/*

 * Copyright (c) 2002, 2015, 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

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 */

#include "precompiled.hpp"

#include "gc/parallel/parallelScavengeHeap.hpp"

#include "gc/parallel/psAdaptiveSizePolicy.hpp"

#include "gc/parallel/psGCAdaptivePolicyCounters.hpp"

#include "gc/parallel/psScavenge.hpp"

#include "gc/shared/collectorPolicy.hpp"

#include "gc/shared/gcCause.hpp"

#include "gc/shared/gcPolicyCounters.hpp"

#include "runtime/timer.hpp"

#include "utilities/top.hpp"

#include <math.h>

PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size,

                                           size_t init_promo_size,

                                           size_t init_survivor_size,

                                           size_t space_alignment,

                                           double gc_pause_goal_sec,

                                           double gc_minor_pause_goal_sec,

                                           uint gc_cost_ratio) :

     AdaptiveSizePolicy(init_eden_size,

                        init_promo_size,

                        init_survivor_size,

                        gc_pause_goal_sec,

                        gc_cost_ratio),

     _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin / 100.0),

     _space_alignment(space_alignment),

     _live_at_last_full_gc(init_promo_size),

     _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec),

     _latest_major_mutator_interval_seconds(0),

     _young_gen_change_for_major_pause_count(0)

{

  // Sizing policy statistics

  _avg_major_pause    =

    new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);

  _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);

  _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);

  _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);

  _major_pause_old_estimator =

    new LinearLeastSquareFit(AdaptiveSizePolicyWeight);

  _major_pause_young_estimator =

    new LinearLeastSquareFit(AdaptiveSizePolicyWeight);

  _major_collection_estimator =

    new LinearLeastSquareFit(AdaptiveSizePolicyWeight);

  _young_gen_size_increment_supplement = YoungGenerationSizeSupplement;

  _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement;

  // Start the timers

  _major_timer.start();

  _old_gen_policy_is_ready = false;

}

size_t PSAdaptiveSizePolicy::calculate_free_based_on_live(size_t live, uintx ratio_as_percentage) {

  // We want to calculate how much free memory there can be based on the

  // amount of live data currently in the old gen. Using the formula:

  // ratio * (free + live) = free

  // Some equation solving later we get:

  // free = (live * ratio) / (1 - ratio)

  const double ratio = ratio_as_percentage / 100.0;

  const double ratio_inverse = 1.0 - ratio;

  const double tmp = live * ratio;

  size_t free = (size_t)(tmp / ratio_inverse);

  return free;

}

size_t PSAdaptiveSizePolicy::calculated_old_free_size_in_bytes() const {

  size_t free_size = (size_t)(_promo_size + avg_promoted()->padded_average());

  size_t live = ParallelScavengeHeap::heap()->old_gen()->used_in_bytes();

  if (MinHeapFreeRatio != 0) {

    size_t min_free = calculate_free_based_on_live(live, MinHeapFreeRatio);

    free_size = MAX2(free_size, min_free);

  }

  if (MaxHeapFreeRatio != 100) {

    size_t max_free = calculate_free_based_on_live(live, MaxHeapFreeRatio);

    free_size = MIN2(max_free, free_size);

  }

  return free_size;

}

void PSAdaptiveSizePolicy::major_collection_begin() {

  // Update the interval time

  _major_timer.stop();

  // Save most recent collection time

  _latest_major_mutator_interval_seconds = _major_timer.seconds();

  _major_timer.reset();

  _major_timer.start();

}

void PSAdaptiveSizePolicy::update_minor_pause_old_estimator(

    double minor_pause_in_ms) {

  double promo_size_in_mbytes = ((double)_promo_size)/((double)M);

  _minor_pause_old_estimator->update(promo_size_in_mbytes,

    minor_pause_in_ms);

}

void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live,

  GCCause::Cause gc_cause) {

  // Update the pause time.

