7068240: G1: Long "parallel other time" and "ext root scanning" when running specific benchmark
Summary: In root processing, move the scanning of the reference processor's discovered lists to before RSet updating and scanning. When scanning the reference processor's discovered lists, use a buffering closure so that the time spent copying any reference object is correctly attributed. Also removed a couple of unused and irrelevant timers.
Reviewed-by: ysr, jmasa
/*
* Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "gc_implementation/g1/concurrentG1Refine.hpp"
#include "gc_implementation/g1/concurrentMark.hpp"
#include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
#include "gc_implementation/g1/g1CollectorPolicy.hpp"
#include "gc_implementation/g1/heapRegionRemSet.hpp"
#include "gc_implementation/shared/gcPolicyCounters.hpp"
#include "runtime/arguments.hpp"
#include "runtime/java.hpp"
#include "runtime/mutexLocker.hpp"
#include "utilities/debug.hpp"
#define PREDICTIONS_VERBOSE 0
// <NEW PREDICTION>
// Different defaults for different number of GC threads
// They were chosen by running GCOld and SPECjbb on debris with different
// numbers of GC threads and choosing them based on the results
// all the same
static double rs_length_diff_defaults[] = {
0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
};
static double cost_per_card_ms_defaults[] = {
0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
};
// all the same
static double fully_young_cards_per_entry_ratio_defaults[] = {
1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
};
static double cost_per_entry_ms_defaults[] = {
0.015, 0.01, 0.01, 0.008, 0.008, 0.0055, 0.0055, 0.005
};
static double cost_per_byte_ms_defaults[] = {
0.00006, 0.00003, 0.00003, 0.000015, 0.000015, 0.00001, 0.00001, 0.000009
};
// these should be pretty consistent
static double constant_other_time_ms_defaults[] = {
5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0
};
static double young_other_cost_per_region_ms_defaults[] = {
0.3, 0.2, 0.2, 0.15, 0.15, 0.12, 0.12, 0.1
};
static double non_young_other_cost_per_region_ms_defaults[] = {
1.0, 0.7, 0.7, 0.5, 0.5, 0.42, 0.42, 0.30
};
// </NEW PREDICTION>
// Help class for avoiding interleaved logging
class LineBuffer: public StackObj {
private:
static const int BUFFER_LEN = 1024;
static const int INDENT_CHARS = 3;
char _buffer[BUFFER_LEN];
int _indent_level;
int _cur;
void vappend(const char* format, va_list ap) {
int res = vsnprintf(&_buffer[_cur], BUFFER_LEN - _cur, format, ap);
if (res != -1) {
_cur += res;
} else {
DEBUG_ONLY(warning("buffer too small in LineBuffer");)
_buffer[BUFFER_LEN -1] = 0;
_cur = BUFFER_LEN; // vsnprintf above should not add to _buffer if we are called again
}
}
public:
explicit LineBuffer(int indent_level): _indent_level(indent_level), _cur(0) {
for (; (_cur < BUFFER_LEN && _cur < (_indent_level * INDENT_CHARS)); _cur++) {
_buffer[_cur] = ' ';
}
}
#ifndef PRODUCT
~LineBuffer() {
assert(_cur == _indent_level * INDENT_CHARS, "pending data in buffer - append_and_print_cr() not called?");
}
#endif
void append(const char* format, ...) {
va_list ap;
va_start(ap, format);
vappend(format, ap);
va_end(ap);
}
void append_and_print_cr(const char* format, ...) {
va_list ap;
va_start(ap, format);
vappend(format, ap);
va_end(ap);
gclog_or_tty->print_cr("%s", _buffer);
_cur = _indent_level * INDENT_CHARS;
}
};
G1CollectorPolicy::G1CollectorPolicy() :
_parallel_gc_threads(G1CollectedHeap::use_parallel_gc_threads()
? ParallelGCThreads : 1),
_n_pauses(0),
_recent_rs_scan_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_recent_pause_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_recent_rs_sizes(new TruncatedSeq(NumPrevPausesForHeuristics)),
_recent_gc_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_all_pause_times_ms(new NumberSeq()),
_stop_world_start(0.0),
_all_stop_world_times_ms(new NumberSeq()),
_all_yield_times_ms(new NumberSeq()),
_all_mod_union_times_ms(new NumberSeq()),
_summary(new Summary()),
#ifndef PRODUCT
_cur_clear_ct_time_ms(0.0),
_min_clear_cc_time_ms(-1.0),
_max_clear_cc_time_ms(-1.0),
_cur_clear_cc_time_ms(0.0),
_cum_clear_cc_time_ms(0.0),
_num_cc_clears(0L),
#endif
_region_num_young(0),
_region_num_tenured(0),
_prev_region_num_young(0),
_prev_region_num_tenured(0),
_aux_num(10),
_all_aux_times_ms(new NumberSeq[_aux_num]),
_cur_aux_start_times_ms(new double[_aux_num]),
_cur_aux_times_ms(new double[_aux_num]),
_cur_aux_times_set(new bool[_aux_num]),
_concurrent_mark_init_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_concurrent_mark_remark_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
// <NEW PREDICTION>
_alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_prev_collection_pause_end_ms(0.0),
_pending_card_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
_rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
_cost_per_card_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_fully_young_cards_per_entry_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
_partially_young_cards_per_entry_ratio_seq(
new TruncatedSeq(TruncatedSeqLength)),
_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_partially_young_cost_per_entry_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_cost_per_byte_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
_constant_other_time_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_young_other_cost_per_region_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_non_young_other_cost_per_region_ms_seq(
new TruncatedSeq(TruncatedSeqLength)),
_pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
_scanned_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
_rs_lengths_seq(new TruncatedSeq(TruncatedSeqLength)),
_pause_time_target_ms((double) MaxGCPauseMillis),
// </NEW PREDICTION>
_in_young_gc_mode(false),
_full_young_gcs(true),
_full_young_pause_num(0),
_partial_young_pause_num(0),
_during_marking(false),
_in_marking_window(false),
_in_marking_window_im(false),
_known_garbage_ratio(0.0),
_known_garbage_bytes(0),
_young_gc_eff_seq(new TruncatedSeq(TruncatedSeqLength)),
_recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
_recent_CS_bytes_used_before(new TruncatedSeq(NumPrevPausesForHeuristics)),
_recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
_recent_avg_pause_time_ratio(0.0),
_num_markings(0),
_n_marks(0),
_n_pauses_at_mark_end(0),
_all_full_gc_times_ms(new NumberSeq()),
// G1PausesBtwnConcMark defaults to -1
// so the hack is to do the cast QQQ FIXME
_pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
_n_marks_since_last_pause(0),
_initiate_conc_mark_if_possible(false),
_during_initial_mark_pause(false),
_should_revert_to_full_young_gcs(false),
_last_full_young_gc(false),
_eden_bytes_before_gc(0),
_survivor_bytes_before_gc(0),
_capacity_before_gc(0),
_prev_collection_pause_used_at_end_bytes(0),
_collection_set(NULL),
_collection_set_size(0),
_collection_set_bytes_used_before(0),
// Incremental CSet attributes
_inc_cset_build_state(Inactive),
_inc_cset_head(NULL),
_inc_cset_tail(NULL),
_inc_cset_size(0),
_inc_cset_young_index(0),
_inc_cset_bytes_used_before(0),
_inc_cset_max_finger(NULL),
_inc_cset_recorded_young_bytes(0),
_inc_cset_recorded_rs_lengths(0),
_inc_cset_predicted_elapsed_time_ms(0.0),
_inc_cset_predicted_bytes_to_copy(0),
#ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
#pragma warning( disable:4355 ) // 'this' : used in base member initializer list
#endif // _MSC_VER
_short_lived_surv_rate_group(new SurvRateGroup(this, "Short Lived",
G1YoungSurvRateNumRegionsSummary)),
_survivor_surv_rate_group(new SurvRateGroup(this, "Survivor",
G1YoungSurvRateNumRegionsSummary)),
// add here any more surv rate groups
_recorded_survivor_regions(0),
_recorded_survivor_head(NULL),
_recorded_survivor_tail(NULL),
_survivors_age_table(true),
_gc_overhead_perc(0.0)
{
// Set up the region size and associated fields. Given that the
// policy is created before the heap, we have to set this up here,
// so it's done as soon as possible.
HeapRegion::setup_heap_region_size(Arguments::min_heap_size());
HeapRegionRemSet::setup_remset_size();
// Verify PLAB sizes
const uint region_size = HeapRegion::GrainWords;
if (YoungPLABSize > region_size || OldPLABSize > region_size) {
char buffer[128];
jio_snprintf(buffer, sizeof(buffer), "%sPLABSize should be at most %u",
OldPLABSize > region_size ? "Old" : "Young", region_size);
vm_exit_during_initialization(buffer);
}
_recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
_prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
_par_last_gc_worker_start_times_ms = new double[_parallel_gc_threads];
_par_last_ext_root_scan_times_ms = new double[_parallel_gc_threads];
_par_last_mark_stack_scan_times_ms = new double[_parallel_gc_threads];
_par_last_update_rs_times_ms = new double[_parallel_gc_threads];
_par_last_update_rs_processed_buffers = new double[_parallel_gc_threads];
_par_last_scan_rs_times_ms = new double[_parallel_gc_threads];
_par_last_obj_copy_times_ms = new double[_parallel_gc_threads];
_par_last_termination_times_ms = new double[_parallel_gc_threads];
_par_last_termination_attempts = new double[_parallel_gc_threads];
_par_last_gc_worker_end_times_ms = new double[_parallel_gc_threads];
_par_last_gc_worker_times_ms = new double[_parallel_gc_threads];
// start conservatively
_expensive_region_limit_ms = 0.5 * (double) MaxGCPauseMillis;
// <NEW PREDICTION>
int index;
if (ParallelGCThreads == 0)
index = 0;
else if (ParallelGCThreads > 8)
index = 7;
else
index = ParallelGCThreads - 1;
_pending_card_diff_seq->add(0.0);
_rs_length_diff_seq->add(rs_length_diff_defaults[index]);
_cost_per_card_ms_seq->add(cost_per_card_ms_defaults[index]);
_fully_young_cards_per_entry_ratio_seq->add(
fully_young_cards_per_entry_ratio_defaults[index]);
_cost_per_entry_ms_seq->add(cost_per_entry_ms_defaults[index]);
_cost_per_byte_ms_seq->add(cost_per_byte_ms_defaults[index]);
_constant_other_time_ms_seq->add(constant_other_time_ms_defaults[index]);
_young_other_cost_per_region_ms_seq->add(
young_other_cost_per_region_ms_defaults[index]);
_non_young_other_cost_per_region_ms_seq->add(
non_young_other_cost_per_region_ms_defaults[index]);
// </NEW PREDICTION>
// Below, we might need to calculate the pause time target based on
// the pause interval. When we do so we are going to give G1 maximum
// flexibility and allow it to do pauses when it needs to. So, we'll
// arrange that the pause interval to be pause time target + 1 to
// ensure that a) the pause time target is maximized with respect to
// the pause interval and b) we maintain the invariant that pause
// time target < pause interval. If the user does not want this
// maximum flexibility, they will have to set the pause interval
// explicitly.
// First make sure that, if either parameter is set, its value is
// reasonable.
if (!FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
if (MaxGCPauseMillis < 1) {
vm_exit_during_initialization("MaxGCPauseMillis should be "
"greater than 0");
}
}
if (!FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
if (GCPauseIntervalMillis < 1) {
vm_exit_during_initialization("GCPauseIntervalMillis should be "
"greater than 0");
}
}
// Then, if the pause time target parameter was not set, set it to
// the default value.
if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
// The default pause time target in G1 is 200ms
FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
} else {
// We do not allow the pause interval to be set without the
// pause time target
vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
"without setting MaxGCPauseMillis");
}
}
// Then, if the interval parameter was not set, set it according to
// the pause time target (this will also deal with the case when the
// pause time target is the default value).
if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
}
// Finally, make sure that the two parameters are consistent.
if (MaxGCPauseMillis >= GCPauseIntervalMillis) {
char buffer[256];
jio_snprintf(buffer, 256,
"MaxGCPauseMillis (%u) should be less than "
"GCPauseIntervalMillis (%u)",
MaxGCPauseMillis, GCPauseIntervalMillis);
vm_exit_during_initialization(buffer);
}
double max_gc_time = (double) MaxGCPauseMillis / 1000.0;
double time_slice = (double) GCPauseIntervalMillis / 1000.0;
_mmu_tracker = new G1MMUTrackerQueue(time_slice, max_gc_time);
_sigma = (double) G1ConfidencePercent / 100.0;
// start conservatively (around 50ms is about right)
_concurrent_mark_init_times_ms->add(0.05);
_concurrent_mark_remark_times_ms->add(0.05);
_concurrent_mark_cleanup_times_ms->add(0.20);
_tenuring_threshold = MaxTenuringThreshold;
// if G1FixedSurvivorSpaceSize is 0 which means the size is not
// fixed, then _max_survivor_regions will be calculated at
// calculate_young_list_target_length during initialization
_max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
assert(GCTimeRatio > 0,
"we should have set it to a default value set_g1_gc_flags() "
"if a user set it to 0");
_gc_overhead_perc = 100.0 * (1.0 / (1.0 + GCTimeRatio));
initialize_all();
}
// Increment "i", mod "len"
static void inc_mod(int& i, int len) {
i++; if (i == len) i = 0;
}
void G1CollectorPolicy::initialize_flags() {
set_min_alignment(HeapRegion::GrainBytes);
set_max_alignment(GenRemSet::max_alignment_constraint(rem_set_name()));
if (SurvivorRatio < 1) {
vm_exit_during_initialization("Invalid survivor ratio specified");
}
CollectorPolicy::initialize_flags();
}
// The easiest way to deal with the parsing of the NewSize /
// MaxNewSize / etc. parameteres is to re-use the code in the
// TwoGenerationCollectorPolicy class. This is similar to what
// ParallelScavenge does with its GenerationSizer class (see
// ParallelScavengeHeap::initialize()). We might change this in the
// future, but it's a good start.
class G1YoungGenSizer : public TwoGenerationCollectorPolicy {
size_t size_to_region_num(size_t byte_size) {
return MAX2((size_t) 1, byte_size / HeapRegion::GrainBytes);
}
public:
G1YoungGenSizer() {
initialize_flags();
initialize_size_info();
}
size_t min_young_region_num() {
return size_to_region_num(_min_gen0_size);
}
size_t initial_young_region_num() {
return size_to_region_num(_initial_gen0_size);
}
size_t max_young_region_num() {
return size_to_region_num(_max_gen0_size);
}
};
void G1CollectorPolicy::init() {
// Set aside an initial future to_space.
