6888336: G1: avoid explicitly marking and pushing objects in survivor spaces
Summary: This change simplifies the interaction between GC and concurrent marking. By disabling survivor spaces during the initial-mark pause we don't need to propagate marks of objects we copy during each GC (since we never need to copy an explicitly marked object).
Reviewed-by: johnc, brutisso
/*
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* 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.
*
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* 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.
*
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*/
#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
#include "gc_implementation/g1/collectionSetChooser.hpp"
#include "gc_implementation/g1/g1MMUTracker.hpp"
#include "memory/collectorPolicy.hpp"
// A G1CollectorPolicy makes policy decisions that determine the
// characteristics of the collector. Examples include:
// * choice of collection set.
// * when to collect.
class HeapRegion;
class CollectionSetChooser;
// Yes, this is a bit unpleasant... but it saves replicating the same thing
// over and over again and introducing subtle problems through small typos and
// cutting and pasting mistakes. The macros below introduces a number
// sequnce into the following two classes and the methods that access it.
#define define_num_seq(name) \
private: \
NumberSeq _all_##name##_times_ms; \
public: \
void record_##name##_time_ms(double ms) { \
_all_##name##_times_ms.add(ms); \
} \
NumberSeq* get_##name##_seq() { \
return &_all_##name##_times_ms; \
}
class MainBodySummary;
class PauseSummary: public CHeapObj {
define_num_seq(total)
define_num_seq(other)
public:
virtual MainBodySummary* main_body_summary() { return NULL; }
};
class MainBodySummary: public CHeapObj {
define_num_seq(satb_drain) // optional
define_num_seq(parallel) // parallel only
define_num_seq(ext_root_scan)
define_num_seq(satb_filtering)
define_num_seq(update_rs)
define_num_seq(scan_rs)
define_num_seq(obj_copy)
define_num_seq(termination) // parallel only
define_num_seq(parallel_other) // parallel only
define_num_seq(mark_closure)
define_num_seq(clear_ct)
};
class Summary: public PauseSummary,
public MainBodySummary {
public:
virtual MainBodySummary* main_body_summary() { return this; }
};
// There are three command line options related to the young gen size:
// NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
// just a short form for NewSize==MaxNewSize). G1 will use its internal
// heuristics to calculate the actual young gen size, so these options
// basically only limit the range within which G1 can pick a young gen
// size. Also, these are general options taking byte sizes. G1 will
// internally work with a number of regions instead. So, some rounding
// will occur.
//
// If nothing related to the the young gen size is set on the command
// line we should allow the young gen to be between
// G1DefaultMinNewGenPercent and G1DefaultMaxNewGenPercent of the
// heap size. This means that every time the heap size changes the
// limits for the young gen size will be updated.
//
// If only -XX:NewSize is set we should use the specified value as the
// minimum size for young gen. Still using G1DefaultMaxNewGenPercent
// of the heap as maximum.
//
// If only -XX:MaxNewSize is set we should use the specified value as the
// maximum size for young gen. Still using G1DefaultMinNewGenPercent
// of the heap as minimum.
//
// If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
// No updates when the heap size changes. There is a special case when
// NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
// different heuristic for calculating the collection set when we do mixed
// collection.
//
// If only -XX:NewRatio is set we should use the specified ratio of the heap
// as both min and max. This will be interpreted as "fixed" just like the
// NewSize==MaxNewSize case above. But we will update the min and max
// everytime the heap size changes.
//
// NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
// combined with either NewSize or MaxNewSize. (A warning message is printed.)
class G1YoungGenSizer : public CHeapObj {
private:
enum SizerKind {
SizerDefaults,
SizerNewSizeOnly,
SizerMaxNewSizeOnly,
SizerMaxAndNewSize,
SizerNewRatio
};
SizerKind _sizer_kind;
size_t _min_desired_young_length;
size_t _max_desired_young_length;
bool _adaptive_size;
size_t calculate_default_min_length(size_t new_number_of_heap_regions);
size_t calculate_default_max_length(size_t new_number_of_heap_regions);
public:
G1YoungGenSizer();
void heap_size_changed(size_t new_number_of_heap_regions);
size_t min_desired_young_length() {
return _min_desired_young_length;
}
size_t max_desired_young_length() {
return _max_desired_young_length;
}
bool adaptive_young_list_length() {
return _adaptive_size;
}
};
class G1CollectorPolicy: public CollectorPolicy {
private:
// either equal to the number of parallel threads, if ParallelGCThreads
// has been set, or 1 otherwise
int _parallel_gc_threads;
// The number of GC threads currently active.
