1 /*
2 * Copyright (c) 2001, 2016, 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/g1Analytics.hpp"
27 #include "gc/g1/g1CollectorPolicy.hpp"
28 #include "gc/g1/g1YoungGenSizer.hpp"
29 #include "gc/g1/heapRegion.hpp"
30 #include "gc/g1/heapRegionRemSet.hpp"
31 #include "gc/shared/gcPolicyCounters.hpp"
32 #include "runtime/globals.hpp"
33 #include "utilities/debug.hpp"
34
35 G1CollectorPolicy::G1CollectorPolicy() {
36
37 // Set up the region size and associated fields. Given that the
38 // policy is created before the heap, we have to set this up here,
39 // so it's done as soon as possible.
40
41 // It would have been natural to pass initial_heap_byte_size() and
42 // max_heap_byte_size() to setup_heap_region_size() but those have
43 // not been set up at this point since they should be aligned with
44 // the region size. So, there is a circular dependency here. We base
45 // the region size on the heap size, but the heap size should be
46 // aligned with the region size. To get around this we use the
47 // unaligned values for the heap.
48 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
49 HeapRegionRemSet::setup_remset_size();
50
51 // Below, we might need to calculate the pause time target based on
52 // the pause interval. When we do so we are going to give G1 maximum
53 // flexibility and allow it to do pauses when it needs to. So, we'll
54 // arrange that the pause interval to be pause time target + 1 to
55 // ensure that a) the pause time target is maximized with respect to
56 // the pause interval and b) we maintain the invariant that pause
57 // time target < pause interval. If the user does not want this
58 // maximum flexibility, they will have to set the pause interval
59 // explicitly.
60
61 // First make sure that, if either parameter is set, its value is
62 // reasonable.
63 guarantee(MaxGCPauseMillis >= 1, "Range checking for MaxGCPauseMillis should guarantee that value is >= 1");
64
65 // Then, if the pause time target parameter was not set, set it to
66 // the default value.
67 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
68 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
69 // The default pause time target in G1 is 200ms
70 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
71 } else {
72 // We do not allow the pause interval to be set without the
73 // pause time target
74 vm_exit_during_initialization("GCPauseIntervalMillis cannot be set "
75 "without setting MaxGCPauseMillis");
76 }
77 }
78
79 // Then, if the interval parameter was not set, set it according to
80 // the pause time target (this will also deal with the case when the
81 // pause time target is the default value).
82 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
83 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
84 }
85 guarantee(GCPauseIntervalMillis >= 1, "Constraint for GCPauseIntervalMillis should guarantee that value is >= 1");
86 guarantee(GCPauseIntervalMillis > MaxGCPauseMillis, "Constraint for GCPauseIntervalMillis should guarantee that GCPauseIntervalMillis > MaxGCPauseMillis");
87 }
88
89 void G1CollectorPolicy::initialize_alignments() {
90 _space_alignment = HeapRegion::GrainBytes;
91 size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
92 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
93 _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
94 }
95
96 void G1CollectorPolicy::initialize_flags() {
97 if (G1HeapRegionSize != HeapRegion::GrainBytes) {
98 FLAG_SET_ERGO(size_t, G1HeapRegionSize, HeapRegion::GrainBytes);
99 }
100
101 guarantee(SurvivorRatio >= 1, "Range checking for SurvivorRatio should guarantee that value is >= 1");
102
103 CollectorPolicy::initialize_flags();
104 }
105