truffle: src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp comparison

comparison src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp @ 1394:1316cec51b4d

6819061: G1: eliminate serial Other times that are proportional to the collection set length 6871109: G1: remove the concept of the scan only prefix Summary: Removed scan only regions and associated code. The young portion of the collection set is now constructed incrementally - when a young region is retired as the current allocation region it is added to the collection set. Reviewed-by: apetrusenko, iveresov, tonyp

author	johnc
date	Thu, 22 Apr 2010 10:02:38 -0700
parents	79e419e5ea3b
children	c18cbe5936b8 2d127394260e

comparison

equal deleted inserted replaced

-:6ecb6e6de3d6
+:1316cec51b4d
 /*
-* Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
+* Copyright 2001-2010 Sun Microsystems, Inc.  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.
 static double cost_per_card_ms_defaults[] = {
 0.01, 0.005, 0.005, 0.003, 0.003, 0.002, 0.002, 0.0015
 };
-static double cost_per_scan_only_region_ms_defaults[] = {
-1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
-};
 // 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
 };
 _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)),
-_cost_per_scan_only_region_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)),
-_cost_per_scan_only_region_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)),
 _last_full_young_gc(false),
 _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",
 _recent_prev_end_times_for_all_gcs_sec->add(os::elapsedTime());
 _prev_collection_pause_end_ms = os::elapsedTime() * 1000.0;
 _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_scan_only_times_ms = new double[_parallel_gc_threads];
-_par_last_scan_only_regions_scanned = new double[_parallel_gc_threads];
 _par_last_update_rs_start_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];
 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]);
-_cost_per_scan_only_region_ms_seq->add(
-cost_per_scan_only_region_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]);
 _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_config during initialization
+// 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");
 _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();
-_scan_only_regions_at_end_of_collection = 0;
+calculate_young_list_min_length();
-calculate_young_list_min_length();
+guarantee( _young_list_min_length == 0, "invariant, not enough info" );
-guarantee( _young_list_min_length == 0, "invariant, not enough info" );
+calculate_young_list_target_length();
-calculate_young_list_target_config();
+} else {
-} 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()
 {
 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();
 int min_regions = (int) ceil(alloc_rate_ms * when_ms);
-int current_region_num = (int) _g1->young_list_length();
+int current_region_num = (int) _g1->young_list()->length();
 _young_list_min_length = min_regions + current_region_num;
 }
 }
-void G1CollectorPolicy::calculate_young_list_target_config() {
+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_config(rs_lengths);
+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;
 _young_list_target_length = MAX2(_young_list_target_length, (size_t)1);
-size_t so_length = calculate_optimal_so_length(_young_list_target_length);
-guarantee( so_length < _young_list_target_length, "invariant" );
-_young_list_so_prefix_length = so_length;
 }
 calculate_survivors_policy();
 }
-// This method calculate the optimal scan-only set for a fixed young
+void G1CollectorPolicy::calculate_young_list_target_length(size_t rs_lengths) {
-// gen size. I couldn't work out how to reuse the more elaborate one,
-// i.e. calculate_young_list_target_config(rs_length), as the loops are
-// fundamentally different (the other one finds a config for different
-// S-O lengths, whereas here we need to do the opposite).
-size_t G1CollectorPolicy::calculate_optimal_so_length(
-size_t young_list_length) {
-if (!G1UseScanOnlyPrefix)
-return 0;
-if (_all_pause_times_ms->num() < 3) {
-// we won't use a scan-only set at the beginning to allow the rest
-// of the predictors to warm up
-return 0;
-}
-if (_cost_per_scan_only_region_ms_seq->num() < 3) {
-// then, we'll only set the S-O set to 1 for a little bit of time,
-// to get enough information on the scanning cost
-return 1;
-}
-size_t pending_cards = (size_t) get_new_prediction(_pending_cards_seq);
-size_t rs_lengths = (size_t) get_new_prediction(_rs_lengths_seq);
-size_t adj_rs_lengths = rs_lengths + predict_rs_length_diff();
-size_t scanned_cards;
-if (full_young_gcs())
-scanned_cards = predict_young_card_num(adj_rs_lengths);
-else
-scanned_cards = predict_non_young_card_num(adj_rs_lengths);
-double base_time_ms = predict_base_elapsed_time_ms(pending_cards,
-scanned_cards);
-size_t so_length = 0;
-double max_gc_eff = 0.0;
-for (size_t i = 0; i < young_list_length; ++i) {
-double gc_eff = 0.0;
-double pause_time_ms = 0.0;
-predict_gc_eff(young_list_length, i, base_time_ms,
-&gc_eff, &pause_time_ms);
-if (gc_eff > max_gc_eff) {
-max_gc_eff = gc_eff;
-so_length = i;
-}
-}
-// set it to 95% of the optimal to make sure we sample the "area"
-// around the optimal length to get up-to-date survival rate data
-return so_length * 950 / 1000;
-}
-// This is a really cool piece of code! It finds the best
-// target configuration (young length / scan-only prefix length) so
-// that GC efficiency is maximized and that we also meet a pause
-// time. It's a triple nested loop. These loops are explained below
-// from the inside-out :-)
-//
-// (a) The innermost loop will try to find the optimal young length
-// for a fixed S-O length. It uses a binary search to speed up the
-// process. We assume that, for a fixed S-O length, as we add more
-// young regions to the CSet, the GC efficiency will only go up (I'll
-// skip the proof). So, using a binary search to optimize this process
-// makes perfect sense.
