Following the same idea, it occurs to me that we should only update

disk stat when "now" is different from disk->stamp.  Otherwise, we
are again needlessly adding zero to the stats.

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Signed-off-by: Jens Axboe <axboe@suse.de>

diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index c42071fd2e955397478ffd9c8d2131827601b39b..4e2b1b06b411d12accfad7ae28ef00cc28dbe95b 100644 (file)
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -2433,6 +2433,9 @@ void disk_round_stats(struct gendisk *disk)
 {
        unsigned long now = jiffies;
 
+       if (now == disk->stamp)
+               return;
+
        if (disk->in_flight) {
                __disk_stat_add(disk, time_in_queue,
                                disk->in_flight * (now - disk->stamp));