_g1 = G1CollectedHeap::heap();
assert(Heap_lock->owned_by_self(), "Locking discipline.");
initialize_gc_policy_counters();
if (G1Gen) {
_in_young_gc_mode = true;
G1YoungGenSizer sizer;
size_t initial_region_num = sizer.initial_young_region_num();
if (UseAdaptiveSizePolicy) {
set_adaptive_young_list_length(true);
_young_list_fixed_length = 0;
} else {
set_adaptive_young_list_length(false);
_young_list_fixed_length = initial_region_num;
}
_free_regions_at_end_of_collection = _g1->free_regions();
calculate_young_list_min_length();
guarantee( _young_list_min_length == 0, "invariant, not enough info" );
calculate_young_list_target_length();
} else {
_young_list_fixed_length = 0;
_in_young_gc_mode = false;
}
// We may immediately start allocating regions and placing them on the
// collection set list. Initialize the per-collection set info
start_incremental_cset_building();
}
// Create the jstat counters for the policy.
void G1CollectorPolicy::initialize_gc_policy_counters()
{
_gc_policy_counters = new GCPolicyCounters("GarbageFirst", 1, 2 + G1Gen);
}
void G1CollectorPolicy::calculate_young_list_min_length() {
_young_list_min_length = 0;
if (!adaptive_young_list_length())
return;
if (_alloc_rate_ms_seq->num() > 3) {
double now_sec = os::elapsedTime();
double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
double alloc_rate_ms = predict_alloc_rate_ms();
size_t min_regions = (size_t) ceil(alloc_rate_ms * when_ms);
size_t current_region_num = _g1->young_list()->length();
_young_list_min_length = min_regions + current_region_num;
}
}
void G1CollectorPolicy::calculate_young_list_target_length() {
if (adaptive_young_list_length()) {
size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
calculate_young_list_target_length(rs_lengths);
} else {
if (full_young_gcs())
_young_list_target_length = _young_list_fixed_length;
else
_young_list_target_length = _young_list_fixed_length / 2;
}
// Make sure we allow the application to allocate at least one
// region before we need to do a collection again.
size_t min_length = _g1->young_list()->length() + 1;
_young_list_target_length = MAX2(_young_list_target_length, min_length);
calculate_max_gc_locker_expansion();
calculate_survivors_policy();
}
void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
guarantee( adaptive_young_list_length(), "pre-condition" );
guarantee( !_in_marking_window || !_last_full_young_gc, "invariant" );
double start_time_sec = os::elapsedTime();
size_t min_reserve_perc = MAX2((size_t)2, (size_t)G1ReservePercent);
min_reserve_perc = MIN2((size_t) 50, min_reserve_perc);
size_t reserve_regions =
(size_t) ((double) min_reserve_perc * (double) _g1->n_regions() / 100.0);
if (full_young_gcs() && _free_regions_at_end_of_collection > 0) {
// we are in fully-young mode and there are free regions in the heap
double survivor_regions_evac_time =
predict_survivor_regions_evac_time();
double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
double base_time_ms = predict_base_elapsed_time_ms(pending_cards, scanned_cards)
+ survivor_regions_evac_time;
// the result
size_t final_young_length = 0;
size_t init_free_regions =
MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
// if we're still under the pause target...
if (base_time_ms <= target_pause_time_ms) {
// We make sure that the shortest young length that makes sense
// fits within the target pause time.
size_t min_young_length = 1;
if (predict_will_fit(min_young_length, base_time_ms,
init_free_regions, target_pause_time_ms)) {
// The shortest young length will fit within the target pause time;
// we'll now check whether the absolute maximum number of young
// regions will fit in the target pause time. If not, we'll do
// a binary search between min_young_length and max_young_length
size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
size_t max_young_length = abs_max_young_length;
if (max_young_length > min_young_length) {
// Let's check if the initial max young length will fit within the
// target pause. If so then there is no need to search for a maximal
// young length - we'll return the initial maximum
if (predict_will_fit(max_young_length, base_time_ms,
init_free_regions, target_pause_time_ms)) {
// The maximum young length will satisfy the target pause time.
// We are done so set min young length to this maximum length.
// The code after the loop will then set final_young_length using
// the value cached in the minimum length.
min_young_length = max_young_length;
} else {
// The maximum possible number of young regions will not fit within
// the target pause time so let's search....
size_t diff = (max_young_length - min_young_length) / 2;
max_young_length = min_young_length + diff;
while (max_young_length > min_young_length) {
if (predict_will_fit(max_young_length, base_time_ms,
init_free_regions, target_pause_time_ms)) {
// The current max young length will fit within the target
// pause time. Note we do not exit the loop here. By setting
// min = max, and then increasing the max below means that
// we will continue searching for an upper bound in the
// range [max..max+diff]
min_young_length = max_young_length;
}
diff = (max_young_length - min_young_length) / 2;
max_young_length = min_young_length + diff;
}
// the above loop found a maximal young length that will fit
// within the target pause time.
}
assert(min_young_length <= abs_max_young_length, "just checking");
}
final_young_length = min_young_length;
}
}
// and we're done!
// we should have at least one region in the target young length
_young_list_target_length =
final_young_length + _recorded_survivor_regions;
// let's keep an eye of how long we spend on this calculation
// right now, I assume that we'll print it when we need it; we
// should really adde it to the breakdown of a pause
double end_time_sec = os::elapsedTime();
double elapsed_time_ms = (end_time_sec - start_time_sec) * 1000.0;
#ifdef TRACE_CALC_YOUNG_LENGTH
// leave this in for debugging, just in case
gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
"elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
target_pause_time_ms,
_young_list_target_length
elapsed_time_ms,
full_young_gcs() ? "full" : "partial",
during_initial_mark_pause() ? " i-m" : "",
_in_marking_window,
_in_marking_window_im);
#endif // TRACE_CALC_YOUNG_LENGTH
if (_young_list_target_length < _young_list_min_length) {
// bummer; this means that, if we do a pause when the maximal
// length dictates, we'll violate the pause spacing target (the
// min length was calculate based on the application's current
// alloc rate);
// so, we have to bite the bullet, and allocate the minimum
// number. We'll violate our target, but we just can't meet it.
#ifdef TRACE_CALC_YOUNG_LENGTH
// leave this in for debugging, just in case
gclog_or_tty->print_cr("adjusted target length from "
SIZE_FORMAT " to " SIZE_FORMAT,
_young_list_target_length, _young_list_min_length);
#endif // TRACE_CALC_YOUNG_LENGTH
_young_list_target_length = _young_list_min_length;
}
} else {
// we are in a partially-young mode or we've run out of regions (due
// to evacuation failure)
#ifdef TRACE_CALC_YOUNG_LENGTH
// leave this in for debugging, just in case
gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
_young_list_min_length);
#endif // TRACE_CALC_YOUNG_LENGTH
// we'll do the pause as soon as possible by choosing the minimum
_young_list_target_length = _young_list_min_length;
}
_rs_lengths_prediction = rs_lengths;
}
// This is used by: calculate_young_list_target_length(rs_length). It
// returns true iff:
// the predicted pause time for the given young list will not overflow
// the target pause time
// and:
// the predicted amount of surviving data will not overflow the
// the amount of free space available for survivor regions.
//
bool
G1CollectorPolicy::predict_will_fit(size_t young_length,
double base_time_ms,
size_t init_free_regions,
double target_pause_time_ms) {
if (young_length >= init_free_regions)
// end condition 1: not enough space for the young regions
return false;
double accum_surv_rate_adj = 0.0;
double accum_surv_rate =
accum_yg_surv_rate_pred((int)(young_length - 1)) - accum_surv_rate_adj;
size_t bytes_to_copy =
(size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
double copy_time_ms = predict_object_copy_time_ms(bytes_to_copy);
double young_other_time_ms =
predict_young_other_time_ms(young_length);
double pause_time_ms =
base_time_ms + copy_time_ms + young_other_time_ms;
if (pause_time_ms > target_pause_time_ms)
// end condition 2: over the target pause time
return false;
size_t free_bytes =
(init_free_regions - young_length) * HeapRegion::GrainBytes;
if ((2.0 + sigma()) * (double) bytes_to_copy > (double) free_bytes)
// end condition 3: out of to-space (conservatively)
return false;
// success!
return true;
}
double G1CollectorPolicy::predict_survivor_regions_evac_time() {
double survivor_regions_evac_time = 0.0;
for (HeapRegion * r = _recorded_survivor_head;
r != NULL && r != _recorded_survivor_tail->get_next_young_region();
r = r->get_next_young_region()) {
survivor_regions_evac_time += predict_region_elapsed_time_ms(r, true);
}
return survivor_regions_evac_time;
}
void G1CollectorPolicy::check_prediction_validity() {
guarantee( adaptive_young_list_length(), "should not call this otherwise" );
size_t rs_lengths = _g1->young_list()->sampled_rs_lengths();
if (rs_lengths > _rs_lengths_prediction) {
// add 10% to avoid having to recalculate often
size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
calculate_young_list_target_length(rs_lengths_prediction);
}
}
HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
bool is_tlab,
bool* gc_overhead_limit_was_exceeded) {
guarantee(false, "Not using this policy feature yet.");
return NULL;
}
// This method controls how a collector handles one or more
// of its generations being fully allocated.
HeapWord* G1CollectorPolicy::satisfy_failed_allocation(size_t size,
bool is_tlab) {
guarantee(false, "Not using this policy feature yet.");
return NULL;
}
#ifndef PRODUCT
bool G1CollectorPolicy::verify_young_ages() {
HeapRegion* head = _g1->young_list()->first_region();
return
verify_young_ages(head, _short_lived_surv_rate_group);
// also call verify_young_ages on any additional surv rate groups
}
bool
G1CollectorPolicy::verify_young_ages(HeapRegion* head,
SurvRateGroup *surv_rate_group) {
guarantee( surv_rate_group != NULL, "pre-condition" );
const char* name = surv_rate_group->name();
bool ret = true;
int prev_age = -1;
for (HeapRegion* curr = head;
curr != NULL;
curr = curr->get_next_young_region()) {
SurvRateGroup* group = curr->surv_rate_group();
if (group == NULL && !curr->is_survivor()) {
gclog_or_tty->print_cr("## %s: encountered NULL surv_rate_group", name);
ret = false;
}
if (surv_rate_group == group) {
int age = curr->age_in_surv_rate_group();
if (age < 0) {
gclog_or_tty->print_cr("## %s: encountered negative age", name);
ret = false;
}
if (age <= prev_age) {
gclog_or_tty->print_cr("## %s: region ages are not strictly increasing "
"(%d, %d)", name, age, prev_age);
ret = false;
}
prev_age = age;
}
}
return ret;
}
#endif // PRODUCT
void G1CollectorPolicy::record_full_collection_start() {
_cur_collection_start_sec = os::elapsedTime();
// Release the future to-space so that it is available for compaction into.
