virtio-blk: support mq_ops->queue_rqs()
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
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
Message-Id: <20220406153207.163134-3-suwan.kim027@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
This commit is contained in:
Suwan Kim
Michael S. Tsirkin
Родитель
4e04005256
Коммит
0e9911fa76
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@ -101,8 +101,7 @@ static inline blk_status_t virtblk_result(struct virtblk_req *vbr)
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}
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}
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static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr,
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struct scatterlist *data_sg, bool have_data)
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static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr)
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{
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struct scatterlist hdr, status, *sgs[3];
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unsigned int num_out = 0, num_in = 0;
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@ -110,11 +109,11 @@ static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr,
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sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
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sgs[num_out++] = &hdr;
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if (have_data) {
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if (vbr->sg_table.nents) {
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if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT))
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sgs[num_out++] = data_sg;
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sgs[num_out++] = vbr->sg_table.sgl;
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else
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sgs[num_out + num_in++] = data_sg;
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sgs[num_out + num_in++] = vbr->sg_table.sgl;
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}
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sg_init_one(&status, &vbr->status, sizeof(vbr->status));
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@ -304,18 +303,12 @@ static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx)
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virtqueue_notify(vq->vq);
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}
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static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
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const struct blk_mq_queue_data *bd)
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static blk_status_t virtblk_prep_rq(struct blk_mq_hw_ctx *hctx,
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struct virtio_blk *vblk,
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struct request *req,
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struct virtblk_req *vbr)
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{
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struct virtio_blk *vblk = hctx->queue->queuedata;
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struct request *req = bd->rq;
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struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
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unsigned long flags;
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int num;
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int qid = hctx->queue_num;
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bool notify = false;
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blk_status_t status;
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int err;
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status = virtblk_setup_cmd(vblk->vdev, req, vbr);
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if (unlikely(status))
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@ -323,14 +316,33 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
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blk_mq_start_request(req);
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num = virtblk_map_data(hctx, req, vbr);
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if (unlikely(num < 0)) {
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vbr->sg_table.nents = virtblk_map_data(hctx, req, vbr);
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if (unlikely(vbr->sg_table.nents < 0)) {
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virtblk_cleanup_cmd(req);
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return BLK_STS_RESOURCE;
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}
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return BLK_STS_OK;
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}
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static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
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const struct blk_mq_queue_data *bd)
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{
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struct virtio_blk *vblk = hctx->queue->queuedata;
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struct request *req = bd->rq;
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struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
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unsigned long flags;
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int qid = hctx->queue_num;
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bool notify = false;
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blk_status_t status;
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int err;
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status = virtblk_prep_rq(hctx, vblk, req, vbr);
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if (unlikely(status))
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return status;
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spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
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err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg_table.sgl, num);
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err = virtblk_add_req(vblk->vqs[qid].vq, vbr);
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if (err) {
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virtqueue_kick(vblk->vqs[qid].vq);
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/* Don't stop the queue if -ENOMEM: we may have failed to
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@ -360,6 +372,75 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
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return BLK_STS_OK;
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}
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static bool virtblk_prep_rq_batch(struct request *req)
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{
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struct virtio_blk *vblk = req->mq_hctx->queue->queuedata;
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struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
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req->mq_hctx->tags->rqs[req->tag] = req;
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return virtblk_prep_rq(req->mq_hctx, vblk, req, vbr) == BLK_STS_OK;
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}
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static bool virtblk_add_req_batch(struct virtio_blk_vq *vq,
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struct request **rqlist,
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struct request **requeue_list)
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{
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unsigned long flags;
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int err;
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bool kick;
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spin_lock_irqsave(&vq->lock, flags);
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while (!rq_list_empty(*rqlist)) {
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struct request *req = rq_list_pop(rqlist);
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struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
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err = virtblk_add_req(vq->vq, vbr);
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if (err) {
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virtblk_unmap_data(req, vbr);
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virtblk_cleanup_cmd(req);
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rq_list_add(requeue_list, req);
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}
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}
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kick = virtqueue_kick_prepare(vq->vq);
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spin_unlock_irqrestore(&vq->lock, flags);
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return kick;
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}
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static void virtio_queue_rqs(struct request **rqlist)
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{
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struct request *req, *next, *prev = NULL;
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struct request *requeue_list = NULL;
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rq_list_for_each_safe(rqlist, req, next) {
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struct virtio_blk_vq *vq = req->mq_hctx->driver_data;
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bool kick;
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if (!virtblk_prep_rq_batch(req)) {
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rq_list_move(rqlist, &requeue_list, req, prev);
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req = prev;
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if (!req)
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continue;
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}
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if (!next || req->mq_hctx != next->mq_hctx) {
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req->rq_next = NULL;
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kick = virtblk_add_req_batch(vq, rqlist, &requeue_list);
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if (kick)
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virtqueue_notify(vq->vq);
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*rqlist = next;
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prev = NULL;
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} else
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prev = req;
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}
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*rqlist = requeue_list;
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}
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/* return id (s/n) string for *disk to *id_str
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*/
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static int virtblk_get_id(struct gendisk *disk, char *id_str)
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@ -794,6 +875,7 @@ static int virtblk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
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static const struct blk_mq_ops virtio_mq_ops = {
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.queue_rq = virtio_queue_rq,
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.queue_rqs = virtio_queue_rqs,
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.commit_rqs = virtio_commit_rqs,
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.init_hctx = virtblk_init_hctx,
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.complete = virtblk_request_done,
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