2 * blktrace support code for fio
9 #include "blktrace_api.h"
12 * Just discard the pdu by seeking past it.
14 static int discard_pdu(int fd, struct blk_io_trace *t)
19 if (lseek(fd, t->pdu_len, SEEK_CUR) < 0)
26 * Check if this is a blktrace binary data file. We read a single trace
27 * into memory and check for the magic signature.
29 int is_blktrace(const char *filename)
31 struct blk_io_trace t;
34 fd = open(filename, O_RDONLY);
36 perror("open blktrace");
40 ret = read(fd, &t, sizeof(t));
44 perror("read blktrace");
46 } else if (ret != sizeof(t)) {
47 log_err("fio: short read on blktrace file\n");
51 if ((t.magic & 0xffffff00) == BLK_IO_TRACE_MAGIC)
58 * Store blk_io_trace data in an ipo for later retrieval.
60 static void store_ipo(struct thread_data *td, unsigned long long offset,
61 unsigned int bytes, int rw, unsigned long long ttime)
63 struct io_piece *ipo = malloc(sizeof(*ipo));
65 memset(ipo, 0, sizeof(*ipo));
66 INIT_LIST_HEAD(&ipo->list);
69 ipo->delay = ttime / 1000;
71 ipo->ddir = DDIR_WRITE;
73 ipo->ddir = DDIR_READ;
75 list_add_tail(&ipo->list, &td->io_log_list);
79 * We only care for queue traces, most of the others are side effects
80 * due to internal workings of the block layer.
82 static void handle_trace(struct thread_data *td, struct blk_io_trace *t,
83 unsigned long long ttime, unsigned long *ios)
87 if ((t->action & 0xffff) != __BLK_TA_QUEUE)
90 rw = (t->action & BLK_TC_ACT(BLK_TC_WRITE)) != 0;
92 store_ipo(td, t->sector, t->bytes, rw, ttime);
96 * Load a blktrace file by reading all the blk_io_trace entries, and storing
97 * them as io_pieces like the fio text version would do.
99 int load_blktrace(struct thread_data *td, const char *filename)
101 unsigned long long ttime;
102 struct blk_io_trace t;
103 unsigned long ios[2];
106 fd = open(filename, O_RDONLY);
108 td_verror(td, errno, "open blktrace file");
116 * Once this is working fully, I'll add a layer between
117 * here and read to cache trace data. Then we can avoid
118 * doing itsy bitsy reads, but instead pull in a larger
119 * chunk of data at the time.
121 int ret = read(fd, &t, sizeof(t));
124 td_verror(td, errno, "read blktrace file");
128 } else if (ret != sizeof(t)) {
129 log_err("fio: short read on blktrace file\n");
133 if ((t.magic & 0xffffff00) != BLK_IO_TRACE_MAGIC) {
134 log_err("fio: bad magic in blktrace data\n");
137 if ((t.magic & 0xff) != BLK_IO_TRACE_VERSION) {
138 log_err("fio: bad blktrace version %d\n", t.magic & 0xff);
141 ret = discard_pdu(fd, &t);
143 td_verror(td, ret, "blktrace lseek");
148 handle_trace(td, &t, t.time - ttime, ios);
154 if (!ios[DDIR_READ] && !ios[DDIR_WRITE]) {
155 log_err("fio: found no ios in blktrace data\n");
157 } else if (ios[DDIR_READ] && !ios[DDIR_READ])
158 td->o.td_ddir = TD_DDIR_READ;
159 else if (!ios[DDIR_READ] && ios[DDIR_WRITE])
160 td->o.td_ddir = TD_DDIR_WRITE;
162 td->o.td_ddir = TD_DDIR_RW;
165 * We need to do direct/raw ios to the device, to avoid getting
166 * read-ahead in our way.