_g1->set_full_collection();
}
void G1CollectorPolicy::record_full_collection_end() {
// Consider this like a collection pause for the purposes of allocation
// since last pause.
double end_sec = os::elapsedTime();
double full_gc_time_sec = end_sec - _cur_collection_start_sec;
double full_gc_time_ms = full_gc_time_sec * 1000.0;
_all_full_gc_times_ms->add(full_gc_time_ms);
update_recent_gc_times(end_sec, full_gc_time_ms);
_g1->clear_full_collection();
// "Nuke" the heuristics that control the fully/partially young GC
// transitions and make sure we start with fully young GCs after the
// Full GC.
set_full_young_gcs(true);
_last_full_young_gc = false;
_should_revert_to_full_young_gcs = false;
clear_initiate_conc_mark_if_possible();
clear_during_initial_mark_pause();
_known_garbage_bytes = 0;
_known_garbage_ratio = 0.0;
_in_marking_window = false;
_in_marking_window_im = false;
_short_lived_surv_rate_group->start_adding_regions();
// also call this on any additional surv rate groups
record_survivor_regions(0, NULL, NULL);
_prev_region_num_young = _region_num_young;
_prev_region_num_tenured = _region_num_tenured;
_free_regions_at_end_of_collection = _g1->free_regions();
// Reset survivors SurvRateGroup.
_survivor_surv_rate_group->reset();
calculate_young_list_min_length();
calculate_young_list_target_length();
}
void G1CollectorPolicy::record_before_bytes(size_t bytes) {
_bytes_in_to_space_before_gc += bytes;
}
void G1CollectorPolicy::record_after_bytes(size_t bytes) {
_bytes_in_to_space_after_gc += bytes;
}
void G1CollectorPolicy::record_stop_world_start() {
_stop_world_start = os::elapsedTime();
}
void G1CollectorPolicy::record_collection_pause_start(double start_time_sec,
size_t start_used) {
if (PrintGCDetails) {
gclog_or_tty->stamp(PrintGCTimeStamps);
gclog_or_tty->print("[GC pause");
if (in_young_gc_mode())
gclog_or_tty->print(" (%s)", full_young_gcs() ? "young" : "partial");
}
assert(_g1->used() == _g1->recalculate_used(),
err_msg("sanity, used: "SIZE_FORMAT" recalculate_used: "SIZE_FORMAT,
_g1->used(), _g1->recalculate_used()));
double s_w_t_ms = (start_time_sec - _stop_world_start) * 1000.0;
_all_stop_world_times_ms->add(s_w_t_ms);
_stop_world_start = 0.0;
_cur_collection_start_sec = start_time_sec;
_cur_collection_pause_used_at_start_bytes = start_used;
_cur_collection_pause_used_regions_at_start = _g1->used_regions();
_pending_cards = _g1->pending_card_num();
_max_pending_cards = _g1->max_pending_card_num();
_bytes_in_to_space_before_gc = 0;
_bytes_in_to_space_after_gc = 0;
_bytes_in_collection_set_before_gc = 0;
YoungList* young_list = _g1->young_list();
_eden_bytes_before_gc = young_list->eden_used_bytes();
_survivor_bytes_before_gc = young_list->survivor_used_bytes();
_capacity_before_gc = _g1->capacity();
#ifdef DEBUG
// initialise these to something well known so that we can spot
// if they are not set properly
for (int i = 0; i < _parallel_gc_threads; ++i) {
_par_last_gc_worker_start_times_ms[i] = -1234.0;
_par_last_ext_root_scan_times_ms[i] = -1234.0;
_par_last_mark_stack_scan_times_ms[i] = -1234.0;
_par_last_update_rs_times_ms[i] = -1234.0;
_par_last_update_rs_processed_buffers[i] = -1234.0;
_par_last_scan_rs_times_ms[i] = -1234.0;
_par_last_obj_copy_times_ms[i] = -1234.0;
_par_last_termination_times_ms[i] = -1234.0;
_par_last_termination_attempts[i] = -1234.0;
_par_last_gc_worker_end_times_ms[i] = -1234.0;
_par_last_gc_worker_times_ms[i] = -1234.0;
}
#endif
for (int i = 0; i < _aux_num; ++i) {
_cur_aux_times_ms[i] = 0.0;
_cur_aux_times_set[i] = false;
}
_satb_drain_time_set = false;
_last_satb_drain_processed_buffers = -1;
if (in_young_gc_mode())
_last_young_gc_full = false;
// do that for any other surv rate groups
_short_lived_surv_rate_group->stop_adding_regions();
_survivors_age_table.clear();
assert( verify_young_ages(), "region age verification" );
}
void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
_mark_closure_time_ms = mark_closure_time_ms;
}
void G1CollectorPolicy::record_concurrent_mark_init_start() {
_mark_init_start_sec = os::elapsedTime();
guarantee(!in_young_gc_mode(), "should not do be here in young GC mode");
}
void G1CollectorPolicy::record_concurrent_mark_init_end_pre(double
mark_init_elapsed_time_ms) {
_during_marking = true;
assert(!initiate_conc_mark_if_possible(), "we should have cleared it by now");
clear_during_initial_mark_pause();
_cur_mark_stop_world_time_ms = mark_init_elapsed_time_ms;
}
void G1CollectorPolicy::record_concurrent_mark_init_end() {
double end_time_sec = os::elapsedTime();
double elapsed_time_ms = (end_time_sec - _mark_init_start_sec) * 1000.0;
_concurrent_mark_init_times_ms->add(elapsed_time_ms);
record_concurrent_mark_init_end_pre(elapsed_time_ms);
_mmu_tracker->add_pause(_mark_init_start_sec, end_time_sec, true);
}
void G1CollectorPolicy::record_concurrent_mark_remark_start() {
_mark_remark_start_sec = os::elapsedTime();
_during_marking = false;
}
void G1CollectorPolicy::record_concurrent_mark_remark_end() {
double end_time_sec = os::elapsedTime();
double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
_concurrent_mark_remark_times_ms->add(elapsed_time_ms);
_cur_mark_stop_world_time_ms += elapsed_time_ms;
_prev_collection_pause_end_ms += elapsed_time_ms;
_mmu_tracker->add_pause(_mark_remark_start_sec, end_time_sec, true);
}
void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
_mark_cleanup_start_sec = os::elapsedTime();
}
void
G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
size_t max_live_bytes) {
record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
record_concurrent_mark_cleanup_end_work2();
}
void
G1CollectorPolicy::
record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
size_t max_live_bytes) {
if (_n_marks < 2) _n_marks++;
if (G1PolicyVerbose > 0)
gclog_or_tty->print_cr("At end of marking, max_live is " SIZE_FORMAT " MB "
" (of " SIZE_FORMAT " MB heap).",
max_live_bytes/M, _g1->capacity()/M);
}
// The important thing about this is that it includes "os::elapsedTime".
void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
double end_time_sec = os::elapsedTime();
double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
_concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
_cur_mark_stop_world_time_ms += elapsed_time_ms;
_prev_collection_pause_end_ms += elapsed_time_ms;
_mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
_num_markings++;
// We did a marking, so reset the "since_last_mark" variables.
double considerConcMarkCost = 1.0;
// If there are available processors, concurrent activity is free...
if (Threads::number_of_non_daemon_threads() * 2 <
os::active_processor_count()) {
considerConcMarkCost = 0.0;
}
_n_pauses_at_mark_end = _n_pauses;
_n_marks_since_last_pause++;
}
void
G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
if (in_young_gc_mode()) {
_should_revert_to_full_young_gcs = false;
_last_full_young_gc = true;
_in_marking_window = false;
if (adaptive_young_list_length())
calculate_young_list_target_length();
}
}
void G1CollectorPolicy::record_concurrent_pause() {
if (_stop_world_start > 0.0) {
double yield_ms = (os::elapsedTime() - _stop_world_start) * 1000.0;
_all_yield_times_ms->add(yield_ms);
}
}
void G1CollectorPolicy::record_concurrent_pause_end() {
}
template<class T>
T sum_of(T* sum_arr, int start, int n, int N) {
T sum = (T)0;
for (int i = 0; i < n; i++) {
int j = (start + i) % N;
sum += sum_arr[j];
}
return sum;
}
void G1CollectorPolicy::print_par_stats(int level,
const char* str,
double* data) {
double min = data[0], max = data[0];
double total = 0.0;
LineBuffer buf(level);
buf.append("[%s (ms):", str);
for (uint i = 0; i < ParallelGCThreads; ++i) {
double val = data[i];
if (val < min)
min = val;
if (val > max)
max = val;
total += val;
buf.append(" %3.1lf", val);
}
buf.append_and_print_cr("");
double avg = total / (double) ParallelGCThreads;
buf.append_and_print_cr(" Avg: %5.1lf, Min: %5.1lf, Max: %5.1lf, Diff: %5.1lf]",
avg, min, max, max - min);
}
void G1CollectorPolicy::print_par_sizes(int level,
const char* str,
double* data) {
double min = data[0], max = data[0];
double total = 0.0;
LineBuffer buf(level);
buf.append("[%s :", str);
for (uint i = 0; i < ParallelGCThreads; ++i) {
double val = data[i];
if (val < min)
min = val;
if (val > max)
max = val;
total += val;
buf.append(" %d", (int) val);
}
buf.append_and_print_cr("");
double avg = total / (double) ParallelGCThreads;
buf.append_and_print_cr(" Sum: %d, Avg: %d, Min: %d, Max: %d, Diff: %d]",
(int)total, (int)avg, (int)min, (int)max, (int)max - (int)min);
}
void G1CollectorPolicy::print_stats (int level,
const char* str,
double value) {
LineBuffer(level).append_and_print_cr("[%s: %5.1lf ms]", str, value);
}
void G1CollectorPolicy::print_stats (int level,
const char* str,
int value) {
LineBuffer(level).append_and_print_cr("[%s: %d]", str, value);
}
double G1CollectorPolicy::avg_value (double* data) {
if (G1CollectedHeap::use_parallel_gc_threads()) {
double ret = 0.0;
for (uint i = 0; i < ParallelGCThreads; ++i)
ret += data[i];
return ret / (double) ParallelGCThreads;
} else {
return data[0];
}
}
double G1CollectorPolicy::max_value (double* data) {
if (G1CollectedHeap::use_parallel_gc_threads()) {
double ret = data[0];
for (uint i = 1; i < ParallelGCThreads; ++i)
if (data[i] > ret)
ret = data[i];
return ret;
} else {
return data[0];
}
}
double G1CollectorPolicy::sum_of_values (double* data) {
if (G1CollectedHeap::use_parallel_gc_threads()) {
double sum = 0.0;
for (uint i = 0; i < ParallelGCThreads; i++)
sum += data[i];
return sum;
} else {
return data[0];
}
}
double G1CollectorPolicy::max_sum (double* data1,
double* data2) {
double ret = data1[0] + data2[0];
if (G1CollectedHeap::use_parallel_gc_threads()) {
for (uint i = 1; i < ParallelGCThreads; ++i) {
double data = data1[i] + data2[i];
if (data > ret)
ret = data;
}
}
return ret;
}
// Anything below that is considered to be zero
#define MIN_TIMER_GRANULARITY 0.0000001
void G1CollectorPolicy::record_collection_pause_end() {
double end_time_sec = os::elapsedTime();
double elapsed_ms = _last_pause_time_ms;
bool parallel = G1CollectedHeap::use_parallel_gc_threads();
size_t rs_size =
_cur_collection_pause_used_regions_at_start - collection_set_size();
size_t cur_used_bytes = _g1->used();
assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
bool last_pause_included_initial_mark = false;
bool update_stats = !_g1->evacuation_failed();
#ifndef PRODUCT
if (G1YoungSurvRateVerbose) {
gclog_or_tty->print_cr("");
_short_lived_surv_rate_group->print();
// do that for any other surv rate groups too
}
#endif // PRODUCT
if (in_young_gc_mode()) {
last_pause_included_initial_mark = during_initial_mark_pause();
if (last_pause_included_initial_mark)
record_concurrent_mark_init_end_pre(0.0);
size_t min_used_targ =
(_g1->capacity() / 100) * InitiatingHeapOccupancyPercent;
if (!_g1->mark_in_progress() && !_last_full_young_gc) {
assert(!last_pause_included_initial_mark, "invariant");
if (cur_used_bytes > min_used_targ &&
cur_used_bytes > _prev_collection_pause_used_at_end_bytes) {
assert(!during_initial_mark_pause(), "we should not see this here");
// Note: this might have already been set, if during the last
// pause we decided to start a cycle but at the beginning of
// this pause we decided to postpone it. That's OK.
set_initiate_conc_mark_if_possible();
}
}
_prev_collection_pause_used_at_end_bytes = cur_used_bytes;
}
_mmu_tracker->add_pause(end_time_sec - elapsed_ms/1000.0,
end_time_sec, false);
guarantee(_cur_collection_pause_used_regions_at_start >=
collection_set_size(),
"Negative RS size?");
// This assert is exempted when we're doing parallel collection pauses,
// because the fragmentation caused by the parallel GC allocation buffers
// can lead to more memory being used during collection than was used
// before. Best leave this out until the fragmentation problem is fixed.
// Pauses in which evacuation failed can also lead to negative
// collections, since no space is reclaimed from a region containing an
// object whose evacuation failed.
