Update io engine comments
[fio.git] / engines / mmap.c
CommitLineData
2866c82d 1/*
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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.
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6 *
7 */
8#include <stdio.h>
9#include <stdlib.h>
10#include <unistd.h>
11#include <errno.h>
12#include <assert.h>
13#include <sys/mman.h>
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14
15#include "../fio.h"
16#include "../os.h"
2866c82d 17
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18static int fio_mmapio_queue(struct thread_data *td, struct io_u *io_u)
19{
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20 struct fio_file *f = io_u->file;
21 unsigned long long real_off = io_u->offset - f->file_offset;
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22
23 if (io_u->ddir == DDIR_READ)
cec6b55d 24 memcpy(io_u->xfer_buf, f->mmap + real_off, io_u->xfer_buflen);
87dc1ab1 25 else if (io_u->ddir == DDIR_WRITE)
cec6b55d 26 memcpy(f->mmap + real_off, io_u->xfer_buf, io_u->xfer_buflen);
b907a5b5 27 else if (io_u->ddir == DDIR_SYNC) {
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28 size_t len = (f->file_size + page_size - 1) & ~page_mask;
29
30 if (msync(f->mmap, len, MS_SYNC)) {
b907a5b5 31 io_u->error = errno;
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32 td_verror(td, io_u->error, "msync");
33 }
b907a5b5 34 }
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35
36 /*
37 * not really direct, but should drop the pages from the cache
38 */
b907a5b5 39 if (td->odirect && io_u->ddir != DDIR_SYNC) {
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40 size_t len = (io_u->xfer_buflen + page_size - 1) & ~page_mask;
41 unsigned long long off = real_off & ~page_mask;
42
43 if (msync(f->mmap + off, len, MS_SYNC) < 0) {
2866c82d 44 io_u->error = errno;
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45 td_verror(td, io_u->error, "msync");
46 }
47 if (madvise(f->mmap + off, len, MADV_DONTNEED) < 0) {
2866c82d 48 io_u->error = errno;
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49 td_verror(td, io_u->error, "madvise");
50 }
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51 }
52
36167d82 53 return FIO_Q_COMPLETED;
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54}
55
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56static int fio_mmapio_open(struct thread_data *td, struct fio_file *f)
57{
58 int ret, flags;
59
60 ret = generic_open_file(td, f);
61 if (ret)
62 return ret;
63
64 if (td_rw(td))
65 flags = PROT_READ | PROT_WRITE;
66 else if (td_write(td)) {
67 flags = PROT_WRITE;
68
69 if (td->verify != VERIFY_NONE)
70 flags |= PROT_READ;
71 } else
72 flags = PROT_READ;
73
74 f->mmap = mmap(NULL, f->file_size, flags, MAP_SHARED, f->fd, f->file_offset);
75 if (f->mmap == MAP_FAILED) {
76 f->mmap = NULL;
77 td_verror(td, errno, "mmap");
78 goto err;
79 }
80
81 if (file_invalidate_cache(td, f))
82 goto err;
83
84 if (!td_random(td)) {
85 if (madvise(f->mmap, f->file_size, MADV_SEQUENTIAL) < 0) {
86 td_verror(td, errno, "madvise");
87 goto err;
88 }
89 } else {
90 if (madvise(f->mmap, f->file_size, MADV_RANDOM) < 0) {
91 td_verror(td, errno, "madvise");
92 goto err;
93 }
94 }
95
96 return 0;
97
98err:
0263882a 99 td->io_ops->close_file(td, f);
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100 return 1;
101}
102
103static void fio_mmapio_close(struct thread_data fio_unused *td,
104 struct fio_file *f)
105{
106 if (f->mmap) {
107 munmap(f->mmap, f->file_size);
108 f->mmap = NULL;
109 }
0263882a 110 generic_close_file(td, f);
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111}
112
5f350952 113static struct ioengine_ops ioengine = {
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114 .name = "mmap",
115 .version = FIO_IOOPS_VERSION,
2866c82d 116 .queue = fio_mmapio_queue,
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117 .open_file = fio_mmapio_open,
118 .close_file = fio_mmapio_close,
0263882a 119 .flags = FIO_SYNCIO | FIO_NOEXTEND,
2866c82d 120};
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121
122static void fio_init fio_mmapio_register(void)
123{
124 register_ioengine(&ioengine);
125}
126
127static void fio_exit fio_mmapio_unregister(void)
128{
129 unregister_ioengine(&ioengine);
130}