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 PSAdaptiveSizePolicy::compute_generation_free_space(
size_t young_live,
size_t eden_live,
size_t old_live,
size_t perm_live,
size_t cur_eden,
size_t max_old_gen_size,
size_t max_eden_size,
bool is_full_gc,
GCCause::Cause gc_cause,
CollectorPolicy* collector_policy) {
// Update statistics
// Time statistics are updated as we go, update footprint stats here
_avg_base_footprint->sample(BaseFootPrintEstimate + perm_live);
avg_young_live()->sample(young_live);
avg_eden_live()->sample(eden_live);
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;
#ifdef ASSERT
size_t original_promo_size = desired_promo_size;
size_t original_eden_size = desired_eden_size;
#endif
// 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();
// Used for diagnostics
clear_generation_free_space_flags();
// Limits on our growth
size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
// 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;
// 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.
adjust_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_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.
adjust_for_throughput(is_full_gc, &desired_promo_size, &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);
if (is_full_gc) {
set_decide_at_full_gc(decide_at_full_gc_true);
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_generation_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 (desired_eden_size > eden_limit) {
gclog_or_tty->print_cr(
"AdaptiveSizePolicy::compute_generation_free_space 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(
"AdaptiveSizePolicy::compute_generation_free_space: gc time limit"
" gc_cost: %f "
" GCTimeLimit: %d",
gc_cost(), GCTimeLimit);
}
}
// Align everything and make a final limit check
const size_t alignment = _intra_generation_alignment;
desired_eden_size = align_size_up(desired_eden_size, alignment);
desired_eden_size = MAX2(desired_eden_size, alignment);
desired_promo_size = align_size_up(desired_promo_size, alignment);
desired_promo_size = MAX2(desired_promo_size, alignment);
eden_limit = align_size_down(eden_limit, alignment);
promo_limit = align_size_down(promo_limit, alignment);
// Is too much time being spent in GC?
// Is the heap trying to grow beyond it's limits?
const size_t free_in_old_gen =
(size_t)(max_old_gen_size - avg_old_live()->average());
if (desired_promo_size > free_in_old_gen && desired_eden_size > eden_limit) {
check_gc_overhead_limit(young_live,
eden_live,
max_old_gen_size,
max_eden_size,
is_full_gc,
gc_cause,
collector_policy);
}
// 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);
}
desired_promo_size = MIN2(desired_promo_size, promo_limit);
if (PrintAdaptiveSizePolicy) {
// Timing stats
gclog_or_tty->print(
"PSAdaptiveSizePolicy::compute_generation_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
" old_eden_size: " SIZE_FORMAT
" desired_promo_size: " SIZE_FORMAT
" desired_eden_size: " SIZE_FORMAT,
_promo_size, _eden_size,
desired_promo_size, desired_eden_size);
gclog_or_tty->cr();
}
decay_supplemental_growth(is_full_gc);
set_promo_size(desired_promo_size);
set_eden_size(desired_eden_size);
};
double compacting_gc_cost() const {
double result = MIN2(1.0, minor_gc_cost() + msc_gc_cost());
assert(result >= 0.0, "Both minor and major costs are non-negative");
return result;
}
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 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.
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 (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 (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());
log_debug(gc, ergo)(
"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) {
log_debug(gc, ergo)(
"PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
" gc_cost: %f "
" GCTimeLimit: " UINTX_FORMAT,
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);
// Timing stats
log_debug(gc, ergo)("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);
log_trace(gc, ergo)("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
log_debug(gc, ergo)("Live_space: " SIZE_FORMAT " free_space: " SIZE_FORMAT,
live_space(), free_space());
log_trace(gc, ergo)("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());
log_debug(gc, ergo)("Old promo_size: " SIZE_FORMAT " desired_promo_size: " SIZE_FORMAT,
_promo_size, desired_promo_size);
set_promo_size(desired_promo_size);
}