1.1 --- a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp Mon Mar 04 13:01:24 2013 +0100
1.2 +++ b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp Mon Mar 04 12:42:14 2013 -0800
1.3 @@ -1806,6 +1806,14 @@
1.4 }
1.5 #endif // !PRODUCT
1.6
1.7 +double G1CollectorPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) {
1.8 + // Returns the given amount of reclaimable bytes (that represents
1.9 + // the amount of reclaimable space still to be collected) as a
1.10 + // percentage of the current heap capacity.
1.11 + size_t capacity_bytes = _g1->capacity();
1.12 + return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1.13 +}
1.14 +
1.15 bool G1CollectorPolicy::next_gc_should_be_mixed(const char* true_action_str,
1.16 const char* false_action_str) {
1.17 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1.18 @@ -1815,19 +1823,21 @@
1.19 ergo_format_reason("candidate old regions not available"));
1.20 return false;
1.21 }
1.22 +
1.23 + // Is the amount of uncollected reclaimable space above G1HeapWastePercent?
1.24 size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1.25 - size_t capacity_bytes = _g1->capacity();
1.26 - double perc = (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
1.27 + double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1.28 double threshold = (double) G1HeapWastePercent;
1.29 - if (perc < threshold) {
1.30 + if (reclaimable_perc <= threshold) {
1.31 ergo_verbose4(ErgoMixedGCs,
1.32 false_action_str,
1.33 - ergo_format_reason("reclaimable percentage lower than threshold")
1.34 + ergo_format_reason("reclaimable percentage not over threshold")
1.35 ergo_format_region("candidate old regions")
1.36 ergo_format_byte_perc("reclaimable")
1.37 ergo_format_perc("threshold"),
1.38 cset_chooser->remaining_regions(),
1.39 - reclaimable_bytes, perc, threshold);
1.40 + reclaimable_bytes,
1.41 + reclaimable_perc, threshold);
1.42 return false;
1.43 }
1.44
1.45 @@ -1838,10 +1848,50 @@
1.46 ergo_format_byte_perc("reclaimable")
1.47 ergo_format_perc("threshold"),
1.48 cset_chooser->remaining_regions(),
1.49 - reclaimable_bytes, perc, threshold);
1.50 + reclaimable_bytes,
1.51 + reclaimable_perc, threshold);
1.52 return true;
1.53 }
1.54
1.55 +uint G1CollectorPolicy::calc_min_old_cset_length() {
1.56 + // The min old CSet region bound is based on the maximum desired
1.57 + // number of mixed GCs after a cycle. I.e., even if some old regions
1.58 + // look expensive, we should add them to the CSet anyway to make
1.59 + // sure we go through the available old regions in no more than the
1.60 + // maximum desired number of mixed GCs.
1.61 + //
1.62 + // The calculation is based on the number of marked regions we added
1.63 + // to the CSet chooser in the first place, not how many remain, so
1.64 + // that the result is the same during all mixed GCs that follow a cycle.
1.65 +
1.66 + const size_t region_num = (size_t) _collectionSetChooser->length();
1.67 + const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
1.68 + size_t result = region_num / gc_num;
1.69 + // emulate ceiling
1.70 + if (result * gc_num < region_num) {
1.71 + result += 1;
1.72 + }
1.73 + return (uint) result;
1.74 +}
1.75 +
1.76 +uint G1CollectorPolicy::calc_max_old_cset_length() {
1.77 + // The max old CSet region bound is based on the threshold expressed
1.78 + // as a percentage of the heap size. I.e., it should bound the
1.79 + // number of old regions added to the CSet irrespective of how many
1.80 + // of them are available.
