[PATCH 02/17] backend: do ioprio_set() before calling the ioengine init callback

[Niklas Cassel <Niklas.Cassel@xxxxxxx>]

From: Niklas Cassel <niklas.cassel@xxxxxxx>

To be able to report clat stats on a per priority granularity (instead of
only high/low priority), we need to do ioprio_set(), and the matching
td->ioprio assignment, before calling the io engine init callback.

When a thread is using more than a single priority (e.g. option
cmdprio_percentage is used), fio_cmdprio_init() will need to allocate and
initialize an array that will hold the clat stats for all the different
priorities that will be used by the struct td.

For fio_cmdprio_init() to be able to initialize a per priority clat array
properly, we need to assign td->ioprio before calling td_io_init().

Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx>
---
 backend.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/backend.c b/backend.c
index c167f908..f7398b23 100644
--- a/backend.c
+++ b/backend.c
@@ -1777,6 +1777,17 @@ static void *thread_main(void *data)
 	if (!init_iolog(td))
 		goto err;
 
+	/* ioprio_set() has to be done before td_io_init() */
+	if (fio_option_is_set(o, ioprio) ||
+	    fio_option_is_set(o, ioprio_class)) {
+		ret = ioprio_set(IOPRIO_WHO_PROCESS, 0, o->ioprio_class, o->ioprio);
+		if (ret == -1) {
+			td_verror(td, errno, "ioprio_set");
+			goto err;
+		}
+		td->ioprio = ioprio_value(o->ioprio_class, o->ioprio);
+	}
+
 	if (td_io_init(td))
 		goto err;
 
@@ -1789,16 +1800,6 @@ static void *thread_main(void *data)
 	if (o->verify_async && verify_async_init(td))
 		goto err;
 
-	if (fio_option_is_set(o, ioprio) ||
-	    fio_option_is_set(o, ioprio_class)) {
-		ret = ioprio_set(IOPRIO_WHO_PROCESS, 0, o->ioprio_class, o->ioprio);
-		if (ret == -1) {
-			td_verror(td, errno, "ioprio_set");
-			goto err;
-		}
-		td->ioprio = ioprio_value(o->ioprio_class, o->ioprio);
-	}
-
 	if (o->cgroup && cgroup_setup(td, cgroup_list, &cgroup_mnt))
 		goto err;
 
-- 
2.34.1