From: Tomohiro Kusumi <tkusumi@xxxxxxxxxx>
Some runtime configurations can cause threads/processes to terminate
without any I/O performed, yet with no explicit error message, which
is quite confusing. In the example below, fio finishes with neither
error nor regular statistics due to file offset + bs being larger
than the file size while in get_io_u().
This commit calls log_err() when this happens. Since it's difficult
to tell the exact reason after thread has left the main I/O loop[*],
it gives advice to use a command line option --debug=io, similar to
the way td_io_init() gives advice.
[*] It can't just replace dprint(FD_IO, ...) calls with td_verror()
for e.g. while in get_io_u(), since those are also used by non error
paths too.
--
# ./fio --name=xxxxx --ioengine=sync --rw=read --bs=2k --size=1m --nrfiles=1k --unlink=1
xxxxx: (g=0): rw=read, bs=(R) 2048B-2048B, (W) 2048B-2048B, (T) 2048B-2048B, ioengine=sync, iodepth=1
fio-2.18-59-g618e
Starting 1 process
xxxxx: Laying out IO files (1024 files / total 1MiB)
Run status group 0 (all jobs):
Disk stats (read/write):
dm-0: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=0/0, aggrmerge=0/0, aggrticks=0/0, aggrin_queue=0, aggrutil=0.00%
sda: ios=0/0, merge=0/0, ticks=0/0, in_queue=0, util=0.00%
Signed-off-by: Tomohiro Kusumi <tkusumi@xxxxxxxxxx>
---
backend.c | 17 +++++++++++++++--
io_u.c | 5 +++--
2 files changed, 18 insertions(+), 4 deletions(-)
diff --git a/backend.c b/backend.c
index 38ef348..e5be187 100644
--- a/backend.c
+++ b/backend.c
@@ -1456,6 +1456,7 @@ static void *thread_main(void *data)
struct thread_data *td = fd->td;
struct thread_options *o = &td->o;
struct sk_out *sk_out = fd->sk_out;
+ uint64_t bytes_done[DDIR_RWDIR_CNT];
int deadlock_loop_cnt;
int clear_state;
int ret;
@@ -1677,7 +1678,9 @@ static void *thread_main(void *data)
sizeof(td->bw_sample_time));
}
+ memset(bytes_done, 0, sizeof(bytes_done));
clear_state = 0;
+
while (keep_running(td)) {
uint64_t verify_bytes;
@@ -1696,8 +1699,6 @@ static void *thread_main(void *data)
if (td->o.verify_only && td_write(td))
verify_bytes = do_dry_run(td);
else {
- uint64_t bytes_done[DDIR_RWDIR_CNT];
-
do_io(td, bytes_done);
if (!ddir_rw_sum(bytes_done)) {
@@ -1776,6 +1777,18 @@ static void *thread_main(void *data)
break;
}
+ /*
+ * If td ended up with no I/O when it should have had,
+ * then something went wrong unless FIO_NOIO or FIO_DISKLESSIO.
+ * (Are we not missing other flags that can be ignored ?)
+ */
+ if ((td->o.size || td->o.io_size) && !ddir_rw_sum(bytes_done) &&
+ !(td_ioengine_flagged(td, FIO_NOIO) ||
+ td_ioengine_flagged(td, FIO_DISKLESSIO)))
+ log_err("%s: No I/O performed by %s, "
+ "perhaps try --debug=io option for details?\n",
+ td->o.name, td->io_ops->name);
+
td_set_runstate(td, TD_FINISHING);
update_rusage_stat(td);
diff --git a/io_u.c b/io_u.c
index 363bfe1..88f35c9 100644
--- a/io_u.c
+++ b/io_u.c
@@ -899,8 +899,9 @@ static int fill_io_u(struct thread_data *td, struct io_u *io_u)
}
if (io_u->offset + io_u->buflen > io_u->file->real_file_size) {
- dprint(FD_IO, "io_u %p, offset too large\n", io_u);
- dprint(FD_IO, " off=%llu/%lu > %llu\n",
+ dprint(FD_IO, "io_u %p, offset + buflen exceeds file size\n",
+ io_u);
+ dprint(FD_IO, " offset=%llu/buflen=%lu > %llu\n",
(unsigned long long) io_u->offset, io_u->buflen,
(unsigned long long) io_u->file->real_file_size);
return 1;
--
2.9.3
--
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