On 2020/06/02 18:15, Ming Lei wrote:
> Pass obtained budget count to blk_mq_dispatch_rq_list(), and prepare
> for supporting fully batching submission.
>
> With the obtained budget count, it is easier to put extra budgets
> in case of .queue_rq failure.
>
> Meantime remove the old 'got_budget' parameter.
>
> Cc: Sagi Grimberg <sagi@xxxxxxxxxxx>
> Cc: Baolin Wang <baolin.wang7@xxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> Tested-by: Baolin Wang <baolin.wang7@xxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> block/blk-mq-sched.c | 8 ++++----
> block/blk-mq.c | 27 +++++++++++++++++++++++----
> block/blk-mq.h | 3 ++-
> 3 files changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index 632c6f8b63f7..4c72073830f3 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -130,7 +130,7 @@ static int blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
> * in blk_mq_dispatch_rq_list().
> */
> list_add(&rq->queuelist, &rq_list);
> - } while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, true));
> + } while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, 1));
>
> return ret;
> }
> @@ -198,7 +198,7 @@ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
> /* round robin for fair dispatch */
> ctx = blk_mq_next_ctx(hctx, rq->mq_ctx);
>
> - } while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, true));
> + } while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, 1));
>
> WRITE_ONCE(hctx->dispatch_from, ctx);
> return ret;
> @@ -238,7 +238,7 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
> */
> if (!list_empty(&rq_list)) {
> blk_mq_sched_mark_restart_hctx(hctx);
> - if (blk_mq_dispatch_rq_list(hctx, &rq_list, false)) {
> + if (blk_mq_dispatch_rq_list(hctx, &rq_list, 0)) {
> if (has_sched_dispatch)
> ret = blk_mq_do_dispatch_sched(hctx);
> else
> @@ -251,7 +251,7 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
> ret = blk_mq_do_dispatch_ctx(hctx);
> } else {
> blk_mq_flush_busy_ctxs(hctx, &rq_list);
> - blk_mq_dispatch_rq_list(hctx, &rq_list, false);
> + blk_mq_dispatch_rq_list(hctx, &rq_list, 0);
> }
>
> return ret;
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 0e3aab91e6c0..901ef0264e44 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1259,7 +1259,8 @@ static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,
> */
> if (!blk_mq_mark_tag_wait(hctx, rq)) {
> /* budget is always obtained before getting tag */
> - blk_mq_put_dispatch_budget(rq->q);
> + if (ask_budget)
> + blk_mq_put_dispatch_budget(rq->q);
> return PREP_DISPATCH_NO_TAG;
> }
> }
> @@ -1267,11 +1268,21 @@ static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,
> return PREP_DISPATCH_OK;
> }
>
> +static void blk_mq_release_budgets(struct request_queue *q,
> + unsigned int nr_budgets)
> +{
> + int i = 0;
> +
> + /* release got budgets */
> + while (i++ < nr_budgets)
A for loop would be simpler I think...
> + blk_mq_put_dispatch_budget(q);
> +}
> +
> /*
> * Returns true if we did some work AND can potentially do more.
> */
> bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
> - bool got_budget)
> + unsigned int nr_budgets)
> {
> enum prep_dispatch prep;
> struct request_queue *q = hctx->queue;
> @@ -1283,7 +1294,7 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
> if (list_empty(list))
> return false;
>
> - WARN_ON(!list_is_singular(list) && got_budget);
> + WARN_ON(!list_is_singular(list) && nr_budgets);
>
> /*
> * Now process all the entries, sending them to the driver.
> @@ -1295,7 +1306,7 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
> rq = list_first_entry(list, struct request, queuelist);
>
> WARN_ON_ONCE(hctx != rq->mq_hctx);
> - prep = blk_mq_prep_dispatch_rq(rq, !got_budget);
> + prep = blk_mq_prep_dispatch_rq(rq, !nr_budgets);
> if (prep != PREP_DISPATCH_OK)
> break;
>
> @@ -1314,6 +1325,12 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
> bd.last = !blk_mq_get_driver_tag(nxt);
> }
>
> + /*
> + * once the request is queued to lld, no need to cover the
> + * budget any more
> + */
> + if (nr_budgets)
> + nr_budgets--;
> ret = q->mq_ops->queue_rq(hctx, &bd);
> if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
> blk_mq_handle_dev_resource(rq, list);
> @@ -1353,6 +1370,8 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
> bool no_tag = false;
> bool no_budget_avail = false;
>
> + blk_mq_release_budgets(q, nr_budgets);
> +
> /*
> * For non-shared tags, the RESTART check
> * will suffice.
> diff --git a/block/blk-mq.h b/block/blk-mq.h
> index d2d737b16e0e..f3a93acfad03 100644
> --- a/block/blk-mq.h
> +++ b/block/blk-mq.h
> @@ -40,7 +40,8 @@ struct blk_mq_ctx {
> void blk_mq_exit_queue(struct request_queue *q);
> int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr);
> void blk_mq_wake_waiters(struct request_queue *q);
> -bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *, bool);
> +bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *,
> + unsigned int);
> void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
> bool kick_requeue_list);
> void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list);
>
--
Damien Le Moal
Western Digital Research
