On 11/30/18 10:29 AM, Jens Axboe wrote: > On 11/30/18 10:27 AM, Christoph Hellwig wrote: >> 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 <axboe@xxxxxxxxx> >>> --- >>> 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. > > But only if RQF_STATS is set, in which case we are passing it in correctly. Oh, needs a stats check for this one, for some reason I was thinking of the end_io path. Will update. -- Jens Axboe