  _major_timer.stop();

  if (should_update_promo_stats(gc_cause)) {

    double major_pause_in_seconds = _major_timer.seconds();

    double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;

    // Sample for performance counter

    _avg_major_pause->sample(major_pause_in_seconds);

    // Cost of collection (unit-less)

    double collection_cost = 0.0;

    if ((_latest_major_mutator_interval_seconds > 0.0) &&

        (major_pause_in_seconds > 0.0)) {

      double interval_in_seconds =

        _latest_major_mutator_interval_seconds + major_pause_in_seconds;

      collection_cost =

        major_pause_in_seconds / interval_in_seconds;

      avg_major_gc_cost()->sample(collection_cost);

      // Sample for performance counter

      _avg_major_interval->sample(interval_in_seconds);

    }

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

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

    double promo_size_in_mbytes = ((double)_promo_size)/((double)M);

    _major_pause_old_estimator->update(promo_size_in_mbytes,

      major_pause_in_ms);

    _major_pause_young_estimator->update(eden_size_in_mbytes,

      major_pause_in_ms);

    if (PrintAdaptiveSizePolicy && Verbose) {

      gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: "

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

        avg_major_gc_cost()->average());

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

        major_pause_in_ms,

        _latest_major_mutator_interval_seconds * MILLIUNITS);

    }

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

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

    _major_collection_estimator->update(promo_size_in_mbytes,

        collection_cost);

  }

  // Update the amount live at the end of a full GC

  _live_at_last_full_gc = amount_live;

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

  // have been done.

  if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {

    _old_gen_policy_is_ready = true;

  }

  // Interval times use this timer to measure the interval that

  // the mutator runs.  Reset after the GC pause has been measured.

  _major_timer.reset();

  _major_timer.start();

}

// If the remaining free space in the old generation is less that

// that expected to be needed by the next collection, do a full

// collection now.

bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {

  // A similar test is done in the scavenge's should_attempt_scavenge().  If

  // this is changed, decide if that test should also be changed.

  bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;

  if (PrintGCDetails && Verbose) {

    if (result) {

      gclog_or_tty->print("  full after scavenge: ");

    } else {

      gclog_or_tty->print("  no full after scavenge: ");

    }

    gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT

      " padded_average_promoted " SIZE_FORMAT

      " free in old gen " SIZE_FORMAT,

      (size_t) average_promoted_in_bytes(),

      (size_t) padded_average_promoted_in_bytes(),

      old_free_in_bytes);

  }

  return result;

}

void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {

  AdaptiveSizePolicy::clear_generation_free_space_flags();

  set_change_old_gen_for_min_pauses(0);

  set_change_young_gen_for_maj_pauses(0);

}

// If this is not a full GC, only test and modify the young generation.

void PSAdaptiveSizePolicy::compute_generations_free_space(

                                           size_t young_live,

                                           size_t eden_live,

                                           size_t old_live,

                                           size_t cur_eden,

                                           size_t max_old_gen_size,

                                           size_t max_eden_size,

                                           bool   is_full_gc) {

  compute_eden_space_size(young_live,

                          eden_live,

                          cur_eden,

                          max_eden_size,

                          is_full_gc);

  compute_old_gen_free_space(old_live,

                             cur_eden,

                             max_old_gen_size,

                             is_full_gc);

}

void PSAdaptiveSizePolicy::compute_eden_space_size(

                                           size_t young_live,

                                           size_t eden_live,

                                           size_t cur_eden,

                                           size_t max_eden_size,

                                           bool   is_full_gc) {

  // Update statistics

  // Time statistics are updated as we go, update footprint stats here

  _avg_base_footprint->sample(BaseFootPrintEstimate);

  avg_young_live()->sample(young_live);

  avg_eden_live()->sample(eden_live);

  // This code used to return if the policy was not ready , i.e.,

  // policy_is_ready() returning false.  The intent was that

  // decisions below needed major collection times and so could

  // not be made before two major collections.  A consequence was

  // adjustments to the young generation were not done until after

  // two major collections even if the minor collections times

  // exceeded the requested goals.  Now let the young generation

  // adjust for the minor collection times.  Major collection times

  // will be zero for the first collection and will naturally be

  // ignored.  Tenured generation adjustments are only made at the

  // full collections so until the second major collection has

  // been reached, no tenured generation adjustments will be made.

