| Message ID | 20220405053122.77626-3-suwan.kim027@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio-blk: support polling I/O and mq_ops->queue_rqs() | expand |
On Tue, Apr 05, 2022 at 02:31:22PM +0900, Suwan Kim wrote: > This patch supports mq_ops->queue_rqs() hook. It has an advantage of > batch submission to virtio-blk driver. It also helps polling I/O because > polling uses batched completion of block layer. Batch submission in > queue_rqs() can boost polling performance. > > In queue_rqs(), it iterates plug->mq_list, collects requests that > belong to same HW queue until it encounters a request from other > HW queue or sees the end of the list. > Then, virtio-blk adds requests into virtqueue and kicks virtqueue > to submit requests. > > If there is an error, it inserts error request to requeue_list and > passes it to ordinary block layer path. > > For verification, I did fio test. > (io_uring, randread, direct=1, bs=4K, iodepth=64 numjobs=N) > I set 4 vcpu and 2 virtio-blk queues for VM and run fio test 5 times. > It shows about 2% improvement. > > | numjobs=2 | numjobs=4 > ----------------------------------------------------------- > fio without queue_rqs() | 291K IOPS | 238K IOPS > ----------------------------------------------------------- > fio with queue_rqs() | 295K IOPS | 243K IOPS > > For polling I/O performance, I also did fio test as below. > (io_uring, hipri, randread, direct=1, bs=512, iodepth=64 numjobs=4) > I set 4 vcpu and 2 poll queues for VM. > It shows about 2% improvement in polling I/O. > > | IOPS | avg latency > ----------------------------------------------------------- > fio poll without queue_rqs() | 424K | 613.05 usec > ----------------------------------------------------------- > fio poll with queue_rqs() | 435K | 601.01 usec > > Signed-off-by: Suwan Kim <suwan.kim027@gmail.com> > --- > drivers/block/virtio_blk.c | 110 +++++++++++++++++++++++++++++++++---- > 1 file changed, 99 insertions(+), 11 deletions(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index 712579dcd3cc..a091034bc551 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -92,6 +92,7 @@ struct virtio_blk { > struct virtblk_req { > struct virtio_blk_outhdr out_hdr; > u8 status; > + int sg_num; > struct sg_table sg_table; > struct scatterlist sg[]; > }; > @@ -311,18 +312,13 @@ static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx) > virtqueue_notify(vq->vq); > } > > -static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, > - const struct blk_mq_queue_data *bd) > +static blk_status_t virtblk_prep_rq(struct blk_mq_hw_ctx *hctx, > + struct virtio_blk *vblk, > + struct request *req, > + struct virtblk_req *vbr) > { > - struct virtio_blk *vblk = hctx->queue->queuedata; > - struct request *req = bd->rq; > - struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); > - unsigned long flags; > - int num; > - int qid = hctx->queue_num; > - bool notify = false; > blk_status_t status; > - int err; > + int num; > > status = virtblk_setup_cmd(vblk->vdev, req, vbr); > if (unlikely(status)) > @@ -335,9 +331,30 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, > virtblk_cleanup_cmd(req); > return BLK_STS_RESOURCE; > } > + vbr->sg_num = num; This can go into the nents field of vbr->sg_table. > + int err; > + > + status = virtblk_prep_rq(hctx, vblk, req, vbr); > + if (unlikely(status)) > + return status; > > spin_lock_irqsave(&vblk->vqs[qid].lock, flags); > - err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg_table.sgl, num); > + err = virtblk_add_req(vblk->vqs[qid].vq, vbr, > + vbr->sg_table.sgl, vbr->sg_num); And while we're at it - virtblk_add_req can lose the data_sg and have_data arguments as they can be derived from vbr.
