pretenured     = new AdaptivePaddedNoZeroDevAverage(

                                                   AdaptiveSizePolicyWeight,

                                                   SurvivorPadding);

   _minor_pause_old_estimator =

     new LinearLeastSquareFit(AdaptiveSizePolicyWeight);

   _minor_pause_young_estimator =

     new LinearLeastSquareFit(AdaptiveSizePolicyWeight);

   _minor_collection_estimator =

     new LinearLeastSquareFit(AdaptiveSizePolicyWeight);

   _major_collection_estimator =

     new LinearLeastSquareFit(AdaptiveSizePolicyWeight);

   // Start the timers

   _minor_timer.start();

   _young_gen_policy_is_ready = false;

 }

 bool AdaptiveSizePolicy::tenuring_threshold_change() const {

   return decrement_tenuring_threshold_for_gc_cost() ||

          increment_tenuring_threshold_for_gc_cost() ||

          decrement_tenuring_threshold_for_survivor_limit();

 }

 void AdaptiveSizePolicy::minor_collection_begin() {

   // Update the interval time

   _minor_timer.stop();

   // Save most recent collection time

   _latest_minor_mutator_interval_seconds = _minor_timer.seconds();

   _minor_timer.reset();

   _minor_timer.start();

 }

 void AdaptiveSizePolicy::update_minor_pause_young_estimator(

     double minor_pause_in_ms) {

   double eden_size_in_mbytes = ((double)_eden_size)/((double)M);

   _minor_pause_young_estimator->update(eden_size_in_mbytes,

     minor_pause_in_ms);

 }

 void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) {

   // Update the pause time.

   _minor_timer.stop();

   if (gc_cause != GCCause::_java_lang_system_gc ||

       UseAdaptiveSizePolicyWithSystemGC) {

     double minor_pause_in_seconds = _minor_timer.seconds();

     double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS;

     // Sample for performance counter

     _avg_minor_pause->sample(minor_pause_in_seconds);

     // Cost of collection (unit-less)

     double collection_cost = 0.0;

     if ((_latest_minor_mutator_interval_seconds > 0.0) &&

         (minor_pause_in_seconds > 0.0)) {

       double interval_in_seconds =

         _latest_minor_mutator_interval_seconds + minor_pause_in_seconds;

       collection_cost =

         minor_pause_in_seconds / interval_in_seconds;

       _avg_minor_gc_cost->sample(collection_cost);

       // Sample for performance counter

       _avg_minor_interval->sample(interval_in_seconds);

     }

     // The policy does not have enough data until at least some

     // minor collections have been done.

     _young_gen_policy_is_ready =

       (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold);

     // Calculate variables used to estimate pause time vs. gen sizes

     double eden_size_in_mbytes = ((double)_eden_size)/((double)M);

     update_minor_pause_young_estimator(minor_pause_in_ms);

     update_minor_pause_old_estimator(minor_pause_in_ms);

     if (PrintAdaptiveSizePolicy && Verbose) {

       gclog_or_tty->print("AdaptiveSizePolicy::minor_collection_end: "

         "minor gc cost: %f  average: %f", collection_cost,

         _avg_minor_gc_cost->average());

       gclog_or_tty->print_cr("  minor pause: %f minor period %f",

         minor_pause_in_ms,

         _latest_minor_mutator_interval_seconds * MILLIUNITS);

     }

     // Calculate variable used to estimate collection cost vs. gen sizes

     assert(collection_cost >= 0.0, "Expected to be non-negative");

     _minor_collection_estimator->update(eden_size_in_mbytes, collection_cost);

   }

   // Interval times use this timer to measure the mutator time.

   // Reset the timer after the GC pause.

   _minor_timer.reset();

   _minor_timer.start();

 }

 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden,

                                             uint percent_change) {

   size_t eden_heap_delta;

   eden_heap_delta = cur_eden / 100 * percent_change;

   return eden_heap_delta;

 }

 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) {

   return eden_increment(cur_eden, YoungGenerationSizeIncrement);

 }

 size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) {

   size_t eden_heap_delta = eden_increment(cur_eden) /

     AdaptiveSizeDecrementScaleFactor;

   return eden_heap_delta;

 }

 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo,

                                              uint percent_change) {

   size_t promo_heap_delta;

   promo_heap_delta = cur_promo / 100 * percent_change;

   return promo_heap_delta;

 }

 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) {

   return promo_increment(cur_promo, TenuredGenerationSizeIncrement);