-//
-// (b) The middle loop will fix the S-O length before calling the
-// innermost one. It will vary it between two parameters, increasing
-// it by a given increment.
-//
-// (c) The outermost loop will call the middle loop three times.
-//   (1) The first time it will explore all possible S-O length values
-//   from 0 to as large as it can get, using a coarse increment (to
-//   quickly "home in" to where the optimal seems to be).
-//   (2) The second time it will explore the values around the optimal
-//   that was found by the first iteration using a fine increment.
-//   (3) Once the optimal config has been determined by the second
-//   iteration, we'll redo the calculation, but setting the S-O length
-//   to 95% of the optimal to make sure we sample the "area"
-//   around the optimal length to get up-to-date survival rate data
-//
-// Termination conditions for the iterations are several: the pause
-// time is over the limit, we do not have enough to-space, etc.
-void G1CollectorPolicy::calculate_young_list_target_config(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 =
 // we are in fully-young mode and there are free regions in the heap
 double survivor_regions_evac_time =
 predict_survivor_regions_evac_time();
-size_t min_so_length = 0;
-size_t max_so_length = 0;
-if (G1UseScanOnlyPrefix) {
-if (_all_pause_times_ms->num() < 3) {
-// we won't use a scan-only set at the beginning to allow the rest
-// of the predictors to warm up
-min_so_length = 0;
-max_so_length = 0;
-} else if (_cost_per_scan_only_region_ms_seq->num() < 3) {
-// then, we'll only set the S-O set to 1 for a little bit of time,
-// to get enough information on the scanning cost
-min_so_length = 1;
-max_so_length = 1;
-} else if (_in_marking_window || _last_full_young_gc) {
-// no S-O prefix during a marking phase either, as at the end
-// of the marking phase we'll have to use a very small young
-// length target to fill up the rest of the CSet with
-// non-young regions and, if we have lots of scan-only regions
-// left-over, we will not be able to add any more non-young
-// regions.
-min_so_length = 0;
-max_so_length = 0;
-} else {
-// this is the common case; we'll never reach the maximum, we
-// one of the end conditions will fire well before that
-// (hopefully!)
-min_so_length = 0;
-max_so_length = _free_regions_at_end_of_collection - 1;
-}
-} else {
-// no S-O prefix, as the switch is not set, but we still need to
-// do one iteration to calculate the best young target that
-// meets the pause time; this way we reuse the same code instead
-// of replicating it
-min_so_length = 0;
-max_so_length = 0;
-}
 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;
+size_t scanned_cards = predict_young_card_num(adj_rs_lengths);
-if (full_young_gcs())
-scanned_cards = predict_young_card_num(adj_rs_lengths);
-else
-scanned_cards = predict_non_young_card_num(adj_rs_lengths);
-// calculate this once, so that we don't have to recalculate it in
-// the innermost loop
 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 final_so_length = 0;
-double final_gc_eff = 0.0;
+size_t init_free_regions =
-// we'll also keep track of how many times we go into the inner loop
+MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions);
-// this is for profiling reasons
-size_t calculations = 0;
+// if we're still under the pause target...
+if (base_time_ms <= target_pause_time_ms) {
-// this determines which of the three iterations the outer loop is in
+// We make sure that the shortest young length that makes sense
-typedef enum {
+// fits within the target pause time.
-pass_type_coarse,
+size_t min_young_length = 1;
-pass_type_fine,
-pass_type_final
+if (predict_will_fit(min_young_length, base_time_ms,
-} pass_type_t;
+init_free_regions, target_pause_time_ms)) {
+// The shortest young length will fit within the target pause time;
-// range of the outer loop's iteration
+// we'll now check whether the absolute maximum number of young
-size_t from_so_length   = min_so_length;
+// regions will fit in the target pause time. If not, we'll do
-size_t to_so_length     = max_so_length;
+// a binary search between min_young_length and max_young_length
-guarantee( from_so_length <= to_so_length, "invariant" );
+size_t abs_max_young_length = _free_regions_at_end_of_collection - 1;
+size_t max_young_length = abs_max_young_length;
-// this will keep the S-O length that's found by the second
-// iteration of the outer loop; we'll keep it just in case the third
+if (max_young_length > min_young_length) {
-// iteration fails to find something
+// Let's check if the initial max young length will fit within the
-size_t fine_so_length   = 0;
+// target pause. If so then there is no need to search for a maximal
+// young length - we'll return the initial maximum
-// the increment step for the coarse (first) iteration
-size_t so_coarse_increments = 5;
+if (predict_will_fit(max_young_length, base_time_ms,
+init_free_regions, target_pause_time_ms)) {
-// the common case, we'll start with the coarse iteration
+// The maximum young length will satisfy the target pause time.
