| /* |
| * Copyright (c) 2016, Oracle and/or its affiliates. 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. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "gc/g1/g1CollectedHeap.hpp" |
| #include "gc/g1/g1CollectionSet.hpp" |
| #include "gc/g1/g1CollectorPolicy.hpp" |
| #include "gc/g1/g1CollectorState.hpp" |
| #include "gc/g1/heapRegion.inline.hpp" |
| #include "gc/g1/heapRegionRemSet.hpp" |
| #include "gc/g1/heapRegionSet.hpp" |
| #include "utilities/debug.hpp" |
| |
| G1CollectorState* G1CollectionSet::collector_state() { |
| return _g1->collector_state(); |
| } |
| |
| G1GCPhaseTimes* G1CollectionSet::phase_times() { |
| return _policy->phase_times(); |
| } |
| |
| CollectionSetChooser* G1CollectionSet::cset_chooser() { |
| return _cset_chooser; |
| } |
| |
| double G1CollectionSet::predict_region_elapsed_time_ms(HeapRegion* hr) { |
| return _policy->predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young()); |
| } |
| |
| |
| G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h) : |
| _g1(g1h), |
| _policy(NULL), |
| _cset_chooser(new CollectionSetChooser()), |
| _eden_region_length(0), |
| _survivor_region_length(0), |
| _old_region_length(0), |
| |
| _head(NULL), |
| _bytes_used_before(0), |
| _recorded_rs_lengths(0), |
| // Incremental CSet attributes |
| _inc_build_state(Inactive), |
| _inc_head(NULL), |
| _inc_tail(NULL), |
| _inc_bytes_used_before(0), |
| _inc_recorded_rs_lengths(0), |
| _inc_recorded_rs_lengths_diffs(0), |
| _inc_predicted_elapsed_time_ms(0.0), |
| _inc_predicted_elapsed_time_ms_diffs(0.0) {} |
| |
| G1CollectionSet::~G1CollectionSet() { |
| delete _cset_chooser; |
| } |
| |
| void G1CollectionSet::init_region_lengths(uint eden_cset_region_length, |
| uint survivor_cset_region_length) { |
| _eden_region_length = eden_cset_region_length; |
| _survivor_region_length = survivor_cset_region_length; |
| _old_region_length = 0; |
| } |
| |
| void G1CollectionSet::set_recorded_rs_lengths(size_t rs_lengths) { |
| _recorded_rs_lengths = rs_lengths; |
| } |
| |
| // Add the heap region at the head of the non-incremental collection set |
| void G1CollectionSet::add_old_region(HeapRegion* hr) { |
| assert(_inc_build_state == Active, "Precondition"); |
| assert(hr->is_old(), "the region should be old"); |
| |
| assert(!hr->in_collection_set(), "should not already be in the CSet"); |
| _g1->register_old_region_with_cset(hr); |
| hr->set_next_in_collection_set(_head); |
| _head = hr; |
| _bytes_used_before += hr->used(); |
| size_t rs_length = hr->rem_set()->occupied(); |
| _recorded_rs_lengths += rs_length; |
| _old_region_length += 1; |
| } |
| |
| // Initialize the per-collection-set information |
| void G1CollectionSet::start_incremental_building() { |
| assert(_inc_build_state == Inactive, "Precondition"); |
| |
| _inc_head = NULL; |
| _inc_tail = NULL; |
| _inc_bytes_used_before = 0; |
| |
| _inc_recorded_rs_lengths = 0; |
| _inc_recorded_rs_lengths_diffs = 0; |
| _inc_predicted_elapsed_time_ms = 0.0; |
| _inc_predicted_elapsed_time_ms_diffs = 0.0; |
| _inc_build_state = Active; |
| } |
| |
| void G1CollectionSet::finalize_incremental_building() { |
| assert(_inc_build_state == Active, "Precondition"); |
| assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint"); |
| |
| // The two "main" fields, _inc_recorded_rs_lengths and |
| // _inc_predicted_elapsed_time_ms, are updated by the thread |
| // that adds a new region to the CSet. Further updates by the |
| // concurrent refinement thread that samples the young RSet lengths |
| // are accumulated in the *_diffs fields. Here we add the diffs to |
| // the "main" fields. |
| |
| if (_inc_recorded_rs_lengths_diffs >= 0) { |
| _inc_recorded_rs_lengths += _inc_recorded_rs_lengths_diffs; |
| } else { |