 }

 size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) {

   size_t promo_heap_delta = promo_increment(cur_promo);

   promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;

   return promo_heap_delta;

 }

 double AdaptiveSizePolicy::time_since_major_gc() const {

   _major_timer.stop();

   double result = _major_timer.seconds();

   _major_timer.start();

   return result;

 }

 // Linear decay of major gc cost

 double AdaptiveSizePolicy::decaying_major_gc_cost() const {

   double major_interval = major_gc_interval_average_for_decay();

   double major_gc_cost_average = major_gc_cost();

   double decayed_major_gc_cost = major_gc_cost_average;

   if(time_since_major_gc() > 0.0) {

     decayed_major_gc_cost = major_gc_cost() *

       (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval)

       / time_since_major_gc();

   }

   // The decayed cost should always be smaller than the

   // average cost but the vagaries of finite arithmetic could

   // produce a larger value in decayed_major_gc_cost so protect

   // against that.

   return MIN2(major_gc_cost_average, decayed_major_gc_cost);

 }

 // Use a value of the major gc cost that has been decayed

 // by the factor

 //

 //      average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale /

 //        time-since-last-major-gc

 //

 // if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale

 // is less than time-since-last-major-gc.

 //

 // In cases where there are initial major gc's that

 // are of a relatively high cost but no later major

 // gc's, the total gc cost can remain high because

 // the major gc cost remains unchanged (since there are no major

 // gc's).  In such a situation the value of the unchanging

 // major gc cost can keep the mutator throughput below

 // the goal when in fact the major gc cost is becoming diminishingly

 // small.  Use the decaying gc cost only to decide whether to

 // adjust for throughput.  Using it also to determine the adjustment

 // to be made for throughput also seems reasonable but there is

 // no test case to use to decide if it is the right thing to do

 // don't do it yet.

 double AdaptiveSizePolicy::decaying_gc_cost() const {

   double decayed_major_gc_cost = major_gc_cost();

   double avg_major_interval = major_gc_interval_average_for_decay();

   if (UseAdaptiveSizeDecayMajorGCCost &&

       (AdaptiveSizeMajorGCDecayTimeScale > 0) &&

       (avg_major_interval > 0.00)) {

     double time_since_last_major_gc = time_since_major_gc();

     // Decay the major gc cost?

     if (time_since_last_major_gc >

         ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) {

       // Decay using the time-since-last-major-gc

       decayed_major_gc_cost = decaying_major_gc_cost();

       if (PrintGCDetails && Verbose) {

         gclog_or_tty->print_cr("\ndecaying_gc_cost: major interval average:"

           " %f  time since last major gc: %f",

           avg_major_interval, time_since_last_major_gc);

         gclog_or_tty->print_cr("  major gc cost: %f  decayed major gc cost: %f",

           major_gc_cost(), decayed_major_gc_cost);

       }

     }

   }

   double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost());

   return result;

 }

 void AdaptiveSizePolicy::clear_generation_free_space_flags() {

   set_change_young_gen_for_min_pauses(0);

   set_change_old_gen_for_maj_pauses(0);

   set_change_old_gen_for_throughput(0);

   set_change_young_gen_for_throughput(0);

   set_decrease_for_footprint(0);

   set_decide_at_full_gc(0);

 }

 void AdaptiveSizePolicy::check_gc_overhead_limit(

                                           size_t young_live,

                                           size_t eden_live,

                                           size_t max_old_gen_size,

                                           size_t max_eden_size,

                                           bool   is_full_gc,

                                           GCCause::Cause gc_cause,

                                           CollectorPolicy* collector_policy) {

   // Ignore explicit GC's.  Exiting here does not set the flag and

   // does not reset the count.  Updating of the averages for system

   // GC's is still controlled by UseAdaptiveSizePolicyWithSystemGC.

   if (GCCause::is_user_requested_gc(gc_cause) ||

       GCCause::is_serviceability_requested_gc(gc_cause)) {

     return;

   }

   // eden_limit is the upper limit on the size of eden based on

   // the maximum size of the young generation and the sizes

   // of the survivor space.

   // The question being asked is whether the gc costs are high

   // and the space being recovered by a collection is low.

   // free_in_young_gen is the free space in the young generation

   // after a collection and promo_live is the free space in the old

   // generation after a collection.

   //

   // Use the minimum of the current value of the live in the

   // young gen or the average of the live in the young gen.