-pass_type_t pass = pass_type_coarse;
+// We are done so set min young length to this maximum length.
-size_t so_length_incr = so_coarse_increments;
+// The code after the loop will then set final_young_length using
+// the value cached in the minimum length.
-if (from_so_length == to_so_length) {
+min_young_length = max_young_length;
-// not point in doing the coarse iteration, we'll go directly into
+} else {
-// the fine one (we essentially trying to find the optimal young
+// The maximum possible number of young regions will not fit within
-// length for a fixed S-O length).
+// the target pause time so let's search....
-so_length_incr = 1;
-pass = pass_type_final;
-} else if (to_so_length - from_so_length < 3 * so_coarse_increments) {
-// again, the range is too short so no point in foind the coarse
-// iteration either
-so_length_incr = 1;
-pass = pass_type_fine;
-}
-bool done = false;
-// this is the outermost loop
-while (!done) {
-#ifdef TRACE_CALC_YOUNG_CONFIG
-// leave this in for debugging, just in case
-gclog_or_tty->print_cr("searching between " SIZE_FORMAT " and " SIZE_FORMAT
-", incr " SIZE_FORMAT ", pass %s",
-from_so_length, to_so_length, so_length_incr,
-(pass == pass_type_coarse) ? "coarse" :
-(pass == pass_type_fine) ? "fine" : "final");
-#endif // TRACE_CALC_YOUNG_CONFIG
-size_t so_length = from_so_length;
-size_t init_free_regions =
-MAX2((size_t)0,
-_free_regions_at_end_of_collection +
-_scan_only_regions_at_end_of_collection - reserve_regions);
-// this determines whether a configuration was found
-bool gc_eff_set = false;
-// this is the middle loop
-while (so_length <= to_so_length) {
-// base time, which excludes region-related time; again we
-// calculate it once to avoid recalculating it in the
-// innermost loop
-double base_time_with_so_ms =
-base_time_ms + predict_scan_only_time_ms(so_length);
-// it's already over the pause target, go around
-if (base_time_with_so_ms > target_pause_time_ms)
-break;
-size_t starting_young_length = so_length+1;
-// we make sure that the short young length that makes sense
-// (one more than the S-O length) is feasible
-size_t min_young_length = starting_young_length;
-double min_gc_eff;
-bool min_ok;
-++calculations;
-min_ok = predict_gc_eff(min_young_length, so_length,
-base_time_with_so_ms,
-init_free_regions, target_pause_time_ms,
-&min_gc_eff);
-if (min_ok) {
-// the shortest young length is indeed feasible; we'll know
-// set up the max young length and we'll do a binary search
-// between min_young_length and max_young_length
-size_t max_young_length = _free_regions_at_end_of_collection - 1;
-double max_gc_eff = 0.0;
-bool max_ok = false;
-// the innermost loop! (finally!)
-while (max_young_length > min_young_length) {
-// we'll make sure that min_young_length is always at a
-// feasible config
-guarantee( min_ok, "invariant" );
-++calculations;
-max_ok = predict_gc_eff(max_young_length, so_length,
-base_time_with_so_ms,
-init_free_regions, target_pause_time_ms,
-&max_gc_eff);
 size_t diff = (max_young_length - min_young_length) / 2;
-if (max_ok) {
+max_young_length = min_young_length + diff;
-min_young_length = max_young_length;
-min_gc_eff = max_gc_eff;
+while (max_young_length > min_young_length) {
-min_ok = true;
+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;
 }
-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");
-// the innermost loop found a config
-guarantee( min_ok, "invariant" );
-if (min_gc_eff > final_gc_eff) {
-// it's the best config so far, so we'll keep it
-final_gc_eff = min_gc_eff;
-final_young_length = min_young_length;
-final_so_length = so_length;
-gc_eff_set = true;
-}
 }
+final_young_length = min_young_length;
-// incremental the fixed S-O length and go around
-so_length += so_length_incr;
 }
+}
-// this is the end of the outermost loop and we need to decide
+// and we're done!