| // This is defensive. The diff should in theory be always positive |
| // as RSets can only grow between GCs. However, given that we |
| // sample their size concurrently with other threads updating them |
| // it's possible that we might get the wrong size back, which |
| // could make the calculations somewhat inaccurate. |
| size_t diffs = (size_t) (-_inc_recorded_rs_lengths_diffs); |
| if (_inc_recorded_rs_lengths >= diffs) { |
| _inc_recorded_rs_lengths -= diffs; |
| } else { |
| _inc_recorded_rs_lengths = 0; |
| } |
| } |
| _inc_predicted_elapsed_time_ms += _inc_predicted_elapsed_time_ms_diffs; |
| |
| _inc_recorded_rs_lengths_diffs = 0; |
| _inc_predicted_elapsed_time_ms_diffs = 0.0; |
| } |
| |
| void G1CollectionSet::update_young_region_prediction(HeapRegion* hr, |
| size_t new_rs_length) { |
| // Update the CSet information that is dependent on the new RS length |
| assert(hr->is_young(), "Precondition"); |
| assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint"); |
| |
| // We could have updated _inc_recorded_rs_lengths and |
| // _inc_predicted_elapsed_time_ms directly but we'd need to do |
| // that atomically, as this code is executed by a concurrent |
| // refinement thread, potentially concurrently with a mutator thread |
| // allocating a new region and also updating the same fields. To |
| // avoid the atomic operations we accumulate these updates on two |
| // separate fields (*_diffs) and we'll just add them to the "main" |
| // fields at the start of a GC. |
| |
| ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length(); |
| ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length; |
| _inc_recorded_rs_lengths_diffs += rs_lengths_diff; |
| |
| double old_elapsed_time_ms = hr->predicted_elapsed_time_ms(); |
| double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr); |
| double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms; |
| _inc_predicted_elapsed_time_ms_diffs += elapsed_ms_diff; |
| |
| hr->set_recorded_rs_length(new_rs_length); |
| hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms); |
| } |
| |
| void G1CollectionSet::add_young_region_common(HeapRegion* hr) { |
| assert(hr->is_young(), "invariant"); |
| assert(hr->young_index_in_cset() > -1, "should have already been set"); |
| assert(_inc_build_state == Active, "Precondition"); |
| |
| // This routine is used when: |
| // * adding survivor regions to the incremental cset at the end of an |
| // evacuation pause or |
| // * adding the current allocation region to the incremental cset |
| // when it is retired. |
| // 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) |
| // 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(); |
| double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr); |
| |
| // Cache the values we have added to the aggregated information |
| // 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); |
| |
| size_t used_bytes = hr->used(); |
| _inc_recorded_rs_lengths += rs_length; |
| _inc_predicted_elapsed_time_ms += region_elapsed_time_ms; |
| _inc_bytes_used_before += used_bytes; |
| |
| assert(!hr->in_collection_set(), "invariant"); |
| _g1->register_young_region_with_cset(hr); |
| assert(hr->next_in_collection_set() == NULL, "invariant"); |
| } |
| |
| // Add the region at the RHS of the incremental cset |
| void G1CollectionSet::add_survivor_regions(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_young_region_common(hr); |
| |
| // Now add the region at the right hand side |
| if (_inc_tail == NULL) { |
| assert(_inc_head == NULL, "invariant"); |
| _inc_head = hr; |
| } else { |
| _inc_tail->set_next_in_collection_set(hr); |
| } |
| _inc_tail = hr; |
| } |
| |
| // Add the region to the LHS of the incremental cset |