uintx _no_of_gc_threads;
enum SomePrivateConstants {
NumPrevPausesForHeuristics = 10
};
G1MMUTracker* _mmu_tracker;
void initialize_flags();
void initialize_all() {
initialize_flags();
initialize_size_info();
initialize_perm_generation(PermGen::MarkSweepCompact);
}
CollectionSetChooser* _collectionSetChooser;
double _cur_collection_start_sec;
size_t _cur_collection_pause_used_at_start_bytes;
size_t _cur_collection_pause_used_regions_at_start;
size_t _prev_collection_pause_used_at_end_bytes;
double _cur_collection_par_time_ms;
double _cur_satb_drain_time_ms;
double _cur_clear_ct_time_ms;
double _cur_ref_proc_time_ms;
double _cur_ref_enq_time_ms;
#ifndef PRODUCT
// Card Table Count Cache stats
double _min_clear_cc_time_ms; // min
double _max_clear_cc_time_ms; // max
double _cur_clear_cc_time_ms; // clearing time during current pause
double _cum_clear_cc_time_ms; // cummulative clearing time
jlong _num_cc_clears; // number of times the card count cache has been cleared
#endif
// These exclude marking times.
TruncatedSeq* _recent_gc_times_ms;
TruncatedSeq* _concurrent_mark_remark_times_ms;
TruncatedSeq* _concurrent_mark_cleanup_times_ms;
Summary* _summary;
NumberSeq* _all_pause_times_ms;
NumberSeq* _all_full_gc_times_ms;
double _stop_world_start;
NumberSeq* _all_stop_world_times_ms;
NumberSeq* _all_yield_times_ms;
int _aux_num;
NumberSeq* _all_aux_times_ms;
double* _cur_aux_start_times_ms;
double* _cur_aux_times_ms;
bool* _cur_aux_times_set;
double* _par_last_gc_worker_start_times_ms;
double* _par_last_ext_root_scan_times_ms;
double* _par_last_satb_filtering_times_ms;
double* _par_last_update_rs_times_ms;
double* _par_last_update_rs_processed_buffers;
double* _par_last_scan_rs_times_ms;
double* _par_last_obj_copy_times_ms;
double* _par_last_termination_times_ms;
double* _par_last_termination_attempts;
double* _par_last_gc_worker_end_times_ms;
double* _par_last_gc_worker_times_ms;
// Each workers 'other' time i.e. the elapsed time of the parallel
// phase of the pause minus the sum of the individual sub-phase
// times for a given worker thread.
double* _par_last_gc_worker_other_times_ms;
// indicates whether we are in young or mixed GC mode
bool _gcs_are_young;
size_t _young_list_target_length;
size_t _young_list_fixed_length;
size_t _prev_eden_capacity; // used for logging
// The max number of regions we can extend the eden by while the GC
// locker is active. This should be >= _young_list_target_length;
size_t _young_list_max_length;
bool _last_gc_was_young;
unsigned _young_pause_num;
unsigned _mixed_pause_num;
bool _during_marking;
bool _in_marking_window;
bool _in_marking_window_im;
SurvRateGroup* _short_lived_surv_rate_group;
SurvRateGroup* _survivor_surv_rate_group;
// add here any more surv rate groups
double _gc_overhead_perc;
double _reserve_factor;
size_t _reserve_regions;
bool during_marking() {
return _during_marking;
}
private:
enum PredictionConstants {
TruncatedSeqLength = 10
};
TruncatedSeq* _alloc_rate_ms_seq;
double _prev_collection_pause_end_ms;
TruncatedSeq* _pending_card_diff_seq;
TruncatedSeq* _rs_length_diff_seq;
TruncatedSeq* _cost_per_card_ms_seq;
TruncatedSeq* _young_cards_per_entry_ratio_seq;
TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
TruncatedSeq* _cost_per_entry_ms_seq;
TruncatedSeq* _mixed_cost_per_entry_ms_seq;
TruncatedSeq* _cost_per_byte_ms_seq;
TruncatedSeq* _constant_other_time_ms_seq;
TruncatedSeq* _young_other_cost_per_region_ms_seq;
TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
TruncatedSeq* _pending_cards_seq;
TruncatedSeq* _rs_lengths_seq;
TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
TruncatedSeq* _young_gc_eff_seq;
G1YoungGenSizer* _young_gen_sizer;
size_t _eden_cset_region_length;
size_t _survivor_cset_region_length;
size_t _old_cset_region_length;
void init_cset_region_lengths(size_t eden_cset_region_length,
size_t survivor_cset_region_length);
size_t eden_cset_region_length() { return _eden_cset_region_length; }
size_t survivor_cset_region_length() { return _survivor_cset_region_length; }
size_t old_cset_region_length() { return _old_cset_region_length; }
size_t _free_regions_at_end_of_collection;
