1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "swap_space.h"
#include <algorithm>
#include <numeric>
#include "base/logging.h"
#include "base/macros.h"
#include "base/mutex.h"
#include "thread-inl.h"
namespace art {
// The chunk size by which the swap file is increased and mapped.
static constexpr size_t kMininumMapSize = 16 * MB;
static constexpr bool kCheckFreeMaps = false;
template <typename FreeBySizeSet>
static void DumpFreeMap(const FreeBySizeSet& free_by_size) {
size_t last_size = static_cast<size_t>(-1);
for (const auto& entry : free_by_size) {
if (last_size != entry.first) {
last_size = entry.first;
LOG(INFO) << "Size " << last_size;
}
LOG(INFO) << " 0x" << std::hex << entry.second->Start()
<< " size=" << std::dec << entry.second->size;
}
}
template <typename FreeByStartSet, typename FreeBySizeSet>
static void RemoveChunk(FreeByStartSet* free_by_start,
FreeBySizeSet* free_by_size,
typename FreeBySizeSet::const_iterator free_by_size_pos) {
auto free_by_start_pos = free_by_size_pos->second;
free_by_size->erase(free_by_size_pos);
free_by_start->erase(free_by_start_pos);
}
template <typename FreeByStartSet, typename FreeBySizeSet>
static void InsertChunk(FreeByStartSet* free_by_start,
FreeBySizeSet* free_by_size,
const SpaceChunk& chunk) {
DCHECK_NE(chunk.size, 0u);
auto insert_result = free_by_start->insert(chunk);
DCHECK(insert_result.second);
free_by_size->emplace(chunk.size, insert_result.first);
}
SwapSpace::SwapSpace(int fd, size_t initial_size)
: fd_(fd),
size_(0),
lock_("SwapSpace lock", static_cast<LockLevel>(LockLevel::kDefaultMutexLevel - 1)) {
// Assume that the file is unlinked.
InsertChunk(&free_by_start_, &free_by_size_, NewFileChunk(initial_size));
}
SwapSpace::~SwapSpace() {
// All arenas are backed by the same file. Just close the descriptor.
close(fd_);
}
template <typename FreeByStartSet, typename FreeBySizeSet>
static size_t CollectFree(const FreeByStartSet& free_by_start, const FreeBySizeSet& free_by_size) {
if (free_by_start.size() != free_by_size.size()) {
LOG(FATAL) << "Size: " << free_by_start.size() << " vs " << free_by_size.size();
}
// Calculate over free_by_size.
size_t sum1 = 0;
for (const auto& entry : free_by_size) {
sum1 += entry.second->size;
}
// Calculate over free_by_start.
size_t sum2 = 0;
for (const auto& entry : free_by_start) {
sum2 += entry.size;
}
if (sum1 != sum2) {
LOG(FATAL) << "Sum: " << sum1 << " vs " << sum2;
}
return sum1;
}
void* SwapSpace::Alloc(size_t size) {
MutexLock lock(Thread::Current(), lock_);
size = RoundUp(size, 8U);
// Check the free list for something that fits.
// TODO: Smarter implementation. Global biggest chunk, ...
SpaceChunk old_chunk;
auto it = free_by_start_.empty()
? free_by_size_.end()
: free_by_size_.lower_bound(FreeBySizeEntry { size, free_by_start_.begin() });
if (it != free_by_size_.end()) {
old_chunk = *it->second;
RemoveChunk(&free_by_start_, &free_by_size_, it);
} else {
// Not a big enough free chunk, need to increase file size.
old_chunk = NewFileChunk(size);
}
void* ret = old_chunk.ptr;
if (old_chunk.size != size) {
// Insert the remainder.
SpaceChunk new_chunk = { old_chunk.ptr + size, old_chunk.size - size };
InsertChunk(&free_by_start_, &free_by_size_, new_chunk);
}
return ret;
}
SpaceChunk SwapSpace::NewFileChunk(size_t min_size) {
#if !defined(__APPLE__)
size_t next_part = std::max(RoundUp(min_size, kPageSize), RoundUp(kMininumMapSize, kPageSize));
int result = TEMP_FAILURE_RETRY(ftruncate64(fd_, size_ + next_part));
if (result != 0) {
PLOG(FATAL) << "Unable to increase swap file.";
}
uint8_t* ptr = reinterpret_cast<uint8_t*>(
mmap(nullptr, next_part, PROT_READ | PROT_WRITE, MAP_SHARED, fd_, size_));
if (ptr == MAP_FAILED) {
LOG(ERROR) << "Unable to mmap new swap file chunk.";
LOG(ERROR) << "Current size: " << size_ << " requested: " << next_part << "/" << min_size;
LOG(ERROR) << "Free list:";
MutexLock lock(Thread::Current(), lock_);
DumpFreeMap(free_by_size_);
LOG(ERROR) << "In free list: " << CollectFree(free_by_start_, free_by_size_);
LOG(FATAL) << "Aborting...";
}
size_ += next_part;
SpaceChunk new_chunk = {ptr, next_part};
maps_.push_back(new_chunk);
return new_chunk;
#else
UNUSED(min_size, kMininumMapSize);
LOG(FATAL) << "No swap file support on the Mac.";
UNREACHABLE();
#endif
}
// TODO: Full coalescing.
void SwapSpace::Free(void* ptrV, size_t size) {
MutexLock lock(Thread::Current(), lock_);
size = RoundUp(size, 8U);
size_t free_before = 0;
if (kCheckFreeMaps) {
free_before = CollectFree(free_by_start_, free_by_size_);
}
SpaceChunk chunk = { reinterpret_cast<uint8_t*>(ptrV), size };
auto it = free_by_start_.lower_bound(chunk);
if (it != free_by_start_.begin()) {
auto prev = it;
--prev;
CHECK_LE(prev->End(), chunk.Start());
if (prev->End() == chunk.Start()) {
// Merge *prev with this chunk.
chunk.size += prev->size;
chunk.ptr -= prev->size;
auto erase_pos = free_by_size_.find(FreeBySizeEntry { prev->size, prev });
DCHECK(erase_pos != free_by_size_.end());
RemoveChunk(&free_by_start_, &free_by_size_, erase_pos);
// "prev" is invalidated but "it" remains valid.
}
}
if (it != free_by_start_.end()) {
CHECK_LE(chunk.End(), it->Start());
if (chunk.End() == it->Start()) {
// Merge *it with this chunk.
chunk.size += it->size;
auto erase_pos = free_by_size_.find(FreeBySizeEntry { it->size, it });
DCHECK(erase_pos != free_by_size_.end());
RemoveChunk(&free_by_start_, &free_by_size_, erase_pos);
// "it" is invalidated but we don't need it anymore.
}
}
InsertChunk(&free_by_start_, &free_by_size_, chunk);
if (kCheckFreeMaps) {
size_t free_after = CollectFree(free_by_start_, free_by_size_);
if (free_after != free_before + size) {
DumpFreeMap(free_by_size_);
CHECK_EQ(free_after, free_before + size) << "Should be " << size << " difference from " << free_before;
}
}
}
} // namespace art
|
