diff -r 6ecb6e6de3d6 -r 1316cec51b4d src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp --- a/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp Mon Apr 19 05:40:21 2010 -0700 +++ b/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp Thu Apr 22 10:02:38 2010 -0700 @@ -1,5 +1,5 @@ /* - * 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 @@ -42,10 +42,6 @@ 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 @@ -125,7 +121,6 @@ _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)), @@ -133,7 +128,6 @@ _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( @@ -186,6 +180,22 @@ _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 @@ -223,8 +233,6 @@ _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]; @@ -254,8 +262,6 @@ _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]); @@ -283,7 +289,7 @@ // 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, @@ -357,15 +363,18 @@ 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(); - guarantee( _young_list_min_length == 0, "invariant, not enough info" ); - calculate_young_list_target_config(); - } else { + _free_regions_at_end_of_collection = _g1->free_regions(); + calculate_young_list_min_length(); + guarantee( _young_list_min_length == 0, "invariant, not enough info" ); + calculate_young_list_target_length(); + } 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. @@ -385,112 +394,29 @@ 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 -// 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) { +void G1CollectorPolicy::calculate_young_list_target_length(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); @@ -504,285 +430,80 @@ 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; - 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 + size_t scanned_cards = predict_young_card_num(adj_rs_lengths); 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; - // we'll also keep track of how many times we go into the inner loop - // this is for profiling reasons - size_t calculations = 0; - - // this determines which of the three iterations the outer loop is in - typedef enum { - pass_type_coarse, - pass_type_fine, - pass_type_final - } pass_type_t; - - // range of the outer loop's iteration - size_t from_so_length = min_so_length; - size_t to_so_length = max_so_length; - guarantee( from_so_length <= to_so_length, "invariant" ); - - // 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 - // iteration fails to find something - size_t fine_so_length = 0; - - // the increment step for the coarse (first) iteration - size_t so_coarse_increments = 5; - - // the common case, we'll start with the coarse iteration - pass_type_t pass = pass_type_coarse; - size_t so_length_incr = so_coarse_increments; - - if (from_so_length == to_so_length) { - // not point in doing the coarse iteration, we'll go directly into - // the fine one (we essentially trying to find the optimal young - // length for a fixed S-O length). - 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; + + size_t init_free_regions = + MAX2((size_t)0, _free_regions_at_end_of_collection - reserve_regions); + + // if we're still under the pause target... + if (base_time_ms <= target_pause_time_ms) { + // We make sure that the shortest young length that makes sense + // fits within the target pause time. + size_t min_young_length = 1; + + if (predict_will_fit(min_young_length, base_time_ms, + init_free_regions, target_pause_time_ms)) { + // The shortest young length will fit within the target pause time; + // we'll now check whether the absolute maximum number of young + // regions will fit in the target pause time. If not, we'll do + // a binary search between min_young_length and max_young_length + size_t abs_max_young_length = _free_regions_at_end_of_collection - 1; + size_t max_young_length = abs_max_young_length; + + if (max_young_length > min_young_length) { + // Let's check if the initial max young length will fit within the + // target pause. If so then there is no need to search for a maximal + // young length - we'll return the initial maximum + + if (predict_will_fit(max_young_length, base_time_ms, + init_free_regions, target_pause_time_ms)) { + // The maximum young length will satisfy the target pause time. + // We are done so set min young length to this maximum length. + // The code after the loop will then set final_young_length using + // the value cached in the minimum length. + min_young_length = max_young_length; + } else { + // The maximum possible number of young regions will not fit within + // the target pause time so let's search.... + + size_t diff = (max_young_length - min_young_length) / 2; + max_young_length = min_young_length + diff; + + while (max_young_length > min_young_length) { + 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; + } + // 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"); + } + final_young_length = min_young_length; + } } - - 