size_t _recorded_rs_lengths;
size_t _max_rs_lengths;
double _recorded_young_free_cset_time_ms;
double _recorded_non_young_free_cset_time_ms;
double _sigma;
double _expensive_region_limit_ms;
size_t _rs_lengths_prediction;
size_t _known_garbage_bytes;
double _known_garbage_ratio;
double sigma() {
return _sigma;
}
// A function that prevents us putting too much stock in small sample
// sets. Returns a number between 2.0 and 1.0, depending on the number
// of samples. 5 or more samples yields one; fewer scales linearly from
// 2.0 at 1 sample to 1.0 at 5.
double confidence_factor(int samples) {
if (samples > 4) return 1.0;
else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
}
double get_new_neg_prediction(TruncatedSeq* seq) {
return seq->davg() - sigma() * seq->dsd();
}
#ifndef PRODUCT
bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
#endif // PRODUCT
void adjust_concurrent_refinement(double update_rs_time,
double update_rs_processed_buffers,
double goal_ms);
uintx no_of_gc_threads() { return _no_of_gc_threads; }
void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
double _pause_time_target_ms;
double _recorded_young_cset_choice_time_ms;
double _recorded_non_young_cset_choice_time_ms;
size_t _pending_cards;
size_t _max_pending_cards;
public:
// Accessors
void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
hr->set_young();
hr->install_surv_rate_group(_short_lived_surv_rate_group);
hr->set_young_index_in_cset(young_index_in_cset);
}
void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
assert(hr->is_young() && hr->is_survivor(), "pre-condition");
hr->install_surv_rate_group(_survivor_surv_rate_group);
hr->set_young_index_in_cset(young_index_in_cset);
}
#ifndef PRODUCT
bool verify_young_ages();
#endif // PRODUCT
double get_new_prediction(TruncatedSeq* seq) {
return MAX2(seq->davg() + sigma() * seq->dsd(),
seq->davg() * confidence_factor(seq->num()));
}
void record_max_rs_lengths(size_t rs_lengths) {
_max_rs_lengths = rs_lengths;
}
size_t predict_pending_card_diff() {
double prediction = get_new_neg_prediction(_pending_card_diff_seq);
if (prediction < 0.00001) {
return 0;
} else {
return (size_t) prediction;
}
}
size_t predict_pending_cards() {
size_t max_pending_card_num = _g1->max_pending_card_num();
size_t diff = predict_pending_card_diff();
size_t prediction;
if (diff > max_pending_card_num) {
prediction = max_pending_card_num;
} else {
prediction = max_pending_card_num - diff;
}
return prediction;
}
size_t predict_rs_length_diff() {
return (size_t) get_new_prediction(_rs_length_diff_seq);
}
double predict_alloc_rate_ms() {
return get_new_prediction(_alloc_rate_ms_seq);
}
double predict_cost_per_card_ms() {
return get_new_prediction(_cost_per_card_ms_seq);
}
double predict_rs_update_time_ms(size_t pending_cards) {
return (double) pending_cards * predict_cost_per_card_ms();
}
double predict_young_cards_per_entry_ratio() {
return get_new_prediction(_young_cards_per_entry_ratio_seq);
}
double predict_mixed_cards_per_entry_ratio() {
if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
return predict_young_cards_per_entry_ratio();
} else {
return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
}
}
size_t predict_young_card_num(size_t rs_length) {
return (size_t) ((double) rs_length *
predict_young_cards_per_entry_ratio());
}
size_t predict_non_young_card_num(size_t rs_length) {
return (size_t) ((double) rs_length *
predict_mixed_cards_per_entry_ratio());
}
double predict_rs_scan_time_ms(size_t card_num) {
if (gcs_are_young()) {
return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
} else {
return predict_mixed_rs_scan_time_ms(card_num);
}
}
double predict_mixed_rs_scan_time_ms(size_t card_num) {
if (_mixed_cost_per_entry_ms_seq->num() < 3) {
return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
} else {
return (double) (card_num *
get_new_prediction(_mixed_cost_per_entry_ms_seq));
}
}
double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
return (1.1 * (double) bytes_to_copy) *
get_new_prediction(_cost_per_byte_ms_seq);
} else {
return (double) bytes_to_copy *
get_new_prediction(_cost_per_byte_ms_during_cm_seq);
