lib/axmap: Add more documentation
[fio.git] / engines / mmap.c
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CommitLineData
1/*
2 * mmap engine
3 *
4 * IO engine that reads/writes from files by doing memcpy to/from
5 * a memory mapped region of the file.
6 *
7 */
8#include <stdio.h>
9#include <stdlib.h>
10#include <errno.h>
11#include <sys/mman.h>
12
13#include "../fio.h"
14#include "../verify.h"
15
16/*
17 * Limits us to 1GiB of mapped files in total
18 */
19#define MMAP_TOTAL_SZ (1 * 1024 * 1024 * 1024UL)
20
21static unsigned long mmap_map_size;
22
23struct fio_mmap_data {
24 void *mmap_ptr;
25 size_t mmap_sz;
26 off_t mmap_off;
27};
28
29static bool fio_madvise_file(struct thread_data *td, struct fio_file *f,
30 size_t length)
31
32{
33 struct fio_mmap_data *fmd = FILE_ENG_DATA(f);
34
35 if (!td->o.fadvise_hint)
36 return true;
37
38 if (!td_random(td)) {
39 if (posix_madvise(fmd->mmap_ptr, length, POSIX_MADV_SEQUENTIAL) < 0) {
40 td_verror(td, errno, "madvise");
41 return false;
42 }
43 } else {
44 if (posix_madvise(fmd->mmap_ptr, length, POSIX_MADV_RANDOM) < 0) {
45 td_verror(td, errno, "madvise");
46 return false;
47 }
48 }
49
50 return true;
51}
52
53static int fio_mmap_file(struct thread_data *td, struct fio_file *f,
54 size_t length, off_t off)
55{
56 struct fio_mmap_data *fmd = FILE_ENG_DATA(f);
57 int flags = 0;
58
59 if (td_rw(td) && !td->o.verify_only)
60 flags = PROT_READ | PROT_WRITE;
61 else if (td_write(td) && !td->o.verify_only) {
62 flags = PROT_WRITE;
63
64 if (td->o.verify != VERIFY_NONE)
65 flags |= PROT_READ;
66 } else
67 flags = PROT_READ;
68
69 fmd->mmap_ptr = mmap(NULL, length, flags, MAP_SHARED, f->fd, off);
70 if (fmd->mmap_ptr == MAP_FAILED) {
71 fmd->mmap_ptr = NULL;
72 td_verror(td, errno, "mmap");
73 goto err;
74 }
75
76 if (!fio_madvise_file(td, f, length))
77 goto err;
78
79 if (posix_madvise(fmd->mmap_ptr, length, POSIX_MADV_DONTNEED) < 0) {
80 td_verror(td, errno, "madvise");
81 goto err;
82 }
83
84#ifdef FIO_MADV_FREE
85 if (f->filetype == FIO_TYPE_BLOCK)
86 (void) posix_madvise(fmd->mmap_ptr, fmd->mmap_sz, FIO_MADV_FREE);
87#endif
88
89err:
90 if (td->error && fmd->mmap_ptr)
91 munmap(fmd->mmap_ptr, length);
92
93 return td->error;
94}
95
96/*
97 * Just mmap an appropriate portion, we cannot mmap the full extent
98 */
99static int fio_mmapio_prep_limited(struct thread_data *td, struct io_u *io_u)
100{
101 struct fio_file *f = io_u->file;
102 struct fio_mmap_data *fmd = FILE_ENG_DATA(f);
103
104 if (io_u->buflen > mmap_map_size) {
105 log_err("fio: bs too big for mmap engine\n");
106 return EIO;
107 }
108
109 fmd->mmap_sz = mmap_map_size;
110 if (fmd->mmap_sz > f->io_size)
111 fmd->mmap_sz = f->io_size;
112
113 fmd->mmap_off = io_u->offset;
114
115 return fio_mmap_file(td, f, fmd->mmap_sz, fmd->mmap_off);
116}
117
118/*
119 * Attempt to mmap the entire file
120 */
121static int fio_mmapio_prep_full(struct thread_data *td, struct io_u *io_u)
122{
123 struct fio_file *f = io_u->file;
124 struct fio_mmap_data *fmd = FILE_ENG_DATA(f);
125 int ret;
126
127 if (fio_file_partial_mmap(f))
128 return EINVAL;
129 if (io_u->offset != (size_t) io_u->offset ||
130 f->io_size != (size_t) f->io_size) {
131 fio_file_set_partial_mmap(f);
132 return EINVAL;
133 }
134
135 fmd->mmap_sz = f->io_size;
136 fmd->mmap_off = 0;
137
138 ret = fio_mmap_file(td, f, fmd->mmap_sz, fmd->mmap_off);
139 if (ret)
140 fio_file_set_partial_mmap(f);
141
142 return ret;
143}
144
145static int fio_mmapio_prep(struct thread_data *td, struct io_u *io_u)
146{
147 struct fio_file *f = io_u->file;