On Tue, Apr 05, 2022 at 02:31:22PM +0900, Suwan Kim wrote: > This patch supports mq_ops->queue_rqs() hook. It has an advantage of > batch submission to virtio-blk driver. It also helps polling I/O because > polling uses batched completion of block layer. Batch submission in > queue_rqs() can boost polling performance. > > In queue_rqs(), it iterates plug->mq_list, collects requests that > belong to same HW queue until it encounters a request from other > HW queue or sees the end of the list. > Then, virtio-blk adds requests into virtqueue and kicks virtqueue > to submit requests. > > If there is an error, it inserts error request to requeue_list and > passes it to ordinary block layer path. > > For verification, I did fio test. > (io_uring, randread, direct=1, bs=4K, iodepth=64 numjobs=N) > I set 4 vcpu and 2 virtio-blk queues for VM and run fio test 5 times. > It shows about 2% improvement. > > | numjobs=2 | numjobs=4 > ----------------------------------------------------------- > fio without queue_rqs() | 291K IOPS | 238K IOPS > ----------------------------------------------------------- > fio with queue_rqs() | 295K IOPS | 243K IOPS > > For polling I/O performance, I also did fio test as below. > (io_uring, hipri, randread, direct=1, bs=512, iodepth=64 numjobs=4) > I set 4 vcpu and 2 poll queues for VM. > It shows about 2% improvement in polling I/O. > > | IOPS | avg latency > ----------------------------------------------------------- > fio poll without queue_rqs() | 424K | 613.05 usec > ----------------------------------------------------------- > fio poll with queue_rqs() | 435K | 601.01 usec > > Signed-off-by: Suwan Kim <suwan.kim027@gmail.com> > --- > drivers/block/virtio_blk.c | 110 +++++++++++++++++++++++++++++++++---- > 1 file changed, 99 insertions(+), 11 deletions(-) Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
On Tue, Apr 05, 2022 at 01:57:06AM -0700, Christoph Hellwig wrote: > On Tue, Apr 05, 2022 at 02:31:22PM +0900, Suwan Kim wrote: > > This patch supports mq_ops->queue_rqs() hook. It has an advantage of > > batch submission to virtio-blk driver. It also helps polling I/O because > > polling uses batched completion of block layer. Batch submission in > > queue_rqs() can boost polling performance. > > > > In queue_rqs(), it iterates plug->mq_list, collects requests that > > belong to same HW queue until it encounters a request from other > > HW queue or sees the end of the list. > > Then, virtio-blk adds requests into virtqueue and kicks virtqueue > > to submit requests. > > > > If there is an error, it inserts error request to requeue_list and > > passes it to ordinary block layer path. > > > > For verification, I did fio test. > > (io_uring, randread, direct=1, bs=4K, iodepth=64 numjobs=N) > > I set 4 vcpu and 2 virtio-blk queues for VM and run fio test 5 times. > > It shows about 2% improvement. > > > > | numjobs=2 | numjobs=4 > > ----------------------------------------------------------- > > fio without queue_rqs() | 291K IOPS | 238K IOPS > > ----------------------------------------------------------- > > fio with queue_rqs() | 295K IOPS | 243K IOPS > > > > For polling I/O performance, I also did fio test as below. > > (io_uring, hipri, randread, direct=1, bs=512, iodepth=64 numjobs=4) > > I set 4 vcpu and 2 poll queues for VM. > > It shows about 2% improvement in polling I/O. > > > > | IOPS | avg latency > > ----------------------------------------------------------- > > fio poll without queue_rqs() | 424K | 613.05 usec > > ----------------------------------------------------------- > > fio poll with queue_rqs() | 435K | 601.01 usec > > > > Signed-off-by: Suwan Kim <suwan.kim027@gmail.com> > > --- > > drivers/block/virtio_blk.c | 110 +++++++++++++++++++++++++++++++++---- > > 1 file changed, 99 insertions(+), 11 