Java example source code file (psAdaptiveSizePolicy.cpp)
The psAdaptiveSizePolicy.cpp Java example source code
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* version 2 for more details (a copy is included in the LICENSE file that
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "precompiled.hpp"
#include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
#include "gc_implementation/parallelScavenge/psGCAdaptivePolicyCounters.hpp"
#include "gc_implementation/parallelScavenge/psScavenge.hpp"
#include "gc_implementation/shared/gcPolicyCounters.hpp"
#include "gc_interface/gcCause.hpp"
#include "memory/collectorPolicy.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;
}
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 (gc_cause != GCCause::_java_lang_system_gc ||
UseAdaptiveSizePolicyWithSystemGC) {
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: %d",
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)
// 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 threshhold 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.
if (is_full_gc) {
set_decide_at_full_gc(decide_at_full_gc_true);
adjust_promo_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_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &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.
if (is_full_gc) {
set_decide_at_full_gc(decide_at_full_gc_true);
adjust_promo_for_throughput(is_full_gc, &desired_promo_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) {
if (is_full_gc) {
set_decide_at_full_gc(decide_at_full_gc_true);
size_t desired_sum = desired_eden_size + desired_promo_size;
desired_promo_size = adjust_promo_for_footprint(desired_promo_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_promo_size > promo_limit) {
// "free_in_old_gen" was the original value for used for promo_limit
size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
gclog_or_tty->print_cr(
"PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
" desired_promo_size: " SIZE_FORMAT
" promo_limit: " SIZE_FORMAT
" free_in_old_gen: " SIZE_FORMAT
" max_old_gen_size: " SIZE_FORMAT
" avg_old_live: " SIZE_FORMAT,
desired_promo_size, promo_limit, free_in_old_gen,
max_old_gen_size, (size_t) avg_old_live()->average());
}
if (gc_cost() > gc_cost_limit) {
gclog_or_tty->print_cr(
"PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
" gc_cost: %f "
" GCTimeLimit: %d",
gc_cost(), GCTimeLimit);
}
}
// Align everything and make a final limit check
desired_promo_size = align_size_up(desired_promo_size, _space_alignment);
desired_promo_size = MAX2(desired_promo_size, _space_alignment);
promo_limit = align_size_down(promo_limit, _space_alignment);
// And one last limit check, now that we've aligned things.
desired_promo_size = MIN2(desired_promo_size, promo_limit);
if (PrintAdaptiveSizePolicy) {
// Timing stats
gclog_or_tty->print(
"PSAdaptiveSizePolicy::compute_old_gen_free_space: 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_promo_size: " SIZE_FORMAT
" desired_promo_size: " SIZE_FORMAT,
_promo_size, desired_promo_size);
gclog_or_tty->cr();
}
set_promo_size(desired_promo_size);
}
void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
// Decay the supplemental increment? Decay the supplement growth
// factor even if it is not used. It is only meant to give a boost
// to the initial growth and if it is not used, then it was not
// needed.
if (is_full_gc) {
// Don't wait for the threshold value for the major collections. If
// here, the supplemental growth term was used and should decay.
if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
== 0) {
_old_gen_size_increment_supplement =
_old_gen_size_increment_supplement >> 1;
}
} else {
if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
(_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
_young_gen_size_increment_supplement =
_young_gen_size_increment_supplement >> 1;
}
}
}
void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc,
size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
if (PSAdjustTenuredGenForMinorPause) {
if (is_full_gc) {
set_decide_at_full_gc(decide_at_full_gc_true);
}
// If the desired eden size is as small as it will get,
// try to adjust the old gen size.
if (*desired_eden_size_ptr <= _space_alignment) {
// Vary the old gen size to reduce the young gen pause. This
// may not be a good idea. This is just a test.
if (minor_pause_old_estimator()->decrement_will_decrease()) {
set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true);
*desired_promo_size_ptr =
_promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
} else {
set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true);
size_t promo_heap_delta =
promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
if ((*desired_promo_size_ptr + promo_heap_delta) >
*desired_promo_size_ptr) {
*desired_promo_size_ptr =
_promo_size + promo_heap_delta;
}
}
}
}
}
void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
size_t* desired_eden_size_ptr) {
// Adjust the young generation size to reduce pause time of
// of collections.
