blktrace support update
This should essentially work, except that it will not delay between
io but just issue the entries as fast as it can. Missing bits:
- Utilize the ipo->delay to suitably delay issuing an io
- Extract device name from blktrace file
- Document it
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/blktrace.c b/blktrace.c
index c9141f6..3f0938f 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -3,10 +3,14 @@
*/
#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)
@@ -18,6 +22,10 @@
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;
@@ -46,8 +54,11 @@
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 int bytes, int rw, unsigned long long ttime)
{
struct io_piece *ipo = malloc(sizeof(*ipo));
@@ -55,6 +66,7 @@
INIT_LIST_HEAD(&ipo->list);
ipo->offset = offset;
ipo->len = bytes;
+ ipo->delay = ttime / 1000;
if (rw)
ipo->ddir = DDIR_WRITE;
else
@@ -63,7 +75,12 @@
list_add_tail(&ipo->list, &td->io_log_list);
}
-static void handle_trace(struct thread_data *td, struct blk_io_trace *t)
+/*
+ * 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)
{
int rw;
@@ -71,12 +88,19 @@
return;
rw = (t->action & BLK_TC_ACT(BLK_TC_WRITE)) != 0;
- store_ipo(td, t->sector, t->bytes, rw);
+ ios[rw]++;
+ 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;
struct blk_io_trace t;
+ unsigned long ios[2];
int fd;
fd = open(filename, O_RDONLY);
@@ -85,35 +109,66 @@
return 1;
}
+ ios[0] = ios[1] = 0;
+ ttime = 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");
- return 1;
+ goto err;
} else if (!ret) {
break;
} else if (ret != sizeof(t)) {
log_err("fio: short read on blktrace file\n");
- return 1;
+ goto err;
}
if ((t.magic & 0xffffff00) != BLK_IO_TRACE_MAGIC) {
log_err("fio: bad magic in blktrace data\n");
- return 1;
+ goto err;
}
if ((t.magic & 0xff) != BLK_IO_TRACE_VERSION) {
log_err("fio: bad blktrace version %d\n", t.magic & 0xff);
- return 1;
+ goto err;
}
ret = discard_pdu(fd, &t);
if (ret) {
td_verror(td, ret, "blktrace lseek");
- return 1;
+ goto err;
}
- handle_trace(td, &t);
+ if (!ttime)
+ ttime = t.time;
+ handle_trace(td, &t, t.time - ttime, ios);
+ ttime = t.time;
} 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;
+ else if (!ios[DDIR_READ] && ios[DDIR_WRITE])
+ td->o.td_ddir = TD_DDIR_WRITE;
+ else
+ td->o.td_ddir = TD_DDIR_RW;
+
+ /*
+ * 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;
}