deletions(-) > > > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > > index 712579dcd3cc..a091034bc551 100644 > > --- a/drivers/block/virtio_blk.c > > +++ b/drivers/block/virtio_blk.c > > @@ -92,6 +92,7 @@ struct virtio_blk { > > struct virtblk_req { > > struct virtio_blk_outhdr out_hdr; > > u8 status; > > + int sg_num; > > struct sg_table sg_table; > > struct scatterlist sg[]; > > }; > > @@ -311,18 +312,13 @@ static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx) > > virtqueue_notify(vq->vq); > > } > > > > -static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, > > - const struct blk_mq_queue_data *bd) > > +static blk_status_t virtblk_prep_rq(struct blk_mq_hw_ctx *hctx, > > + struct virtio_blk *vblk, > > + struct request *req, > > + struct virtblk_req *vbr) > > { > > - struct virtio_blk *vblk = hctx->queue->queuedata; > > - struct request *req = bd->rq; > > - struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); > > - unsigned long flags; > > - int num; > > - int qid = hctx->queue_num; > > - bool notify = false; > > blk_status_t status; > > - int err; > > + int num; > > > > status = virtblk_setup_cmd(vblk->vdev, req, vbr); > > if (unlikely(status)) > > @@ -335,9 +331,30 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, > > virtblk_cleanup_cmd(req); > > return BLK_STS_RESOURCE; > > } > > + vbr->sg_num = num; > > This can go into the nents field of vbr->sg_table. > > > + int err; > > + > > + status = virtblk_prep_rq(hctx, vblk, req, vbr); > > + if (unlikely(status)) > > + return status; > > > > spin_lock_irqsave(&vblk->vqs[qid].lock, flags); > > - err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg_table.sgl, num); > > + err = virtblk_add_req(vblk->vqs[qid].vq, vbr, > > + vbr->sg_table.sgl, vbr->sg_num); > > And while we're at it - virtblk_add_req can lose the data_sg and > have_data arguments as they can be derived from vbr. Ok. I will remove vbr->sg_num and save it to vbr->sg_table.nents. Regards, Suwan Kim
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 712579dcd3cc..a091034bc551 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -92,6 +92,7 @@ struct virtio_blk { struct virtblk_req { struct virtio_blk_outhdr out_hdr; u8 status; + int sg_num; struct sg_table sg_table; struct scatterlist sg[]; }; @@ -311,18 +312,13 @@ static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx) virtqueue_notify(vq->vq); } -static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, - const struct blk_mq_queue_data *bd) +static blk_status_t virtblk_prep_rq(struct blk_mq_hw_ctx *hctx, + struct virtio_blk *vblk, + struct request *req, + struct virtblk_req *vbr) { - struct virtio_blk *vblk = hctx->queue->queuedata; - struct request *req = bd->rq; - struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); - unsigned long flags; - int num; - int qid = hctx->queue_num; - bool notify = false; blk_status_t status; - int err; + int num; status = virtblk_setup_cmd(vblk->vdev, req, vbr); if (unlikely(status)) @@ -335,9 +331,30 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, virtblk_cleanup_cmd(req); return BLK_STS_RESOURCE; } + vbr->sg_num = num; + + return BLK_STS_OK; +} + +static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, + const struct blk_mq_queue_data *bd) +{ + struct virtio_blk *vblk = hctx->queue->queuedata; + struct request *req = bd->rq; + struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); + unsigned long flags; + int qid = hctx->queue_num; + bool notify = false; + blk_status_t status; + int err; + + status = virtblk_prep_rq(hctx, vblk, req, vbr); + if (unlikely(status)) + return status; spin_lock_irqsave(&vblk->vqs[qid].lock, flags); - err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg_table.sgl, num); + err = virtblk_add_req(vblk->vqs[qid].vq, vbr, + vbr->sg_table.sgl, vbr->sg_num); if (err) { virtqueue_kick(vblk->vqs[qid].vq); /* Don't