// Further, we're now always doing parallel collection. But I'm still
// leaving this here as a placeholder for a more precise assertion later.
// (DLD, 10/05.)
assert((true || parallel) // Always using GC LABs now.
|| _g1->evacuation_failed()
|| _cur_collection_pause_used_at_start_bytes >= cur_used_bytes,
"Negative collection");
size_t freed_bytes =
_cur_collection_pause_used_at_start_bytes - cur_used_bytes;
size_t surviving_bytes = _collection_set_bytes_used_before - freed_bytes;
double survival_fraction =
(double)surviving_bytes/
(double)_collection_set_bytes_used_before;
_n_pauses++;
double ext_root_scan_time = avg_value(_par_last_ext_root_scan_times_ms);
double mark_stack_scan_time = avg_value(_par_last_mark_stack_scan_times_ms);
double update_rs_time = avg_value(_par_last_update_rs_times_ms);
double update_rs_processed_buffers =
sum_of_values(_par_last_update_rs_processed_buffers);
double scan_rs_time = avg_value(_par_last_scan_rs_times_ms);
double obj_copy_time = avg_value(_par_last_obj_copy_times_ms);
double termination_time = avg_value(_par_last_termination_times_ms);
double parallel_known_time = update_rs_time +
ext_root_scan_time +
mark_stack_scan_time +
scan_rs_time +
obj_copy_time +
termination_time;
double parallel_other_time = _cur_collection_par_time_ms - parallel_known_time;
PauseSummary* summary = _summary;
if (update_stats) {
_recent_rs_scan_times_ms->add(scan_rs_time);
_recent_pause_times_ms->add(elapsed_ms);
_recent_rs_sizes->add(rs_size);
MainBodySummary* body_summary = summary->main_body_summary();
guarantee(body_summary != NULL, "should not be null!");
if (_satb_drain_time_set)
body_summary->record_satb_drain_time_ms(_cur_satb_drain_time_ms);
else
body_summary->record_satb_drain_time_ms(0.0);
body_summary->record_ext_root_scan_time_ms(ext_root_scan_time);
body_summary->record_mark_stack_scan_time_ms(mark_stack_scan_time);
body_summary->record_update_rs_time_ms(update_rs_time);
body_summary->record_scan_rs_time_ms(scan_rs_time);
body_summary->record_obj_copy_time_ms(obj_copy_time);
if (parallel) {
body_summary->record_parallel_time_ms(_cur_collection_par_time_ms);
body_summary->record_clear_ct_time_ms(_cur_clear_ct_time_ms);
body_summary->record_termination_time_ms(termination_time);
body_summary->record_parallel_other_time_ms(parallel_other_time);
}
body_summary->record_mark_closure_time_ms(_mark_closure_time_ms);
// We exempt parallel collection from this check because Alloc Buffer
// fragmentation can produce negative collections. Same with evac
// failure.
// Further, we're now always doing parallel collection. But I'm still
// leaving this here as a placeholder for a more precise assertion later.
// (DLD, 10/05.
assert((true || parallel)
|| _g1->evacuation_failed()
|| surviving_bytes <= _collection_set_bytes_used_before,
"Or else negative collection!");
_recent_CS_bytes_used_before->add(_collection_set_bytes_used_before);
_recent_CS_bytes_surviving->add(surviving_bytes);
// this is where we update the allocation rate of the application
double app_time_ms =
(_cur_collection_start_sec * 1000.0 - _prev_collection_pause_end_ms);
if (app_time_ms < MIN_TIMER_GRANULARITY) {
// This usually happens due to the timer not having the required
// granularity. Some Linuxes are the usual culprits.
// We'll just set it to something (arbitrarily) small.
app_time_ms = 1.0;
}
size_t regions_allocated =
(_region_num_young - _prev_region_num_young) +
(_region_num_tenured - _prev_region_num_tenured);
double alloc_rate_ms = (double) regions_allocated / app_time_ms;
_alloc_rate_ms_seq->add(alloc_rate_ms);
_prev_region_num_young = _region_num_young;
_prev_region_num_tenured = _region_num_tenured;
double interval_ms =
(end_time_sec - _recent_prev_end_times_for_all_gcs_sec->oldest()) * 1000.0;
update_recent_gc_times(end_time_sec, elapsed_ms);
_recent_avg_pause_time_ratio = _recent_gc_times_ms->sum()/interval_ms;
if (recent_avg_pause_time_ratio() < 0.0 ||
(recent_avg_pause_time_ratio() - 1.0 > 0.0)) {
#ifndef PRODUCT
// Dump info to allow post-facto debugging
gclog_or_tty->print_cr("recent_avg_pause_time_ratio() out of bounds");
gclog_or_tty->print_cr("-------------------------------------------");
gclog_or_tty->print_cr("Recent GC Times (ms):");
_recent_gc_times_ms->dump();
gclog_or_tty->print_cr("(End Time=%3.3f) Recent GC End Times (s):", end_time_sec);
_recent_prev_end_times_for_all_gcs_sec->dump();
gclog_or_tty->print_cr("GC = %3.3f, Interval = %3.3f, Ratio = %3.3f",
_recent_gc_times_ms->sum(), interval_ms, recent_avg_pause_time_ratio());
// In debug mode, terminate the JVM if the user wants to debug at this point.
assert(!G1FailOnFPError, "Debugging data for CR 6898948 has been dumped above");
#endif // !PRODUCT
// Clip ratio between 0.0 and 1.0, and continue. This will be fixed in
// CR 6902692 by redoing the manner in which the ratio is incrementally computed.
if (_recent_avg_pause_time_ratio < 0.0) {
_recent_avg_pause_time_ratio = 0.0;
} else {
assert(_recent_avg_pause_time_ratio - 1.0 > 0.0, "Ctl-point invariant");
_recent_avg_pause_time_ratio = 1.0;
}
}
}
if (G1PolicyVerbose > 1) {
gclog_or_tty->print_cr(" Recording collection pause(%d)", _n_pauses);
}
if (G1PolicyVerbose > 1) {
gclog_or_tty->print_cr(" ET: %10.6f ms (avg: %10.6f ms)\n"
" ET-RS: %10.6f ms (avg: %10.6f ms)\n"
" |RS|: " SIZE_FORMAT,
elapsed_ms, recent_avg_time_for_pauses_ms(),
scan_rs_time, recent_avg_time_for_rs_scan_ms(),
rs_size);
gclog_or_tty->print_cr(" Used at start: " SIZE_FORMAT"K"
" At end " SIZE_FORMAT "K\n"
" garbage : " SIZE_FORMAT "K"
" of " SIZE_FORMAT "K\n"
" survival : %6.2f%% (%6.2f%% avg)",
_cur_collection_pause_used_at_start_bytes/K,
_g1->used()/K, freed_bytes/K,
_collection_set_bytes_used_before/K,
survival_fraction*100.0,
recent_avg_survival_fraction()*100.0);
gclog_or_tty->print_cr(" Recent %% gc pause time: %6.2f",
recent_avg_pause_time_ratio() * 100.0);
}
double other_time_ms = elapsed_ms;
if (_satb_drain_time_set) {
other_time_ms -= _cur_satb_drain_time_ms;
}
if (parallel) {
other_time_ms -= _cur_collection_par_time_ms + _cur_clear_ct_time_ms;
} else {
other_time_ms -=
update_rs_time +
ext_root_scan_time + mark_stack_scan_time +
scan_rs_time + obj_copy_time;
}
if (PrintGCDetails) {
gclog_or_tty->print_cr("%s, %1.8lf secs]",
(last_pause_included_initial_mark) ? " (initial-mark)" : "",
elapsed_ms / 1000.0);
if (_satb_drain_time_set) {
print_stats(1, "SATB Drain Time", _cur_satb_drain_time_ms);
}
if (_last_satb_drain_processed_buffers >= 0) {
print_stats(2, "Processed Buffers", _last_satb_drain_processed_buffers);
}
if (parallel) {
print_stats(1, "Parallel Time", _cur_collection_par_time_ms);
print_par_stats(2, "GC Worker Start Time", _par_last_gc_worker_start_times_ms);
print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
print_par_sizes(3, "Processed Buffers", _par_last_update_rs_processed_buffers);
print_par_stats(2, "Ext Root Scanning", _par_last_ext_root_scan_times_ms);
print_par_stats(2, "Mark Stack Scanning", _par_last_mark_stack_scan_times_ms);
print_par_stats(2, "Scan RS", _par_last_scan_rs_times_ms);
print_par_stats(2, "Object Copy", _par_last_obj_copy_times_ms);
print_par_stats(2, "Termination", _par_last_termination_times_ms);
print_par_sizes(3, "Termination Attempts", _par_last_termination_attempts);
print_par_stats(2, "GC Worker End Time", _par_last_gc_worker_end_times_ms);
for (int i = 0; i < _parallel_gc_threads; i++) {
_par_last_gc_worker_times_ms[i] = _par_last_gc_worker_end_times_ms[i] - _par_last_gc_worker_start_times_ms[i];
}
print_par_stats(2, "GC Worker Times", _par_last_gc_worker_times_ms);
print_stats(2, "Parallel Other", parallel_other_time);
print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
} else {
print_stats(1, "Update RS", update_rs_time);
print_stats(2, "Processed Buffers",
(int)update_rs_processed_buffers);
print_stats(1, "Ext Root Scanning", ext_root_scan_time);
print_stats(1, "Mark Stack Scanning", mark_stack_scan_time);
print_stats(1, "Scan RS", scan_rs_time);
print_stats(1, "Object Copying", obj_copy_time);
}
#ifndef PRODUCT
print_stats(1, "Cur Clear CC", _cur_clear_cc_time_ms);
print_stats(1, "Cum Clear CC", _cum_clear_cc_time_ms);
print_stats(1, "Min Clear CC", _min_clear_cc_time_ms);
print_stats(1, "Max Clear CC", _max_clear_cc_time_ms);
if (_num_cc_clears > 0) {
print_stats(1, "Avg Clear CC", _cum_clear_cc_time_ms / ((double)_num_cc_clears));
}
#endif
print_stats(1, "Other", other_time_ms);
print_stats(2, "Choose CSet", _recorded_young_cset_choice_time_ms);
for (int i = 0; i < _aux_num; ++i) {
if (_cur_aux_times_set[i]) {
char buffer[96];
sprintf(buffer, "Aux%d", i);
print_stats(1, buffer, _cur_aux_times_ms[i]);
}
}
}
_all_pause_times_ms->add(elapsed_ms);
if (update_stats) {
summary->record_total_time_ms(elapsed_ms);
summary->record_other_time_ms(other_time_ms);
}
for (int i = 0; i < _aux_num; ++i)
if (_cur_aux_times_set[i])
_all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
// Reset marks-between-pauses counter.
_n_marks_since_last_pause = 0;
// Update the efficiency-since-mark vars.
double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
if (elapsed_ms < MIN_TIMER_GRANULARITY) {
// This usually happens due to the timer not having the required
// granularity. Some Linuxes are the usual culprits.
// We'll just set it to something (arbitrarily) small.