   // If the current value drops quickly, that should be taken

   // into account (i.e., don't trigger if the amount of free

   // space has suddenly jumped up).  If the current is much

   // higher than the average, use the average since it represents

   // the longer term behavor.

   const size_t live_in_eden =

     MIN2(eden_live, (size_t) avg_eden_live()->average());

   const size_t free_in_eden = max_eden_size > live_in_eden ?

     max_eden_size - live_in_eden : 0;

   const size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());

   const size_t total_free_limit = free_in_old_gen + free_in_eden;

   const size_t total_mem = max_old_gen_size + max_eden_size;

   const double mem_free_limit = total_mem * (GCHeapFreeLimit/100.0);

   const double mem_free_old_limit = max_old_gen_size * (GCHeapFreeLimit/100.0);

   const double mem_free_eden_limit = max_eden_size * (GCHeapFreeLimit/100.0);

   const double gc_cost_limit = GCTimeLimit/100.0;

   size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());

   // But don't force a promo size below the current promo size. Otherwise,

   // the promo size will shrink for no good reason.

   promo_limit = MAX2(promo_limit, _promo_size);

   if (PrintAdaptiveSizePolicy && (Verbose ||

       (free_in_old_gen < (size_t) mem_free_old_limit &&

        free_in_eden < (size_t) mem_free_eden_limit))) {

     gclog_or_tty->print_cr(

           "PSAdaptiveSizePolicy::compute_generation_free_space limits:"

           " promo_limit: " SIZE_FORMAT

           " max_eden_size: " SIZE_FORMAT

           " total_free_limit: " SIZE_FORMAT

           " max_old_gen_size: " SIZE_FORMAT

           " max_eden_size: " SIZE_FORMAT

           " mem_free_limit: " SIZE_FORMAT,

           promo_limit, max_eden_size, total_free_limit,

           max_old_gen_size, max_eden_size,

           (size_t) mem_free_limit);

   }

   bool print_gc_overhead_limit_would_be_exceeded = false;

   if (is_full_gc) {

     if (gc_cost() > gc_cost_limit &&

       free_in_old_gen < (size_t) mem_free_old_limit &&

       free_in_eden < (size_t) mem_free_eden_limit) {

       // Collections, on average, are taking too much time, and

       //      gc_cost() > gc_cost_limit

       // we have too little space available after a full gc.

       //      total_free_limit < mem_free_limit

       // where

       //   total_free_limit is the free space available in

       //     both generations

       //   total_mem is the total space available for allocation

       //     in both generations (survivor spaces are not included

       //     just as they are not included in eden_limit).

       //   mem_free_limit is a fraction of total_mem judged to be an

       //     acceptable amount that is still unused.

       // The heap can ask for the value of this variable when deciding

       // whether to thrown an OutOfMemory error.

       // Note that the gc time limit test only works for the collections

       // of the young gen + tenured gen and not for collections of the

       // permanent gen.  That is because the calculation of the space

       // freed by the collection is the free space in the young gen +

       // tenured gen.

       // At this point the GC overhead limit is being exceeded.

       inc_gc_overhead_limit_count();

       if (UseGCOverheadLimit) {

         if (gc_overhead_limit_count() >=

             AdaptiveSizePolicyGCTimeLimitThreshold){

           // All conditions have been met for throwing an out-of-memory

           set_gc_overhead_limit_exceeded(true);

           // Avoid consecutive OOM due to the gc time limit by resetting

           // the counter.

           reset_gc_overhead_limit_count();

         } else {

           // The required consecutive collections which exceed the

           // GC time limit may or may not have been reached. We

           // are approaching that condition and so as not to

           // throw an out-of-memory before all SoftRef's have been

           // cleared, set _should_clear_all_soft_refs in CollectorPolicy.

           // The clearing will be done on the next GC.

           bool near_limit = gc_overhead_limit_near();

           if (near_limit) {

             collector_policy->set_should_clear_all_soft_refs(true);

             if (PrintGCDetails && Verbose) {

               gclog_or_tty->print_cr("  Nearing GC overhead limit, "

                 "will be clearing all SoftReference");

             }

           }

         }

       }

       // Set this even when the overhead limit will not

       // cause an out-of-memory.  Diagnostic message indicating

       // that the overhead limit is being exceeded is sometimes

       // printed.

       print_gc_overhead_limit_would_be_exceeded = true;

     } else {

       // Did not exceed overhead limits

       reset_gc_overhead_limit_count();

     }

   }

   if (UseGCOverheadLimit && PrintGCDetails && Verbose) {

     if (gc_overhead_limit_exceeded()) {

       gclog_or_tty->print_cr("      GC is exceeding overhead limit "

         "of %d%%", GCTimeLimit);

       reset_gc_overhead_limit_count();

     } else if (print_gc_overhead_limit_would_be_exceeded) {

       assert(gc_overhead_limit_count() > 0, "Should not be printing");

       gclog_or_tty->print_cr("      GC would exceed overhead limit "

         "of %d%% %d consecutive time(s)",

         GCTimeLimit, gc_overhead_limit_count());

     }

   }

 }

 // Printing

 bool AdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) const {

   //  Should only be used with adaptive size policy turned on.

