Mercurial > hg > truffle
diff src/share/vm/gc_implementation/shared/adaptiveSizePolicy.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 0bfd3fb24150 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/shared/adaptiveSizePolicy.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,392 @@ +/* + * Copyright 2004-2006 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/_adaptiveSizePolicy.cpp.incl" + +elapsedTimer AdaptiveSizePolicy::_minor_timer; +elapsedTimer AdaptiveSizePolicy::_major_timer; + +// The throughput goal is implemented as +// _throughput_goal = 1 - ( 1 / (1 + gc_cost_ratio)) +// gc_cost_ratio is the ratio +// application cost / gc cost +// For example a gc_cost_ratio of 4 translates into a +// throughput goal of .80 + +AdaptiveSizePolicy::AdaptiveSizePolicy(size_t init_eden_size, + size_t init_promo_size, + size_t init_survivor_size, + double gc_pause_goal_sec, + uint gc_cost_ratio) : + _eden_size(init_eden_size), + _promo_size(init_promo_size), + _survivor_size(init_survivor_size), + _gc_pause_goal_sec(gc_pause_goal_sec), + _throughput_goal(1.0 - double(1.0 / (1.0 + (double) gc_cost_ratio))), + _gc_time_limit_exceeded(false), + _print_gc_time_limit_would_be_exceeded(false), + _gc_time_limit_count(0), + _latest_minor_mutator_interval_seconds(0), + _threshold_tolerance_percent(1.0 + ThresholdTolerance/100.0), + _young_gen_change_for_minor_throughput(0), + _old_gen_change_for_major_throughput(0) { + _avg_minor_pause = + new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding); + _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight); + _avg_minor_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight); + _avg_major_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight); + + _avg_young_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); + _avg_old_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); + _avg_eden_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); + + _avg_survived = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight, + SurvivorPadding); + _avg_pretenured = new AdaptivePaddedNoZeroDevAverage( + AdaptiveSizePolicyWeight, + SurvivorPadding); + + _minor_pause_old_estimator = + new LinearLeastSquareFit(AdaptiveSizePolicyWeight); + _minor_pause_young_estimator = + new LinearLeastSquareFit(AdaptiveSizePolicyWeight); + _minor_collection_estimator = + new LinearLeastSquareFit(AdaptiveSizePolicyWeight); + _major_collection_estimator = + new LinearLeastSquareFit(AdaptiveSizePolicyWeight); + + // Start the timers + _minor_timer.start(); + + _young_gen_policy_is_ready = false; +} + +bool AdaptiveSizePolicy::tenuring_threshold_change() const { + return decrement_tenuring_threshold_for_gc_cost() || + increment_tenuring_threshold_for_gc_cost() || + decrement_tenuring_threshold_for_survivor_limit(); +} + +void AdaptiveSizePolicy::minor_collection_begin() { + // Update the interval time + _minor_timer.stop(); + // Save most recent collection time + _latest_minor_mutator_interval_seconds = _minor_timer.seconds(); + _minor_timer.reset(); + _minor_timer.start(); +} + +void AdaptiveSizePolicy::update_minor_pause_young_estimator( + double minor_pause_in_ms) { + double eden_size_in_mbytes = ((double)_eden_size)/((double)M); + _minor_pause_young_estimator->update(eden_size_in_mbytes, + minor_pause_in_ms); +} + +void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) { + // Update the pause time. + _minor_timer.stop(); + + if (gc_cause != GCCause::_java_lang_system_gc || + UseAdaptiveSizePolicyWithSystemGC) { + double minor_pause_in_seconds = _minor_timer.seconds(); + double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS; + + // Sample for performance counter + _avg_minor_pause->sample(minor_pause_in_seconds); + + // Cost of collection (unit-less) + double collection_cost = 0.0; + if ((_latest_minor_mutator_interval_seconds > 0.0) && + (minor_pause_in_seconds > 0.0)) { + double interval_in_seconds = + _latest_minor_mutator_interval_seconds + minor_pause_in_seconds; + collection_cost = + minor_pause_in_seconds / interval_in_seconds; + _avg_minor_gc_cost->sample(collection_cost); + // Sample for performance counter + _avg_minor_interval->sample(interval_in_seconds); + } + + // The policy does not have enough data until at least some + // minor collections have been done. + _young_gen_policy_is_ready = + (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold); + + // Calculate variables used to estimate pause time