1 /*
2 * Copyright (c) 2015, 2020, 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 #include "precompiled.hpp"
25 #include "gc/shared/gcLogPrecious.hpp"
26 #include "gc/z/zAddressSpaceLimit.hpp"
27 #include "gc/z/zAddress.hpp"
28 #include "gc/z/zGlobals.hpp"
29 #include "gc/z/zVirtualMemory.inline.hpp"
30 #include "services/memTracker.hpp"
31 #include "utilities/debug.hpp"
32 #include "utilities/align.hpp"
33
34 ZVirtualMemoryManager::ZVirtualMemoryManager(size_t max_capacity) :
35 _manager(),
36 _initialized(false) {
37
38 // Check max supported heap size
39 if (max_capacity > ZAddressOffsetMax) {
40 log_error_p(gc)("Java heap too large (max supported heap size is " SIZE_FORMAT "G)",
41 ZAddressOffsetMax / G);
42 return;
43 }
44
45 // Reserve address space
46 if (!reserve(max_capacity)) {
47 // try to reserve with a reduced number of address bits
48 log_info_p(gc, init)("Re-configuring ZAddressBits to " SIZE_FORMAT ", allocation with " SIZE_FORMAT " failed", _address_bits_seen, ZAddressBits);
49 ZAddressBits = _address_bits_seen;
50 ZAddress::initialize();
51 if (!reserve(max_capacity)) {
52 log_error_pd(gc)("Failed to reserve enough address space for Java heap");
53 return;
54 }
55 }
56
57 // Initialize OS specific parts
58 initialize_os();
59
60 // Successfully initialized
61 _initialized = true;
62 }
63
64 size_t ZVirtualMemoryManager::reserve_discontiguous(uintptr_t start, size_t size, size_t min_range) {
65 if (size < min_range) {
66 // Too small
67 return 0;
68 }
69
70 assert(is_aligned(size, ZGranuleSize), "Misaligned");
71
72 if (reserve_contiguous_platform(start, size)) {
73 // Make the address range free
74 _manager.free(start, size);
75 return size;
76 }
77
78 const size_t half = size / 2;
79 if (half < min_range) {
80 // Too small
81 return 0;
82 }
83
84 // Divide and conquer
85 const size_t first_part = align_down(half, ZGranuleSize);
86 const size_t second_part = size - first_part;
87 return reserve_discontiguous(start, first_part, min_range) +
88 reserve_discontiguous(start + first_part, second_part, min_range);
89 }
90
91 size_t ZVirtualMemoryManager::reserve_discontiguous(size_t size) {
92 // Don't try to reserve address ranges smaller than 1% of the requested size.
93 // This avoids an explosion of reservation attempts in case large parts of the
94 // address space is already occupied.
95 const size_t min_range = align_up(size / 100, ZGranuleSize);
96 size_t start = 0;
97 size_t reserved = 0;
98
99 // Reserve size somewhere between [0, ZAddressOffsetMax)
100 while (reserved < size && start < ZAddressOffsetMax) {
101 const size_t remaining = MIN2(size - reserved, ZAddressOffsetMax - start);
102 reserved += reserve_discontiguous(start, remaining, min_range);
103 start += remaining;
104 }
105
106 return reserved;
107 }
108
109 bool ZVirtualMemoryManager::reserve_contiguous(size_t size) {
110 // Allow at most 8192 attempts spread evenly across [0, ZAddressOffsetMax)
111 const size_t end = ZAddressOffsetMax - size;
112 const size_t increment = align_up(end / 8192, ZGranuleSize);
113
114 for (size_t start = 0; start <= end; start += increment) {
115 if (reserve_contiguous_platform(start, size)) {
116 // Make the address range free
117 _manager.free(start, size);
118
119 // Success
120 return true;
121 }
122 }
123
124 // Failed
125 return false;
126 }
127
128 bool ZVirtualMemoryManager::reserve(size_t max_capacity) {
129 const size_t limit = MIN2(ZAddressOffsetMax, ZAddressSpaceLimit::heap_view());
130 const size_t size = MIN2(max_capacity * ZVirtualToPhysicalRatio, limit);
131
132 size_t reserved = size;
133 bool contiguous = true;
134
135 // Prefer a contiguous address space
136 if (!reserve_contiguous(size)) {
137 // Fall back to a discontiguous address space
138 reserved = reserve_discontiguous(size);
139 contiguous = false;
140 }
141
142 log_info_p(gc, init)("Address Space Type: %s/%s/%s",
143 (contiguous ? "Contiguous" : "Discontiguous"),
144 (limit == ZAddressOffsetMax ? "Unrestricted" : "Restricted"),
145 (reserved == size ? "Complete" : "Degraded"));
146 log_info_p(gc, init)("Address Space Size: " SIZE_FORMAT "M x " SIZE_FORMAT " = " SIZE_FORMAT "M",
147 reserved / M, ZHeapViews, (reserved * ZHeapViews) / M);
148
149 return reserved >= max_capacity;
150 }
151
152 void ZVirtualMemoryManager::nmt_reserve(uintptr_t start, size_t size) {
153 MemTracker::record_virtual_memory_reserve((void*)start, size, CALLER_PC);
154 MemTracker::record_virtual_memory_type((void*)start, mtJavaHeap);
155 }
156
157 bool ZVirtualMemoryManager::is_initialized() const {
158 return _initialized;
159 }
160
161 ZVirtualMemory ZVirtualMemoryManager::alloc(size_t size, bool force_low_address) {
162 uintptr_t start;
163
164 // Small pages are allocated at low addresses, while medium/large pages
165 // are allocated at high addresses (unless forced to be at a low address).
166 if (force_low_address || size <= ZPageSizeSmall) {
167 start = _manager.alloc_from_front(size);
168 } else {
169 start = _manager.alloc_from_back(size);
170 }
171
172 return ZVirtualMemory(start, size);
173 }
174
175 void ZVirtualMemoryManager::free(const ZVirtualMemory& vmem) {
176 _manager.free(vmem.start(), vmem.size());
177 }