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8294850: Make rs length/pending card predictors dependent on gc phase
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Reviewed-by: kbarrett, iwalulya, ayang
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Thomas Schatzl committed Oct 14, 2022
1 parent 21e4f06 commit 64813f4
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Showing 3 changed files with 65 additions and 41 deletions.
51 changes: 37 additions & 14 deletions src/hotspot/share/gc/g1/g1Analytics.cpp
View file
Expand Up @@ -78,7 +78,8 @@ G1Analytics::G1Analytics(const G1Predictions* predictor) :
_concurrent_mark_cleanup_times_ms(new TruncatedSeq(NumPrevPausesForHeuristics)),
_alloc_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_prev_collection_pause_end_ms(0.0),
_rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
_young_rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
_mixed_rs_length_diff_seq(new TruncatedSeq(TruncatedSeqLength)),
_concurrent_refine_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_dirtied_cards_rate_ms_seq(new TruncatedSeq(TruncatedSeqLength)),
_young_card_merge_to_scan_ratio_seq(new TruncatedSeq(TruncatedSeqLength)),
Expand All @@ -91,8 +92,10 @@ G1Analytics::G1Analytics(const G1Predictions* predictor) :
_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)),
_rs_length_seq(new TruncatedSeq(TruncatedSeqLength)),
_young_pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
_mixed_pending_cards_seq(new TruncatedSeq(TruncatedSeqLength)),
_young_rs_length_seq(new TruncatedSeq(TruncatedSeqLength)),
_mixed_rs_length_seq(new TruncatedSeq(TruncatedSeqLength)),
_cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
_recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
_long_term_pause_time_ratio(0.0),
Expand All @@ -104,7 +107,7 @@ G1Analytics::G1Analytics(const G1Predictions* predictor) :

int index = MIN2(ParallelGCThreads - 1, 7u);

_rs_length_diff_seq->add(rs_length_diff_defaults[index]);
_young_rs_length_diff_seq->add(rs_length_diff_defaults[index]);
// Start with inverse of maximum STW cost.
_concurrent_refine_rate_ms_seq->add(1/cost_per_logged_card_ms_defaults[0]);
// Some applications have very low rates for logging cards.
Expand Down Expand Up @@ -193,8 +196,12 @@ void G1Analytics::report_card_merge_to_scan_ratio(double merge_to_scan_ratio, bo
}
}

void G1Analytics::report_rs_length_diff(double rs_length_diff) {
_rs_length_diff_seq->add(rs_length_diff);
void G1Analytics::report_rs_length_diff(double rs_length_diff, bool for_young_gc) {
if (for_young_gc) {
_young_rs_length_diff_seq->add(rs_length_diff);
} else {
_mixed_rs_length_diff_seq->add(rs_length_diff);
}
}

void G1Analytics::report_cost_per_byte_ms(double cost_per_byte_ms, bool mark_or_rebuild_in_progress) {
Expand All @@ -217,12 +224,20 @@ void G1Analytics::report_constant_other_time_ms(double constant_other_time_ms) {
_constant_other_time_ms_seq->add(constant_other_time_ms);
}

void G1Analytics::report_pending_cards(double pending_cards) {
_pending_cards_seq->add(pending_cards);
void G1Analytics::report_pending_cards(double pending_cards, bool for_young_gc) {
if (for_young_gc) {
_young_pending_cards_seq->add(pending_cards);
} else {
_mixed_pending_cards_seq->add(pending_cards);
}
}

void G1Analytics::report_rs_length(double rs_length) {
_rs_length_seq->add(rs_length);
void G1Analytics::report_rs_length(double rs_length, bool for_young_gc) {
if (for_young_gc) {
_young_rs_length_seq->add(rs_length);
} else {
_mixed_rs_length_seq->add(rs_length);
}
}

double G1Analytics::predict_alloc_rate_ms() const {
Expand Down Expand Up @@ -301,12 +316,20 @@ double G1Analytics::predict_cleanup_time_ms() const {
return predict_zero_bounded(_concurrent_mark_cleanup_times_ms);
}

size_t G1Analytics::predict_rs_length() const {
return predict_size(_rs_length_seq) + predict_size(_rs_length_diff_seq);
size_t G1Analytics::predict_rs_length(bool for_young_gc) const {
if (for_young_gc || !enough_samples_available(_mixed_rs_length_seq)) {
return predict_size(_young_rs_length_seq) + predict_size(_young_rs_length_diff_seq);
} else {
return predict_size(_mixed_rs_length_seq) + predict_size(_mixed_rs_length_diff_seq);
}
}

size_t G1Analytics::predict_pending_cards() const {
return predict_size(_pending_cards_seq);
size_t G1Analytics::predict_pending_cards(bool for_young_gc) const {
if (for_young_gc || !enough_samples_available(_mixed_pending_cards_seq)) {
return predict_size(_young_pending_cards_seq);
} else {
return predict_size(_mixed_pending_cards_seq);
}
}

double G1Analytics::oldest_known_gc_end_time_sec() const {
Expand Down
19 changes: 11 additions & 8 deletions src/hotspot/share/gc/g1/g1Analytics.hpp
View file
Expand Up @@ -45,7 +45,8 @@ class G1Analytics: public CHeapObj<mtGC> {
TruncatedSeq* _alloc_rate_ms_seq;
double _prev_collection_pause_end_ms;