//
// The AdaptiveSizePolicyInitializingSteps test is not used
// here. It has not seemed to be needed but perhaps should
// be added for consistency.
if (minor_pause_young_estimator()->decrement_will_decrease()) {
// reduce eden size
set_change_young_gen_for_min_pauses(
decrease_young_gen_for_min_pauses_true);
*desired_eden_size_ptr = *desired_eden_size_ptr -
eden_decrement_aligned_down(*desired_eden_size_ptr);
} else {
// EXPERIMENTAL ADJUSTMENT
// Only record that the estimator indicated such an action.
// *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
set_change_young_gen_for_min_pauses(
increase_young_gen_for_min_pauses_true);
}
}
void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
size_t* desired_promo_size_ptr,
size_t* desired_eden_size_ptr) {
size_t promo_heap_delta = 0;
// Add some checks for a threshold for a change. For example,
// a change less than the required alignment is probably not worth
// attempting.
if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr);
// major pause adjustments
} else if (is_full_gc) {
// Adjust for the major pause time only at full gc's because the
// affects of a change can only be seen at full gc's.
// Reduce old generation size to reduce pause?
if (major_pause_old_estimator()->decrement_will_decrease()) {
// reduce old generation size
set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
*desired_promo_size_ptr = _promo_size - promo_heap_delta;
} else {
// EXPERIMENTAL ADJUSTMENT
// Only record that the estimator indicated such an action.
// *desired_promo_size_ptr = _promo_size +
// promo_increment_aligned_up(*desired_promo_size_ptr);
set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
}
}
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(
"PSAdaptiveSizePolicy::adjust_promo_for_pause_time "
"adjusting gen sizes for major pause (avg %f goal %f). "
"desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
_avg_major_pause->average(), gc_pause_goal_sec(),
*desired_promo_size_ptr, promo_heap_delta);
}
}
void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
size_t* desired_promo_size_ptr,
size_t* desired_eden_size_ptr) {
size_t eden_heap_delta = 0;
// Add some checks for a threshold for a change. For example,
// a change less than the required alignment is probably not worth
// attempting.
if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
adjust_eden_for_minor_pause_time(is_full_gc,
desired_eden_size_ptr);
// major pause adjustments
} else if (is_full_gc) {
// Adjust for the major pause time only at full gc's because the
// affects of a change can only be seen at full gc's.
if (PSAdjustYoungGenForMajorPause) {
// If the promo size is at the minimum (i.e., the old gen
// size will not actually decrease), consider changing the
// young gen size.
if (*desired_promo_size_ptr < _space_alignment) {
// If increasing the young generation will decrease the old gen
// pause, do it.
// During startup there is noise in the statistics for deciding
// on whether to increase or decrease the young gen size. For
// some number of iterations, just try to increase the young
// gen size if the major pause is too long to try and establish
// good statistics for later decisions.
if (major_pause_young_estimator()->increment_will_decrease() ||
(_young_gen_change_for_major_pause_count
<= AdaptiveSizePolicyInitializingSteps)) {
set_change_young_gen_for_maj_pauses(
increase_young_gen_for_maj_pauses_true);
eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
*desired_eden_size_ptr = _eden_size + eden_heap_delta;
_young_gen_change_for_major_pause_count++;
} else {
// Record that decreasing the young gen size would decrease
// the major pause
set_change_young_gen_for_maj_pauses(
decrease_young_gen_for_maj_pauses_true);
eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
*desired_eden_size_ptr = _eden_size - eden_heap_delta;
}
}
}
}
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(
"PSAdaptiveSizePolicy::adjust_eden_for_pause_time "
"adjusting gen sizes for major pause (avg %f goal %f). "
"desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
_avg_major_pause->average(), gc_pause_goal_sec(),
*desired_eden_size_ptr, eden_heap_delta);
}
}
void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
size_t* desired_promo_size_ptr) {
// Add some checks for a threshold for a change. For example,
// a change less than the required alignment is probably not worth
// attempting.
if ((gc_cost() + mutator_cost()) == 0.0) {
return;
}
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput("
"is_full: %d, promo: " SIZE_FORMAT "): ",
is_full_gc, *desired_promo_size_ptr);
gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
"minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
}
// Tenured generation
if (is_full_gc) {
// Calculate the change to use for the tenured gen.
size_t scaled_promo_heap_delta = 0;
// Can the increment to the generation be scaled?
