On 5/17/23 07:33, Bart Van Assche wrote:
> Start dispatching from the start of a zone instead of from the starting
> position of the most recently dispatched request.
>
> If a zoned write is requeued with an LBA that is lower than already
> inserted zoned writes, make sure that it is submitted first.
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Cc: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
> Cc: Ming Lei <ming.lei@xxxxxxxxxx>
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> ---
> block/mq-deadline.c | 34 ++++++++++++++++++++++++++++++++--
> 1 file changed, 32 insertions(+), 2 deletions(-)
>
> diff --git a/block/mq-deadline.c b/block/mq-deadline.c
> index 6d0b99042c96..059727fa4b98 100644
> --- a/block/mq-deadline.c
> +++ b/block/mq-deadline.c
> @@ -156,13 +156,28 @@ deadline_latter_request(struct request *rq)
> return NULL;
> }
>
> -/* Return the first request for which blk_rq_pos() >= pos. */
> +/*
> + * Return the first request for which blk_rq_pos() >= @pos. For zoned devices,
> + * return the first request after the highest zone start <= @pos.
This comment is strange. What about:
For zoned devices, return the first request after the start of the zone
containing @pos.
> + */
> static inline struct request *deadline_from_pos(struct dd_per_prio *per_prio,
> enum dd_data_dir data_dir, sector_t pos)
> {
> struct rb_node *node = per_prio->sort_list[data_dir].rb_node;
> struct request *rq, *res = NULL;
>
> + if (!node)
> + return NULL;
> +
> + rq = rb_entry_rq(node);
> + /*
> + * A zoned write may have been requeued with a starting position that
> + * is below that of the most recently dispatched request. Hence, for
> + * zoned writes, start searching from the start of a zone.
> + */
> + if (blk_rq_is_seq_zoned_write(rq))
> + pos -= round_down(pos, rq->q->limits.chunk_sectors);
> +
> while (node) {
> rq = rb_entry_rq(node);
> if (blk_rq_pos(rq) >= pos) {
> @@ -806,6 +821,8 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
> list_add(&rq->queuelist, &per_prio->dispatch);
> rq->fifo_time = jiffies;
> } else {
> + struct list_head *insert_before;
> +
> deadline_add_rq_rb(per_prio, rq);
>
> if (rq_mergeable(rq)) {
> @@ -818,7 +835,20 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
> * set expire time and add to fifo list
> */
> rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
> - list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]);
> + insert_before = &per_prio->fifo_list[data_dir];
> +#ifdef CONFIG_BLK_DEV_ZONED
> + /*
> + * Insert zoned writes such that requests are sorted by
> + * position per zone.
> + */
> + if (blk_rq_is_seq_zoned_write(rq)) {
> + struct request *rq2 = deadline_latter_request(rq);
> +
> + if (rq2 && blk_rq_zone_no(rq2) == blk_rq_zone_no(rq))
> + insert_before = &rq2->queuelist;
> + }
> +#endif
> + list_add_tail(&rq->queuelist, insert_before);
Why not:
insert_before = &per_prio->fifo_list[data_dir];
if (IS_ENABLED(CONFIG_BLK_DEV_ZONED)
&& blk_rq_is_seq_zoned_write(rq)) {
/*
* Insert zoned writes such that requests are sorted by
* position per zone.
*/
struct request *rq2 = deadline_latter_request(rq);
if (rq2 && blk_rq_zone_no(rq2) == blk_rq_zone_no(rq))
insert_before = &rq2->queuelist;
}
list_add_tail(&rq->queuelist, insert_before);
to avoid the ugly #ifdef ?
--
Damien Le Moal
Western Digital Research