proc_ms = 1.0;
}
double cur_efficiency = (double) freed_bytes / proc_ms;
bool new_in_marking_window = _in_marking_window;
bool new_in_marking_window_im = false;
if (during_initial_mark_pause()) {
new_in_marking_window = true;
new_in_marking_window_im = true;
}
if (in_young_gc_mode()) {
if (_last_full_young_gc) {
set_full_young_gcs(false);
_last_full_young_gc = false;
}
if ( !_last_young_gc_full ) {
if ( _should_revert_to_full_young_gcs ||
_known_garbage_ratio < 0.05 ||
(adaptive_young_list_length() &&
(get_gc_eff_factor() * cur_efficiency < predict_young_gc_eff())) ) {
set_full_young_gcs(true);
}
}
_should_revert_to_full_young_gcs = false;
if (_last_young_gc_full && !_during_marking)
_young_gc_eff_seq->add(cur_efficiency);
}
_short_lived_surv_rate_group->start_adding_regions();
// do that for any other surv rate groupsx
// <NEW PREDICTION>
if (update_stats) {
double pause_time_ms = elapsed_ms;
size_t diff = 0;
if (_max_pending_cards >= _pending_cards)
diff = _max_pending_cards - _pending_cards;
_pending_card_diff_seq->add((double) diff);
double cost_per_card_ms = 0.0;
if (_pending_cards > 0) {
cost_per_card_ms = update_rs_time / (double) _pending_cards;
_cost_per_card_ms_seq->add(cost_per_card_ms);
}
size_t cards_scanned = _g1->cards_scanned();
double cost_per_entry_ms = 0.0;
if (cards_scanned > 10) {
cost_per_entry_ms = scan_rs_time / (double) cards_scanned;
if (_last_young_gc_full)
_cost_per_entry_ms_seq->add(cost_per_entry_ms);
else
_partially_young_cost_per_entry_ms_seq->add(cost_per_entry_ms);
}
if (_max_rs_lengths > 0) {
double cards_per_entry_ratio =
(double) cards_scanned / (double) _max_rs_lengths;
if (_last_young_gc_full)
_fully_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
else
_partially_young_cards_per_entry_ratio_seq->add(cards_per_entry_ratio);
}
size_t rs_length_diff = _max_rs_lengths - _recorded_rs_lengths;
if (rs_length_diff >= 0)
_rs_length_diff_seq->add((double) rs_length_diff);
size_t copied_bytes = surviving_bytes;
double cost_per_byte_ms = 0.0;
if (copied_bytes > 0) {
cost_per_byte_ms = obj_copy_time / (double) copied_bytes;
if (_in_marking_window)
_cost_per_byte_ms_during_cm_seq->add(cost_per_byte_ms);
else
_cost_per_byte_ms_seq->add(cost_per_byte_ms);
}
double all_other_time_ms = pause_time_ms -
(update_rs_time + scan_rs_time + obj_copy_time +
_mark_closure_time_ms + termination_time);
double young_other_time_ms = 0.0;
if (_recorded_young_regions > 0) {
young_other_time_ms =
_recorded_young_cset_choice_time_ms +
_recorded_young_free_cset_time_ms;
_young_other_cost_per_region_ms_seq->add(young_other_time_ms /
(double) _recorded_young_regions);
}
double non_young_other_time_ms = 0.0;
if (_recorded_non_young_regions > 0) {
non_young_other_time_ms =
_recorded_non_young_cset_choice_time_ms +
_recorded_non_young_free_cset_time_ms;
_non_young_other_cost_per_region_ms_seq->add(non_young_other_time_ms /
(double) _recorded_non_young_regions);
}
double constant_other_time_ms = all_other_time_ms -
(young_other_time_ms + non_young_other_time_ms);
_constant_other_time_ms_seq->add(constant_other_time_ms);
double survival_ratio = 0.0;
if (_bytes_in_collection_set_before_gc > 0) {
survival_ratio = (double) bytes_in_to_space_during_gc() /
(double) _bytes_in_collection_set_before_gc;
}
_pending_cards_seq->add((double) _pending_cards);
_scanned_cards_seq->add((double) cards_scanned);
_rs_lengths_seq->add((double) _max_rs_lengths);
double expensive_region_limit_ms =
(double) MaxGCPauseMillis - predict_constant_other_time_ms();
if (expensive_region_limit_ms < 0.0) {
// this means that the other time was predicted to be longer than
// than the max pause time
expensive_region_limit_ms = (double) MaxGCPauseMillis;
}
_expensive_region_limit_ms = expensive_region_limit_ms;
if (PREDICTIONS_VERBOSE) {
gclog_or_tty->print_cr("");
gclog_or_tty->print_cr("PREDICTIONS %1.4lf %d "
"REGIONS %d %d %d "
"PENDING_CARDS %d %d "
"CARDS_SCANNED %d %d "
"RS_LENGTHS %d %d "
"RS_UPDATE %1.6lf %1.6lf RS_SCAN %1.6lf %1.6lf "
"SURVIVAL_RATIO %1.6lf %1.6lf "
"OBJECT_COPY %1.6lf %1.6lf OTHER_CONSTANT %1.6lf %1.6lf "
"OTHER_YOUNG %1.6lf %1.6lf "
"OTHER_NON_YOUNG %1.6lf %1.6lf "
"VTIME_DIFF %1.6lf TERMINATION %1.6lf "
"ELAPSED %1.6lf %1.6lf ",
_cur_collection_start_sec,
(!_last_young_gc_full) ? 2 :
(last_pause_included_initial_mark) ? 1 : 0,
_recorded_region_num,
_recorded_young_regions,
_recorded_non_young_regions,
_predicted_pending_cards, _pending_cards,
_predicted_cards_scanned, cards_scanned,
_predicted_rs_lengths, _max_rs_lengths,
_predicted_rs_update_time_ms, update_rs_time,
_predicted_rs_scan_time_ms, scan_rs_time,
_predicted_survival_ratio, survival_ratio,
_predicted_object_copy_time_ms, obj_copy_time,
_predicted_constant_other_time_ms, constant_other_time_ms,
_predicted_young_other_time_ms, young_other_time_ms,
_predicted_non_young_other_time_ms,
non_young_other_time_ms,
_vtime_diff_ms, termination_time,
_predicted_pause_time_ms, elapsed_ms);
}
if (G1PolicyVerbose > 0) {
gclog_or_tty->print_cr("Pause Time, predicted: %1.4lfms (predicted %s), actual: %1.4lfms",
_predicted_pause_time_ms,
(_within_target) ? "within" : "outside",
elapsed_ms);
}
}
_in_marking_window = new_in_marking_window;
_in_marking_window_im = new_in_marking_window_im;
_free_regions_at_end_of_collection = _g1->free_regions();
calculate_young_list_min_length();
calculate_young_list_target_length();
// Note that _mmu_tracker->max_gc_time() returns the time in seconds.
double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
// </NEW PREDICTION>
}
#define EXT_SIZE_FORMAT "%d%s"
#define EXT_SIZE_PARAMS(bytes) \
byte_size_in_proper_unit((bytes)), \
proper_unit_for_byte_size((bytes))
void G1CollectorPolicy::print_heap_transition() {
if (PrintGCDetails) {
YoungList* young_list = _g1->young_list();
size_t eden_bytes = young_list->eden_used_bytes();
size_t survivor_bytes = young_list->survivor_used_bytes();
size_t used_before_gc = _cur_collection_pause_used_at_start_bytes;
size_t used = _g1->used();
size_t capacity = _g1->capacity();
gclog_or_tty->print_cr(
" [Eden: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
"Survivors: "EXT_SIZE_FORMAT"->"EXT_SIZE_FORMAT" "
"Heap: "EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")->"
EXT_SIZE_FORMAT"("EXT_SIZE_FORMAT")]",
EXT_SIZE_PARAMS(_eden_bytes_before_gc),
EXT_SIZE_PARAMS(eden_bytes),
EXT_SIZE_PARAMS(_survivor_bytes_before_gc),
EXT_SIZE_PARAMS(survivor_bytes),
EXT_SIZE_PARAMS(used_before_gc),
EXT_SIZE_PARAMS(_capacity_before_gc),
EXT_SIZE_PARAMS(used),
EXT_SIZE_PARAMS(capacity));
} else if (PrintGC) {
_g1->print_size_transition(gclog_or_tty,
_cur_collection_pause_used_at_start_bytes,
_g1->used(), _g1->capacity());
}
}
// <NEW PREDICTION>
void G1CollectorPolicy::adjust_concurrent_refinement(double update_rs_time,
double update_rs_processed_buffers,
double goal_ms) {
DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
ConcurrentG1Refine *cg1r = G1CollectedHeap::heap()->concurrent_g1_refine();
if (G1UseAdaptiveConcRefinement) {
const int k_gy = 3, k_gr = 6;
const double inc_k = 1.1, dec_k = 0.9;
int g = cg1r->green_zone();
if (update_rs_time > goal_ms) {
g = (int)(g * dec_k); // Can become 0, that's OK. That would mean a mutator-only processing.
} else {
if (update_rs_time < goal_ms && update_rs_processed_buffers > g) {
g = (int)MAX2(g * inc_k, g + 1.0);
}
}
// Change the refinement threads params
cg1r->set_green_zone(g);
cg1r->set_yellow_zone(g * k_gy);
cg1r->set_red_zone(g * k_gr);
cg1r->reinitialize_threads();
int processing_threshold_delta = MAX2((int)(cg1r->green_zone() * sigma()), 1);
int processing_threshold = MIN2(cg1r->green_zone() + processing_threshold_delta,
cg1r->yellow_zone());
// Change the barrier params
dcqs.set_process_completed_threshold(processing_threshold);
dcqs.set_max_completed_queue(cg1r->red_zone());
}
int curr_queue_size = dcqs.completed_buffers_num();
if (curr_queue_size >= cg1r->yellow_zone()) {
dcqs.set_completed_queue_padding(curr_queue_size);
} else {
dcqs.set_completed_queue_padding(0);
}
dcqs.notify_if_necessary();
}
double
G1CollectorPolicy::
predict_young_collection_elapsed_time_ms(size_t adjustment) {
guarantee( adjustment == 0 || adjustment == 1, "invariant" );
G1CollectedHeap* g1h = G1CollectedHeap::heap();
size_t young_num = g1h->young_list()->length();
if (young_num == 0)
return 0.0;
young_num += adjustment;
size_t pending_cards = predict_pending_cards();
size_t rs_lengths = g1h->young_list()->sampled_rs_lengths() +
predict_rs_length_diff();
size_t card_num;
if (full_young_gcs())
card_num = predict_young_card_num(rs_lengths);
else
card_num = predict_non_young_card_num(rs_lengths);
size_t young_byte_size = young_num * HeapRegion::GrainBytes;
double accum_yg_surv_rate =
_short_lived_surv_rate_group->accum_surv_rate(adjustment);
size_t bytes_to_copy =
(size_t) (accum_yg_surv_rate * (double) HeapRegion::GrainBytes);
return
predict_rs_update_time_ms(pending_cards) +
predict_rs_scan_time_ms(card_num) +
predict_object_copy_time_ms(bytes_to_copy) +
predict_young_other_time_ms(young_num) +
predict_constant_other_time_ms();
}
double
G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards) {
size_t rs_length = predict_rs_length_diff();
size_t card_num;
if (full_young_gcs())
card_num = predict_young_card_num(rs_length);
else
card_num = predict_non_young_card_num(rs_length);
return predict_base_elapsed_time_ms(pending_cards, card_num);
}
double
G1CollectorPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
size_t scanned_cards) {
return
predict_rs_update_time_ms(pending_cards) +
predict_rs_scan_time_ms(scanned_cards) +
predict_constant_other_time_ms();
}
double
G1CollectorPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
bool young) {
size_t rs_length = hr->rem_set()->occupied();
size_t card_num;
if (full_young_gcs())
card_num = predict_young_card_num(rs_length);
else
card_num = predict_non_young_card_num(rs_length);
size_t bytes_to_copy = predict_bytes_to_copy(hr);
double region_elapsed_time_ms =
predict_rs_scan_time_ms(card_num) +
predict_object_copy_time_ms(bytes_to_copy);
if (young)
region_elapsed_time_ms += predict_young_other_time_ms(1);
else
region_elapsed_time_ms += predict_non_young_other_time_ms(1);
return region_elapsed_time_ms;
}
size_t
G1CollectorPolicy::predict_bytes_to_copy(HeapRegion* hr) {
size_t bytes_to_copy;
if (hr->is_marked())
bytes_to_copy = hr->max_live_bytes();
else {
guarantee( hr->is_young() && hr->age_in_surv_rate_group() != -1,
"invariant" );
int age = hr->age_in_surv_rate_group();
double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
bytes_to_copy = (size_t) ((double) hr->used() * yg_surv_rate);
}
return bytes_to_copy;
}
void
G1CollectorPolicy::start_recording_regions() {
_recorded_rs_lengths = 0;
_recorded_young_regions = 0;
_recorded_non_young_regions = 0;
#if PREDICTIONS_VERBOSE
_recorded_marked_bytes = 0;
_recorded_young_bytes = 0;
_predicted_bytes_to_copy = 0;
_predicted_rs_lengths = 0;
_predicted_cards_scanned = 0;
#endif // PREDICTIONS_VERBOSE
}
void
G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
#if PREDICTIONS_VERBOSE
if (!young) {
_recorded_marked_bytes += hr->max_live_bytes();
}
_predicted_bytes_to_copy += predict_bytes_to_copy(hr);
#endif // PREDICTIONS_VERBOSE
size_t rs_length = hr->rem_set()->occupied();
_recorded_rs_lengths += rs_length;
}
void
G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
assert(!hr->is_young(), "should not call this");
++_recorded_non_young_regions;
record_cset_region_info(hr, false);
}
void
G1CollectorPolicy::set_recorded_young_regions(size_t n_regions) {
_recorded_young_regions = n_regions;
}
void G1CollectorPolicy::set_recorded_young_bytes(size_t bytes) {
#if PREDICTIONS_VERBOSE
_recorded_young_bytes = bytes;
#endif // PREDICTIONS_VERBOSE
}
void G1CollectorPolicy::set_recorded_rs_lengths(size_t rs_lengths) {
_recorded_rs_lengths = rs_lengths;
}
void G1CollectorPolicy::set_predicted_bytes_to_copy(size_t bytes) {
_predicted_bytes_to_copy = bytes;
}
void
G1CollectorPolicy::end_recording_regions() {
// The _predicted_pause_time_ms field is referenced in code
// not under PREDICTIONS_VERBOSE. Let's initialize it.