-// what to do during the next iteration
-if (pass == pass_type_coarse) {
-// we just did the coarse pass (first iteration)
-if (!gc_eff_set)
-// we didn't find a feasible config so we'll just bail out; of
-// course, it might be the case that we missed it; but I'd say
-// it's a bit unlikely
-done = true;
-else {
-// We did find a feasible config with optimal GC eff during
-// the first pass. So the second pass we'll only consider the
-// S-O lengths around that config with a fine increment.
-guarantee( so_length_incr == so_coarse_increments, "invariant" );
-guarantee( final_so_length >= min_so_length, "invariant" );
-#ifdef TRACE_CALC_YOUNG_CONFIG
-// leave this in for debugging, just in case
-gclog_or_tty->print_cr("  coarse pass: SO length " SIZE_FORMAT,
-final_so_length);
-#endif // TRACE_CALC_YOUNG_CONFIG
-from_so_length =
-(final_so_length - min_so_length > so_coarse_increments) ?
-final_so_length - so_coarse_increments + 1 : min_so_length;
-to_so_length =
-(max_so_length - final_so_length > so_coarse_increments) ?
-final_so_length + so_coarse_increments - 1 : max_so_length;
-pass = pass_type_fine;
-so_length_incr = 1;
-}
-} else if (pass == pass_type_fine) {
-// we just finished the second pass
-if (!gc_eff_set) {
-// we didn't find a feasible config (yes, it's possible;
-// notice that, sometimes, we go directly into the fine
-// iteration and skip the coarse one) so we bail out
-done = true;
-} else {
-// We did find a feasible config with optimal GC eff
-guarantee( so_length_incr == 1, "invariant" );
-if (final_so_length == 0) {
-// The config is of an empty S-O set, so we'll just bail out
-done = true;
-} else {
-// we'll go around once more, setting the S-O length to 95%
-// of the optimal
-size_t new_so_length = 950 * final_so_length / 1000;
-#ifdef TRACE_CALC_YOUNG_CONFIG
-// leave this in for debugging, just in case
-gclog_or_tty->print_cr("  fine pass: SO length " SIZE_FORMAT
-", setting it to " SIZE_FORMAT,
-final_so_length, new_so_length);
-#endif // TRACE_CALC_YOUNG_CONFIG
-from_so_length = new_so_length;
-to_so_length = new_so_length;
-fine_so_length = final_so_length;
-pass = pass_type_final;
-}
-}
-} else if (pass == pass_type_final) {
-// we just finished the final (third) pass
-if (!gc_eff_set)
-// we didn't find a feasible config, so we'll just use the one
-// we found during the second pass, which we saved
-final_so_length = fine_so_length;
-// and we're done!
-done = true;
-} else {
-guarantee( false, "should never reach here" );
-}
-// we now go around the outermost loop
-}
 // we should have at least one region in the target young length
 _young_list_target_length =
 MAX2((size_t) 1, final_young_length + _recorded_survivor_regions);
-if (final_so_length >= final_young_length)
-// and we need to ensure that the S-O length is not greater than
-// the target young length (this is being a bit careful)
-final_so_length = 0;
-_young_list_so_prefix_length = final_so_length;
-guarantee( !_in_marking_window || !_last_full_young_gc ||
-_young_list_so_prefix_length == 0, "invariant" );
 // 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_CONFIG
+#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
+gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", "
-", SO = " SIZE_FORMAT ", "
+"elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT,
-"elapsed %1.2lf ms, calcs: " SIZE_FORMAT " (%s%s) "
-SIZE_FORMAT SIZE_FORMAT,
 target_pause_time_ms,
-_young_list_target_length - _young_list_so_prefix_length,
+_young_list_target_length
-_young_list_so_prefix_length,
 elapsed_time_ms,
-calculations,
 full_young_gcs() ? "full" : "partial",
 during_initial_mark_pause() ? " i-m" : "",
 _in_marking_window,
 _in_marking_window_im);
-#endif // TRACE_CALC_YOUNG_CONFIG
+#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 optimal
+// bummer; this means that, if we do a pause when the maximal
-// config dictates, we'll violate the pause spacing target (the
+// 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.