vs. gen sizes + double eden_size_in_mbytes = ((double)_eden_size)/((double)M); + update_minor_pause_young_estimator(minor_pause_in_ms); + update_minor_pause_old_estimator(minor_pause_in_ms); + + if (PrintAdaptiveSizePolicy && Verbose) { + gclog_or_tty->print("AdaptiveSizePolicy::minor_collection_end: " + "minor gc cost: %f average: %f", collection_cost, + _avg_minor_gc_cost->average()); + gclog_or_tty->print_cr(" minor pause: %f minor period %f", + minor_pause_in_ms, + _latest_minor_mutator_interval_seconds * MILLIUNITS); + } + + // Calculate variable used to estimate collection cost vs. gen sizes + assert(collection_cost >= 0.0, "Expected to be non-negative"); + _minor_collection_estimator->update(eden_size_in_mbytes, collection_cost); + } + + // Interval times use this timer to measure the mutator time. + // Reset the timer after the GC pause. + _minor_timer.reset(); + _minor_timer.start(); +} + +size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden, + uint percent_change) { + size_t eden_heap_delta; + eden_heap_delta = cur_eden / 100 * percent_change; + return eden_heap_delta; +} + +size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) { + return eden_increment(cur_eden, YoungGenerationSizeIncrement); +} + +size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) { + size_t eden_heap_delta = eden_increment(cur_eden) / + AdaptiveSizeDecrementScaleFactor; + return eden_heap_delta; +} + +size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo, + uint percent_change) { + size_t promo_heap_delta; + promo_heap_delta = cur_promo / 100 * percent_change; + return promo_heap_delta; +} + +size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) { + return promo_increment(cur_promo, TenuredGenerationSizeIncrement); +} + +size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) { + size_t promo_heap_delta = promo_increment(cur_promo); + promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor; + return promo_heap_delta; +} + +double AdaptiveSizePolicy::time_since_major_gc() const { + _major_timer.stop(); + double result = _major_timer.seconds(); + _major_timer.start(); + return result; +} + +// Linear decay of major gc cost +double AdaptiveSizePolicy::decaying_major_gc_cost() const { + double major_interval = major_gc_interval_average_for_decay(); + double major_gc_cost_average = major_gc_cost(); + double decayed_major_gc_cost = major_gc_cost_average; + if(time_since_major_gc() > 0.0) { + decayed_major_gc_cost = major_gc_cost() * + (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval) + / time_since_major_gc(); + } + + // The decayed cost should always be smaller than the + // average cost but the vagaries of finite arithmetic could + // produce a larger value in decayed_major_gc_cost so protect + // against that. + return MIN2(major_gc_cost_average, decayed_major_gc_cost); +} + +// Use a value of the major gc cost that has been decayed +// by the factor +// +// average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale / +// time-since-last-major-gc +// +// if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale +// is less than time-since-last-major-gc. +// +// In cases where there are initial major gc's that +// are of a relatively high cost but no later major +// gc's, the total gc cost can remain high because +// the major gc cost remains unchanged (since there are no major +// gc's). In such a situation the value of the unchanging +// major gc cost can keep the mutator throughput below +// the goal when in fact the major gc cost is becoming diminishingly +// small. Use the decaying gc cost only to decide whether to +// adjust for throughput. Using it also to determine the adjustment +// to be made for throughput also seems reasonable but there is +// no test case to use to decide if it is the right thing to do +// don't do it yet. + +double AdaptiveSizePolicy::decaying_gc_cost() const { + double decayed_major_gc_cost = major_gc_cost(); + double avg_major_interval = major_gc_interval_average_for_decay(); + if (UseAdaptiveSizeDecayMajorGCCost && + (AdaptiveSizeMajorGCDecayTimeScale > 0) && + (avg_major_interval > 0.00)) { + double time_since_last_major_gc = time_since_major_gc(); + + // Decay the major gc cost? + if (time_since_last_major_gc > + ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) { + + // Decay using the time-since-last-major-gc + decayed_major_gc_cost = decaying_major_gc_cost(); + if (PrintGCDetails && Verbose) { + gclog_or_tty->print_cr("\ndecaying_gc_cost: major interval average:" + " %f time since last major gc: %f", + avg_major_interval, time_since_last_major_gc); + gclog_or_tty->print_cr(" major gc cost: %f decayed major gc cost: %f", + major_gc_cost(), decayed_major_gc_cost); + } + } + } + double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost()); + return result; +} + + +void AdaptiveSizePolicy::clear_generation_free_space_flags() { + set_change_young_gen_for_min_pauses(0); + set_change_old_gen_for_maj_pauses(0); + + set_change_old_gen_for_throughput(0); + set_change_young_gen_for_throughput(0); + set_decrease_for_footprint(0); + set_decide_at_full_gc(0); +} + +// Printing + +bool AdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) const { + + // Should only be used with adaptive size policy turned on. + // Otherwise, there may be variables that are undefined. + if (!UseAdaptiveSizePolicy) return false; + + // Print goal for which action is needed. + char* action = NULL; + bool change_for_pause = false; + if ((change_old_gen_for_maj_pauses() == + decrease_old_gen_for_maj_pauses_true) || + (change_young_gen_for_min_pauses() == + decrease_young_gen_for_min_pauses_true)) { + action = (char*) " *** pause time goal ***"; + change_for_pause = true; + } else if ((change_old_gen_for_throughput() == + increase_old_gen_for_throughput_true) || + (change_young_gen_for_throughput() == + increase_young_gen_for_througput_true)) { + action = (char*) " *** throughput goal ***"; + } else if (decrease_for_footprint()) { + action = (char*) " *** reduced footprint ***"; + } else { + // No actions were taken. This can legitimately be the + // situation if not enough data has been gathered to make + // decisions. + return false; + } + + // Pauses + // Currently the size of the old gen is only adjusted to + // change the major pause times. + char* young_gen_action = NULL; + char* tenured_gen_action = NULL; + + char* shrink_msg = (char*) "(attempted to shrink)"; + char* grow_msg = (char*) "(attempted to grow)"; + char* no_change_msg = (char*) "(no change)"; + if (change_young_gen_for_min_pauses() == + decrease_young_gen_for_min_pauses_true) { + young_gen_action = shrink_msg; + } else if (change_for_pause) { + young_gen_action = no_change_msg; + } + + if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) { + tenured_gen_action = shrink_msg; + } else if (change_for_pause) { + tenured_gen_action = no_change_msg; + } + + // Throughput + if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) { + assert(change_young_gen_for_throughput() == + increase_young_gen_for_througput_true, + "Both generations should be growing"); + young_gen_action = grow_msg; + tenured_gen_action = grow_msg; + } else if (change_young_gen_for_throughput() == + increase_young_gen_for_througput_true) { + // Only the young generation may grow at start up (before + // enough full collections have been done to grow the old generation). + young_gen_action = grow_msg; + tenured_gen_action = no_change_msg; + } + + // Minimum footprint + if (decrease_for_footprint() != 0) { + young_gen_action = shrink_msg; + tenured_gen_action = shrink_msg; + } + + st->print_cr(" UseAdaptiveSizePolicy actions to meet %s", action); + st->print_cr(" GC overhead (%%)"); + st->print_cr(" Young generation: %7.2f\t %s", + 100.0 * avg_minor_gc_cost()->average(), + young_gen_action); + st->print_cr(" Tenured generation: %7.2f\t %s", + 100.0 * avg_major_gc_cost()->average(), + tenured_gen_action); + return true; +} + +bool AdaptiveSizePolicy::print_adaptive_size_policy_on( + outputStream* st, + int tenuring_threshold_arg) const { + if (!AdaptiveSizePolicy::print_adaptive_size_policy_on(st)) { + return false; + } + + // Tenuring threshold + bool tenuring_threshold_changed = true; + if (decrement_tenuring_threshold_for_survivor_limit()) { + st->print(" Tenuring threshold: (attempted to decrease to avoid" + " survivor space overflow) = "); + } else if (decrement_tenuring_threshold_for_gc_cost()) { + st->print(" Tenuring threshold: (attempted to decrease to balance" + " GC costs) = "); + } else if (increment_tenuring_threshold_for_gc_cost()) { + st->print(" Tenuring threshold: (attempted to increase to balance" + " GC costs) = "); + } else { + tenuring_threshold_changed = false; + assert(!tenuring_threshold_change(), "(no change was attempted)"); + } + if (tenuring_threshold_changed) { + st->print_cr("%d", tenuring_threshold_arg); + } + return true; +}