_predicted_pause_time_ms = -1.0;
#if PREDICTIONS_VERBOSE
_predicted_pending_cards = predict_pending_cards();
_predicted_rs_lengths = _recorded_rs_lengths + predict_rs_length_diff();
if (full_young_gcs())
_predicted_cards_scanned += predict_young_card_num(_predicted_rs_lengths);
else
_predicted_cards_scanned +=
predict_non_young_card_num(_predicted_rs_lengths);
_recorded_region_num = _recorded_young_regions + _recorded_non_young_regions;
_predicted_rs_update_time_ms =
predict_rs_update_time_ms(_g1->pending_card_num());
_predicted_rs_scan_time_ms =
predict_rs_scan_time_ms(_predicted_cards_scanned);
_predicted_object_copy_time_ms =
predict_object_copy_time_ms(_predicted_bytes_to_copy);
_predicted_constant_other_time_ms =
predict_constant_other_time_ms();
_predicted_young_other_time_ms =
predict_young_other_time_ms(_recorded_young_regions);
_predicted_non_young_other_time_ms =
predict_non_young_other_time_ms(_recorded_non_young_regions);
_predicted_pause_time_ms =
_predicted_rs_update_time_ms +
_predicted_rs_scan_time_ms +
_predicted_object_copy_time_ms +
_predicted_constant_other_time_ms +
_predicted_young_other_time_ms +
_predicted_non_young_other_time_ms;
#endif // PREDICTIONS_VERBOSE
}
void G1CollectorPolicy::check_if_region_is_too_expensive(double
predicted_time_ms) {
// I don't think we need to do this when in young GC mode since
// marking will be initiated next time we hit the soft limit anyway...
if (predicted_time_ms > _expensive_region_limit_ms) {
if (!in_young_gc_mode()) {
set_full_young_gcs(true);
// We might want to do something different here. However,
// right now we don't support the non-generational G1 mode
// (and in fact we are planning to remove the associated code,
// see CR 6814390). So, let's leave it as is and this will be
// removed some time in the future
ShouldNotReachHere();
set_during_initial_mark_pause();
} else
// no point in doing another partial one
_should_revert_to_full_young_gcs = true;
}
}
// </NEW PREDICTION>
void G1CollectorPolicy::update_recent_gc_times(double end_time_sec,
double elapsed_ms) {
_recent_gc_times_ms->add(elapsed_ms);
_recent_prev_end_times_for_all_gcs_sec->add(end_time_sec);
_prev_collection_pause_end_ms = end_time_sec * 1000.0;
}
double G1CollectorPolicy::recent_avg_time_for_pauses_ms() {
if (_recent_pause_times_ms->num() == 0) {
return (double) MaxGCPauseMillis;
}
return _recent_pause_times_ms->avg();
}
double G1CollectorPolicy::recent_avg_time_for_rs_scan_ms() {
if (_recent_rs_scan_times_ms->num() == 0) {
return (double)MaxGCPauseMillis/3.0;
}
return _recent_rs_scan_times_ms->avg();
}
int G1CollectorPolicy::number_of_recent_gcs() {
assert(_recent_rs_scan_times_ms->num() ==
_recent_pause_times_ms->num(), "Sequence out of sync");
assert(_recent_pause_times_ms->num() ==
_recent_CS_bytes_used_before->num(), "Sequence out of sync");
assert(_recent_CS_bytes_used_before->num() ==
_recent_CS_bytes_surviving->num(), "Sequence out of sync");
return _recent_pause_times_ms->num();
}
double G1CollectorPolicy::recent_avg_survival_fraction() {
return recent_avg_survival_fraction_work(_recent_CS_bytes_surviving,
_recent_CS_bytes_used_before);
}
double G1CollectorPolicy::last_survival_fraction() {
return last_survival_fraction_work(_recent_CS_bytes_surviving,
_recent_CS_bytes_used_before);
}
double
G1CollectorPolicy::recent_avg_survival_fraction_work(TruncatedSeq* surviving,
TruncatedSeq* before) {
assert(surviving->num() == before->num(), "Sequence out of sync");
if (before->sum() > 0.0) {
double recent_survival_rate = surviving->sum() / before->sum();
// We exempt parallel collection from this check because Alloc Buffer
// fragmentation can produce negative collections.
// Further, we're now always doing parallel collection. But I'm still
// leaving this here as a placeholder for a more precise assertion later.
// (DLD, 10/05.)
assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
_g1->evacuation_failed() ||
recent_survival_rate <= 1.0, "Or bad frac");
return recent_survival_rate;
} else {
return 1.0; // Be conservative.
}
}
double
G1CollectorPolicy::last_survival_fraction_work(TruncatedSeq* surviving,
TruncatedSeq* before) {
assert(surviving->num() == before->num(), "Sequence out of sync");
if (surviving->num() > 0 && before->last() > 0.0) {
double last_survival_rate = surviving->last() / before->last();
// We exempt parallel collection from this check because Alloc Buffer
// fragmentation can produce negative collections.
// Further, we're now always doing parallel collection. But I'm still
// leaving this here as a placeholder for a more precise assertion later.
// (DLD, 10/05.)
assert((true || G1CollectedHeap::use_parallel_gc_threads()) ||
last_survival_rate <= 1.0, "Or bad frac");
return last_survival_rate;
} else {
return 1.0;
}
}
static const int survival_min_obs = 5;
static double survival_min_obs_limits[] = { 0.9, 0.7, 0.5, 0.3, 0.1 };
static const double min_survival_rate = 0.1;
double
G1CollectorPolicy::conservative_avg_survival_fraction_work(double avg,
double latest) {
double res = avg;
if (number_of_recent_gcs() < survival_min_obs) {
res = MAX2(res, survival_min_obs_limits[number_of_recent_gcs()]);
}
res = MAX2(res, latest);
res = MAX2(res, min_survival_rate);
// In the parallel case, LAB fragmentation can produce "negative
// collections"; so can evac failure. Cap at 1.0
res = MIN2(res, 1.0);
return res;
}
size_t G1CollectorPolicy::expansion_amount() {
if ((recent_avg_pause_time_ratio() * 100.0) > _gc_overhead_perc) {
// We will double the existing space, or take
// G1ExpandByPercentOfAvailable % of the available expansion
// space, whichever is smaller, bounded below by a minimum
// expansion (unless that's all that's left.)
const size_t min_expand_bytes = 1*M;
size_t reserved_bytes = _g1->max_capacity();
size_t committed_bytes = _g1->capacity();
size_t uncommitted_bytes = reserved_bytes - committed_bytes;
size_t expand_bytes;
size_t expand_bytes_via_pct =
uncommitted_bytes * G1ExpandByPercentOfAvailable / 100;
expand_bytes = MIN2(expand_bytes_via_pct, committed_bytes);
expand_bytes = MAX2(expand_bytes, min_expand_bytes);
expand_bytes = MIN2(expand_bytes, uncommitted_bytes);
if (G1PolicyVerbose > 1) {
gclog_or_tty->print("Decided to expand: ratio = %5.2f, "
"committed = %d%s, uncommited = %d%s, via pct = %d%s.\n"
" Answer = %d.\n",
recent_avg_pause_time_ratio(),
byte_size_in_proper_unit(committed_bytes),
proper_unit_for_byte_size(committed_bytes),
byte_size_in_proper_unit(uncommitted_bytes),
proper_unit_for_byte_size(uncommitted_bytes),
byte_size_in_proper_unit(expand_bytes_via_pct),
proper_unit_for_byte_size(expand_bytes_via_pct),
byte_size_in_proper_unit(expand_bytes),
proper_unit_for_byte_size(expand_bytes));
}
return expand_bytes;
} else {
return 0;
}
}
void G1CollectorPolicy::note_start_of_mark_thread() {
_mark_thread_startup_sec = os::elapsedTime();
}
class CountCSClosure: public HeapRegionClosure {
G1CollectorPolicy* _g1_policy;
public:
CountCSClosure(G1CollectorPolicy* g1_policy) :
_g1_policy(g1_policy) {}
bool doHeapRegion(HeapRegion* r) {
_g1_policy->_bytes_in_collection_set_before_gc += r->used();
return false;
}
};
void G1CollectorPolicy::count_CS_bytes_used() {
CountCSClosure cs_closure(this);
_g1->collection_set_iterate(&cs_closure);
}
void G1CollectorPolicy::print_summary (int level,
const char* str,
NumberSeq* seq) const {
double sum = seq->sum();
LineBuffer(level + 1).append_and_print_cr("%-24s = %8.2lf s (avg = %8.2lf ms)",
str, sum / 1000.0, seq->avg());
}
void G1CollectorPolicy::print_summary_sd (int level,
const char* str,
NumberSeq* seq) const {
print_summary(level, str, seq);
LineBuffer(level + 6).append_and_print_cr("(num = %5d, std dev = %8.2lf ms, max = %8.2lf ms)",
seq->num(), seq->sd(), seq->maximum());
}
void G1CollectorPolicy::check_other_times(int level,
NumberSeq* other_times_ms,
NumberSeq* calc_other_times_ms) const {
bool should_print = false;
LineBuffer buf(level + 2);
double max_sum = MAX2(fabs(other_times_ms->sum()),
fabs(calc_other_times_ms->sum()));
double min_sum = MIN2(fabs(other_times_ms->sum()),
fabs(calc_other_times_ms->sum()));
double sum_ratio = max_sum / min_sum;
if (sum_ratio > 1.1) {
should_print = true;
buf.append_and_print_cr("## CALCULATED OTHER SUM DOESN'T MATCH RECORDED ###");
}
double max_avg = MAX2(fabs(other_times_ms->avg()),
fabs(calc_other_times_ms->avg()));
double min_avg = MIN2(fabs(other_times_ms->avg()),
fabs(calc_other_times_ms->avg()));
double avg_ratio = max_avg / min_avg;
if (avg_ratio > 1.1) {
should_print = true;
buf.append_and_print_cr("## CALCULATED OTHER AVG DOESN'T MATCH RECORDED ###");
}
if (other_times_ms->sum() < -0.01) {
buf.append_and_print_cr("## RECORDED OTHER SUM IS NEGATIVE ###");
}
if (other_times_ms->avg() < -0.01) {
buf.append_and_print_cr("## RECORDED OTHER AVG IS NEGATIVE ###");
}
if (calc_other_times_ms->sum() < -0.01) {
should_print = true;
buf.append_and_print_cr("## CALCULATED OTHER SUM IS NEGATIVE ###");
}
if (calc_other_times_ms->avg() < -0.01) {
should_print = true;
buf.append_and_print_cr("## CALCULATED OTHER AVG IS NEGATIVE ###");
}
if (should_print)
print_summary(level, "Other(Calc)", calc_other_times_ms);
}
void G1CollectorPolicy::print_summary(PauseSummary* summary) const {
bool parallel = G1CollectedHeap::use_parallel_gc_threads();
MainBodySummary* body_summary = summary->main_body_summary();
if (summary->get_total_seq()->num() > 0) {
print_summary_sd(0, "Evacuation Pauses", summary->get_total_seq());
if (body_summary != NULL) {
print_summary(1, "SATB Drain", body_summary->get_satb_drain_seq());
if (parallel) {
print_summary(1, "Parallel Time", body_summary->get_parallel_seq());
print_summary(2, "Update RS", body_summary->get_update_rs_seq());
print_summary(2, "Ext Root Scanning",
body_summary->get_ext_root_scan_seq());
print_summary(2, "Mark Stack Scanning",
body_summary->get_mark_stack_scan_seq());
print_summary(2, "Scan RS", body_summary->get_scan_rs_seq());
print_summary(2, "Object Copy", body_summary->get_obj_copy_seq());
print_summary(2, "Termination", body_summary->get_termination_seq());
print_summary(2, "Other", body_summary->get_parallel_other_seq());
{
NumberSeq* other_parts[] = {
body_summary->get_update_rs_seq(),
body_summary->get_ext_root_scan_seq(),
body_summary->get_mark_stack_scan_seq(),
body_summary->get_scan_rs_seq(),
body_summary->get_obj_copy_seq(),
body_summary->get_termination_seq()
};
NumberSeq calc_other_times_ms(body_summary->get_parallel_seq(),
6, other_parts);
check_other_times(2, body_summary->get_parallel_other_seq(),
&calc_other_times_ms);
}
print_summary(1, "Mark Closure", body_summary->get_mark_closure_seq());
print_summary(1, "Clear CT", body_summary->get_clear_ct_seq());
} else {
print_summary(1, "Update RS", body_summary->get_update_rs_seq());
print_summary(1, "Ext Root Scanning",
body_summary->get_ext_root_scan_seq());
print_summary(1, "Mark Stack Scanning",
body_summary->get_mark_stack_scan_seq());
print_summary(1, "Scan RS", body_summary->get_scan_rs_seq());
print_summary(1, "Object Copy", body_summary->get_obj_copy_seq());
}
}
print_summary(1, "Other", summary->get_other_seq());
{
if (body_summary != NULL) {
NumberSeq calc_other_times_ms;
if (parallel) {
// parallel
NumberSeq* other_parts[] = {
body_summary->get_satb_drain_seq(),
body_summary->get_parallel_seq(),
body_summary->get_clear_ct_seq()
};
calc_other_times_ms = NumberSeq(summary->get_total_seq(),
3, other_parts);
} else {
// serial
NumberSeq* other_parts[] = {
body_summary->get_satb_drain_seq(),
body_summary->get_update_rs_seq(),
body_summary->get_ext_root_scan_seq(),
body_summary->get_mark_stack_scan_seq(),
body_summary->get_scan_rs_seq(),
body_summary->get_obj_copy_seq()
};
calc_other_times_ms = NumberSeq(summary->get_total_seq(),
6, other_parts);
}
check_other_times(1, summary->get_other_seq(), &calc_other_times_ms);
}
}
} else {
LineBuffer(1).append_and_print_cr("none");
}
LineBuffer(0).append_and_print_cr("");
}
void G1CollectorPolicy::print_tracing_info() const {
if (TraceGen0Time) {
gclog_or_tty->print_cr("ALL PAUSES");
print_summary_sd(0, "Total", _all_pause_times_ms);
gclog_or_tty->print_cr("");
gclog_or_tty->print_cr("");
gclog_or_tty->print_cr(" Full Young GC Pauses: %8d", _full_young_pause_num);
gclog_or_tty->print_cr(" Partial Young GC Pauses: %8d", _partial_young_pause_num);
gclog_or_tty->print_cr("");
gclog_or_tty->print_cr("EVACUATION PAUSES");
print_summary(_summary);
gclog_or_tty->print_cr("MISC");
print_summary_sd(0, "Stop World", _all_stop_world_times_ms);
print_summary_sd(0, "Yields", _all_yield_times_ms);
for (int i = 0; i < _aux_num; ++i) {
if (_all_aux_times_ms[i].num() > 0) {
char buffer[96];
sprintf(buffer, "Aux%d", i);
print_summary_sd(0, buffer, &_all_aux_times_ms[i]);
}
}
size_t all_region_num = _region_num_young + _region_num_tenured;
gclog_or_tty->print_cr(" New Regions %8d, Young %8d (%6.2lf%%), "
"Tenured %8d (%6.2lf%%)",
all_region_num,
_region_num_young,
(double) _region_num_young / (double) all_region_num * 100.0,
_region_num_tenured,
(double) _region_num_tenured / (double) all_region_num * 100.0);
}
if (TraceGen1Time) {
if (_all_full_gc_times_ms->num() > 0) {
gclog_or_tty->print("\n%4d full_gcs: total time = %8.2f s",
_all_full_gc_times_ms->num(),
_all_full_gc_times_ms->sum() / 1000.0);
gclog_or_tty->print_cr(" (avg = %8.2fms).", _all_full_gc_times_ms->avg());
gclog_or_tty->print_cr(" [std. dev = %8.2f ms, max = %8.2f ms]",
_all_full_gc_times_ms->sd(),
_all_full_gc_times_ms->maximum());
}
}
}
void G1CollectorPolicy::print_yg_surv_rate_info() const {
#ifndef PRODUCT
_short_lived_surv_rate_group->print_surv_rate_summary();
// add this call for any other surv rate groups
#endif // PRODUCT
}
void
G1CollectorPolicy::update_region_num(bool young) {
if (young) {
++_region_num_young;
} else {
++_region_num_tenured;
}
}
#ifndef PRODUCT
// for debugging, bit of a hack...
