[dm-devel] [RFC PATCH V2 04/13] block: create io poll context for submission and poll task
Mike Snitzer
snitzer at redhat.com
Fri Mar 19 17:05:09 UTC 2021
On Thu, Mar 18 2021 at 12:48pm -0400,
Ming Lei <ming.lei at redhat.com> wrote:
> Create per-task io poll context for both IO submission and poll task
> if the queue is bio based and supports polling.
>
> This io polling context includes two queues:
1) submission queue(sq) for storing HIPRI bio submission result(cookie)
and the bio, written by submission task and read by poll task.
2) polling queue(pq) for holding data moved from sq, only used in poll
context for running bio polling.
(nit, but it just reads a bit clearer to enumerate the 2 queues)
> Following patches will support bio poll.
>
> Signed-off-by: Ming Lei <ming.lei at redhat.com>
> ---
> block/blk-core.c | 71 ++++++++++++++++++++++++++++++++-------
> block/blk-ioc.c | 1 +
> block/blk-mq.c | 14 ++++++++
> block/blk.h | 46 +++++++++++++++++++++++++
> include/linux/iocontext.h | 2 ++
> 5 files changed, 122 insertions(+), 12 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index d58f8a0c80de..0b00c21cbefb 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -792,16 +792,59 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q,
> return BLK_STS_OK;
> }
>
> -static inline void blk_create_io_context(struct request_queue *q)
> +static inline struct blk_bio_poll_ctx *blk_get_bio_poll_ctx(void)
> {
> - /*
> - * Various block parts want %current->io_context, so allocate it up
> - * front rather than dealing with lots of pain to allocate it only
> - * where needed. This may fail and the block layer knows how to live
> - * with it.
> - */
> - if (unlikely(!current->io_context))
> - create_task_io_context(current, GFP_ATOMIC, q->node);
> + struct io_context *ioc = current->io_context;
> +
> + return ioc ? ioc->data : NULL;
> +}
> +
> +static inline unsigned int bio_grp_list_size(unsigned int nr_grps)
> +{
> + return sizeof(struct bio_grp_list) + nr_grps *
> + sizeof(struct bio_grp_list_data);
> +}
> +
> +static void bio_poll_ctx_init(struct blk_bio_poll_ctx *pc)
> +{
> + pc->sq = (void *)pc + sizeof(*pc);
> + pc->sq->max_nr_grps = BLK_BIO_POLL_SQ_SZ;
> +
> + pc->pq = (void *)pc->sq + bio_grp_list_size(BLK_BIO_POLL_SQ_SZ);
> + pc->pq->max_nr_grps = BLK_BIO_POLL_PQ_SZ;
> +
> + spin_lock_init(&pc->sq_lock);
> + mutex_init(&pc->pq_lock);
> +}
> +
> +void bio_poll_ctx_alloc(struct io_context *ioc)
> +{
> + struct blk_bio_poll_ctx *pc;
> + unsigned int size = sizeof(*pc) +
> + bio_grp_list_size(BLK_BIO_POLL_SQ_SZ) +
> + bio_grp_list_size(BLK_BIO_POLL_PQ_SZ);
> +
> + pc = kzalloc(GFP_ATOMIC, size);
> + if (pc) {
> + bio_poll_ctx_init(pc);
> + if (cmpxchg(&ioc->data, NULL, (void *)pc))
> + kfree(pc);
> + }
> +}
> +
> +static inline bool blk_queue_support_bio_poll(struct request_queue *q)
> +{
> + return !queue_is_mq(q) && blk_queue_poll(q);
> +}
> +
> +static inline void blk_bio_poll_preprocess(struct request_queue *q,
> + struct bio *bio)
> +{
> + if (!(bio->bi_opf & REQ_HIPRI))
> + return;
> +
> + if (!blk_queue_poll(q) || (!queue_is_mq(q) && !blk_get_bio_poll_ctx()))
> + bio->bi_opf &= ~REQ_HIPRI;
> }
>
> static noinline_for_stack bool submit_bio_checks(struct bio *bio)
> @@ -848,10 +891,14 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
> }
> }
>
> - blk_create_io_context(q);
> + /*
> + * Created per-task io poll queue if we supports bio polling
> + * and it is one HIPRI bio.