-size_t so_length = 0;
+#ifdef TRACE_CALC_YOUNG_LENGTH
-// a note further up explains why we do not want an S-O length
-// during marking
-if (!_in_marking_window && !_last_full_young_gc)
-// but we can still try to see whether we can find an optimal
-// S-O length
-so_length = calculate_optimal_so_length(_young_list_min_length);
-#ifdef TRACE_CALC_YOUNG_CONFIG
 // leave this in for debugging, just in case
 gclog_or_tty->print_cr("adjusted target length from "
-SIZE_FORMAT " to " SIZE_FORMAT
+SIZE_FORMAT " to " SIZE_FORMAT,
-", SO " SIZE_FORMAT,
+_young_list_target_length, _young_list_min_length);
-_young_list_target_length, _young_list_min_length,
+#endif // TRACE_CALC_YOUNG_LENGTH
-so_length);
-#endif // TRACE_CALC_YOUNG_CONFIG
+_young_list_target_length = _young_list_min_length;
-_young_list_target_length =
-MAX2(_young_list_min_length, (size_t)1);
-_young_list_so_prefix_length = so_length;
 }
 } else {
 // we are in a partially-young mode or we've run out of regions (due
 // to evacuation failure)
-#ifdef TRACE_CALC_YOUNG_CONFIG
+#ifdef TRACE_CALC_YOUNG_LENGTH
 // leave this in for debugging, just in case
 gclog_or_tty->print_cr("(partial) setting target to " SIZE_FORMAT
-", SO " SIZE_FORMAT,
+_young_list_min_length);
-_young_list_min_length, 0);
+#endif // TRACE_CALC_YOUNG_LENGTH
-#endif // TRACE_CALC_YOUNG_CONFIG
+// we'll do the pause as soon as possible by choosing the minimum
-// we'll do the pause as soon as possible and with no S-O prefix
-// (see above for the reasons behind the latter)
 _young_list_target_length =
 MAX2(_young_list_min_length, (size_t) 1);
-_young_list_so_prefix_length = 0;
 }
 _rs_lengths_prediction = rs_lengths;
 }
-// This is used by: calculate_optimal_so_length(length). It returns
+// This is used by: calculate_young_list_target_length(rs_length). It
-// the GC eff and predicted pause time for a particular config
+// returns true iff:
-void
+//   the predicted pause time for the given young list will not overflow
-G1CollectorPolicy::predict_gc_eff(size_t young_length,
+//   the target pause time
-size_t so_length,
+// and:
-double base_time_ms,
+//   the predicted amount of surviving data will not overflow the
-double* ret_gc_eff,
+//   the amount of free space available for survivor regions.
-double* ret_pause_time_ms) {
+//
-double so_time_ms = predict_scan_only_time_ms(so_length);
-double accum_surv_rate_adj = 0.0;
-if (so_length > 0)
-accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
-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 - so_length);
-double pause_time_ms =
-base_time_ms + so_time_ms + copy_time_ms + young_other_time_ms;
-size_t reclaimed_bytes =
-(young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
-double gc_eff = (double) reclaimed_bytes / pause_time_ms;
-*ret_gc_eff = gc_eff;
-*ret_pause_time_ms = pause_time_ms;
-}
-// This is used by: calculate_young_list_target_config(rs_length). It
-// returns the GC eff of a particular config. It returns false if that
-// config violates any of the end conditions of the search in the
-// calling method, or true upon success. The end conditions were put
-// here since it's called twice and it was best not to replicate them
-// in the caller. Also, passing the parameteres avoids having to
-// recalculate them in the innermost loop.
 bool
-G1CollectorPolicy::predict_gc_eff(size_t young_length,
+G1CollectorPolicy::predict_will_fit(size_t young_length,
-size_t so_length,
+double base_time_ms,
-double base_time_with_so_ms,
+size_t init_free_regions,
-size_t init_free_regions,
+double target_pause_time_ms) {
-double target_pause_time_ms,
-double* ret_gc_eff) {
-*ret_gc_eff = 0.0;
 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;
-if (so_length > 0)
-accum_surv_rate_adj = accum_yg_surv_rate_pred((int)(so_length - 1));
 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 - so_length);
+predict_young_other_time_ms(young_length);
 double pause_time_ms =
-base_time_with_so_ms + copy_time_ms + young_other_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 reclaimed_bytes =
-(young_length - so_length) * HeapRegion::GrainBytes - bytes_to_copy;
 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!
-double gc_eff = (double) reclaimed_bytes / pause_time_ms;
-*ret_gc_eff = gc_eff;
 return true;
 }
 double G1CollectorPolicy::predict_survivor_regions_evac_time() {
 double survivor_regions_evac_time = 0.0;
 }
 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();
+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_config(rs_lengths_prediction);
+calculate_young_list_target_length(rs_lengths_prediction);
 }
 }
 HeapWord* G1CollectorPolicy::mem_allocate_work(size_t size,
 bool is_tlab,
 }
 #ifndef PRODUCT
 bool G1CollectorPolicy::verify_young_ages() {
-HeapRegion* head = _g1->young_list_first_region();
+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
 }
 _known_garbage_bytes = 0;
 _known_garbage_ratio = 0.0;
 _in_marking_window = false;
 _in_marking_window_im = false;
-_short_lived_surv_rate_group->record_scan_only_prefix(0);
 _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();
-_scan_only_regions_at_end_of_collection = 0;
 // Reset survivors SurvRateGroup.