if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
size_t promo_heap_delta =
promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
double scale_by_ratio = major_gc_cost() / gc_cost();
scaled_promo_heap_delta =
(size_t) (scale_by_ratio * (double) promo_heap_delta);
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(
"Scaled tenured increment: " SIZE_FORMAT " by %f down to "
SIZE_FORMAT,
promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
}
} else if (major_gc_cost() >= 0.0) {
// Scaling is not going to work. If the major gc time is the
// larger, give it a full increment.
if (major_gc_cost() >= minor_gc_cost()) {
scaled_promo_heap_delta =
promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
}
} else {
// Don't expect to get here but it's ok if it does
// in the product build since the delta will be 0
// and nothing will change.
assert(false, "Unexpected value for gc costs");
}
switch (AdaptiveSizeThroughPutPolicy) {
case 1:
// Early in the run the statistics might not be good. Until
// a specific number of collections have been, use the heuristic
// that a larger generation size means lower collection costs.
if (major_collection_estimator()->increment_will_decrease() ||
(_old_gen_change_for_major_throughput
<= AdaptiveSizePolicyInitializingSteps)) {
// Increase tenured generation size to reduce major collection cost
if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
*desired_promo_size_ptr) {
*desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
}
set_change_old_gen_for_throughput(
increase_old_gen_for_throughput_true);
_old_gen_change_for_major_throughput++;
} else {
// EXPERIMENTAL ADJUSTMENT
// Record that decreasing the old gen size would decrease
// the major collection cost but don't do it.
// *desired_promo_size_ptr = _promo_size -
// promo_decrement_aligned_down(*desired_promo_size_ptr);
set_change_old_gen_for_throughput(
decrease_old_gen_for_throughput_true);
}
break;
default:
// Simplest strategy
if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
*desired_promo_size_ptr) {
*desired_promo_size_ptr = *desired_promo_size_ptr +
scaled_promo_heap_delta;
}
set_change_old_gen_for_throughput(
increase_old_gen_for_throughput_true);
_old_gen_change_for_major_throughput++;
}
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(
"adjusting tenured gen for throughput (avg %f goal %f). "
"desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
mutator_cost(), _throughput_goal,
*desired_promo_size_ptr, scaled_promo_heap_delta);
}
}
}
void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
size_t* desired_eden_size_ptr) {
// Add some checks for a threshold for a change. For example,
// a change less than the required alignment is probably not worth
// attempting.
if ((gc_cost() + mutator_cost()) == 0.0) {
return;
}
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput("
"is_full: %d, cur_eden: " SIZE_FORMAT "): ",
is_full_gc, *desired_eden_size_ptr);
gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
"minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
}
// Young generation
size_t scaled_eden_heap_delta = 0;
// Can the increment to the generation be scaled?
if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
size_t eden_heap_delta =
eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
double scale_by_ratio = minor_gc_cost() / gc_cost();
assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
scaled_eden_heap_delta =
(size_t) (scale_by_ratio * (double) eden_heap_delta);
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(
"Scaled eden increment: " SIZE_FORMAT " by %f down to "
SIZE_FORMAT,
eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
}
} else if (minor_gc_cost() >= 0.0) {
// Scaling is not going to work. If the minor gc time is the
// larger, give it a full increment.
if (minor_gc_cost() > major_gc_cost()) {
scaled_eden_heap_delta =
eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
}
} else {
// Don't expect to get here but it's ok if it does
// in the product build since the delta will be 0
// and nothing will change.
assert(false, "Unexpected value for gc costs");
}
// Use a heuristic for some number of collections to give
// the averages time to settle down.
switch (AdaptiveSizeThroughPutPolicy) {
case 1:
if (minor_collection_estimator()->increment_will_decrease() ||
(_young_gen_change_for_minor_throughput
<= AdaptiveSizePolicyInitializingSteps)) {
// Expand young generation size to reduce frequency of
// of collections.
if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
*desired_eden_size_ptr) {
*desired_eden_size_ptr =
*desired_eden_size_ptr + scaled_eden_heap_delta;
}
set_change_young_gen_for_throughput(
increase_young_gen_for_througput_true);
_young_gen_change_for_minor_throughput++;
} else {
// EXPERIMENTAL ADJUSTMENT
// Record that decreasing the young gen size would decrease
// the minor collection cost but don't do it.
