On Fri, Nov 30, 2018 at 08:56:25AM -0700, Jens Axboe wrote: > We only need the request fields and the end_io time if we have stats > enabled, or if we have a scheduler attached as those may use it for > completion time stats. > > Signed-off-by: Jens Axboe <ax...@kernel.dk> > --- > block/blk-mq.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 7dcef565dc0f..2b458e9da946 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -316,7 +316,8 @@ static struct request *blk_mq_rq_ctx_init(struct > blk_mq_alloc_data *data, > RB_CLEAR_NODE(&rq->rb_node); > rq->rq_disk = NULL; > rq->part = NULL; > - rq->start_time_ns = ktime_get_ns(); > + if (data->q->elevator) > + rq->start_time_ns = ktime_get_ns();
We also seem to use start_time_ns it in blk_account_io_done. Also update it in attempt_merge, which might have some odd results for completly uninitialized fields.
