[PATCH 3/4] blk-throttle: Avoid tracking latency if low limit is invalid

[Baolin Wang]

The IO latency tracking is only for LOW limit, so we should add a
validation to avoid redundant latency tracking if the LOW limit
is not valid.

Signed-off-by: Baolin Wang <baolin.w...@linux.alibaba.com>
---
 block/blk-throttle.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 7e72102..b0d8f7c 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2100,7 +2100,7 @@ static void throtl_update_latency_buckets(struct 
throtl_data *td)
        unsigned long last_latency[2] = { 0 };
        unsigned long latency[2];
 
-       if (!blk_queue_nonrot(td->queue))
+       if (!blk_queue_nonrot(td->queue) || !td->limit_valid[LIMIT_LOW])
                return;
        if (time_before(jiffies, td->last_calculate_time + HZ))
                return;
@@ -2338,6 +2338,8 @@ void blk_throtl_bio_endio(struct bio *bio)
        if (!blkg)
                return;
        tg = blkg_to_tg(blkg);
+       if (!tg->td->limit_valid[LIMIT_LOW])
+               return;
 
        finish_time_ns = ktime_get_ns();
        tg->last_finish_time = finish_time_ns >> 10;
-- 
1.8.3.1