1 /*
2 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/g1/collectionSetChooser.hpp"
27 #include "gc/g1/g1RemSetTrackingPolicy.hpp"
28 #include "gc/g1/heapRegion.inline.hpp"
29 #include "gc/g1/heapRegionRemSet.hpp"
30 #include "runtime/safepoint.hpp"
31
32 bool G1RemSetTrackingPolicy::needs_scan_for_rebuild(HeapRegion* r) const {
33 // All non-free, non-young, non-closed archive regions need to be scanned for references;
34 // At every gc we gather references to other regions in young, and closed archive
35 // regions by definition do not have references going outside the closed archive.
36 // Free regions trivially do not need scanning because they do not contain live
37 // objects.
38 return !(r->is_young() || r->is_closed_archive() || r->is_free());
39 }
40
41 void G1RemSetTrackingPolicy::update_at_allocate(HeapRegion* r) {
42 if (r->is_young()) {
43 // Always collect remembered set for young regions.
44 r->rem_set()->set_state_complete();
45 } else if (r->is_humongous()) {
46 // Collect remembered sets for humongous regions by default to allow eager reclaim.
109 assert(!r->is_humongous(), "Region %u is humongous", r->hrm_index());
110
111 // Only consider updating the remembered set for old gen regions - excluding archive regions
112 // which never move (but are "Old" regions).
113 if (!r->is_old() || r->is_archive()) {
114 return false;
115 }
116
117 assert(!r->rem_set()->is_updating(), "Remembered set of region %u is updating before rebuild", r->hrm_index());
118
119 size_t between_ntams_and_top = (r->top() - r->next_top_at_mark_start()) * HeapWordSize;
120 size_t total_live_bytes = live_bytes + between_ntams_and_top;
121
122 bool selected_for_rebuild = false;
123 // For old regions, to be of interest for rebuilding the remembered set the following must apply:
124 // - They must contain some live data in them.
125 // - Only need to rebuild non-complete remembered sets.
126 // - Otherwise only add those old gen regions which occupancy is low enough that there
127 // is a chance that we will ever evacuate them in the mixed gcs.
128 if ((total_live_bytes > 0) &&
129 CollectionSetChooser::region_occupancy_low_enough_for_evac(total_live_bytes) &&
130 !r->rem_set()->is_tracked()) {
131
132 r->rem_set()->set_state_updating();
133 selected_for_rebuild = true;
134 }
135
136 print_before_rebuild(r, selected_for_rebuild, total_live_bytes, live_bytes);
137
138 return selected_for_rebuild;
139 }
140
141 void G1RemSetTrackingPolicy::update_after_rebuild(HeapRegion* r) {
142 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
143
144 if (r->is_old_or_humongous_or_archive()) {
145 if (r->rem_set()->is_updating()) {
146 assert(!r->is_archive(), "Archive region %u with remembered set", r->hrm_index());
147 r->rem_set()->set_state_complete();
148 }
149 G1CollectedHeap* g1h = G1CollectedHeap::heap();
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1 /*
2 * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/g1/g1CollectionSetChooser.hpp"
27 #include "gc/g1/g1RemSetTrackingPolicy.hpp"
28 #include "gc/g1/heapRegion.inline.hpp"
29 #include "gc/g1/heapRegionRemSet.hpp"
30 #include "runtime/safepoint.hpp"
31
32 bool G1RemSetTrackingPolicy::needs_scan_for_rebuild(HeapRegion* r) const {
33 // All non-free, non-young, non-closed archive regions need to be scanned for references;
34 // At every gc we gather references to other regions in young, and closed archive
35 // regions by definition do not have references going outside the closed archive.
36 // Free regions trivially do not need scanning because they do not contain live
37 // objects.
38 return !(r->is_young() || r->is_closed_archive() || r->is_free());
39 }
40
41 void G1RemSetTrackingPolicy::update_at_allocate(HeapRegion* r) {
42 if (r->is_young()) {
43 // Always collect remembered set for young regions.
44 r->rem_set()->set_state_complete();
45 } else if (r->is_humongous()) {
46 // Collect remembered sets for humongous regions by default to allow eager reclaim.
109 assert(!r->is_humongous(), "Region %u is humongous", r->hrm_index());
110
111 // Only consider updating the remembered set for old gen regions - excluding archive regions
112 // which never move (but are "Old" regions).
113 if (!r->is_old() || r->is_archive()) {
114 return false;
115 }
116
117 assert(!r->rem_set()->is_updating(), "Remembered set of region %u is updating before rebuild", r->hrm_index());
118
119 size_t between_ntams_and_top = (r->top() - r->next_top_at_mark_start()) * HeapWordSize;
120 size_t total_live_bytes = live_bytes + between_ntams_and_top;
121
122 bool selected_for_rebuild = false;
123 // For old regions, to be of interest for rebuilding the remembered set the following must apply:
124 // - They must contain some live data in them.
125 // - Only need to rebuild non-complete remembered sets.
126 // - Otherwise only add those old gen regions which occupancy is low enough that there
127 // is a chance that we will ever evacuate them in the mixed gcs.
128 if ((total_live_bytes > 0) &&
129 G1CollectionSetChooser::region_occupancy_low_enough_for_evac(total_live_bytes) &&
130 !r->rem_set()->is_tracked()) {
131
132 r->rem_set()->set_state_updating();
133 selected_for_rebuild = true;
134 }
135
136 print_before_rebuild(r, selected_for_rebuild, total_live_bytes, live_bytes);
137
138 return selected_for_rebuild;
139 }
140
141 void G1RemSetTrackingPolicy::update_after_rebuild(HeapRegion* r) {
142 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
143
144 if (r->is_old_or_humongous_or_archive()) {
145 if (r->rem_set()->is_updating()) {
146 assert(!r->is_archive(), "Archive region %u with remembered set", r->hrm_index());
147 r->rem_set()->set_state_complete();
148 }
149 G1CollectedHeap* g1h = G1CollectedHeap::heap();
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