}
}
double predict_object_copy_time_ms(size_t bytes_to_copy) {
if (_in_marking_window && !_in_marking_window_im) {
return predict_object_copy_time_ms_during_cm(bytes_to_copy);
} else {
return (double) bytes_to_copy *
get_new_prediction(_cost_per_byte_ms_seq);
}
}
double predict_constant_other_time_ms() {
return get_new_prediction(_constant_other_time_ms_seq);
}
double predict_young_other_time_ms(size_t young_num) {
return (double) young_num *
get_new_prediction(_young_other_cost_per_region_ms_seq);
}
double predict_non_young_other_time_ms(size_t non_young_num) {
return (double) non_young_num *
get_new_prediction(_non_young_other_cost_per_region_ms_seq);
}
void check_if_region_is_too_expensive(double predicted_time_ms);
double predict_young_collection_elapsed_time_ms(size_t adjustment);
double predict_base_elapsed_time_ms(size_t pending_cards);
double predict_base_elapsed_time_ms(size_t pending_cards,
size_t scanned_cards);
size_t predict_bytes_to_copy(HeapRegion* hr);
double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
void set_recorded_rs_lengths(size_t rs_lengths);
size_t cset_region_length() { return young_cset_region_length() +
old_cset_region_length(); }
size_t young_cset_region_length() { return eden_cset_region_length() +
survivor_cset_region_length(); }
void record_young_free_cset_time_ms(double time_ms) {
_recorded_young_free_cset_time_ms = time_ms;
}
void record_non_young_free_cset_time_ms(double time_ms) {
_recorded_non_young_free_cset_time_ms = time_ms;
}
double predict_young_gc_eff() {
return get_new_neg_prediction(_young_gc_eff_seq);
}
double predict_survivor_regions_evac_time();
void cset_regions_freed() {
bool propagate = _last_gc_was_young && !_in_marking_window;
_short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
_survivor_surv_rate_group->all_surviving_words_recorded(propagate);
// also call it on any more surv rate groups
}
void set_known_garbage_bytes(size_t known_garbage_bytes) {
_known_garbage_bytes = known_garbage_bytes;
size_t heap_bytes = _g1->capacity();
_known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
}
void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
_known_garbage_bytes -= known_garbage_bytes;
size_t heap_bytes = _g1->capacity();
_known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
}
G1MMUTracker* mmu_tracker() {
return _mmu_tracker;
}
double max_pause_time_ms() {
return _mmu_tracker->max_gc_time() * 1000.0;
}
double predict_remark_time_ms() {
return get_new_prediction(_concurrent_mark_remark_times_ms);
}
double predict_cleanup_time_ms() {
return get_new_prediction(_concurrent_mark_cleanup_times_ms);
}
// Returns an estimate of the survival rate of the region at yg-age
// "yg_age".
double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
TruncatedSeq* seq = surv_rate_group->get_seq(age);
if (seq->num() == 0)
gclog_or_tty->print("BARF! age is %d", age);
guarantee( seq->num() > 0, "invariant" );
double pred = get_new_prediction(seq);
if (pred > 1.0)
pred = 1.0;
return pred;
}
double predict_yg_surv_rate(int age) {
return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
}
double accum_yg_surv_rate_pred(int age) {
return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
}
private:
void print_stats(int level, const char* str, double value);
void print_stats(int level, const char* str, int value);
void print_par_stats(int level, const char* str, double* data);
void print_par_sizes(int level, const char* str, double* data);
void check_other_times(int level,
NumberSeq* other_times_ms,
NumberSeq* calc_other_times_ms) const;
void print_summary (PauseSummary* stats) const;
void print_summary (int level, const char* str, NumberSeq* seq) const;
void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
double avg_value (double* data);
double max_value (double* data);
double sum_of_values (double* data);
double max_sum (double* data1, double* data2);
double _last_pause_time_ms;
size_t _bytes_in_collection_set_before_gc;
size_t _bytes_copied_during_gc;
// Used to count used bytes in CS.
friend class CountCSClosure;
// Statistics kept per GC stoppage, pause or full.
TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
// Add a new GC of the given duration and end time to the record.
void update_recent_gc_times(double end_time_sec, double elapsed_ms);
// The head of the list (via "next_in_collection_set()") representing the
// current collection set. Set from the incrementally built collection
// set at the start of the pause.
HeapRegion* _collection_set;
// The number of bytes in the collection set before the pause. Set from
// the incrementally built collection set at the start of an evacuation
// pause.
size_t _collection_set_bytes_used_before;
// The associated information that is maintained while the incremental
// collection set is being built with young regions. Used to populate
// the recorded info for the evacuation pause.
enum CSetBuildType {
Active, // We are actively building the collection set
Inactive // We are not actively building the collection set
};
CSetBuildType _inc_cset_build_state;
// The head of the incrementally built collection set.
HeapRegion* _inc_cset_head;
// The tail of the incrementally built collection set.
HeapRegion* _inc_cset_tail;
// The number of bytes in the incrementally built collection set.
// Used to set _collection_set_bytes_used_before at the start of
// an evacuation pause.
size_t _inc_cset_bytes_used_before;
// Used to record the highest end of heap region in collection set
HeapWord* _inc_cset_max_finger;
// The RSet lengths recorded for regions in the CSet. It is updated
// by the thread that adds a new region to the CSet. We assume that
// only one thread can be allocating a new CSet region (currently,
// it does so after taking the Heap_lock) hence no need to
// synchronize updates to this field.
size_t _inc_cset_recorded_rs_lengths;
// A concurrent refinement thread periodcially samples the young
// region RSets and needs to update _inc_cset_recorded_rs_lengths as
// the RSets grow. Instead of having to syncronize updates to that
// field we accumulate them in this field and add it to
// _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
ssize_t _inc_cset_recorded_rs_lengths_diffs;
// The predicted elapsed time it will take to collect the regions in
// the CSet. This is updated by the thread that adds a new region to
// the CSet. See the comment for _inc_cset_recorded_rs_lengths about
// MT-safety assumptions.
double _inc_cset_predicted_elapsed_time_ms;
// See the comment for _inc_cset_recorded_rs_lengths_diffs.
double _inc_cset_predicted_elapsed_time_ms_diffs;
// Stash a pointer to the g1 heap.
G1CollectedHeap* _g1;
// The ratio of gc time to elapsed time, computed over recent pauses.
double _recent_avg_pause_time_ratio;
double recent_avg_pause_time_ratio() {
return _recent_avg_pause_time_ratio;
}
// At the end of a pause we check the heap occupancy and we decide
// whether we will start a marking cycle during the next pause. If
// we decide that we want to do that, we will set this parameter to
// true. So, this parameter will stay true between the end of a
// pause and the beginning of a subsequent pause (not necessarily
// the next one, see the comments on the next field) when we decide
// that we will indeed start a marking cycle and do the initial-mark
// work.
volatile bool _initiate_conc_mark_if_possible;
// If initiate_conc_mark_if_possible() is set at the beginning of a
// pause, it is a suggestion that the pause should start a marking
// cycle by doing the initial-mark work. However, it is possible
// that the concurrent marking thread is still finishing up the
// previous marking cycle (e.g., clearing the next marking
// bitmap). If that is the case we cannot start a new cycle and
// we'll have to wait for the concurrent marking thread to finish
// what it is doing. In this case we will postpone the marking cycle
// initiation decision for the next pause. When we eventually decide
// to start a cycle, we will set _during_initial_mark_pause which
// will stay true until the end of the initial-mark pause and it's
// the condition that indicates that a pause is doing the
// initial-mark work.
volatile bool _during_initial_mark_pause;
bool _should_revert_to_young_gcs;
bool _last_young_gc;
// This set of variables tracks the collector efficiency, in order to
// determine whether we should initiate a new marking.