static char*
region_num_to_mbs(int length) {
static char buffer[64];
double bytes = (double) (length * HeapRegion::GrainBytes);
double mbs = bytes / (double) (1024 * 1024);
sprintf(buffer, "%7.2lfMB", mbs);
return buffer;
}
#endif // PRODUCT
size_t G1CollectorPolicy::max_regions(int purpose) {
switch (purpose) {
case GCAllocForSurvived:
return _max_survivor_regions;
case GCAllocForTenured:
return REGIONS_UNLIMITED;
default:
ShouldNotReachHere();
return REGIONS_UNLIMITED;
};
}
void G1CollectorPolicy::calculate_max_gc_locker_expansion() {
size_t expansion_region_num = 0;
if (GCLockerEdenExpansionPercent > 0) {
double perc = (double) GCLockerEdenExpansionPercent / 100.0;
double expansion_region_num_d = perc * (double) _young_list_target_length;
// We use ceiling so that if expansion_region_num_d is > 0.0 (but
// less than 1.0) we'll get 1.
expansion_region_num = (size_t) ceil(expansion_region_num_d);
} else {
assert(expansion_region_num == 0, "sanity");
}
_young_list_max_length = _young_list_target_length + expansion_region_num;
assert(_young_list_target_length <= _young_list_max_length, "post-condition");
}
// Calculates survivor space parameters.
void G1CollectorPolicy::calculate_survivors_policy()
{
if (G1FixedSurvivorSpaceSize == 0) {
_max_survivor_regions = _young_list_target_length / SurvivorRatio;
} else {
_max_survivor_regions = G1FixedSurvivorSpaceSize / HeapRegion::GrainBytes;
}
if (G1FixedTenuringThreshold) {
_tenuring_threshold = MaxTenuringThreshold;
} else {
_tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
HeapRegion::GrainWords * _max_survivor_regions);
}
}
#ifndef PRODUCT
class HRSortIndexIsOKClosure: public HeapRegionClosure {
CollectionSetChooser* _chooser;
public:
HRSortIndexIsOKClosure(CollectionSetChooser* chooser) :
_chooser(chooser) {}
bool doHeapRegion(HeapRegion* r) {
if (!r->continuesHumongous()) {
assert(_chooser->regionProperlyOrdered(r), "Ought to be.");
}
return false;
}
};
bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
HRSortIndexIsOKClosure cl(_collectionSetChooser);
_g1->heap_region_iterate(&cl);
return true;
}
#endif
bool
G1CollectorPolicy::force_initial_mark_if_outside_cycle() {
bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
if (!during_cycle) {
set_initiate_conc_mark_if_possible();
return true;
} else {
return false;
}
}
void
G1CollectorPolicy::decide_on_conc_mark_initiation() {
// We are about to decide on whether this pause will be an
// initial-mark pause.
// First, during_initial_mark_pause() should not be already set. We
// will set it here if we have to. However, it should be cleared by
// the end of the pause (it's only set for the duration of an
// initial-mark pause).
assert(!during_initial_mark_pause(), "pre-condition");
if (initiate_conc_mark_if_possible()) {
// We had noticed on a previous pause that the heap occupancy has
// gone over the initiating threshold and we should start a
// concurrent marking cycle. So we might initiate one.
bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
if (!during_cycle) {
// The concurrent marking thread is not "during a cycle", i.e.,
// it has completed the last one. So we can go ahead and
// initiate a new cycle.
set_during_initial_mark_pause();
// And we can now clear initiate_conc_mark_if_possible() as
// we've already acted on it.
clear_initiate_conc_mark_if_possible();
} else {
// The concurrent marking thread is still finishing up the
// previous cycle. If we start one right now the two cycles
// overlap. In particular, the concurrent marking thread might
// be in the process of clearing the next marking bitmap (which
// we will use for the next cycle if we start one). Starting a
// cycle now will be bad given that parts of the marking
// information might get cleared by the marking thread. And we
// cannot wait for the marking thread to finish the cycle as it
// periodically yields while clearing the next marking bitmap
// and, if it's in a yield point, it's waiting for us to
// finish. So, at this point we will not start a cycle and we'll
// let the concurrent marking thread complete the last one.
}
}
}
void
G1CollectorPolicy_BestRegionsFirst::
record_collection_pause_start(double start_time_sec, size_t start_used) {
G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
}
class KnownGarbageClosure: public HeapRegionClosure {
CollectionSetChooser* _hrSorted;
public:
KnownGarbageClosure(CollectionSetChooser* hrSorted) :
_hrSorted(hrSorted)
{}
bool doHeapRegion(HeapRegion* r) {
// We only include humongous regions in collection
// sets when concurrent mark shows that their contained object is
// unreachable.
// Do we have any marking information for this region?
if (r->is_marked()) {
// We don't include humongous regions in collection
// sets because we collect them immediately at the end of a marking
// cycle. We also don't include young regions because we *must*
// include them in the next collection pause.
if (!r->isHumongous() && !r->is_young()) {
_hrSorted->addMarkedHeapRegion(r);
}
}
return false;
}
};
class ParKnownGarbageHRClosure: public HeapRegionClosure {
CollectionSetChooser* _hrSorted;
jint _marked_regions_added;
jint _chunk_size;
jint _cur_chunk_idx;
jint _cur_chunk_end; // Cur chunk [_cur_chunk_idx, _cur_chunk_end)
int _worker;
int _invokes;
void get_new_chunk() {
_cur_chunk_idx = _hrSorted->getParMarkedHeapRegionChunk(_chunk_size);
_cur_chunk_end = _cur_chunk_idx + _chunk_size;
}
void add_region(HeapRegion* r) {
if (_cur_chunk_idx == _cur_chunk_end) {
get_new_chunk();
}
assert(_cur_chunk_idx < _cur_chunk_end, "postcondition");
_hrSorted->setMarkedHeapRegion(_cur_chunk_idx, r);
_marked_regions_added++;
_cur_chunk_idx++;
}
public:
ParKnownGarbageHRClosure(CollectionSetChooser* hrSorted,
jint chunk_size,
int worker) :
_hrSorted(hrSorted), _chunk_size(chunk_size), _worker(worker),
_marked_regions_added(0), _cur_chunk_idx(0), _cur_chunk_end(0),
_invokes(0)
{}
bool doHeapRegion(HeapRegion* r) {
// We only include humongous regions in collection
// sets when concurrent mark shows that their contained object is
// unreachable.
_invokes++;
// Do we have any marking information for this region?
if (r->is_marked()) {
// We don't include humongous regions in collection
// sets because we collect them immediately at the end of a marking
// cycle.
// We also do not include young regions in collection sets
if (!r->isHumongous() && !r->is_young()) {
add_region(r);
}
}
return false;
}
jint marked_regions_added() { return _marked_regions_added; }
int invokes() { return _invokes; }
};
class ParKnownGarbageTask: public AbstractGangTask {
CollectionSetChooser* _hrSorted;
jint _chunk_size;
G1CollectedHeap* _g1;
public:
ParKnownGarbageTask(CollectionSetChooser* hrSorted, jint chunk_size) :
AbstractGangTask("ParKnownGarbageTask"),
_hrSorted(hrSorted), _chunk_size(chunk_size),
_g1(G1CollectedHeap::heap())
{}
void work(int i) {
ParKnownGarbageHRClosure parKnownGarbageCl(_hrSorted, _chunk_size, i);
// Back to zero for the claim value.
_g1->heap_region_par_iterate_chunked(&parKnownGarbageCl, i,
HeapRegion::InitialClaimValue);
jint regions_added = parKnownGarbageCl.marked_regions_added();
_hrSorted->incNumMarkedHeapRegions(regions_added);
if (G1PrintParCleanupStats) {
gclog_or_tty->print_cr(" Thread %d called %d times, added %d regions to list.",
i, parKnownGarbageCl.invokes(), regions_added);
}
}
};
void
G1CollectorPolicy_BestRegionsFirst::
record_concurrent_mark_cleanup_end(size_t freed_bytes,
size_t max_live_bytes) {
double start;
if (G1PrintParCleanupStats) start = os::elapsedTime();
record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
_collectionSetChooser->clearMarkedHeapRegions();
double clear_marked_end;
if (G1PrintParCleanupStats) {
clear_marked_end = os::elapsedTime();
gclog_or_tty->print_cr(" clear marked regions + work1: %8.3f ms.",
(clear_marked_end - start)*1000.0);
}
if (G1CollectedHeap::use_parallel_gc_threads()) {
const size_t OverpartitionFactor = 4;
const size_t MinWorkUnit = 8;
const size_t WorkUnit =
MAX2(_g1->n_regions() / (ParallelGCThreads * OverpartitionFactor),
MinWorkUnit);
_collectionSetChooser->prepareForAddMarkedHeapRegionsPar(_g1->n_regions(),
WorkUnit);
ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
(int) WorkUnit);
_g1->workers()->run_task(&parKnownGarbageTask);
assert(_g1->check_heap_region_claim_values(HeapRegion::InitialClaimValue),
"sanity check");
} else {
KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
_g1->heap_region_iterate(&knownGarbagecl);
}
double known_garbage_end;
if (G1PrintParCleanupStats) {
known_garbage_end = os::elapsedTime();
gclog_or_tty->print_cr(" compute known garbage: %8.3f ms.",
(known_garbage_end - clear_marked_end)*1000.0);
}
_collectionSetChooser->sortMarkedHeapRegions();
double sort_end;
if (G1PrintParCleanupStats) {
sort_end = os::elapsedTime();
gclog_or_tty->print_cr(" sorting: %8.3f ms.",
(sort_end - known_garbage_end)*1000.0);
}
record_concurrent_mark_cleanup_end_work2();
double work2_end;
if (G1PrintParCleanupStats) {
work2_end = os::elapsedTime();
gclog_or_tty->print_cr(" work2: %8.3f ms.",
(work2_end - sort_end)*1000.0);
}
}
// Add the heap region at the head of the non-incremental collection set
void G1CollectorPolicy::
add_to_collection_set(HeapRegion* hr) {
assert(_inc_cset_build_state == Active, "Precondition");
assert(!hr->is_young(), "non-incremental add of young region");
if (_g1->mark_in_progress())
_g1->concurrent_mark()->registerCSetRegion(hr);
assert(!hr->in_collection_set(), "should not already be in the CSet");
hr->set_in_collection_set(true);
hr->set_next_in_collection_set(_collection_set);
_collection_set = hr;
_collection_set_size++;
_collection_set_bytes_used_before += hr->used();
_g1->register_region_with_in_cset_fast_test(hr);
}
// Initialize the per-collection-set information
void G1CollectorPolicy::start_incremental_cset_building() {
assert(_inc_cset_build_state == Inactive, "Precondition");
_inc_cset_head = NULL;
_inc_cset_tail = NULL;
_inc_cset_size = 0;
_inc_cset_bytes_used_before = 0;
if (in_young_gc_mode()) {
_inc_cset_young_index = 0;
}
_inc_cset_max_finger = 0;
_inc_cset_recorded_young_bytes = 0;
_inc_cset_recorded_rs_lengths = 0;
_inc_cset_predicted_elapsed_time_ms = 0;
_inc_cset_predicted_bytes_to_copy = 0;
_inc_cset_build_state = Active;
}
void G1CollectorPolicy::add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length) {
// This routine is used when:
// * adding survivor regions to the incremental cset at the end of an
// evacuation pause,
// * adding the current allocation region to the incremental cset
// when it is retired, and
// * updating existing policy information for a region in the
// incremental cset via young list RSet sampling.