 _survivor_surv_rate_group->reset();
 calculate_young_list_min_length();
-calculate_young_list_target_config();
+calculate_young_list_target_length();
 }
 void G1CollectorPolicy::record_before_bytes(size_t bytes) {
 _bytes_in_to_space_before_gc += bytes;
 }
 // if they are not set properly
 for (int i = 0; i < _parallel_gc_threads; ++i) {
 _par_last_ext_root_scan_times_ms[i] = -666.0;
 _par_last_mark_stack_scan_times_ms[i] = -666.0;
-_par_last_scan_only_times_ms[i] = -666.0;
-_par_last_scan_only_regions_scanned[i] = -666.0;
 _par_last_update_rs_start_times_ms[i] = -666.0;
 _par_last_update_rs_times_ms[i] = -666.0;
 _par_last_update_rs_processed_buffers[i] = -666.0;
 _par_last_scan_rs_start_times_ms[i] = -666.0;
 _par_last_scan_rs_times_ms[i] = -666.0;
 _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();
-size_t short_lived_so_length = _young_list_so_prefix_length;
-_short_lived_surv_rate_group->record_scan_only_prefix(short_lived_so_length);
-tag_scan_only(short_lived_so_length);
 _survivors_age_table.clear();
 assert( verify_young_ages(), "region age verification" );
-}
-void G1CollectorPolicy::tag_scan_only(size_t short_lived_scan_only_length) {
-// done in a way that it can be extended for other surv rate groups too...
-HeapRegion* head = _g1->young_list_first_region();
-bool finished_short_lived = (short_lived_scan_only_length == 0);
-if (finished_short_lived)
-return;
-for (HeapRegion* curr = head;
-curr != NULL;
-curr = curr->get_next_young_region()) {
-SurvRateGroup* surv_rate_group = curr->surv_rate_group();
-int age = curr->age_in_surv_rate_group();
-if (surv_rate_group == _short_lived_surv_rate_group) {
-if ((size_t)age < short_lived_scan_only_length)
-curr->set_scan_only();
-else
-finished_short_lived = true;
-}
-if (finished_short_lived)
-return;
-}
-guarantee( false, "we should never reach here" );
 }
 void G1CollectorPolicy::record_mark_closure_time(double mark_closure_time_ms) {
 _mark_closure_time_ms = mark_closure_time_ms;
 }
 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_config();
+calculate_young_list_target_length();
 }
 }
 void G1CollectorPolicy::record_concurrent_pause() {
 if (_stop_world_start > 0.0) {
 "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++;
 summary = _summary;
 }
 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 scan_only_time = avg_value(_par_last_scan_only_times_ms);
-double scan_only_regions_scanned =
-sum_of_values(_par_last_scan_only_regions_scanned);
 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_other_time = _cur_collection_par_time_ms -
 (update_rs_time + ext_root_scan_time + mark_stack_scan_time +
-scan_only_time + scan_rs_time + obj_copy_time + termination_time);
+scan_rs_time + obj_copy_time + termination_time);
 if (update_stats) {
 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_scan_only_time_ms(scan_only_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);
 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_only_time +
+ext_root_scan_time + mark_stack_scan_time +
 scan_rs_time + obj_copy_time;
 }
 if (PrintGCDetails) {
 gclog_or_tty->print_cr("%s%s, %1.8lf secs]",
 print_par_stats(2, "Update RS", _par_last_update_rs_times_ms);
 print_par_buffers(3, "Processed Buffers",
 _par_last_update_rs_processed_buffers, true);
 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-Only Scanning", _par_last_scan_only_times_ms);
-print_par_buffers(3, "Scan-Only Regions",
-_par_last_scan_only_regions_scanned, true);
 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_stats(2, "Other", parallel_other_time);
 print_stats(1, "Clear CT", _cur_clear_ct_time_ms);
 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-Only Scanning", scan_only_time);
 print_stats(1, "Scan RS", scan_rs_time);
 print_stats(1, "Object Copying", obj_copy_time);
 }
 }
 #ifndef PRODUCT
 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]);
 if (_pending_cards > 0) {
 cost_per_card_ms = update_rs_time / (double) _pending_cards;
 _cost_per_card_ms_seq->add(cost_per_card_ms);
 }
-double cost_per_scan_only_region_ms = 0.0;
-if (scan_only_regions_scanned > 0.0) {
-cost_per_scan_only_region_ms =
-scan_only_time / scan_only_regions_scanned;
-if (_in_marking_window_im)
-_cost_per_scan_only_region_ms_during_cm_seq->add(cost_per_scan_only_region_ms);
-else
-_cost_per_scan_only_region_ms_seq->add(cost_per_scan_only_region_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;
 else
 _cost_per_byte_ms_seq->add(cost_per_byte_ms);
 }
 double all_other_time_ms = pause_time_ms -