// *desired_eden_size_ptr = _eden_size -
// eden_decrement_aligned_down(*desired_eden_size_ptr);
set_change_young_gen_for_throughput(
decrease_young_gen_for_througput_true);
}
break;
default:
if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
*desired_eden_size_ptr) {
*desired_eden_size_ptr =
*desired_eden_size_ptr + scaled_eden_heap_delta;
}
set_change_young_gen_for_throughput(
increase_young_gen_for_througput_true);
_young_gen_change_for_minor_throughput++;
}
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(
"adjusting eden for throughput (avg %f goal %f). desired_eden_size "
SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
mutator_cost(), _throughput_goal,
*desired_eden_size_ptr, scaled_eden_heap_delta);
}
}
size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
size_t desired_promo_size, size_t desired_sum) {
assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
size_t change = promo_decrement(desired_promo_size);
change = scale_down(change, desired_promo_size, desired_sum);
size_t reduced_size = desired_promo_size - change;
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(
"AdaptiveSizePolicy::adjust_promo_for_footprint "
"adjusting tenured gen for footprint. "
"starting promo size " SIZE_FORMAT
" reduced promo size " SIZE_FORMAT,
" promo delta " SIZE_FORMAT,
desired_promo_size, reduced_size, change );
}
assert(reduced_size <= desired_promo_size, "Inconsistent result");
return reduced_size;
}
size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
size_t desired_eden_size, size_t desired_sum) {
assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
size_t change = eden_decrement(desired_eden_size);
change = scale_down(change, desired_eden_size, desired_sum);
size_t reduced_size = desired_eden_size - change;
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(
"AdaptiveSizePolicy::adjust_eden_for_footprint "
"adjusting eden for footprint. "
" starting eden size " SIZE_FORMAT
" reduced eden size " SIZE_FORMAT
" eden delta " SIZE_FORMAT,
desired_eden_size, reduced_size, change);
}
assert(reduced_size <= desired_eden_size, "Inconsistent result");
return reduced_size;
}
// Scale down "change" by the factor
// part / total
// Don't align the results.
size_t PSAdaptiveSizePolicy::scale_down(size_t change,
double part,
double total) {
assert(part <= total, "Inconsistent input");
size_t reduced_change = change;
if (total > 0) {
double fraction = part / total;
reduced_change = (size_t) (fraction * (double) change);
}
assert(reduced_change <= change, "Inconsistent result");
return reduced_change;
}
size_t PSAdaptiveSizePolicy::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 PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
return eden_increment(cur_eden, YoungGenerationSizeIncrement);
}
size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
return align_size_up(result, _space_alignment);
}
size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
size_t result = eden_increment(cur_eden);
return align_size_down(result, _space_alignment);
}
size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
size_t cur_eden) {
size_t result = eden_increment(cur_eden,
YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
return align_size_up(result, _space_alignment);
}
size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
size_t eden_heap_delta = eden_decrement(cur_eden);
return align_size_down(eden_heap_delta, _space_alignment);
}
size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
size_t eden_heap_delta = eden_increment(cur_eden) /
AdaptiveSizeDecrementScaleFactor;
return eden_heap_delta;
}
size_t PSAdaptiveSizePolicy::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 PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
}
size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
return align_size_up(result, _space_alignment);
}
size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
return align_size_down(result, _space_alignment);
}
size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
size_t cur_promo) {
size_t result = promo_increment(cur_promo,
TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
return align_size_up(result, _space_alignment);
}
size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
size_t promo_heap_delta = promo_decrement(cur_promo);
return align_size_down(promo_heap_delta, _space_alignment);
}
size_t PSAdaptiveSizePolicy::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;
}
uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
bool is_survivor_overflow,
uint tenuring_threshold,
size_t survivor_limit) {
assert(survivor_limit >= _space_alignment,
"survivor_limit too small");
assert((size_t)align_size_down(survivor_limit, _space_alignment)
== survivor_limit, "survivor_limit not aligned");
// This method is called even if the tenuring threshold and survivor
// spaces are not adjusted so that the averages are sampled above.
if (!UsePSAdaptiveSurvivorSizePolicy ||
!young_gen_policy_is_ready()) {
return tenuring_threshold;
}
// We'll decide whether to increase or decrease the tenuring
// threshold based partly on the newly computed survivor size
// (if we hit the maximum limit allowed, we'll always choose to
// decrement the threshold).
bool incr_tenuring_threshold = false;
bool decr_tenuring_threshold = false;
set_decrement_tenuring_threshold_for_gc_cost(false);
set_increment_tenuring_threshold_for_gc_cost(false);
set_decrement_tenuring_threshold_for_survivor_limit(false);
if (!is_survivor_overflow) {
// Keep running averages on how much survived
// We use the tenuring threshold to equalize the cost of major
// and minor collections.
