On 4/22/21 2:20 PM, Ming Lei wrote: > Limit at most 8 queues are polled in each blk_pull(), avoid to > add extra latency when queue depth is high. > > Reviewed-by: Jeffle Xu <[email protected]> > Signed-off-by: Ming Lei <[email protected]> > --- > block/blk-poll.c | 78 ++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 55 insertions(+), 23 deletions(-) > > diff --git a/block/blk-poll.c b/block/blk-poll.c > index 249d73ff6f81..20e7c47cc984 100644 > --- a/block/blk-poll.c > +++ b/block/blk-poll.c > @@ -288,36 +288,32 @@ static void bio_grp_list_move(struct bio_grp_list *dst, > src->nr_grps -= cnt; > } > > -static int blk_mq_poll_io(struct bio *bio) > +#define POLL_HCTX_MAX_CNT 8 > + > +static bool blk_add_unique_hctx(struct blk_mq_hw_ctx **data, int *cnt, > + struct blk_mq_hw_ctx *hctx) > { > - struct request_queue *q = bio->bi_bdev->bd_disk->queue; > - blk_qc_t cookie = bio_get_poll_data(bio); > - int ret = 0; > + int i; > > - /* wait until the bio is submitted really */ > - if (!blk_qc_t_ready(cookie)) > - return 0; > > - if (!bio_flagged(bio, BIO_DONE) && blk_qc_t_valid(cookie)) { > - struct blk_mq_hw_ctx *hctx = > - q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)]; > + for (i = 0; i < *cnt; i++) { > + if (data[i] == hctx) > + goto exit; > + } > > - ret += blk_mq_poll_hctx(q, hctx); > + if (i < POLL_HCTX_MAX_CNT) { > + data[i] = hctx; > + (*cnt)++; > } > - return ret; > + exit: > + return *cnt == POLL_HCTX_MAX_CNT; > } > > -static int blk_bio_poll_and_end_io(struct bio_grp_list *grps) > +static void blk_build_poll_queues(struct bio_grp_list *grps, > + struct blk_mq_hw_ctx **data, int *cnt) > { > - int ret = 0; > int i; > > - /* > - * Poll hw queue first. > - * > - * TODO: limit max poll times and make sure to not poll same > - * hw queue one more time. > - */ > for (i = 0; i < grps->nr_grps; i++) { > struct bio_grp_list_data *grp = &grps->head[i]; > struct bio *bio; > @@ -325,11 +321,31 @@ static int blk_bio_poll_and_end_io(struct bio_grp_list > *grps) > if (bio_grp_list_grp_empty(grp)) > continue; > > - for (bio = grp->list.head; bio; bio = bio->bi_poll) > - ret += blk_mq_poll_io(bio); > + for (bio = grp->list.head; bio; bio = bio->bi_poll) { > + blk_qc_t cookie; > + struct blk_mq_hw_ctx *hctx; > + struct request_queue *q; > + > + if (bio_flagged(bio, BIO_DONE)) > + continue; > + > + /* wait until the bio is submitted really */ > + cookie = bio_get_poll_data(bio); > + if (!blk_qc_t_ready(cookie) || !blk_qc_t_valid(cookie)) > + continue; > + > + q = bio->bi_bdev->bd_disk->queue; > + hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)]; > + if (blk_add_unique_hctx(data, cnt, hctx)) > + return; > + } > } > +} > + > +static void blk_bio_poll_reap_ios(struct bio_grp_list *grps) > +{ > + int i; > > - /* reap bios */ > for (i = 0; i < grps->nr_grps; i++) { > struct bio_grp_list_data *grp = &grps->head[i]; > struct bio *bio; > @@ -354,6 +370,22 @@ static int blk_bio_poll_and_end_io(struct bio_grp_list > *grps) > } > __bio_grp_list_merge(&grp->list, &bl); > } > +} > + > +static int blk_bio_poll_and_end_io(struct bio_grp_list *grps) > +{ > + int ret = 0; > + int i; > + struct blk_mq_hw_ctx *hctx[POLL_HCTX_MAX_CNT]; > + int cnt = 0; > + > + blk_build_poll_queues(grps, hctx, &cnt); > + > + for (i = 0; i < cnt; i++) > + ret += blk_mq_poll_hctx(hctx[i]->queue, hctx[i]); > + > + blk_bio_poll_reap_ios(grps); > + > return ret; > } > > Can't we make it a sysfs attribute instead of hard-coding it? '8' seems a bit arbitrary to me, I'd rather have the ability to modify it...
Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect [email protected] +49 911 74053 688 SUSE Software Solutions Germany GmbH, 90409 Nürnberg GF: F. Imendörffer, HRB 36809 (AG Nürnberg) -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