   // Otherwise, there may be variables that are undefined.

   if (!UseAdaptiveSizePolicy) return false;

   // Print goal for which action is needed.

   char* action = NULL;

   bool change_for_pause = false;

   if ((change_old_gen_for_maj_pauses() ==

          decrease_old_gen_for_maj_pauses_true) ||

       (change_young_gen_for_min_pauses() ==

          decrease_young_gen_for_min_pauses_true)) {

     action = (char*) " *** pause time goal ***";

     change_for_pause = true;

   } else if ((change_old_gen_for_throughput() ==

                increase_old_gen_for_throughput_true) ||

             (change_young_gen_for_throughput() ==

                increase_young_gen_for_througput_true)) {

     action = (char*) " *** throughput goal ***";

   } else if (decrease_for_footprint()) {

     action = (char*) " *** reduced footprint ***";

   } else {

     // No actions were taken.  This can legitimately be the

     // situation if not enough data has been gathered to make

     // decisions.

     return false;

   }

   // Pauses

   // Currently the size of the old gen is only adjusted to

   // change the major pause times.

   char* young_gen_action = NULL;

   char* tenured_gen_action = NULL;

   char* shrink_msg = (char*) "(attempted to shrink)";

   char* grow_msg = (char*) "(attempted to grow)";

   char* no_change_msg = (char*) "(no change)";

   if (change_young_gen_for_min_pauses() ==

       decrease_young_gen_for_min_pauses_true) {

     young_gen_action = shrink_msg;

   } else if (change_for_pause) {

     young_gen_action = no_change_msg;

   }

   if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) {

     tenured_gen_action = shrink_msg;

   } else if (change_for_pause) {

     tenured_gen_action = no_change_msg;

   }

   // Throughput

   if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) {

     assert(change_young_gen_for_throughput() ==

            increase_young_gen_for_througput_true,

            "Both generations should be growing");

     young_gen_action = grow_msg;

     tenured_gen_action = grow_msg;

   } else if (change_young_gen_for_throughput() ==

              increase_young_gen_for_througput_true) {

     // Only the young generation may grow at start up (before

     // enough full collections have been done to grow the old generation).

     young_gen_action = grow_msg;

     tenured_gen_action = no_change_msg;

   }

   // Minimum footprint

   if (decrease_for_footprint() != 0) {

     young_gen_action = shrink_msg;

     tenured_gen_action = shrink_msg;

   }

   st->print_cr("    UseAdaptiveSizePolicy actions to meet %s", action);

   st->print_cr("                       GC overhead (%%)");

   st->print_cr("    Young generation:     %7.2f\t  %s",

     100.0 * avg_minor_gc_cost()->average(),

     young_gen_action);

   st->print_cr("    Tenured generation:   %7.2f\t  %s",

     100.0 * avg_major_gc_cost()->average(),

     tenured_gen_action);

   return true;

 }

 bool AdaptiveSizePolicy::print_adaptive_size_policy_on(

                                             outputStream* st,

                                             int tenuring_threshold_arg) const {

   if (!AdaptiveSizePolicy::print_adaptive_size_policy_on(st)) {

     return false;

   }

   // Tenuring threshold

   bool tenuring_threshold_changed = true;

   if (decrement_tenuring_threshold_for_survivor_limit()) {

     st->print("    Tenuring threshold:    (attempted to decrease to avoid"

               " survivor space overflow) = ");

   } else if (decrement_tenuring_threshold_for_gc_cost()) {

     st->print("    Tenuring threshold:    (attempted to decrease to balance"

               " GC costs) = ");

   } else if (increment_tenuring_threshold_for_gc_cost()) {

     st->print("    Tenuring threshold:    (attempted to increase to balance"

               " GC costs) = ");

   } else {

     tenuring_threshold_changed = false;

     assert(!tenuring_threshold_change(), "(no change was attempted)");

   }

   if (tenuring_threshold_changed) {

     st->print_cr("%d", tenuring_threshold_arg);

   }

   return true;

 }