ktime_to_ns(ktime_get()) which is expensive do not need to be executed if
blk_iolatency_enabled() return false in blkcg_iolatency_done_bio().
Postponing ktime_to_ns(ktime_get()) execution can reduce CPU usage
when blk_iolatency was disabled.
---
V2:
1.Fix compile warnings.
Signed-off-by: Hongnan Li <hongnan.li@xxxxxxxxxxxxxxxxx>
---
block/blk-iolatency.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index c128d50..f90429c 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -591,7 +591,7 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
struct rq_wait *rqw;
struct iolatency_grp *iolat;
u64 window_start;
- u64 now = ktime_to_ns(ktime_get());
+ u64 now;
bool issue_as_root = bio_issue_as_root_blkg(bio);
bool enabled = false;
int inflight = 0;
@@ -608,6 +608,7 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
if (!enabled)
return;
+ now = ktime_to_ns(ktime_get());
while (blkg && blkg->parent) {
iolat = blkg_to_lat(blkg);
if (!iolat) {
--
1.8.3.1