  // Until we know better, desired promotion size uses the last calculation

  size_t desired_promo_size = _promo_size;

  // Start eden at the current value.  The desired value that is stored

  // in _eden_size is not bounded by constraints of the heap and can

  // run away.

  //

  // As expected setting desired_eden_size to the current

  // value of desired_eden_size as a starting point

  // caused desired_eden_size to grow way too large and caused

  // an overflow down stream.  It may have improved performance in

  // some case but is dangerous.

  size_t desired_eden_size = cur_eden;

  // Cache some values. There's a bit of work getting these, so

  // we might save a little time.

  const double major_cost = major_gc_cost();

  const double minor_cost = minor_gc_cost();

  // This method sets the desired eden size.  That plus the

  // desired survivor space sizes sets the desired young generation

  // size.  This methods does not know what the desired survivor

  // size is but expects that other policy will attempt to make

  // the survivor sizes compatible with the live data in the

  // young generation.  This limit is an estimate of the space left

  // in the young generation after the survivor spaces have been

  // subtracted out.

  size_t eden_limit = max_eden_size;

  const double gc_cost_limit = GCTimeLimit / 100.0;

  // Which way should we go?

  // if pause requirement is not met

  //   adjust size of any generation with average paus exceeding

  //   the pause limit.  Adjust one pause at a time (the larger)

  //   and only make adjustments for the major pause at full collections.

  // else if throughput requirement not met

  //   adjust the size of the generation with larger gc time.  Only

  //   adjust one generation at a time.

  // else

  //   adjust down the total heap size.  Adjust down the larger of the

  //   generations.

  // Add some checks for a threshold for a change.  For example,

  // a change less than the necessary alignment is probably not worth

  // attempting.

  if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||

      (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {

    //

    // Check pauses

    //

    // Make changes only to affect one of the pauses (the larger)

    // at a time.

    adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);

  } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {

    // Adjust only for the minor pause time goal

    adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size);

  } else if(adjusted_mutator_cost() < _throughput_goal) {

    // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.

    // This sometimes resulted in skipping to the minimize footprint

    // code.  Change this to try and reduce GC time if mutator time is

    // negative for whatever reason.  Or for future consideration,

    // bail out of the code if mutator time is negative.

    //

    // Throughput

    //

    assert(major_cost >= 0.0, "major cost is < 0.0");

    assert(minor_cost >= 0.0, "minor cost is < 0.0");

    // Try to reduce the GC times.

    adjust_eden_for_throughput(is_full_gc, &desired_eden_size);

  } else {

    // Be conservative about reducing the footprint.

    //   Do a minimum number of major collections first.

    //   Have reasonable averages for major and minor collections costs.

    if (UseAdaptiveSizePolicyFootprintGoal &&

        young_gen_policy_is_ready() &&

        avg_major_gc_cost()->average() >= 0.0 &&

        avg_minor_gc_cost()->average() >= 0.0) {

      size_t desired_sum = desired_eden_size + desired_promo_size;

      desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum);

    }

  }

  // Note we make the same tests as in the code block below;  the code

  // seems a little easier to read with the printing in another block.

  if (PrintAdaptiveSizePolicy) {

    if (desired_eden_size > eden_limit) {

      gclog_or_tty->print_cr(

            "PSAdaptiveSizePolicy::compute_eden_space_size limits:"

            " desired_eden_size: " SIZE_FORMAT

            " old_eden_size: " SIZE_FORMAT

            " eden_limit: " SIZE_FORMAT

            " cur_eden: " SIZE_FORMAT

            " max_eden_size: " SIZE_FORMAT

            " avg_young_live: " SIZE_FORMAT,

            desired_eden_size, _eden_size, eden_limit, cur_eden,

            max_eden_size, (size_t)avg_young_live()->average());

    }

    if (gc_cost() > gc_cost_limit) {

      gclog_or_tty->print_cr(

            "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit"

            " gc_cost: %f "

            " GCTimeLimit: " UINTX_FORMAT,

            gc_cost(), GCTimeLimit);

    }

  }

  // Align everything and make a final limit check

  desired_eden_size  = align_size_up(desired_eden_size, _space_alignment);

  desired_eden_size  = MAX2(desired_eden_size, _space_alignment);

  eden_limit  = align_size_down(eden_limit, _space_alignment);

  // And one last limit check, now that we've aligned things.

  if (desired_eden_size > eden_limit) {

    // If the policy says to get a larger eden but

    // is hitting the limit, don't decrease eden.