// Therefore this routine may be called at a safepoint by the
// VM thread, or in-between safepoints by mutator threads (when
// retiring the current allocation region) or a concurrent
// refine thread (RSet sampling).
double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr, true);
size_t used_bytes = hr->used();
_inc_cset_recorded_rs_lengths += rs_length;
_inc_cset_predicted_elapsed_time_ms += region_elapsed_time_ms;
_inc_cset_bytes_used_before += used_bytes;
// Cache the values we have added to the aggregated informtion
// in the heap region in case we have to remove this region from
// the incremental collection set, or it is updated by the
// rset sampling code
hr->set_recorded_rs_length(rs_length);
hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
#if PREDICTIONS_VERBOSE
size_t bytes_to_copy = predict_bytes_to_copy(hr);
_inc_cset_predicted_bytes_to_copy += bytes_to_copy;
// Record the number of bytes used in this region
_inc_cset_recorded_young_bytes += used_bytes;
// Cache the values we have added to the aggregated informtion
// in the heap region in case we have to remove this region from
// the incremental collection set, or it is updated by the
// rset sampling code
hr->set_predicted_bytes_to_copy(bytes_to_copy);
#endif // PREDICTIONS_VERBOSE
}
void G1CollectorPolicy::remove_from_incremental_cset_info(HeapRegion* hr) {
// This routine is currently only called as part of the updating of
// existing policy information for regions in the incremental cset that
// is performed by the concurrent refine thread(s) as part of young list
// RSet sampling. Therefore we should not be at a safepoint.
assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
assert(hr->is_young(), "it should be");
size_t used_bytes = hr->used();
size_t old_rs_length = hr->recorded_rs_length();
double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
// Subtract the old recorded/predicted policy information for
// the given heap region from the collection set info.
_inc_cset_recorded_rs_lengths -= old_rs_length;
_inc_cset_predicted_elapsed_time_ms -= old_elapsed_time_ms;
_inc_cset_bytes_used_before -= used_bytes;
// Clear the values cached in the heap region
hr->set_recorded_rs_length(0);
hr->set_predicted_elapsed_time_ms(0);
#if PREDICTIONS_VERBOSE
size_t old_predicted_bytes_to_copy = hr->predicted_bytes_to_copy();
_inc_cset_predicted_bytes_to_copy -= old_predicted_bytes_to_copy;
// Subtract the number of bytes used in this region
_inc_cset_recorded_young_bytes -= used_bytes;
// Clear the values cached in the heap region
hr->set_predicted_bytes_to_copy(0);
#endif // PREDICTIONS_VERBOSE
}
void G1CollectorPolicy::update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length) {
// Update the collection set information that is dependent on the new RS length
assert(hr->is_young(), "Precondition");
remove_from_incremental_cset_info(hr);
add_to_incremental_cset_info(hr, new_rs_length);
}
void G1CollectorPolicy::add_region_to_incremental_cset_common(HeapRegion* hr) {
assert( hr->is_young(), "invariant");
assert( hr->young_index_in_cset() == -1, "invariant" );
assert(_inc_cset_build_state == Active, "Precondition");
// We need to clear and set the cached recorded/cached collection set
// information in the heap region here (before the region gets added
// to the collection set). An individual heap region's cached values
// are calculated, aggregated with the policy collection set info,
// and cached in the heap region here (initially) and (subsequently)
// by the Young List sampling code.
size_t rs_length = hr->rem_set()->occupied();
add_to_incremental_cset_info(hr, rs_length);
HeapWord* hr_end = hr->end();
_inc_cset_max_finger = MAX2(_inc_cset_max_finger, hr_end);
assert(!hr->in_collection_set(), "invariant");
hr->set_in_collection_set(true);
assert( hr->next_in_collection_set() == NULL, "invariant");
_inc_cset_size++;
_g1->register_region_with_in_cset_fast_test(hr);
hr->set_young_index_in_cset((int) _inc_cset_young_index);
++_inc_cset_young_index;
}
// Add the region at the RHS of the incremental cset
void G1CollectorPolicy::add_region_to_incremental_cset_rhs(HeapRegion* hr) {
// We should only ever be appending survivors at the end of a pause
assert( hr->is_survivor(), "Logic");
// Do the 'common' stuff
add_region_to_incremental_cset_common(hr);
// Now add the region at the right hand side
if (_inc_cset_tail == NULL) {
assert(_inc_cset_head == NULL, "invariant");
_inc_cset_head = hr;
} else {
_inc_cset_tail->set_next_in_collection_set(hr);
}
_inc_cset_tail = hr;
}
// Add the region to the LHS of the incremental cset
void G1CollectorPolicy::add_region_to_incremental_cset_lhs(HeapRegion* hr) {
// Survivors should be added to the RHS at the end of a pause
assert(!hr->is_survivor(), "Logic");
// Do the 'common' stuff
add_region_to_incremental_cset_common(hr);
// Add the region at the left hand side
hr->set_next_in_collection_set(_inc_cset_head);
if (_inc_cset_head == NULL) {
assert(_inc_cset_tail == NULL, "Invariant");
_inc_cset_tail = hr;
}
_inc_cset_head = hr;
}
#ifndef PRODUCT
void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream* st) {
assert(list_head == inc_cset_head() || list_head == collection_set(), "must be");
st->print_cr("\nCollection_set:");
HeapRegion* csr = list_head;
while (csr != NULL) {
HeapRegion* next = csr->next_in_collection_set();
assert(csr->in_collection_set(), "bad CS");
st->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
"age: %4d, y: %d, surv: %d",
csr->bottom(), csr->end(),
csr->top(),
csr->prev_top_at_mark_start(),
csr->next_top_at_mark_start(),
csr->top_at_conc_mark_count(),
csr->age_in_surv_rate_group_cond(),
csr->is_young(),
csr->is_survivor());
csr = next;
}
}
#endif // !PRODUCT
void
G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
double target_pause_time_ms) {
// Set this here - in case we're not doing young collections.
double non_young_start_time_sec = os::elapsedTime();
start_recording_regions();
guarantee(target_pause_time_ms > 0.0,
err_msg("target_pause_time_ms = %1.6lf should be positive",
target_pause_time_ms));
guarantee(_collection_set == NULL, "Precondition");
double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
double predicted_pause_time_ms = base_time_ms;
double time_remaining_ms = target_pause_time_ms - base_time_ms;
// the 10% and 50% values are arbitrary...
if (time_remaining_ms < 0.10 * target_pause_time_ms) {
time_remaining_ms = 0.50 * target_pause_time_ms;
_within_target = false;
} else {
_within_target = true;
}
// We figure out the number of bytes available for future to-space.
// For new regions without marking information, we must assume the
// worst-case of complete survival. If we have marking information for a
// region, we can bound the amount of live data. We can add a number of
// such regions, as long as the sum of the live data bounds does not
// exceed the available evacuation space.
size_t max_live_bytes = _g1->free_regions() * HeapRegion::GrainBytes;
size_t expansion_bytes =
_g1->expansion_regions() * HeapRegion::GrainBytes;
_collection_set_bytes_used_before = 0;
_collection_set_size = 0;
// Adjust for expansion and slop.
max_live_bytes = max_live_bytes + expansion_bytes;
HeapRegion* hr;
if (in_young_gc_mode()) {
double young_start_time_sec = os::elapsedTime();
if (G1PolicyVerbose > 0) {
gclog_or_tty->print_cr("Adding %d young regions to the CSet",
_g1->young_list()->length());
}
_young_cset_length = 0;
_last_young_gc_full = full_young_gcs() ? true : false;
if (_last_young_gc_full)
++_full_young_pause_num;
else
++_partial_young_pause_num;
// The young list is laid with the survivor regions from the previous
// pause are appended to the RHS of the young list, i.e.
// [Newly Young Regions ++ Survivors from last pause].
hr = _g1->young_list()->first_survivor_region();
while (hr != NULL) {
assert(hr->is_survivor(), "badly formed young list");
hr->set_young();
hr = hr->get_next_young_region();
}
// Clear the fields that point to the survivor list - they are
// all young now.
_g1->young_list()->clear_survivors();
if (_g1->mark_in_progress())
_g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
_young_cset_length = _inc_cset_young_index;
_collection_set = _inc_cset_head;
_collection_set_size = _inc_cset_size;
_collection_set_bytes_used_before = _inc_cset_bytes_used_before;
// For young regions in the collection set, we assume the worst
// case of complete survival
max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
// The number of recorded young regions is the incremental
// collection set's current size
set_recorded_young_regions(_inc_cset_size);
set_recorded_rs_lengths(_inc_cset_recorded_rs_lengths);
set_recorded_young_bytes(_inc_cset_recorded_young_bytes);
#if PREDICTIONS_VERBOSE
set_predicted_bytes_to_copy(_inc_cset_predicted_bytes_to_copy);
#endif // PREDICTIONS_VERBOSE
if (G1PolicyVerbose > 0) {
gclog_or_tty->print_cr(" Added " PTR_FORMAT " Young Regions to CS.",
_inc_cset_size);
gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
max_live_bytes/K);
}
assert(_inc_cset_size == _g1->young_list()->length(), "Invariant");
double young_end_time_sec = os::elapsedTime();
_recorded_young_cset_choice_time_ms =
(young_end_time_sec - young_start_time_sec) * 1000.0;
// We are doing young collections so reset this.
non_young_start_time_sec = young_end_time_sec;
// Note we can use either _collection_set_size or
// _young_cset_length here
if (_collection_set_size > 0 && _last_young_gc_full) {
// don't bother adding more regions...
goto choose_collection_set_end;
}
}
if (!in_young_gc_mode() || !full_young_gcs()) {
bool should_continue = true;
NumberSeq seq;
double avg_prediction = 100000000000000000.0; // something very large
do {
hr = _collectionSetChooser->getNextMarkedRegion(time_remaining_ms,
avg_prediction);
if (hr != NULL) {
double predicted_time_ms = predict_region_elapsed_time_ms(hr, false);
time_remaining_ms -= predicted_time_ms;
predicted_pause_time_ms += predicted_time_ms;
add_to_collection_set(hr);
record_non_young_cset_region(hr);
max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
if (G1PolicyVerbose > 0) {
gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)",
max_live_bytes/K);
}
seq.add(predicted_time_ms);
avg_prediction = seq.avg() + seq.sd();
}
should_continue =
( hr != NULL) &&
( (adaptive_young_list_length()) ? time_remaining_ms > 0.0
: _collection_set_size < _young_list_fixed_length );
} while (should_continue);
if (!adaptive_young_list_length() &&
_collection_set_size < _young_list_fixed_length)
_should_revert_to_full_young_gcs = true;
}
choose_collection_set_end:
stop_incremental_cset_building();
count_CS_bytes_used();
end_recording_regions();
double non_young_end_time_sec = os::elapsedTime();
_recorded_non_young_cset_choice_time_ms =
(non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
}
void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
G1CollectorPolicy::record_full_collection_end();
_collectionSetChooser->updateAfterFullCollection();
}
void G1CollectorPolicy_BestRegionsFirst::
expand_if_possible(size_t numRegions) {
size_t expansion_bytes = numRegions * HeapRegion::GrainBytes;
_g1->expand(expansion_bytes);
}
void G1CollectorPolicy_BestRegionsFirst::
record_collection_pause_end() {
G1CollectorPolicy::record_collection_pause_end();
assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
}