| void G1CollectionSet::add_eden_region(HeapRegion* hr) { |
| // Survivors should be added to the RHS at the end of a pause |
| assert(hr->is_eden(), "Logic"); |
| |
| // Do the 'common' stuff |
| add_young_region_common(hr); |
| |
| // Add the region at the left hand side |
| hr->set_next_in_collection_set(_inc_head); |
| if (_inc_head == NULL) { |
| assert(_inc_tail == NULL, "Invariant"); |
| _inc_tail = hr; |
| } |
| _inc_head = hr; |
| } |
| |
| #ifndef PRODUCT |
| void G1CollectionSet::print(HeapRegion* list_head, outputStream* st) { |
| assert(list_head == inc_head() || list_head == head(), "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(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d", |
| HR_FORMAT_PARAMS(csr), |
| p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()), |
| csr->age_in_surv_rate_group_cond()); |
| csr = next; |
| } |
| } |
| #endif // !PRODUCT |
| |
| double G1CollectionSet::finalize_young_part(double target_pause_time_ms) { |
| double young_start_time_sec = os::elapsedTime(); |
| |
| YoungList* young_list = _g1->young_list(); |
| finalize_incremental_building(); |
| |
| guarantee(target_pause_time_ms > 0.0, |
| "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms); |
| guarantee(_head == NULL, "Precondition"); |
| |
| size_t pending_cards = _policy->pending_cards(); |
| double base_time_ms = _policy->predict_base_elapsed_time_ms(pending_cards); |
| double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0); |
| |
| log_trace(gc, ergo, cset)("Start choosing CSet. pending cards: " SIZE_FORMAT " predicted base time: %1.2fms remaining time: %1.2fms target pause time: %1.2fms", |
| pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms); |
| |
| collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young()); |
| |
| // 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]. |
| |
| uint survivor_region_length = young_list->survivor_length(); |
| uint eden_region_length = young_list->eden_length(); |
| init_region_lengths(eden_region_length, survivor_region_length); |
| |
| HeapRegion* hr = young_list->first_survivor_region(); |
| while (hr != NULL) { |
| assert(hr->is_survivor(), "badly formed young list"); |
| // There is a convention that all the young regions in the CSet |
| // are tagged as "eden", so we do this for the survivors here. We |
| // use the special set_eden_pre_gc() as it doesn't check that the |
| // region is free (which is not the case here). |
| hr->set_eden_pre_gc(); |
| hr = hr->get_next_young_region(); |
| } |
| |
| // Clear the fields that point to the survivor list - they are all young now. |
| young_list->clear_survivors(); |
| |
| _head = _inc_head; |
| _bytes_used_before = _inc_bytes_used_before; |
| time_remaining_ms = MAX2(time_remaining_ms - _inc_predicted_elapsed_time_ms, 0.0); |
| |
| log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms", |
| eden_region_length, survivor_region_length, _inc_predicted_elapsed_time_ms, target_pause_time_ms); |
| |
| // The number of recorded young regions is the incremental |
| // collection set's current size |
| set_recorded_rs_lengths(_inc_recorded_rs_lengths); |
| |
| double young_end_time_sec = os::elapsedTime(); |
| phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0); |
| |
| return time_remaining_ms; |
| } |
| |
| void G1CollectionSet::finalize_old_part(double time_remaining_ms) { |
| double non_young_start_time_sec = os::elapsedTime(); |
| double predicted_old_time_ms = 0.0; |
| |
| if (!collector_state()->gcs_are_young()) { |
| cset_chooser()->verify(); |
| const uint min_old_cset_length = _policy->calc_min_old_cset_length(); |
| const uint max_old_cset_length = _policy->calc_max_old_cset_length(); |
| |
| uint expensive_region_num = 0; |
| bool check_time_remaining = _policy->adaptive_young_list_length(); |
| |
| HeapRegion* hr = cset_chooser()->peek(); |
| while (hr != NULL) { |
| if (old_region_length() >= max_old_cset_length) { |
| // Added maximum number of old regions to the CSet. |
| log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached max). old %u regions, max %u regions", |
| old_region_length(), max_old_cset_length); |
| break; |
| } |
| |
| // Stop adding regions if the remaining reclaimable space is |
| // not above G1HeapWastePercent. |
| size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes(); |
| double reclaimable_perc = _policy->reclaimable_bytes_perc(reclaimable_bytes); |
| double threshold = (double) G1HeapWastePercent; |
| if (reclaimable_perc <= threshold) { |
| // We've added enough old regions that the amount of uncollected |
| // reclaimable space is at or below the waste threshold. Stop |
| // adding old regions to the CSet. |
| log_debug(gc, ergo, cset)("Finish adding old regions to CSet (reclaimable percentage not over threshold). " |
| "old %u regions, max %u regions, reclaimable: " SIZE_FORMAT "B (%1.2f%%) threshold: " UINTX_FORMAT "%%", |
| old_region_length(), max_old_cset_length, reclaimable_bytes, reclaimable_perc, G1HeapWastePercent); |
| break; |
| } |
| |
| double predicted_time_ms = predict_region_elapsed_time_ms(hr); |
| if (check_time_remaining) { |
| if (predicted_time_ms > time_remaining_ms) { |
| // Too expensive for the current CSet. |
| |
| if (old_region_length() >= min_old_cset_length) { |
| // We have added the minimum number of old regions to the CSet, |
| // we are done with this CSet. |
| log_debug(gc, ergo, cset)("Finish adding old regions to CSet (predicted time is too high). " |
| "predicted time: %1.2fms, remaining time: %1.2fms old %u regions, min %u regions", |
| predicted_time_ms, time_remaining_ms, old_region_length(), min_old_cset_length); |
| break; |
| } |
| |
| // We'll add it anyway given that we haven't reached the |
| // minimum number of old regions. |
| expensive_region_num += 1; |
| } |
| } else { |
| if (old_region_length() >= min_old_cset_length) { |
| // In the non-auto-tuning case, we'll finish adding regions |
| // to the CSet if we reach the minimum. |
| |
| log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached min). old %u regions, min %u regions", |
| old_region_length(), min_old_cset_length); |
| break; |
| } |
| } |
| |
| // We will add this region to the CSet. |
| time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0); |
| predicted_old_time_ms += predicted_time_ms; |
| cset_chooser()->pop(); // already have region via peek() |
| _g1->old_set_remove(hr); |
| add_old_region(hr); |
| |
| hr = cset_chooser()->peek(); |
| } |
| if (hr == NULL) { |
| log_debug(gc, ergo, cset)("Finish adding old regions to CSet (candidate old regions not available)"); |
| } |
| |
| if (expensive_region_num > 0) { |
| // We print the information once here at the end, predicated on |
| // whether we added any apparently expensive regions or not, to |
| // avoid generating output per region. |
| log_debug(gc, ergo, cset)("Added expensive regions to CSet (old CSet region num not reached min)." |
| "old: %u regions, expensive: %u regions, min: %u regions, remaining time: %1.2fms", |
| old_region_length(), expensive_region_num, min_old_cset_length, time_remaining_ms); |
| } |
| |
| cset_chooser()->verify(); |
| } |
| |
| stop_incremental_building(); |
| |
| log_debug(gc, ergo, cset)("Finish choosing CSet. old: %u regions, predicted old region time: %1.2fms, time remaining: %1.2f", |
| old_region_length(), predicted_old_time_ms, time_remaining_ms); |
| |
| double non_young_end_time_sec = os::elapsedTime(); |
| phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0); |
| } |