1.81 +
1.82 + G1CollectedHeap* g1h = G1CollectedHeap::heap();
1.83 + const size_t region_num = g1h->n_regions();
1.84 + const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
1.85 + size_t result = region_num * perc / 100;
1.86 + // emulate ceiling
1.87 + if (100 * result < region_num * perc) {
1.88 + result += 1;
1.89 + }
1.90 + return (uint) result;
1.91 +}
1.92 +
1.93 +
1.94 void G1CollectorPolicy::finalize_cset(double target_pause_time_ms) {
1.95 double young_start_time_sec = os::elapsedTime();
1.96
1.97 @@ -1855,7 +1905,7 @@
1.98
1.99 double base_time_ms = predict_base_elapsed_time_ms(_pending_cards);
1.100 double predicted_pause_time_ms = base_time_ms;
1.101 - double time_remaining_ms = target_pause_time_ms - base_time_ms;
1.102 + double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
1.103
1.104 ergo_verbose4(ErgoCSetConstruction | ErgoHigh,
1.105 "start choosing CSet",
1.106 @@ -1893,7 +1943,7 @@
1.107
1.108 _collection_set = _inc_cset_head;
1.109 _collection_set_bytes_used_before = _inc_cset_bytes_used_before;
1.110 - time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
1.111 + time_remaining_ms = MAX2(time_remaining_ms - _inc_cset_predicted_elapsed_time_ms, 0.0);
1.112 predicted_pause_time_ms += _inc_cset_predicted_elapsed_time_ms;
1.113
1.114 ergo_verbose3(ErgoCSetConstruction | ErgoHigh,
1.115 @@ -1917,8 +1967,8 @@
1.116 if (!gcs_are_young()) {
1.117 CollectionSetChooser* cset_chooser = _collectionSetChooser;
1.118 cset_chooser->verify();
1.119 - const uint min_old_cset_length = cset_chooser->calc_min_old_cset_length();
1.120 - const uint max_old_cset_length = cset_chooser->calc_max_old_cset_length();
1.121 + const uint min_old_cset_length = calc_min_old_cset_length();
1.122 + const uint max_old_cset_length = calc_max_old_cset_length();
1.123
1.124 uint expensive_region_num = 0;
1.125 bool check_time_remaining = adaptive_young_list_length();
1.126 @@ -1936,6 +1986,30 @@
1.127 break;
1.128 }
1.129
1.130 +
1.131 + // Stop adding regions if the remaining reclaimable space is
1.132 + // not above G1HeapWastePercent.
1.133 + size_t reclaimable_bytes = cset_chooser->remaining_reclaimable_bytes();
1.134 + double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
1.135 + double threshold = (double) G1HeapWastePercent;
1.136 + if (reclaimable_perc <= threshold) {
1.137 + // We've added enough old regions that the amount of uncollected
1.138 + // reclaimable space is at or below the waste threshold. Stop
1.139 + // adding old regions to the CSet.
1.140 + ergo_verbose5(ErgoCSetConstruction,
1.141 + "finish adding old regions to CSet",
1.142 + ergo_format_reason("reclaimable percentage not over threshold")
1.143 + ergo_format_region("old")
1.144 + ergo_format_region("max")
1.145 + ergo_format_byte_perc("reclaimable")
1.146 + ergo_format_perc("threshold"),
1.147 + old_cset_region_length(),
1.148 + max_old_cset_length,
1.149 + reclaimable_bytes,
1.150 + reclaimable_perc, threshold);
1.151 + break;
1.152 + }
1.153 +
1.154 double predicted_time_ms = predict_region_elapsed_time_ms(hr, gcs_are_young());
1.155 if (check_time_remaining) {
1.156 if (predicted_time_ms > time_remaining_ms) {
1.157 @@ -1975,7 +2049,7 @@
1.158 }
1.159
1.160 // We will add this region to the CSet.
1.161 - time_remaining_ms -= predicted_time_ms;
1.162 + time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
1.163 predicted_pause_time_ms += predicted_time_ms;
1.164 cset_chooser->remove_and_move_to_next(hr);
1.165 _g1->old_set_remove(hr);