// ThresholdTolerance is used to indicate how sensitive the
// tenuring threshold is to differences in cost betweent the
// collection types.
// Get the times of interest. This involves a little work, so
// we cache the values here.
const double major_cost = major_gc_cost();
const double minor_cost = minor_gc_cost();
if (minor_cost > major_cost * _threshold_tolerance_percent) {
// Minor times are getting too long; lower the threshold so
// less survives and more is promoted.
decr_tenuring_threshold = true;
set_decrement_tenuring_threshold_for_gc_cost(true);
} else if (major_cost > minor_cost * _threshold_tolerance_percent) {
// Major times are too long, so we want less promotion.
incr_tenuring_threshold = true;
set_increment_tenuring_threshold_for_gc_cost(true);
}
} else {
// Survivor space overflow occurred, so promoted and survived are
// not accurate. We'll make our best guess by combining survived
// and promoted and count them as survivors.
//
// We'll lower the tenuring threshold to see if we can correct
// things. Also, set the survivor size conservatively. We're
// trying to avoid many overflows from occurring if defnew size
// is just too small.
decr_tenuring_threshold = true;
}
// The padded average also maintains a deviation from the average;
// we use this to see how good of an estimate we have of what survived.
// We're trying to pad the survivor size as little as possible without
// overflowing the survivor spaces.
size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
_space_alignment);
target_size = MAX2(target_size, _space_alignment);
if (target_size > survivor_limit) {
// Target size is bigger than we can handle. Let's also reduce
// the tenuring threshold.
target_size = survivor_limit;
decr_tenuring_threshold = true;
set_decrement_tenuring_threshold_for_survivor_limit(true);
}
// Finally, increment or decrement the tenuring threshold, as decided above.
// We test for decrementing first, as we might have hit the target size
// limit.
if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
if (tenuring_threshold > 1) {
tenuring_threshold--;
}
} else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
if (tenuring_threshold < MaxTenuringThreshold) {
tenuring_threshold++;
}
}
// We keep a running average of the amount promoted which is used
// to decide when we should collect the old generation (when
// the amount of old gen free space is less than what we expect to
// promote).
if (PrintAdaptiveSizePolicy) {
// A little more detail if Verbose is on
if (Verbose) {
gclog_or_tty->print( " avg_survived: %f"
" avg_deviation: %f",
_avg_survived->average(),
_avg_survived->deviation());
}
gclog_or_tty->print( " avg_survived_padded_avg: %f",
_avg_survived->padded_average());
if (Verbose) {
gclog_or_tty->print( " avg_promoted_avg: %f"
" avg_promoted_dev: %f",
avg_promoted()->average(),
avg_promoted()->deviation());
}
gclog_or_tty->print_cr( " avg_promoted_padded_avg: %f"
" avg_pretenured_padded_avg: %f"
" tenuring_thresh: %d"
" target_size: " SIZE_FORMAT,
avg_promoted()->padded_average(),
_avg_pretenured->padded_average(),
tenuring_threshold, target_size);
}
set_survivor_size(target_size);
return tenuring_threshold;
}
void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
size_t survived,
size_t promoted) {
// Update averages
if (!is_survivor_overflow) {
// Keep running averages on how much survived
_avg_survived->sample(survived);
} else {
size_t survived_guess = survived + promoted;
_avg_survived->sample(survived_guess);
}
avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
if (PrintAdaptiveSizePolicy) {
gclog_or_tty->print_cr(
"AdaptiveSizePolicy::update_averages:"
" survived: " SIZE_FORMAT
" promoted: " SIZE_FORMAT
" overflow: %s",
survived, promoted, is_survivor_overflow ? "true" : "false");
}
}
bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
const {
if (!UseAdaptiveSizePolicy) return false;
return AdaptiveSizePolicy::print_adaptive_size_policy_on(
st,
PSScavenge::tenuring_threshold());
}
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