TruncatedSeq* _rs_length_diff_seq;
TruncatedSeq* _young_rs_length_diff_seq;
TruncatedSeq* _mixed_rs_length_diff_seq;
TruncatedSeq* _concurrent_refine_rate_ms_seq;
TruncatedSeq* _dirtied_cards_rate_ms_seq;
// The ratio between the number of merged cards and actually scanned cards, for
Expand All @@ -67,8 +68,10 @@ class G1Analytics: public CHeapObj<mtGC> {
TruncatedSeq* _young_other_cost_per_region_ms_seq;
TruncatedSeq* _non_young_other_cost_per_region_ms_seq;

TruncatedSeq* _pending_cards_seq;
TruncatedSeq* _rs_length_seq;
TruncatedSeq* _young_pending_cards_seq;
TruncatedSeq* _mixed_pending_cards_seq;
TruncatedSeq* _young_rs_length_seq;
TruncatedSeq* _mixed_rs_length_seq;

TruncatedSeq* _cost_per_byte_ms_during_cm_seq;

Expand Down Expand Up @@ -126,13 +129,13 @@ class G1Analytics: public CHeapObj<mtGC> {
void report_cost_per_card_scan_ms(double cost_per_remset_card_ms, bool for_young_gc);
void report_cost_per_card_merge_ms(double cost_per_card_ms, bool for_young_gc);
void report_card_merge_to_scan_ratio(double cards_per_entry_ratio, bool for_young_gc);
void report_rs_length_diff(double rs_length_diff);
void report_rs_length_diff(double rs_length_diff, bool for_young_gc);
void report_cost_per_byte_ms(double cost_per_byte_ms, bool mark_or_rebuild_in_progress);
void report_young_other_cost_per_region_ms(double other_cost_per_region_ms);
void report_non_young_other_cost_per_region_ms(double other_cost_per_region_ms);
void report_constant_other_time_ms(double constant_other_time_ms);
void report_pending_cards(double pending_cards);
void report_rs_length(double rs_length);
void report_pending_cards(double pending_cards, bool for_young_gc);
void report_rs_length(double rs_length, bool for_young_gc);

double predict_alloc_rate_ms() const;
int num_alloc_rate_ms() const;
Expand Down Expand Up @@ -161,8 +164,8 @@ class G1Analytics: public CHeapObj<mtGC> {

double predict_cleanup_time_ms() const;

size_t predict_rs_length() const;
size_t predict_pending_cards() const;
size_t predict_rs_length(bool for_young_gc) const;
size_t predict_pending_cards(bool for_young_gc) const;

// 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);
Expand Down
36 changes: 17 additions & 19 deletions src/hotspot/share/gc/g1/g1Policy.cpp
View file
Expand Up @@ -194,8 +194,9 @@ uint G1Policy::calculate_desired_eden_length_by_mmu() const {
}

void G1Policy::update_young_length_bounds() {
update_young_length_bounds(_analytics->predict_pending_cards(),
_analytics->predict_rs_length());
bool for_young_gc = collector_state()->in_young_only_phase();
update_young_length_bounds(_analytics->predict_pending_cards(for_young_gc),
_analytics->predict_rs_length(for_young_gc));
}

void G1Policy::update_young_length_bounds(size_t pending_cards, size_t rs_length) {
Expand Down Expand Up @@ -525,14 +526,15 @@ void G1Policy::revise_young_list_target_length_if_necessary(size_t rs_length) {
update_rs_length_prediction(rs_length_prediction);

G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
// We have no measure of the number of cards in the thread log buffers, assume
// these are very few compared to the sum of the two other sources.
// We have no measure of the number of cards in the thread buffers, assume
// these are very few compared to the ones in the DCQS.
update_young_length_bounds(dcqs.num_cards(), rs_length_prediction);
}
}

void G1Policy::update_rs_length_prediction() {
update_rs_length_prediction(_analytics->predict_rs_length());
bool for_young_gc = collector_state()->in_young_only_phase();
update_rs_length_prediction(_analytics->predict_rs_length(for_young_gc));
}

void G1Policy::update_rs_length_prediction(size_t prediction) {
Expand Down Expand Up @@ -753,6 +755,7 @@ void G1Policy::record_young_collection_end(bool concurrent_operation_is_full_mar
double pause_time_ms = (end_time_sec - start_time_sec) * 1000.0;

