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8142935: Adding old gen regions does not consider available free space

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Track live data size as added to cset during mixed GCs

Reviewed-by: kbarrett, drwhite
This commit is contained in:
Tom Benson 2016-03-21 15:59:58 -04:00 committed by Thomas Benson
parent fd827daa57
commit dc360cad53
4 changed files with 50 additions and 6 deletions
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14
hotspot/src/share/vm/gc/g1/g1CollectionSet.cpp
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@ -59,12 +59,14 @@ G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h) :
_head(NULL),
_bytes_used_before(0),
_bytes_live_before(0),
_recorded_rs_lengths(0),
// Incremental CSet attributes
_inc_build_state(Inactive),
_inc_head(NULL),
_inc_tail(NULL),
_inc_bytes_used_before(0),
_inc_bytes_live_before(0),
_inc_recorded_rs_lengths(0),
_inc_recorded_rs_lengths_diffs(0),
_inc_predicted_elapsed_time_ms(0.0),
@ -95,6 +97,7 @@ void G1CollectionSet::add_old_region(HeapRegion* hr) {
hr->set_next_in_collection_set(_head);
_head = hr;
_bytes_used_before += hr->used();
_bytes_live_before += hr->live_bytes();
size_t rs_length = hr->rem_set()->occupied();
_recorded_rs_lengths += rs_length;
_old_region_length += 1;
@ -107,6 +110,7 @@ void G1CollectionSet::start_incremental_building() {
_inc_head = NULL;
_inc_tail = NULL;
_inc_bytes_used_before = 0;
_inc_bytes_live_before = 0;
_inc_recorded_rs_lengths = 0;
_inc_recorded_rs_lengths_diffs = 0;
@ -209,6 +213,7 @@ void G1CollectionSet::add_young_region_common(HeapRegion* hr) {
_inc_recorded_rs_lengths += rs_length;
_inc_predicted_elapsed_time_ms += region_elapsed_time_ms;
_inc_bytes_used_before += used_bytes;
_inc_bytes_live_before += hr->live_bytes();
assert(!hr->in_collection_set(), "invariant");
_g1->register_young_region_with_cset(hr);
@ -311,6 +316,7 @@ double G1CollectionSet::finalize_young_part(double target_pause_time_ms) {
_head = _inc_head;
_bytes_used_before = _inc_bytes_used_before;
_bytes_live_before = _inc_bytes_live_before;
time_remaining_ms = MAX2(time_remaining_ms - _inc_predicted_elapsed_time_ms, 0.0);
log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
@ -334,6 +340,7 @@ void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
cset_chooser()->verify();
const uint min_old_cset_length = _policy->calc_min_old_cset_length();
const uint max_old_cset_length = _policy->calc_max_old_cset_length();
const size_t estimated_available_bytes = _policy->available_bytes_estimate();
uint expensive_region_num = 0;
bool check_time_remaining = _policy->adaptive_young_list_length();
@ -362,6 +369,13 @@ void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
break;
}
// Stop adding regions if the live bytes (according to the last marking)
// added so far would exceed the estimated free bytes.
if ((_bytes_live_before + hr->live_bytes()) > estimated_available_bytes) {
log_debug(gc, ergo, cset)("Finish adding old regions to CSet (reached estimated free space limit)");
break;
}
double predicted_time_ms = predict_region_elapsed_time_ms(hr);
if (check_time_remaining) {
if (predicted_time_ms > time_remaining_ms) {

10
hotspot/src/share/vm/gc/g1/g1CollectionSet.hpp
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@ -57,6 +57,9 @@ class G1CollectionSet VALUE_OBJ_CLASS_SPEC {
// (if any) to the collection set.
size_t _bytes_used_before;
// The sum of live bytes in the collection set, set as described above.
size_t _bytes_live_before;
size_t _recorded_rs_lengths;
// The associated information that is maintained while the incremental
@ -81,6 +84,9 @@ class G1CollectionSet VALUE_OBJ_CLASS_SPEC {
// an evacuation pause.
size_t _inc_bytes_used_before;
// The number of live bytes in the incrementally built collection set.
size_t _inc_bytes_live_before;
// 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,
@ -173,6 +179,10 @@ public:
_bytes_used_before = 0;
}
void reset_bytes_live_before() {
_bytes_live_before = 0;
}
// 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.

17
hotspot/src/share/vm/gc/g1/g1CollectorPolicy.cpp
View File

@ -221,12 +221,7 @@ bool G1CollectorPolicy::predict_will_fit(uint young_length,
// When copying, we will likely need more bytes free than is live in the region.
// Add some safety margin to factor in the confidence of our guess, and the
// natural expected waste.
// (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
// of the calculation: the lower the confidence, the more headroom.
// (100 + TargetPLABWastePct) represents the increase in expected bytes during
// copying due to anticipated waste in the PLABs.
double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy);
size_t expected_bytes_to_copy = (size_t)(bytes_to_copy * safety_factor());
if (expected_bytes_to_copy > free_bytes) {
// end condition 3: out-of-space
@ -592,6 +587,7 @@ void G1CollectorPolicy::record_collection_pause_start(double start_time_sec) {
_pending_cards = _g1->pending_card_num();
_collection_set->reset_bytes_used_before();
_collection_set->reset_bytes_live_before();
_bytes_copied_during_gc = 0;
collector_state()->set_last_gc_was_young(false);
@ -1266,6 +1262,15 @@ uint G1CollectorPolicy::calc_max_old_cset_length() const {
return (uint) result;
}
size_t G1CollectorPolicy::available_bytes_estimate() {
size_t estimated_available_bytes = 0;
if (_free_regions_at_end_of_collection > _reserve_regions) {
uint available_regions = _free_regions_at_end_of_collection - _reserve_regions;
estimated_available_bytes = (size_t)((available_regions * HeapRegion::GrainBytes) / safety_factor());
}
return estimated_available_bytes;
}
void G1CollectorPolicy::finalize_collection_set(double target_pause_time_ms) {
double time_remaining_ms = _collection_set->finalize_young_part(target_pause_time_ms);
_collection_set->finalize_old_part(time_remaining_ms);

15
hotspot/src/share/vm/gc/g1/g1CollectorPolicy.hpp
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@ -169,6 +169,21 @@ public:
double accum_yg_surv_rate_pred(int age) const;
// When copying, we will likely need more bytes free than is live in the region.
// Add some safety margin to factor in the confidence of our guess, and the
// natural expected waste.
// (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
// of the calculation: the lower the confidence, the more headroom.
// (100 + TargetPLABWastePct) represents the increase in expected bytes during
// copying due to anticipated waste in the PLABs.
double safety_factor() const {
return (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
}
// Returns an estimate of the available bytes at end of collection, adjusted by
// the safety factor.
size_t available_bytes_estimate();
protected:
G1CollectionSet* _collection_set;
virtual double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const;