-(update_rs_time + scan_only_time + scan_rs_time + obj_copy_time +
+(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 =
 _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 %d "
+"REGIONS %d %d %d "
 "PENDING_CARDS %d %d "
 "CARDS_SCANNED %d %d "
 "RS_LENGTHS %d %d "
-"SCAN_ONLY_SCAN %1.6lf %1.6lf "
 "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 "
 _cur_collection_start_sec,
 (!_last_young_gc_full) ? 2 :
 (last_pause_included_initial_mark) ? 1 : 0,
 _recorded_region_num,
 _recorded_young_regions,
-_recorded_scan_only_regions,
 _recorded_non_young_regions,
 _predicted_pending_cards, _pending_cards,
 _predicted_cards_scanned, cards_scanned,
 _predicted_rs_lengths, _max_rs_lengths,
-_predicted_scan_only_scan_time_ms, scan_only_time,
 _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,
 }
 _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();
-_scan_only_regions_at_end_of_collection = _g1->young_list_length();
 calculate_young_list_min_length();
-calculate_young_list_target_config();
+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>
 _target_pause_time_ms = -1.0;
 }
 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();
+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() +
+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
 }
 void
 G1CollectorPolicy::start_recording_regions() {
 _recorded_rs_lengths            = 0;
-_recorded_scan_only_regions     = 0;
 _recorded_young_regions         = 0;
 _recorded_non_young_regions     = 0;
 #if PREDICTIONS_VERBOSE
-_predicted_rs_lengths           = 0;
-_predicted_cards_scanned        = 0;
 _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(HeapRegion* hr, bool young) {
+G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) {
-if (young) {
-++_recorded_young_regions;
-} else {
-++_recorded_non_young_regions;
-}
 #if PREDICTIONS_VERBOSE
-if (young) {
+if (!young) {
-_recorded_young_bytes += hr->used();
-} else {
 _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_scan_only_regions(size_t scan_only_length) {
+G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) {
-_recorded_scan_only_regions = scan_only_length;
+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_scan_only_scan_time_ms =
-predict_scan_only_time_ms(_recorded_scan_only_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_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_scan_only_scan_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 +
 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-Only Scanning",
-body_summary->get_scan_only_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_only_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(),
 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-Only Scanning",
-body_summary->get_scan_only_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());
 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_only_seq(),
 body_summary->get_scan_rs_seq(),
 body_summary->get_obj_copy_seq()
 };
 calc_other_times_ms = NumberSeq(summary->get_total_seq(),
 7, other_parts);
 bool
 G1CollectorPolicy::should_add_next_region_to_young_list() {
 assert(in_young_gc_mode(), "should be in young GC mode");
 bool ret;
-size_t young_list_length = _g1->young_list_length();
+size_t young_list_length = _g1->young_list()->length();
 size_t young_list_max_length = _young_list_target_length;
 if (G1FixedEdenSize) {
 young_list_max_length -= _max_survivor_regions;
 }
 if (young_list_length < young_list_max_length) {
 G1CollectorPolicy_BestRegionsFirst::should_do_collection_pause(size_t
 word_size) {
 assert(_g1->regions_accounted_for(), "Region leakage!");
 double max_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
-size_t young_list_length = _g1->young_list_length();
+size_t young_list_length = _g1->young_list()->length();
 size_t young_list_max_length = _young_list_target_length;
 if (G1FixedEdenSize) {
 young_list_max_length -= _max_survivor_regions;
 }
 bool reached_target_length = young_list_length >= young_list_max_length;
 if (in_young_gc_mode()) {
 if (reached_target_length) {
-assert( young_list_length > 0 && _g1->young_list_length() > 0,
+assert( young_list_length > 0 && _g1->young_list()->length() > 0,
 "invariant" );
 _target_pause_time_ms = max_pause_time_ms;
 return true;
 }
 } else {
 gclog_or_tty->print_cr("  work2: %8.3f ms.",
 (work2_end - sort_end)*1000.0);
 }
 }
-// Add the heap region to the collection set and return the conservative
+// Add the heap region at the head of the non-incremental collection set
-// estimate of the number of live bytes.