stop the queue if -ENOMEM: we may have failed to @@ -367,6 +384,76 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, return BLK_STS_OK; } +static bool virtblk_prep_rq_batch(struct request *req) +{ + struct virtio_blk *vblk = req->mq_hctx->queue->queuedata; + struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); + + req->mq_hctx->tags->rqs[req->tag] = req; + + return virtblk_prep_rq(req->mq_hctx, vblk, req, vbr) == BLK_STS_OK; +} + +static bool virtblk_add_req_batch(struct virtio_blk_vq *vq, + struct request **rqlist, + struct request **requeue_list) +{ + unsigned long flags; + int err; + bool kick; + + spin_lock_irqsave(&vq->lock, flags); + + while (!rq_list_empty(*rqlist)) { + struct request *req = rq_list_pop(rqlist); + struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); + + err = virtblk_add_req(vq->vq, vbr, + vbr->sg_table.sgl, vbr->sg_num); + if (err) { + virtblk_unmap_data(req, vbr); + virtblk_cleanup_cmd(req); + rq_list_add(requeue_list, req); + } + } + + kick = virtqueue_kick_prepare(vq->vq); + spin_unlock_irqrestore(&vq->lock, flags); + + return kick; +} + +static void virtio_queue_rqs(struct request **rqlist) +{ + struct request *req, *next, *prev = NULL; + struct request *requeue_list = NULL; + + rq_list_for_each_safe(rqlist, req, next) { + struct virtio_blk_vq *vq = req->mq_hctx->driver_data; + bool kick; + + if (!virtblk_prep_rq_batch(req)) { + rq_list_move(rqlist, &requeue_list, req, prev); + req = prev; + if (!req) + continue; + } + + if (!next || req->mq_hctx != next->mq_hctx) { + req->rq_next = NULL; + kick = virtblk_add_req_batch(vq, rqlist, &requeue_list); + if (kick) + virtqueue_notify(vq->vq); + + *rqlist = next; + prev = NULL; + } else + prev = req; + } + + *rqlist = requeue_list; +} + /* return id (s/n) string for *disk to *id_str */ static int virtblk_get_id(struct gendisk *disk, char *id_str) @@ -834,6 +921,7 @@ static int virtblk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, static const struct blk_mq_ops virtio_mq_ops = { .queue_rq = virtio_queue_rq, + .queue_rqs = virtio_queue_rqs, .commit_rqs = virtio_commit_rqs, .init_hctx = virtblk_init_hctx, .complete = virtblk_request_done,
This patch supports mq_ops->queue_rqs() hook. It has an advantage of batch submission to virtio-blk driver. It also helps polling I/O because polling uses batched completion of block layer. Batch submission in queue_rqs() can boost polling performance. In queue_rqs(), it iterates plug->mq_list, collects requests that belong to same HW queue until it encounters a request from other HW queue or sees the end of the list. Then, virtio-blk adds requests into virtqueue and kicks virtqueue to submit requests. If there is an error, it inserts error request to requeue_list and passes it to ordinary block layer path. For verification, I did fio test. (io_uring, randread, direct=1, bs=4K, iodepth=64 numjobs=N) I set 4 vcpu and 2 virtio-blk queues for VM and run fio test 5 times. It shows about 2% improvement. | numjobs=2 | numjobs=4 ----------------------------------------------------------- fio without queue_rqs() | 291K IOPS | 238K IOPS ----------------------------------------------------------- fio with queue_rqs() | 295K IOPS | 243K IOPS For polling I/O performance, I also did fio test as below. (io_uring, hipri, randread, direct=1, bs=512, iodepth=64 numjobs=4) I set 4 vcpu and 2 poll queues for VM. It shows about 2% improvement in polling I/O. | IOPS | avg latency ----------------------------------------------------------- fio poll without queue_rqs() | 424K | 613.05 usec ----------------------------------------------------------- fio poll with queue_rqs() | 435K | 601.01 usec Signed-off-by: Suwan Kim <suwan.kim027@gmail.com> --- drivers/block/virtio_blk.c | 110 +++++++++++++++++++++++++++++++++---- 1 file changed, 99 insertions(+), 11 deletions(-)