Hello, Bart.
On Tue, Dec 12, 2017 at 09:37:11PM +0000, Bart Van Assche wrote:
> Have you considered the following instead of introducing MQ_RQ_IDLE and
> MQ_RQ_IN_FLIGHT? I think this could help to limit the number of new atomic
> operations introduced in the hot path by this patch series.
But nothing in the hot paths is atomic.
> static inline bool blk_mq_rq_in_flight(struct request *rq)
> {
> return list_empty(&rq->queuelist);
> }
And the fact that we encode the generation number and state into a
single variable contributes to not needing atomic operations.
Breaking up the state and generation like the above would need more
synchronization, not less.
Thanks.
--
tejun
