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/*
* blktrace support code for fio
*/
#include <stdio.h>
#include <stdlib.h>
#include "list.h"
#include "fio.h"
#include "blktrace_api.h"
/*
* Just discard the pdu by seeking past it.
*/
static int discard_pdu(int fd, struct blk_io_trace *t)
{
if (t->pdu_len == 0)
return 0;
if (lseek(fd, t->pdu_len, SEEK_CUR) < 0)
return errno;
return 0;
}
/*
* Check if this is a blktrace binary data file. We read a single trace
* into memory and check for the magic signature.
*/
int is_blktrace(const char *filename)
{
struct blk_io_trace t;
int fd, ret;
fd = open(filename, O_RDONLY);
if (fd < 0) {
perror("open blktrace");
return 0;
}
ret = read(fd, &t, sizeof(t));
close(fd);
if (ret < 0) {
perror("read blktrace");
return 0;
} else if (ret != sizeof(t)) {
log_err("fio: short read on blktrace file\n");
return 0;
}
if ((t.magic & 0xffffff00) == BLK_IO_TRACE_MAGIC)
return 1;
return 0;
}
/*
* Store blk_io_trace data in an ipo for later retrieval.
*/
static void store_ipo(struct thread_data *td, unsigned long long offset,
unsigned int bytes, int rw, unsigned long long ttime)
{
struct io_piece *ipo = malloc(sizeof(*ipo));
memset(ipo, 0, sizeof(*ipo));
INIT_LIST_HEAD(&ipo->list);
/*
* the 512 is wrong here, it should be the hardware sector size...
*/
ipo->offset = offset * 512;
ipo->len = bytes;
ipo->delay = ttime / 1000;
if (rw)
ipo->ddir = DDIR_WRITE;
else
ipo->ddir = DDIR_READ;
list_add_tail(&ipo->list, &td->io_log_list);
}
/*
* We only care for queue traces, most of the others are side effects
* due to internal workings of the block layer.
*/
static void handle_trace(struct thread_data *td, struct blk_io_trace *t,
unsigned long long ttime, unsigned long *ios,
unsigned int *bs)
{
int rw;
if ((t->action & 0xffff) != __BLK_TA_QUEUE)
return;
if (t->action & BLK_TC_ACT(BLK_TC_PC))
return;
/*
* should not happen, need to look into that...
*/
if (!t->bytes)
return;
rw = (t->action & BLK_TC_ACT(BLK_TC_WRITE)) != 0;
if (t->bytes > bs[rw])
bs[rw] = t->bytes;
ios[rw]++;
td->o.size += t->bytes;
store_ipo(td, t->sector, t->bytes, rw, ttime);
}
/*
* Load a blktrace file by reading all the blk_io_trace entries, and storing
* them as io_pieces like the fio text version would do.
*/
int load_blktrace(struct thread_data *td, const char *filename)
{
unsigned long long ttime, delay;
struct blk_io_trace t;
unsigned long ios[2];
unsigned int cpu;
unsigned int rw_bs[2];
int fd;
fd = open(filename, O_RDONLY);
if (fd < 0) {
td_verror(td, errno, "open blktrace file");
return 1;
}
td->o.size = 0;
cpu = 0;
ttime = 0;
ios[0] = ios[1] = 0;
rw_bs[0] = rw_bs[1] = 0;
do {
/*
* Once this is working fully, I'll add a layer between
* here and read to cache trace data. Then we can avoid
* doing itsy bitsy reads, but instead pull in a larger
* chunk of data at the time.
*/
int ret = read(fd, &t, sizeof(t));
if (ret < 0) {
td_verror(td, errno, "read blktrace file");
goto err;
} else if (!ret) {
break;
} else if (ret != sizeof(t)) {
log_err("fio: short read on blktrace file\n");
goto err;
}
if ((t.magic & 0xffffff00) != BLK_IO_TRACE_MAGIC) {
log_err("fio: bad magic in blktrace data\n");
goto err;
}
if ((t.magic & 0xff) != BLK_IO_TRACE_VERSION) {
log_err("fio: bad blktrace version %d\n", t.magic & 0xff);
goto err;
}
ret = discard_pdu(fd, &t);
if (ret) {
td_verror(td, ret, "blktrace lseek");
goto err;
}
if (!ttime) {
ttime = t.time;
cpu = t.cpu;
}
delay = 0;
if (cpu == t.cpu)
delay = t.time - ttime;
handle_trace(td, &t, delay, ios, rw_bs);
ttime = t.time;
cpu = t.cpu;
} while (1);
close(fd);
if (!ios[DDIR_READ] && !ios[DDIR_WRITE]) {
log_err("fio: found no ios in blktrace data\n");
return 1;
} else if (ios[DDIR_READ] && !ios[DDIR_READ]) {
td->o.td_ddir = TD_DDIR_READ;
td->o.max_bs[DDIR_READ] = rw_bs[DDIR_READ];
} else if (!ios[DDIR_READ] && ios[DDIR_WRITE]) {
td->o.td_ddir = TD_DDIR_WRITE;
td->o.max_bs[DDIR_WRITE] = rw_bs[DDIR_WRITE];
} else {
td->o.td_ddir = TD_DDIR_RW;
td->o.max_bs[DDIR_READ] = rw_bs[DDIR_READ];
td->o.max_bs[DDIR_WRITE] = rw_bs[DDIR_WRITE];
}
/*
* We need to do direct/raw ios to the device, to avoid getting
* read-ahead in our way.
*/
td->o.odirect = 1;
return 0;
err:
close(fd);
return 1;
}
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