> + */
Create per-task io poll queue if bio polling supported and HIPRI set.
> + blk_create_io_context(q, blk_queue_support_bio_poll(q) &&
> + (bio->bi_opf & REQ_HIPRI));
>
> - if (!blk_queue_poll(q))
> - bio->bi_opf &= ~REQ_HIPRI;
> + blk_bio_poll_preprocess(q, bio);
>
> switch (bio_op(bio)) {
> case REQ_OP_DISCARD:
> diff --git a/block/blk-ioc.c b/block/blk-ioc.c
> index b0cde18c4b8c..5574c398eff6 100644
> --- a/block/blk-ioc.c
> +++ b/block/blk-ioc.c
> @@ -19,6 +19,7 @@ static struct kmem_cache *iocontext_cachep;
>
> static inline void free_io_context(struct io_context *ioc)
> {
> + kfree(ioc->data);
> kmem_cache_free(iocontext_cachep, ioc);
> }
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 63c81df3b8b5..c832faa52ca0 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -3852,6 +3852,17 @@ static bool blk_mq_poll_hybrid(struct request_queue *q,
> return blk_mq_poll_hybrid_sleep(q, rq);
> }
>
> +static int blk_bio_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
> +{
> + /*
> + * Create poll queue for storing poll bio and its cookie from
> + * submission queue
> + */
> + blk_create_io_context(q, true);
> +
> + return 0;
> +}
> +
> /**
> * blk_poll - poll for IO completions
> * @q: the queue
> @@ -3875,6 +3886,9 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
> if (current->plug)
> blk_flush_plug_list(current->plug, false);
>
> + if (!queue_is_mq(q))
> + return blk_bio_poll(q, cookie, spin);
> +
> hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
>
> /*
> diff --git a/block/blk.h b/block/blk.h
> index 3b53e44b967e..ae58a706327e 100644
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -357,4 +357,50 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
> struct page *page, unsigned int len, unsigned int offset,
> unsigned int max_sectors, bool *same_page);
>
> +/* grouping bios belonging to same group into one list */
Reads awkwardly, maybe:
/* Grouping bios that share same data into one list */
> +struct bio_grp_list_data {
> + /* group data */
Don't think this ^ comment is needed (variable name achieves same).
> + void *grp_data;
> +
> + /* all bios in this list share same 'grp_data' */
> + struct bio_list list;
> +};
> +
> +struct bio_grp_list {
> + unsigned int max_nr_grps, nr_grps;
> + struct bio_grp_list_data head[0];
> +};
> +
> +struct blk_bio_poll_ctx {
> + spinlock_t sq_lock;
> + struct bio_grp_list *sq;
> +
> + struct mutex pq_lock;
> + struct bio_grp_list *pq;
> +};
> +
> +#define BLK_BIO_POLL_SQ_SZ 32U
> +#define BLK_BIO_POLL_PQ_SZ (BLK_BIO_POLL_SQ_SZ * 2)
> +
> +void bio_poll_ctx_alloc(struct io_context *ioc);
> +
> +static inline void blk_create_io_context(struct request_queue *q,
> + bool need_poll_ctx)
> +{
> + struct io_context *ioc;
> +
> + /*
> + * Various block parts want %current->io_context, so allocate it up
> + * front rather than dealing with lots of pain to allocate it only
> + * where needed. This may fail and the block layer knows how to live
> + * with it.
> + */
> + if (unlikely(!current->io_context))
> + create_task_io_context(current, GFP_ATOMIC, q->node);
> +
> + ioc = current->io_context;
> + if (need_poll_ctx && unlikely(ioc && !ioc->data))
> + bio_poll_ctx_alloc(ioc);
> +}
> +
> #endif /* BLK_INTERNAL_H */
> diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
> index 0a9dc40b7be8..f9a467571356 100644
> --- a/include/linux/iocontext.h
> +++ b/include/linux/iocontext.h
> @@ -110,6 +110,8 @@ struct io_context {
> struct io_cq __rcu *icq_hint;
> struct hlist_head icq_list;
>
> + void *data;
> +
> struct work_struct release_work;
> };
>
> --
> 2.29.2
>
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