path: root/block/blk-merge.c
diff options
authorMikulas Patocka <mpatocka@redhat.com>2018-12-06 11:41:19 -0500
committerJens Axboe <axboe@kernel.dk>2018-12-10 08:30:37 -0700
commit5b18b5a737600fd20ba2045f320d5926ebbf341a (patch)
treefe35e150bf36785dfe3ed8c845e3b043e56f9f90 /block/blk-merge.c
parent112f158f66cbe25fd561a5dfe9c3826e06abf757 (diff)
block: delete part_round_stats and switch to less precise counting
We want to convert to per-cpu in_flight counters. The function part_round_stats needs the in_flight counter every jiffy, it would be too costly to sum all the percpu variables every jiffy, so it must be deleted. part_round_stats is used to calculate two counters - time_in_queue and io_ticks. time_in_queue can be calculated without part_round_stats, by adding the duration of the I/O when the I/O ends (the value is almost as exact as the previously calculated value, except that time for in-progress I/Os is not counted). io_ticks can be approximated by increasing the value when I/O is started or ended and the jiffies value has changed. If the I/Os take less than a jiffy, the value is as exact as the previously calculated value. If the I/Os take more than a jiffy, io_ticks can drift behind the previously calculated value. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-merge.c')
1 files changed, 0 insertions, 1 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index a120d59b9705..9da5629d0887 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -689,7 +689,6 @@ static void blk_account_io_merge(struct request *req)
part = req->part;
- part_round_stats(req->q, part);
part_dec_in_flight(req->q, part, rq_data_dir(req));