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) { - min_young_length = max_young_length; - min_gc_eff = max_gc_eff; - min_ok = true; - } - max_young_length = min_young_length + diff; - } - - // 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; - } - } - - // 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 - // 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 - } + // and we're done! // 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 @@ -790,142 +511,91 @@ 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 - ", SO = " SIZE_FORMAT ", " - "elapsed %1.2lf ms, calcs: " SIZE_FORMAT " (%s%s) " - SIZE_FORMAT SIZE_FORMAT, + gclog_or_tty->print_cr("target = %1.1lf ms, young = " SIZE_FORMAT ", " + "elapsed %1.2lf ms, (%s%s) " SIZE_FORMAT SIZE_FORMAT, target_pause_time_ms, - _young_list_target_length - _young_list_so_prefix_length, - _young_list_so_prefix_length, + _young_list_target_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 - // config dictates, we'll violate the pause spacing target (the + // bummer; this means that, if we do a pause when the maximal + // 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; - // 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 +#ifdef TRACE_CALC_YOUNG_LENGTH // leave this in for debugging, just in case gclog_or_tty->print_cr("adjusted target length from " - SIZE_FORMAT " to " SIZE_FORMAT - ", SO " SIZE_FORMAT, - _young_list_target_length, _young_list_min_length, - so_length); -#endif // TRACE_CALC_YOUNG_CONFIG - - _young_list_target_length = - MAX2(_young_list_min_length, (size_t)1); - _young_list_so_prefix_length = so_length; + SIZE_FORMAT " to " SIZE_FORMAT, + _young_list_target_length, _young_list_min_length); +#endif // TRACE_CALC_YOUNG_LENGTH + + _young_list_target_length = _young_list_min_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, 0); -#endif // TRACE_CALC_YOUNG_CONFIG - - // 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_min_length); +#endif // TRACE_CALC_YOUNG_LENGTH + // we'll do the pause as soon as possible by choosing the minimum _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 -// the GC eff and predicted pause time for a particular config -void -G1CollectorPolicy::predict_gc_eff(size_t young_length, - size_t so_length, - double base_time_ms, - double* ret_gc_eff, - 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. +// This is used by: calculate_young_list_target_length(rs_length). It +// returns true iff: +// the predicted pause time for the given young list will not overflow +// the target pause time +// and: +// the predicted amount of surviving data will not overflow the +// the amount of free space available for survivor regions. +// bool -G1CollectorPolicy::predict_gc_eff(size_t young_length, - size_t so_length, - double base_time_with_so_ms, - size_t init_free_regions, - double target_pause_time_ms, - double* ret_gc_eff) { - *ret_gc_eff = 0.0; +G1CollectorPolicy::predict_will_fit(size_t young_length, + double base_time_ms, + size_t init_free_regions, + double target_pause_time_ms) { 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; @@ -934,9 +604,6 @@ return false; // success! - double gc_eff = (double) reclaimed_bytes / pause_time_ms; - *ret_gc_eff = gc_eff; - return true; } @@ -953,11 +620,11 @@ 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); } } @@ -979,7 +646,7 @@ #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 @@ -1056,7 +723,6 @@ _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 @@ -1066,11 +732,10 @@ _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) { @@ -1119,8 +784,6 @@ 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; @@ -1143,47 +806,13 @@ 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; } @@ -1277,7 +906,7 @@ _last_full_young_gc = true; _in_marking_window = false; if (adaptive_young_list_length()) - calculate_young_list_target_config(); + calculate_young_list_target_length(); } } @@ -1512,6 +1141,7 @@ 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; @@ -1599,9 +1229,6 @@ 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); @@ -1611,7 +1238,7 @@ 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!"); @@ -1622,7 +1249,6 @@ 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); @@ -1676,7 +1302,7 @@ 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; } @@ -1701,9 +1327,6 @@ _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); @@ -1715,7 +1338,6 @@ (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); } @@ -1730,6 +1352,8 @@ } #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]; @@ -1815,16 +1439,6 @@ _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; @@ -1860,7 +1474,7 @@ } 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; @@ -1907,11 +1521,10 @@ 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 " @@ -1924,12 +1537,10 @@ (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, @@ -1954,14 +1565,12 @@ _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); - // _target_pause_time_ms = -1.0; @@ -2016,13 +1625,13 @@ 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()) @@ -2106,31 +1715,22 @@ 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) { - if (young) { - ++_recorded_young_regions; - } else { - ++_recorded_non_young_regions; - } +G1CollectorPolicy::record_cset_region_info(HeapRegion* hr, bool young) { #if PREDICTIONS_VERBOSE - if (young) { - _recorded_young_bytes += hr->used(); - } else { + if (!young) { _recorded_marked_bytes += hr->max_live_bytes(); } _predicted_bytes_to_copy += predict_bytes_to_copy(hr); @@ -2141,12 +1741,37 @@ } void -G1CollectorPolicy::record_scan_only_regions(size_t scan_only_length) { - _recorded_scan_only_regions = scan_only_length; +G1CollectorPolicy::record_non_young_cset_region(HeapRegion* hr) { + 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(); @@ -2157,8 +1782,6 @@ 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 = @@ -2173,7 +1796,6 @@ 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 + @@ -2463,8 +2085,6 @@ 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()); @@ -2474,7 +2094,6 @@ 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() @@ -2492,8 +2111,6 @@ 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()); } @@ -2519,7 +2136,6 @@ 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() }; @@ -2613,7 +2229,7 @@ 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; @@ -2676,7 +2292,7 @@ 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; @@ -2685,7 +2301,7 @@ 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; @@ -2946,10 +2562,12 @@ } } -// Add the heap region to the collection set and return the conservative -// estimate of the number of live bytes. +// Add the heap region at the head of the non-incremental collection set 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"], " @@ -2961,8 +2579,7 @@ if (_g1->mark_in_progress()) _g1->concurrent_mark()->registerCSetRegion(hr); - assert(!hr->in_collection_set(), - "should not already be in the CSet"); + assert(!hr->in_collection_set(), "should not already be in the CSet"); hr->set_in_collection_set(true); hr->set_next_in_collection_set(_collection_set); _collection_set = hr; @@ -2971,10 +2588,230 @@ _g1->register_region_with_in_cset_fast_test(hr); } -void -G1CollectorPolicy_BestRegionsFirst:: -choose_collection_set() { - double non_young_start_time_sec; +// Initialize the per-collection-set information +void G1CollectorPolicy::start_incremental_cset_building() { + assert(_inc_cset_build_state == Inactive, "Precondition"); + + _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 @@ -3027,47 +2864,79 @@ 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->young_index_in_cset() == -1, "invariant" ); - assert( hr->age_in_surv_rate_group() != -1, "invariant" ); - hr->set_young_index_in_cset((int) _young_cset_length); - - ++_young_cset_length; - double predicted_time_ms = predict_region_elapsed_time_ms(hr, true); - time_remaining_ms -= predicted_time_ms; - predicted_pause_time_ms += predicted_time_ms; - assert(!hr->in_collection_set(), "invariant"); - add_to_collection_set(hr); - record_cset_region(hr, true); - max_live_bytes -= MIN2(hr->max_live_bytes(), max_live_bytes); - if (G1PolicyVerbose > 0) { - gclog_or_tty->print_cr(" Added [" PTR_FORMAT ", " PTR_FORMAT") to CS.", - hr->bottom(), hr->end()); - gclog_or_tty->print_cr(" (" SIZE_FORMAT " KB left in heap.)", - max_live_bytes/K); - } - hr = _g1->pop_region_from_young_list(); + assert(hr->is_survivor(), "badly formed young list"); + hr->set_young(); + hr = hr->get_next_young_region(); } - record_scan_only_regions(_g1->young_list_scan_only_length()); + // Clear the fields that point to the survivor list - they are + // all young now. + _g1->young_list()->clear_survivors(); + + if (_g1->mark_in_progress()) + _g1->concurrent_mark()->register_collection_set_finger(_inc_cset_max_finger); + + _young_cset_length = _inc_cset_young_index; + _collection_set = _inc_cset_head; + _collection_set_size = _inc_cset_size; + _collection_set_bytes_used_before = _inc_cset_bytes_used_before; + + // For young regions in the collection set, we assume the worst + // case of complete survival + max_live_bytes -= _inc_cset_size * HeapRegion::GrainBytes; + + time_remaining_ms -= _inc_cset_predicted_elapsed_time_ms; + 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(); - - if (_young_cset_length > 0 && _last_young_gc_full) { + // We are doing young collections so reset this. + non_young_start_time_sec = young_end_time_sec; + + // 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; } @@ -3077,6 +2946,11 @@ 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); @@ -3085,7 +2959,7 @@ 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.)", @@ -3103,9 +2977,17 @@ 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(); @@ -3113,6 +2995,8 @@ 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() {