blk-throttle: Avoid getting the current time if tg->last_finish_time is 0

We only update the tg->last_finish_time when the low limitaion is
enabled, so we can move the tg->last_finish_time validation a little
forward to avoid getting the unnecessary current time stamp if the
the low limitation is not enabled.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 4007b26..7e72102 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2077,10 +2077,14 @@ static void throtl_downgrade_check(struct throtl_grp *tg)
 
 static void blk_throtl_update_idletime(struct throtl_grp *tg)
 {
-       unsigned long now = ktime_get_ns() >> 10;
+       unsigned long now;
        unsigned long last_finish_time = tg->last_finish_time;
 
-       if (now <= last_finish_time || last_finish_time == 0 ||
+       if (last_finish_time == 0)
+               return;
+
+       now = ktime_get_ns() >> 10;
+       if (now <= last_finish_time ||
            last_finish_time == tg->checked_last_finish_time)
                return;