    // This can lead to a general drifting down of the

    // eden size.  Let the tenuring calculation push more

    // into the old gen.

    desired_eden_size = MAX2(eden_limit, cur_eden);

  }

  if (PrintAdaptiveSizePolicy) {

    // Timing stats

    gclog_or_tty->print(

               "PSAdaptiveSizePolicy::compute_eden_space_size: costs"

               " minor_time: %f"

               " major_cost: %f"

               " mutator_cost: %f"

               " throughput_goal: %f",

               minor_gc_cost(), major_gc_cost(), mutator_cost(),

               _throughput_goal);

    // We give more details if Verbose is set

    if (Verbose) {

      gclog_or_tty->print( " minor_pause: %f"

                  " major_pause: %f"

                  " minor_interval: %f"

                  " major_interval: %f"

                  " pause_goal: %f",

                  _avg_minor_pause->padded_average(),

                  _avg_major_pause->padded_average(),

                  _avg_minor_interval->average(),

                  _avg_major_interval->average(),

                  gc_pause_goal_sec());

    }

    // Footprint stats

    gclog_or_tty->print( " live_space: " SIZE_FORMAT

                " free_space: " SIZE_FORMAT,

                live_space(), free_space());

    // More detail

    if (Verbose) {

      gclog_or_tty->print( " base_footprint: " SIZE_FORMAT

                  " avg_young_live: " SIZE_FORMAT

                  " avg_old_live: " SIZE_FORMAT,

                  (size_t)_avg_base_footprint->average(),

                  (size_t)avg_young_live()->average(),

                  (size_t)avg_old_live()->average());

    }

    // And finally, our old and new sizes.

    gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT

               " desired_eden_size: " SIZE_FORMAT,

               _eden_size, desired_eden_size);

    gclog_or_tty->cr();

  }

  set_eden_size(desired_eden_size);

}

void PSAdaptiveSizePolicy::compute_old_gen_free_space(

                                           size_t old_live,

                                           size_t cur_eden,

                                           size_t max_old_gen_size,

                                           bool   is_full_gc) {

  // Update statistics

  // Time statistics are updated as we go, update footprint stats here

  if (is_full_gc) {

    // old_live is only accurate after a full gc

    avg_old_live()->sample(old_live);

  }

  // This code used to return if the policy was not ready , i.e.,

  // policy_is_ready() returning false.  The intent was that

  // decisions below needed major collection times and so could

  // not be made before two major collections.  A consequence was

  // adjustments to the young generation were not done until after

  // two major collections even if the minor collections times

  // exceeded the requested goals.  Now let the young generation

  // adjust for the minor collection times.  Major collection times

  // will be zero for the first collection and will naturally be

  // ignored.  Tenured generation adjustments are only made at the

  // full collections so until the second major collection has

  // been reached, no tenured generation adjustments will be made.

  // Until we know better, desired promotion size uses the last calculation

  size_t desired_promo_size = _promo_size;

  // Start eden at the current value.  The desired value that is stored

  // in _eden_size is not bounded by constraints of the heap and can

  // run away.

  //

  // As expected setting desired_eden_size to the current

  // value of desired_eden_size as a starting point

  // caused desired_eden_size to grow way too large and caused

  // an overflow down stream.  It may have improved performance in

  // some case but is dangerous.

  size_t desired_eden_size = cur_eden;

  // Cache some values. There's a bit of work getting these, so

  // we might save a little time.

  const double major_cost = major_gc_cost();

  const double minor_cost = minor_gc_cost();

  // Limits on our growth

  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);

  const double gc_cost_limit = GCTimeLimit/100.0;

  // Which way should we go?

  // if pause requirement is not met

  //   adjust size of any generation with average paus exceeding

  //   the pause limit.  Adjust one pause at a time (the larger)