backend: do ioprio_set() before calling the ioengine init callback

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@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Link: https://lore.kernel.org/r/20220203192814.18552-3-Niklas.Cassel@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/backend.c b/backend.c
index c167f908625f39fd8e344c9f75c705f7fd71adf4..f7398b2315d8651e7d147c24b905843c19a44ccc 100644 (file)
--- 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;