truffle: src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.cpp comparison

comparison src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.cpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	0bfd3fb24150

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--1:000000000000
+:a61af66fc99e
+/*
+* Copyright 2002-2007 Sun Microsystems, Inc.  All Rights Reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+* CA 95054 USA or visit www.sun.com if you need additional information or
+* have any questions.
+*
+*/
+#include "incls/_precompiled.incl"
+#include "incls/_psAdaptiveSizePolicy.cpp.incl"
+#include <math.h>
+PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size,
+size_t init_promo_size,
+size_t init_survivor_size,
+size_t intra_generation_alignment,
+double gc_pause_goal_sec,
+double gc_minor_pause_goal_sec,
+uint gc_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),
+_intra_generation_alignment(intra_generation_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_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) {
+// 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) {
+// 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 = eden_limit > live_in_eden ?
+eden_limit - live_in_eden : 0;
+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);
+if (PrintAdaptiveSizePolicy && (Verbose ||
+(total_free_limit < (size_t) mem_free_limit))) {
+gclog_or_tty->print_cr(
+"PSAdaptiveSizePolicy::compute_generation_free_space limits:"
+" promo_limit: " SIZE_FORMAT
+" eden_limit: " 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, eden_limit, total_free_limit,
+max_old_gen_size, max_eden_size,
+(size_t) mem_free_limit);
+}
+if (is_full_gc) {
+if (gc_cost() > gc_cost_limit &&
+total_free_limit < (size_t) mem_free_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.
+// Ignore explicit GC's. Ignoring explicit GC's at this level
+// is the equivalent of the GC did not happen as far as the
+// overhead calculation is concerted (i.e., the flag is not set
+// and the count is not affected).  Also the average will not
+// have been updated unless UseAdaptiveSizePolicyWithSystemGC is on.
+if (!GCCause::is_user_requested_gc(gc_cause) &&
+!GCCause::is_serviceability_requested_gc(gc_cause)) {
+inc_gc_time_limit_count();
+if (UseGCOverheadLimit &&
+(gc_time_limit_count() > AdaptiveSizePolicyGCTimeLimitThreshold)){
+// All conditions have been met for throwing an out-of-memory
+_gc_time_limit_exceeded = true;
+// Avoid consecutive OOM due to the gc time limit by resetting
+// the counter.
+reset_gc_time_limit_count();
+}
+_print_gc_time_limit_would_be_exceeded = true;
+}
+} else {
+// Did not exceed overhead limits
+reset_gc_time_limit_count();
+}
+}
+}
+// 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);
+};
+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_for_minor_pause_time(bool is_full_gc,
+size_t* desired_promo_size_ptr, 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);
+}
+if (PSAdjustTenuredGenForMinorPause) {
+// If the desired eden size is as small as it will get,
+// try to adjust the old gen size.
+if (*desired_eden_size_ptr <= _intra_generation_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_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;
+size_t eden_heap_delta = 0;
+// Add some checks for a threshhold for a change.  For example,
+// a change less than the required alignment is probably not worth
+// attempting.
+if (is_full_gc) {
+set_decide_at_full_gc(decide_at_full_gc_true);
+}
+if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
+adjust_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 (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 < _intra_generation_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(
+"AdaptiveSizePolicy::compute_generation_free_space "
+"adjusting gen sizes for major pause (avg %f goal %f). "
+"desired_promo_size " SIZE_FORMAT "desired_eden_size "
+SIZE_FORMAT
+" promo delta " SIZE_FORMAT  " eden delta " SIZE_FORMAT,
+_avg_major_pause->average(), gc_pause_goal_sec(),
+*desired_promo_size_ptr, *desired_eden_size_ptr,
+promo_heap_delta, eden_heap_delta);
+}
+}
+void PSAdaptiveSizePolicy::adjust_for_throughput(bool is_full_gc,
+size_t* desired_promo_size_ptr,
+size_t* desired_eden_size_ptr) {
+// Add some checks for a threshhold for a change.  For example,
+// a change less than the required alignment is probably not worth
+// attempting.
+if (is_full_gc) {
+set_decide_at_full_gc(decide_at_full_gc_true);
+}
+if ((gc_cost() + mutator_cost()) == 0.0) {
+return;
+}
+if (PrintAdaptiveSizePolicy && Verbose) {
+gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_for_throughput("
+"is_full: %d, promo: " SIZE_FORMAT ",  cur_eden: " SIZE_FORMAT "): ",
+is_full_gc, *desired_promo_size_ptr, *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());
+}
+// 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);
+}
+}
+// 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::compute_generation_free_space "
+"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::compute_generation_free_space "
+"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, _intra_generation_alignment);
+}
+size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
+size_t result = eden_increment(cur_eden);
+return align_size_down(result, _intra_generation_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, _intra_generation_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, _intra_generation_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, _intra_generation_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, _intra_generation_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, _intra_generation_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, _intra_generation_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;
+}
+int PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
+bool is_survivor_overflow,
+int tenuring_threshold,
+size_t survivor_limit) {
+assert(survivor_limit >= _intra_generation_alignment,
+"survivor_limit too small");
+assert((size_t)align_size_down(survivor_limit, _intra_generation_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(),
+_intra_generation_alignment);
+target_size = MAX2(target_size, _intra_generation_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( "  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);
+tty->cr();
+}
+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(
+"AdaptiveSizePolicy::compute_survivor_space_size_and_thresh:"
+"  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());
+}

Mercurial > hg > truffle

comparison src/share/vm/gc_implementation/parallelScavenge/psAdaptiveSizePolicy.cpp @ 0:a61af66fc99e jdk7-b24