G1GCPauseType this_pause = collector_state()->young_gc_pause_type(concurrent_operation_is_full_mark);
bool is_young_only_pause = G1GCPauseTypeHelper::is_young_only_pause(this_pause);

if (G1GCPauseTypeHelper::is_concurrent_start_pause(this_pause)) {
record_concurrent_mark_init_end();
Expand Down Expand Up @@ -806,7 +809,7 @@ void G1Policy::record_young_collection_end(bool concurrent_operation_is_full_mar
maybe_start_marking();
}
} else {
assert(G1GCPauseTypeHelper::is_young_only_pause(this_pause), "must be");
assert(is_young_only_pause, "must be");
}

_eden_surv_rate_group->start_adding_regions();
Expand All @@ -830,8 +833,7 @@ void G1Policy::record_young_collection_end(bool concurrent_operation_is_full_mar
average_time_ms(G1GCPhaseTimes::MergeHCC) +
average_time_ms(G1GCPhaseTimes::MergeLB) +
average_time_ms(G1GCPhaseTimes::OptMergeRS);
_analytics->report_cost_per_card_merge_ms(avg_time_merge_cards / total_cards_merged,
G1GCPauseTypeHelper::is_young_only_pause(this_pause));
_analytics->report_cost_per_card_merge_ms(avg_time_merge_cards / total_cards_merged, is_young_only_pause);
}

// Update prediction for card scan
Expand All @@ -842,8 +844,7 @@ void G1Policy::record_young_collection_end(bool concurrent_operation_is_full_mar
double avg_time_dirty_card_scan = average_time_ms(G1GCPhaseTimes::ScanHR) +
average_time_ms(G1GCPhaseTimes::OptScanHR);

_analytics->report_cost_per_card_scan_ms(avg_time_dirty_card_scan / total_cards_scanned,
G1GCPauseTypeHelper::is_young_only_pause(this_pause));
_analytics->report_cost_per_card_scan_ms(avg_time_dirty_card_scan / total_cards_scanned, is_young_only_pause);
}

// Update prediction for the ratio between cards from the remembered
Expand All @@ -857,12 +858,11 @@ void G1Policy::record_young_collection_end(bool concurrent_operation_is_full_mar
if (total_cards_scanned > 0) {
merge_to_scan_ratio = (double) from_rs_length_cards / total_cards_scanned;
}
_analytics->report_card_merge_to_scan_ratio(merge_to_scan_ratio,
G1GCPauseTypeHelper::is_young_only_pause(this_pause));
_analytics->report_card_merge_to_scan_ratio(merge_to_scan_ratio, is_young_only_pause);

const size_t recorded_rs_length = _collection_set->recorded_rs_length();
const size_t rs_length_diff = _rs_length > recorded_rs_length ? _rs_length - recorded_rs_length : 0;
_analytics->report_rs_length_diff(rs_length_diff);
_analytics->report_rs_length_diff(rs_length_diff, is_young_only_pause);

// Update prediction for copy cost per byte
size_t copied_bytes = p->sum_thread_work_items(G1GCPhaseTimes::MergePSS, G1GCPhaseTimes::MergePSSCopiedBytes);
Expand All @@ -887,11 +887,8 @@ void G1Policy::record_young_collection_end(bool concurrent_operation_is_full_mar
// Do not update RS lengths and the number of pending cards with information from mixed gc:
// these are is wildly different to during young only gc and mess up young gen sizing right
// after the mixed gc phase.
// During mixed gc we do not use them for young gen sizing.
if (G1GCPauseTypeHelper::is_young_only_pause(this_pause)) {
_analytics->report_pending_cards((double) _pending_cards_at_gc_start);
_analytics->report_rs_length((double) _rs_length);
}
_analytics->report_pending_cards((double) _pending_cards_at_gc_start, is_young_only_pause);
_analytics->report_rs_length((double) _rs_length, is_young_only_pause);
}

assert(!(G1GCPauseTypeHelper::is_concurrent_start_pause(this_pause) && collector_state()->mark_or_rebuild_in_progress()),
Expand Down Expand Up @@ -1036,7 +1033,8 @@ double G1Policy::predict_base_time_ms(size_t pending_cards,
}

double G1Policy::predict_base_time_ms(size_t pending_cards) const {
size_t rs_length = _analytics->predict_rs_length();
bool for_young_gc = collector_state()->in_young_only_phase();
size_t rs_length = _analytics->predict_rs_length(for_young_gc);
return predict_base_time_ms(pending_cards, rs_length);
}

Expand Down

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