148 struct fio_mmap_data *fmd = FILE_ENG_DATA(f);
149 int ret;
150
151 /*
152 * It fits within existing mapping, use it
153 */
154 if (io_u->offset >= fmd->mmap_off &&
155 io_u->offset + io_u->buflen <= fmd->mmap_off + fmd->mmap_sz)
156 goto done;
157
158 /*
159 * unmap any existing mapping
160 */
161 if (fmd->mmap_ptr) {
162 if (munmap(fmd->mmap_ptr, fmd->mmap_sz) < 0)
163 return errno;
164 fmd->mmap_ptr = NULL;
165 }
166
167 if (fio_mmapio_prep_full(td, io_u)) {
168 td_clear_error(td);
169 ret = fio_mmapio_prep_limited(td, io_u);
170 if (ret)
171 return ret;
172 }
173
174done:
175 io_u->mmap_data = fmd->mmap_ptr + io_u->offset - fmd->mmap_off -
176 f->file_offset;
177 return 0;
178}
179
180static enum fio_q_status fio_mmapio_queue(struct thread_data *td,
181 struct io_u *io_u)
182{
183 struct fio_file *f = io_u->file;
184 struct fio_mmap_data *fmd = FILE_ENG_DATA(f);
185
186 fio_ro_check(td, io_u);
187
188 if (io_u->ddir == DDIR_READ)
189 memcpy(io_u->xfer_buf, io_u->mmap_data, io_u->xfer_buflen);
190 else if (io_u->ddir == DDIR_WRITE)
191 memcpy(io_u->mmap_data, io_u->xfer_buf, io_u->xfer_buflen);
192 else if (ddir_sync(io_u->ddir)) {
193 if (msync(fmd->mmap_ptr, fmd->mmap_sz, MS_SYNC)) {
194 io_u->error = errno;
195 td_verror(td, io_u->error, "msync");
196 }
197 } else if (io_u->ddir == DDIR_TRIM) {
198 int ret = do_io_u_trim(td, io_u);
199
200 if (!ret)
201 td_verror(td, io_u->error, "trim");
202 }
203
204
205 /*
206 * not really direct, but should drop the pages from the cache
207 */
208 if (td->o.odirect && ddir_rw(io_u->ddir)) {
209 if (msync(io_u->mmap_data, io_u->xfer_buflen, MS_SYNC) < 0) {
210 io_u->error = errno;
211 td_verror(td, io_u->error, "msync");
212 }
213 if (posix_madvise(io_u->mmap_data, io_u->xfer_buflen, POSIX_MADV_DONTNEED) < 0) {
214 io_u->error = errno;
215 td_verror(td, io_u->error, "madvise");
216 }
217 }
218
219 return FIO_Q_COMPLETED;
220}
221
222static int fio_mmapio_init(struct thread_data *td)
223{
224 struct thread_options *o = &td->o;
225
226 if ((o->rw_min_bs & page_mask) &&
227 (o->odirect || o->fsync_blocks || o->fdatasync_blocks)) {
228 log_err("fio: mmap options dictate a minimum block size of "
229 "%llu bytes\n", (unsigned long long) page_size);
230 return 1;
231 }
232
233 mmap_map_size = MMAP_TOTAL_SZ / o->nr_files;
234 return 0;
235}
236
237static int fio_mmapio_open_file(struct thread_data *td, struct fio_file *f)
238{
239 struct fio_mmap_data *fmd;
240 int ret;
241
242 ret = generic_open_file(td, f);
243 if (ret)
244 return ret;
245
246 fmd = calloc(1, sizeof(*fmd));
247 if (!fmd) {
248 int fio_unused __ret;
249 __ret = generic_close_file(td, f);
250 return 1;
251 }
252
253 FILE_SET_ENG_DATA(f, fmd);
254 return 0;
255}
256
257static int fio_mmapio_close_file(struct thread_data *td, struct fio_file *f)
258{
259 struct fio_mmap_data *fmd = FILE_ENG_DATA(f);
260
261 FILE_SET_ENG_DATA(f, NULL);
262 free(fmd);
263 fio_file_clear_partial_mmap(f);
264
265 return generic_close_file(td, f);
266}
267
268static struct ioengine_ops ioengine = {
269 .name = "mmap",
270 .version = FIO_IOOPS_VERSION,
271 .init = fio_mmapio_init,
272 .prep = fio_mmapio_prep,
273 .queue = fio_mmapio_queue,
274 .open_file = fio_mmapio_open_file,
275 .close_file = fio_mmapio_close_file,
276 .get_file_size = generic_get_file_size,
277 .flags = FIO_SYNCIO | FIO_NOEXTEND,
278};
279
280static void fio_init fio_mmapio_register(void)
281{
282 register_ioengine(&ioengine);
283}
284
285static void fio_exit fio_mmapio_unregister(void)
286{
287 unregister_ioengine(&ioengine);
288}