double _cur_mark_stop_world_time_ms;
double _mark_remark_start_sec;
double _mark_cleanup_start_sec;
double _mark_closure_time_ms;
// Update the young list target length either by setting it to the
// desired fixed value or by calculating it using G1's pause
// prediction model. If no rs_lengths parameter is passed, predict
// the RS lengths using the prediction model, otherwise use the
// given rs_lengths as the prediction.
void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
// Calculate and return the minimum desired young list target
// length. This is the minimum desired young list length according
// to the user's inputs.
size_t calculate_young_list_desired_min_length(size_t base_min_length);
// Calculate and return the maximum desired young list target
// length. This is the maximum desired young list length according
// to the user's inputs.
size_t calculate_young_list_desired_max_length();
// Calculate and return the maximum young list target length that
// can fit into the pause time goal. The parameters are: rs_lengths
// represent the prediction of how large the young RSet lengths will
// be, base_min_length is the alreay existing number of regions in
// the young list, min_length and max_length are the desired min and
// max young list length according to the user's inputs.
size_t calculate_young_list_target_length(size_t rs_lengths,
size_t base_min_length,
size_t desired_min_length,
size_t desired_max_length);
// Check whether a given young length (young_length) fits into the
// given target pause time and whether the prediction for the amount
// of objects to be copied for the given length will fit into the
// given free space (expressed by base_free_regions). It is used by
// calculate_young_list_target_length().
bool predict_will_fit(size_t young_length, double base_time_ms,
size_t base_free_regions, double target_pause_time_ms);
// Count the number of bytes used in the CS.
void count_CS_bytes_used();
public:
G1CollectorPolicy();
virtual G1CollectorPolicy* as_g1_policy() { return this; }
virtual CollectorPolicy::Name kind() {
return CollectorPolicy::G1CollectorPolicyKind;
}
// Check the current value of the young list RSet lengths and
// compare it against the last prediction. If the current value is
// higher, recalculate the young list target length prediction.
void revise_young_list_target_length_if_necessary();
size_t bytes_in_collection_set() {
return _bytes_in_collection_set_before_gc;
}
unsigned calc_gc_alloc_time_stamp() {
return _all_pause_times_ms->num() + 1;
}
// This should be called after the heap is resized.
void record_new_heap_size(size_t new_number_of_regions);
void init();
// Create jstat counters for the policy.
virtual void initialize_gc_policy_counters();
virtual HeapWord* mem_allocate_work(size_t size,
bool is_tlab,
bool* gc_overhead_limit_was_exceeded);
// This method controls how a collector handles one or more
// of its generations being fully allocated.
virtual HeapWord* satisfy_failed_allocation(size_t size,
bool is_tlab);
BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
// Update the heuristic info to record a collection pause of the given
// start time, where the given number of bytes were used at the start.
// This may involve changing the desired size of a collection set.
void record_stop_world_start();
void record_collection_pause_start(double start_time_sec, size_t start_used);
// Must currently be called while the world is stopped.
void record_concurrent_mark_init_end(double
mark_init_elapsed_time_ms);
void record_mark_closure_time(double mark_closure_time_ms) {
_mark_closure_time_ms = mark_closure_time_ms;
}
void record_concurrent_mark_remark_start();
void record_concurrent_mark_remark_end();
void record_concurrent_mark_cleanup_start();
void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
void record_concurrent_mark_cleanup_completed();
void record_concurrent_pause();
void record_concurrent_pause_end();
void record_collection_pause_end(int no_of_gc_threads);
void print_heap_transition();
// Record the fact that a full collection occurred.