 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 (G1PrintHeapRegions) {
 gclog_or_tty->print_cr("added region to cset "
 "%d:["PTR_FORMAT", "PTR_FORMAT"], "
 "top "PTR_FORMAT", %s",
 hr->hrs_index(), hr->bottom(), hr->end(),
 }
 if (_g1->mark_in_progress())
 _g1->concurrent_mark()->registerCSetRegion(hr);
-assert(!hr->in_collection_set(),
+assert(!hr->in_collection_set(), "should not already be in the CSet");
-"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);
 }
-void
+// Initialize the per-collection-set information
-G1CollectorPolicy_BestRegionsFirst::
+void G1CollectorPolicy::start_incremental_cset_building() {
-choose_collection_set() {
+assert(_inc_cset_build_state == Inactive, "Precondition");
-double non_young_start_time_sec;
+_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;
+if (G1PrintHeapRegions) {
+gclog_or_tty->print_cr(" added region to incremental cset (RHS) "
+"%d:["PTR_FORMAT", "PTR_FORMAT"], "
+"top "PTR_FORMAT", young %s",
+hr->hrs_index(), hr->bottom(), hr->end(),
+hr->top(), (hr->is_young()) ? "YES" : "NO");
+}
+}
+// 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;
+if (G1PrintHeapRegions) {
+gclog_or_tty->print_cr(" added region to incremental cset (LHS) "
+"%d:["PTR_FORMAT", "PTR_FORMAT"], "
+"top "PTR_FORMAT", young %s",
+hr->hrs_index(), hr->bottom(), hr->end(),
+hr->top(), (hr->is_young()) ? "YES" : "NO");
+}
+}
+#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
+bool
+G1CollectorPolicy_BestRegionsFirst::choose_collection_set() {
+// Set this here - in case we're not doing young collections.
+double non_young_start_time_sec = os::elapsedTime();
+// The result that this routine will return. This will be set to
+// false if:
+// * we're doing a young or partially young collection and we
+//   have added the youg regions to collection set, or
+// * we add old regions to the collection set.
+bool abandon_collection = true;
 start_recording_regions();
 guarantee(_target_pause_time_ms > -1.0
 NOT_PRODUCT(|| Universe::heap()->gc_cause() == GCCause::_scavenge_alot),
 "_target_pause_time_ms should have been set!");
 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());
+_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;
-hr = _g1->pop_region_from_young_list();
+// 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");
-assert( hr->young_index_in_cset() == -1, "invariant" );
+hr->set_young();
-assert( hr->age_in_surv_rate_group() != -1, "invariant" );
+hr = hr->get_next_young_region();
-hr->set_young_index_in_cset((int) _young_cset_length);
+}
-++_young_cset_length;
+// Clear the fields that point to the survivor list - they are
-double predicted_time_ms = predict_region_elapsed_time_ms(hr, true);
+// all young now.
-time_remaining_ms -= predicted_time_ms;
+_g1->young_list()->clear_survivors();
-predicted_pause_time_ms += predicted_time_ms;
-assert(!hr->in_collection_set(), "invariant");
+if (_g1->mark_in_progress())
-add_to_collection_set(hr);
+_g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger);
-record_cset_region(hr, true);
-max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes);
+_young_cset_length = _inc_cset_young_index;
-if (G1PolicyVerbose > 0) {
+_collection_set = _inc_cset_head;
-gclog_or_tty->print_cr("  Added [" PTR_FORMAT ", " PTR_FORMAT") to CS.",
+_collection_set_size = _inc_cset_size;
-hr->bottom(), hr->end());
+_collection_set_bytes_used_before = _inc_cset_bytes_used_before;
-gclog_or_tty->print_cr("    (" SIZE_FORMAT " KB left in heap.)",
-max_live_bytes/K);
+// For young regions in the collection set, we assume the worst
-}
+// case of complete survival
-hr = _g1->pop_region_from_young_list();
+max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes;
-}
+time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms;
-record_scan_only_regions(_g1->young_list_scan_only_length());
+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");
+if (_inc_cset_size > 0) {
+assert(_collection_set != NULL, "Invariant");
+abandon_collection = false;
+}
 double young_end_time_sec = os::elapsedTime();
 _recorded_young_cset_choice_time_ms =
 (young_end_time_sec - young_start_time_sec) * 1000.0;
-non_young_start_time_sec = os::elapsedTime();
+// We are doing young collections so reset this.
+non_young_start_time_sec = young_end_time_sec;
-if (_young_cset_length > 0 && _last_young_gc_full) {
+// 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
+// Save the current size of the collection set to detect
+// if we actually added any old regions.
+size_t n_young_regions = _collection_set_size;
 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_cset_region(hr, false);
+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);
 }
 } while (should_continue);
 if (!adaptive_young_list_length() &&
 _collection_set_size < _young_list_fixed_length)
 _should_revert_to_full_young_gcs  = true;
+if (_collection_set_size > n_young_regions) {
+// We actually added old regions to the collection set
+// so we are not abandoning this collection.
+abandon_collection = false;
+}
 }
 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;
+return abandon_collection;
 }
 void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
 G1CollectorPolicy::record_full_collection_end();
 _collectionSetChooser->updateAfterFullCollection();

Mercurial > hg > truffle

comparison src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp @ 1394:1316cec51b4d