1 /*
2 * Copyright (c) 2018, Red Hat, Inc. and/or its affiliates.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
26 #include "gc_implementation/shenandoah/heuristics/shenandoahCompactHeuristics.hpp"
27 #include "gc_implementation/shenandoah/shenandoahFreeSet.hpp"
28 #include "gc_implementation/shenandoah/shenandoahHeapRegion.hpp"
29 #include "gc_implementation/shenandoah/shenandoahLogging.hpp"
30
31 ShenandoahCompactHeuristics::ShenandoahCompactHeuristics() : ShenandoahHeuristics() {
32 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahUncommit);
33 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahAlwaysClearSoftRefs);
34 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold, 10);
35 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold, 100);
36 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay, 5000);
37 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000);
38 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold, 20);
39 }
40
41 bool ShenandoahCompactHeuristics::should_start_normal_gc() const {
42 ShenandoahHeap* heap = ShenandoahHeap::heap();
43
44 size_t available = heap->free_set()->available();
45 size_t threshold_bytes_allocated = heap->capacity() * ShenandoahAllocationThreshold / 100;
46
47 if (available < threshold_bytes_allocated) {
48 log_info(gc)("Trigger: Free (" SIZE_FORMAT "M) is lower than allocated recently (" SIZE_FORMAT "M)",
49 available / M, threshold_bytes_allocated / M);
50 return true;
51 }
52
53 size_t bytes_allocated = heap->bytes_allocated_since_gc_start();
54 if (bytes_allocated > threshold_bytes_allocated) {
55 log_info(gc)("Trigger: Allocated since last cycle (" SIZE_FORMAT "M) is larger than allocation threshold (" SIZE_FORMAT "M)",
56 bytes_allocated / M, threshold_bytes_allocated / M);
57 return true;
58 }
59
60 return ShenandoahHeuristics::should_start_normal_gc();
61 }
62
63 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
64 RegionData* data, size_t size,
65 size_t actual_free) {
66
67 // Do not select too large CSet that would overflow the available free space
68 size_t max_cset = actual_free * 3 / 4;
69
70 log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "M, Max CSet: " SIZE_FORMAT "M",
71 actual_free / M, max_cset / M);
72
73 size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
74
75 size_t live_cset = 0;
76 for (size_t idx = 0; idx < size; idx++) {
77 ShenandoahHeapRegion* r = data[idx]._region;
78 size_t new_cset = live_cset + r->get_live_data_bytes();
79 if (new_cset < max_cset && r->garbage() > threshold) {
80 live_cset = new_cset;
81 cset->add_region(r);
82 }
83 }
84 }
85
86 const char* ShenandoahCompactHeuristics::name() {
87 return "compact";
88 }
89
90 bool ShenandoahCompactHeuristics::is_diagnostic() {
91 return false;
92 }
93
94 bool ShenandoahCompactHeuristics::is_experimental() {
95 return false;
96 }