void record_full_collection_start();
void record_full_collection_end();
void record_gc_worker_start_time(int worker_i, double ms) {
_par_last_gc_worker_start_times_ms[worker_i] = ms;
}
void record_ext_root_scan_time(int worker_i, double ms) {
_par_last_ext_root_scan_times_ms[worker_i] = ms;
}
void record_satb_filtering_time(int worker_i, double ms) {
_par_last_satb_filtering_times_ms[worker_i] = ms;
}
void record_satb_drain_time(double ms) {
assert(_g1->mark_in_progress(), "shouldn't be here otherwise");
_cur_satb_drain_time_ms = ms;
}
void record_update_rs_time(int thread, double ms) {
_par_last_update_rs_times_ms[thread] = ms;
}
void record_update_rs_processed_buffers (int thread,
double processed_buffers) {
_par_last_update_rs_processed_buffers[thread] = processed_buffers;
}
void record_scan_rs_time(int thread, double ms) {
_par_last_scan_rs_times_ms[thread] = ms;
}
void reset_obj_copy_time(int thread) {
_par_last_obj_copy_times_ms[thread] = 0.0;
}
void reset_obj_copy_time() {
reset_obj_copy_time(0);
}
void record_obj_copy_time(int thread, double ms) {
_par_last_obj_copy_times_ms[thread] += ms;
}
void record_termination(int thread, double ms, size_t attempts) {
_par_last_termination_times_ms[thread] = ms;
_par_last_termination_attempts[thread] = (double) attempts;
}
void record_gc_worker_end_time(int worker_i, double ms) {
_par_last_gc_worker_end_times_ms[worker_i] = ms;
}
void record_pause_time_ms(double ms) {
_last_pause_time_ms = ms;
}
void record_clear_ct_time(double ms) {
_cur_clear_ct_time_ms = ms;
}
void record_par_time(double ms) {
_cur_collection_par_time_ms = ms;
}
void record_aux_start_time(int i) {
guarantee(i < _aux_num, "should be within range");
_cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
}
void record_aux_end_time(int i) {
guarantee(i < _aux_num, "should be within range");
double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
_cur_aux_times_set[i] = true;
_cur_aux_times_ms[i] += ms;
}
void record_ref_proc_time(double ms) {
_cur_ref_proc_time_ms = ms;
}
void record_ref_enq_time(double ms) {
_cur_ref_enq_time_ms = ms;
}
#ifndef PRODUCT
void record_cc_clear_time(double ms) {
if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
_min_clear_cc_time_ms = ms;
if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
_max_clear_cc_time_ms = ms;
_cur_clear_cc_time_ms = ms;
_cum_clear_cc_time_ms += ms;
_num_cc_clears++;
}
#endif
// Record how much space we copied during a GC. This is typically
// called when a GC alloc region is being retired.
void record_bytes_copied_during_gc(size_t bytes) {
_bytes_copied_during_gc += bytes;
}
// The amount of space we copied during a GC.
size_t bytes_copied_during_gc() {
return _bytes_copied_during_gc;
}
// Choose a new collection set. Marks the chosen regions as being
// "in_collection_set", and links them together. The head and number of
// the collection set are available via access methods.
void choose_collection_set(double target_pause_time_ms);
// The head of the list (via "next_in_collection_set()") representing the
// current collection set.
HeapRegion* collection_set() { return _collection_set; }
void clear_collection_set() { _collection_set = NULL; }
// Add old region "hr" to the CSet.
void add_old_region_to_cset(HeapRegion* hr);
// Incremental CSet Support
// The head of the incrementally built collection set.
HeapRegion* inc_cset_head() { return _inc_cset_head; }
// The tail of the incrementally built collection set.
HeapRegion* inc_set_tail() { return _inc_cset_tail; }
// Initialize incremental collection set info.
void start_incremental_cset_building();
// Perform any final calculations on the incremental CSet fields
// before we can use them.
void finalize_incremental_cset_building();
void clear_incremental_cset() {
_inc_cset_head = NULL;
_inc_cset_tail = NULL;
}
// Stop adding regions to the incremental collection set
void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
// Add information about hr to the aggregated information for the
// incrementally built collection set.
void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
// Update information about hr in the aggregated information for
// the incrementally built collection set.
void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
private:
// Update the incremental cset information when adding a region
// (should not be called directly).
void add_region_to_incremental_cset_common(HeapRegion* hr);
public:
// Add hr to the LHS of the incremental collection set.
void add_region_to_incremental_cset_lhs(HeapRegion* hr);
// Add hr to the RHS of the incremental collection set.
void add_region_to_incremental_cset_rhs(HeapRegion* hr);
#ifndef PRODUCT
void print_collection_set(HeapRegion* list_head, outputStream* st);
#endif // !PRODUCT
bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
bool during_initial_mark_pause() { return _during_initial_mark_pause; }
void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
// This sets the initiate_conc_mark_if_possible() flag to start a
// new cycle, as long as we are not already in one. It's best if it
// is called during a safepoint when the test whether a cycle is in
// progress or not is stable.
bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
// This is called at the very beginning of an evacuation pause (it
// has to be the first thing that the pause does). If
// initiate_conc_mark_if_possible() is true, and the concurrent
// marking thread has completed its work during the previous cycle,
// it will set during_initial_mark_pause() to so that the pause does
// the initial-mark work and start a marking cycle.
void decide_on_conc_mark_initiation();
// If an expansion would be appropriate, because recent GC overhead had
// exceeded the desired limit, return an amount to expand by.
size_t expansion_amount();
#ifndef PRODUCT
// Check any appropriate marked bytes info, asserting false if
// something's wrong, else returning "true".
bool assertMarkedBytesDataOK();
#endif
// Print tracing information.
void print_tracing_info() const;
// Print stats on young survival ratio
void print_yg_surv_rate_info() const;
void finished_recalculating_age_indexes(bool is_survivors) {
if (is_survivors) {
_survivor_surv_rate_group->finished_recalculating_age_indexes();
} else {
_short_lived_surv_rate_group->finished_recalculating_age_indexes();
}
// do that for any other surv rate groups
}
bool is_young_list_full() {
size_t young_list_length = _g1->young_list()->length();
size_t young_list_target_length = _young_list_target_length;
return young_list_length >= young_list_target_length;
}
bool can_expand_young_list() {
size_t young_list_length = _g1->young_list()->length();
size_t young_list_max_length = _young_list_max_length;
return young_list_length < young_list_max_length;
}
size_t young_list_max_length() {
return _young_list_max_length;
}
bool gcs_are_young() {
return _gcs_are_young;
}
void set_gcs_are_young(bool gcs_are_young) {
_gcs_are_young = gcs_are_young;
}
bool adaptive_young_list_length() {
return _young_gen_sizer->adaptive_young_list_length();
}
inline double get_gc_eff_factor() {
double ratio = _known_garbage_ratio;
double square = ratio * ratio;
// square = square * square;
double ret = square * 9.0 + 1.0;
#if 0
gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
#endif // 0
guarantee(0.0 <= ret && ret < 10.0, "invariant!");
return ret;
}
private:
//
// Survivor regions policy.
//
// Current tenuring threshold, set to 0 if the collector reaches the
// maximum amount of suvivors regions.
int _tenuring_threshold;
// The limit on the number of regions allocated for survivors.
size_t _max_survivor_regions;
// For reporting purposes.
size_t _eden_bytes_before_gc;
size_t _survivor_bytes_before_gc;
size_t _capacity_before_gc;
// The amount of survor regions after a collection.
size_t _recorded_survivor_regions;
// List of survivor regions.
HeapRegion* _recorded_survivor_head;
HeapRegion* _recorded_survivor_tail;
ageTable _survivors_age_table;
public:
inline GCAllocPurpose
evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
if (age < _tenuring_threshold && src_region->is_young()) {
return GCAllocForSurvived;
} else {
return GCAllocForTenured;
}
}
inline bool track_object_age(GCAllocPurpose purpose) {
return purpose == GCAllocForSurvived;
}
static const size_t REGIONS_UNLIMITED = ~(size_t)0;
size_t max_regions(int purpose);
// The limit on regions for a particular purpose is reached.
void note_alloc_region_limit_reached(int purpose) {
if (purpose == GCAllocForSurvived) {
_tenuring_threshold = 0;
}
}
void note_start_adding_survivor_regions() {
_survivor_surv_rate_group->start_adding_regions();
}
void note_stop_adding_survivor_regions() {
_survivor_surv_rate_group->stop_adding_regions();
}
void tenure_all_objects() {
_max_survivor_regions = 0;
_tenuring_threshold = 0;
}
void record_survivor_regions(size_t regions,
HeapRegion* head,
HeapRegion* tail) {
_recorded_survivor_regions = regions;
_recorded_survivor_head = head;
_recorded_survivor_tail = tail;
}
size_t recorded_survivor_regions() {
return _recorded_survivor_regions;
}
void record_thread_age_table(ageTable* age_table)
{
_survivors_age_table.merge_par(age_table);
}
void update_max_gc_locker_expansion();
// Calculates survivor space parameters.
void update_survivors_policy();
};
// This should move to some place more general...
// If we have "n" measurements, and we've kept track of their "sum" and the
// "sum_of_squares" of the measurements, this returns the variance of the
// sequence.
inline double variance(int n, double sum_of_squares, double sum) {
double n_d = (double)n;
double avg = sum/n_d;
return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
}
#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP