1 /*
2 * Copyright (c) 2016, 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 #include "precompiled.hpp"
25 #include "gc/z/zLock.inline.hpp"
26 #include "gc/z/zMarkStack.inline.hpp"
27 #include "gc/z/zMarkStackAllocator.hpp"
28 #include "logging/log.hpp"
29 #include "runtime/atomic.hpp"
30 #include "runtime/os.hpp"
31 #include "utilities/debug.hpp"
32
33 uintptr_t ZMarkStackSpaceStart;
34
35 ZMarkStackSpace::ZMarkStackSpace() :
36 _expand_lock(),
37 _start(0),
38 _top(0),
39 _end(0) {
40 assert(ZMarkStackSpaceLimit >= ZMarkStackSpaceExpandSize, "ZMarkStackSpaceLimit too small");
41
42 // Reserve address space
43 const size_t size = ZMarkStackSpaceLimit;
44 const size_t alignment = (size_t)os::vm_allocation_granularity();
45 const uintptr_t addr = (uintptr_t)os::reserve_memory(size, NULL, alignment, mtGC);
46 if (addr == 0) {
47 log_error(gc, marking)("Failed to reserve address space for mark stacks");
48 return;
49 }
50
51 // Successfully initialized
52 _start = _top = _end = addr;
53
54 // Register mark stack space start
55 ZMarkStackSpaceStart = _start;
56 }
57
58 bool ZMarkStackSpace::is_initialized() const {
59 return _start != 0;
60 }
61
62 uintptr_t ZMarkStackSpace::alloc_space(size_t size) {
63 uintptr_t top = Atomic::load(&_top);
64
65 for (;;) {
66 const uintptr_t end = Atomic::load(&_end);
67 const uintptr_t new_top = top + size;
68 if (new_top > end) {
69 // Not enough space left
70 return 0;
71 }
72
73 const uintptr_t prev_top = Atomic::cmpxchg(new_top, &_top, top);
74 if (prev_top == top) {
75 // Success
76 return top;
77 }
78
79 // Retry
80 top = prev_top;
81 }
82 }
83
84 uintptr_t ZMarkStackSpace::expand_and_alloc_space(size_t size) {
85 ZLocker<ZLock> locker(&_expand_lock);
86
87 // Retry allocation before expanding
88 uintptr_t addr = alloc_space(size);
89 if (addr != 0) {
90 return addr;
91 }
92
93 // Check expansion limit
94 const size_t expand_size = ZMarkStackSpaceExpandSize;
95 const size_t old_size = _end - _start;
96 const size_t new_size = old_size + expand_size;
97 if (new_size > ZMarkStackSpaceLimit) {
98 // Expansion limit reached. This is a fatal error since we
99 // currently can't recover from running out of mark stack space.
100 fatal("Mark stack space exhausted. Use -XX:ZMarkStackSpaceLimit=<size> to increase the "
101 "maximum number of bytes allocated for mark stacks. Current limit is " SIZE_FORMAT "M.",
102 ZMarkStackSpaceLimit / M);
103 }
104
105 log_debug(gc, marking)("Expanding mark stack space: " SIZE_FORMAT "M->" SIZE_FORMAT "M",
106 old_size / M, new_size / M);
107
108 // Expand
109 os::commit_memory_or_exit((char*)_end, expand_size, false /* executable */, "Mark stack space");
110
111 // Increment top before end to make sure another
112 // thread can't steal out newly expanded space.
113 addr = Atomic::add(size, &_top) - size;
114 Atomic::add(expand_size, &_end);
115
116 return addr;
117 }
118
119 uintptr_t ZMarkStackSpace::alloc(size_t size) {
120 const uintptr_t addr = alloc_space(size);
121 if (addr != 0) {
122 return addr;
123 }
124
125 return expand_and_alloc_space(size);
126 }
127
128 ZMarkStackAllocator::ZMarkStackAllocator() :
129 _freelist(),
130 _space() {
131 guarantee(sizeof(ZMarkStack) == ZMarkStackSize, "Size mismatch");
132 guarantee(sizeof(ZMarkStackMagazine) <= ZMarkStackSize, "Size mismatch");
133
134 // Prime free list to avoid an immediate space
135 // expansion when marking starts.
136 if (_space.is_initialized()) {
137 prime_freelist();
138 }
139 }
140
141 bool ZMarkStackAllocator::is_initialized() const {
142 return _space.is_initialized();
143 }
144
145 void ZMarkStackAllocator::prime_freelist() {
146 for (size_t size = 0; size < ZMarkStackSpaceExpandSize; size += ZMarkStackMagazineSize) {
147 const uintptr_t addr = _space.alloc(ZMarkStackMagazineSize);
148 ZMarkStackMagazine* const magazine = create_magazine_from_space(addr, ZMarkStackMagazineSize);
149 free_magazine(magazine);
150 }
151 }
152
153 ZMarkStackMagazine* ZMarkStackAllocator::create_magazine_from_space(uintptr_t addr, size_t size) {
154 assert(is_aligned(size, ZMarkStackSize), "Invalid size");
155
156 // Use first stack as magazine
157 ZMarkStackMagazine* const magazine = new ((void*)addr) ZMarkStackMagazine();
158 for (size_t i = ZMarkStackSize; i < size; i += ZMarkStackSize) {
159 ZMarkStack* const stack = new ((void*)(addr + i)) ZMarkStack();
160 const bool success = magazine->push(stack);
161 assert(success, "Magazine should never get full");
162 }
163
164 return magazine;
165 }
166
167 ZMarkStackMagazine* ZMarkStackAllocator::alloc_magazine() {
168 // Try allocating from the free list first
169 ZMarkStackMagazine* const magazine = _freelist.pop_atomic();
170 if (magazine != NULL) {
171 return magazine;
172 }
173
174 // Allocate new magazine
175 const uintptr_t addr = _space.alloc(ZMarkStackMagazineSize);
176 if (addr == 0) {
177 return NULL;
178 }
179
180 return create_magazine_from_space(addr, ZMarkStackMagazineSize);
181 }
182
183 void ZMarkStackAllocator::free_magazine(ZMarkStackMagazine* magazine) {
184 _freelist.push_atomic(magazine);
185 }