From 95e7249691f082a5178d4d6f60fcdee91da458ab Mon Sep 17 00:00:00 2001 From: Mike Christie Date: Wed, 13 Dec 2023 23:26:49 -0600 Subject: scsi: virtio_scsi: Add mq_poll support This adds polling support to virtio-scsi. It's based on and works similar to virtblk support where we add a module param to specify the number of poll queues then subtract to calculate the IO queues. When using 8 poll queues and a vhost worker per queue we see 4K IOPs with fio: fio --filename=/dev/sda --direct=1 --rw=randread --bs=4k \ --ioengine=io_uring --hipri --iodepth=128 --numjobs=$NUM_JOBS increase like: jobs base poll 1 207K 296K 2 392K 552K 3 581K 860K 4 765K 1235K 5 936K 1598K 6 1104K 1880K 7 1253K 2095K 8 1311k 2187K Signed-off-by: Mike Christie Message-Id: <20231214052649.57743-1-michael.christie@oracle.com> Signed-off-by: Michael S. Tsirkin --- drivers/scsi/virtio_scsi.c | 78 +++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 73 insertions(+), 5 deletions(-) diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 9d1bdcdc1331..4cf20be668a6 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -37,6 +37,11 @@ #define VIRTIO_SCSI_EVENT_LEN 8 #define VIRTIO_SCSI_VQ_BASE 2 +static unsigned int virtscsi_poll_queues; +module_param(virtscsi_poll_queues, uint, 0644); +MODULE_PARM_DESC(virtscsi_poll_queues, + "The number of dedicated virtqueues for polling I/O"); + /* Command queue element */ struct virtio_scsi_cmd { struct scsi_cmnd *sc; @@ -76,6 +81,7 @@ struct virtio_scsi { struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN]; u32 num_queues; + int io_queues[HCTX_MAX_TYPES]; struct hlist_node node; @@ -722,9 +728,49 @@ static int virtscsi_abort(struct scsi_cmnd *sc) static void virtscsi_map_queues(struct Scsi_Host *shost) { struct virtio_scsi *vscsi = shost_priv(shost); - struct blk_mq_queue_map *qmap = &shost->tag_set.map[HCTX_TYPE_DEFAULT]; + int i, qoff; + + for (i = 0, qoff = 0; i < shost->nr_maps; i++) { + struct blk_mq_queue_map *map = &shost->tag_set.map[i]; + + map->nr_queues = vscsi->io_queues[i]; + map->queue_offset = qoff; + qoff += map->nr_queues; + + if (map->nr_queues == 0) + continue; + + /* + * Regular queues have interrupts and hence CPU affinity is + * defined by the core virtio code, but polling queues have + * no interrupts so we let the block layer assign CPU affinity. + */ + if (i == HCTX_TYPE_POLL) + blk_mq_map_queues(map); + else + blk_mq_virtio_map_queues(map, vscsi->vdev, 2); + } +} + +static int virtscsi_mq_poll(struct Scsi_Host *shost, unsigned int queue_num) +{ + struct virtio_scsi *vscsi = shost_priv(shost); + struct virtio_scsi_vq *virtscsi_vq = &vscsi->req_vqs[queue_num]; + unsigned long flags; + unsigned int len; + int found = 0; + void *buf; + + spin_lock_irqsave(&virtscsi_vq->vq_lock, flags); + + while ((buf = virtqueue_get_buf(virtscsi_vq->vq, &len)) != NULL) { + virtscsi_complete_cmd(vscsi, buf); + found++; + } + + spin_unlock_irqrestore(&virtscsi_vq->vq_lock, flags); - blk_mq_virtio_map_queues(qmap, vscsi->vdev, 2); + return found; } static void virtscsi_commit_rqs(struct Scsi_Host *shost, u16 hwq) @@ -751,6 +797,7 @@ static const struct scsi_host_template virtscsi_host_template = { .this_id = -1, .cmd_size = sizeof(struct virtio_scsi_cmd), .queuecommand = virtscsi_queuecommand, + .mq_poll = virtscsi_mq_poll, .commit_rqs = virtscsi_commit_rqs, .change_queue_depth = virtscsi_change_queue_depth, .eh_abort_handler = virtscsi_abort, @@ -795,13 +842,14 @@ static int virtscsi_init(struct virtio_device *vdev, { int err; u32 i; - u32 num_vqs; + u32 num_vqs, num_poll_vqs, num_req_vqs; vq_callback_t **callbacks; const char **names; struct virtqueue **vqs; struct irq_affinity desc = { .pre_vectors = 2 }; - num_vqs = vscsi->num_queues + VIRTIO_SCSI_VQ_BASE; + num_req_vqs = vscsi->num_queues; + num_vqs = num_req_vqs + VIRTIO_SCSI_VQ_BASE; vqs = kmalloc_array(num_vqs, sizeof(struct virtqueue *), GFP_KERNEL); callbacks = kmalloc_array(num_vqs, sizeof(vq_callback_t *), GFP_KERNEL); @@ -812,15 +860,31 @@ static int virtscsi_init(struct virtio_device *vdev, goto out; } + num_poll_vqs = min_t(unsigned int, virtscsi_poll_queues, + num_req_vqs - 1); + vscsi->io_queues[HCTX_TYPE_DEFAULT] = num_req_vqs - num_poll_vqs; + vscsi->io_queues[HCTX_TYPE_READ] = 0; + vscsi->io_queues[HCTX_TYPE_POLL] = num_poll_vqs; + + dev_info(&vdev->dev, "%d/%d/%d default/read/poll queues\n", + vscsi->io_queues[HCTX_TYPE_DEFAULT], + vscsi->io_queues[HCTX_TYPE_READ], + vscsi->io_queues[HCTX_TYPE_POLL]); + callbacks[0] = virtscsi_ctrl_done; callbacks[1] = virtscsi_event_done; names[0] = "control"; names[1] = "event"; - for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++) { + for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs - num_poll_vqs; i++) { callbacks[i] = virtscsi_req_done; names[i] = "request"; } + for (; i < num_vqs; i++) { + callbacks[i] = NULL; + names[i] = "request_poll"; + } + /* Discover virtqueues and write information to configuration. */ err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, &desc); if (err) @@ -874,6 +938,7 @@ static int virtscsi_probe(struct virtio_device *vdev) sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1; shost->sg_tablesize = sg_elems; + shost->nr_maps = 1; vscsi = shost_priv(shost); vscsi->vdev = vdev; vscsi->num_queues = num_queues; @@ -883,6 +948,9 @@ static int virtscsi_probe(struct virtio_device *vdev) if (err) goto virtscsi_init_failed; + if (vscsi->io_queues[HCTX_TYPE_POLL]) + shost->nr_maps = HCTX_TYPE_POLL + 1; + shost->can_queue = virtqueue_get_vring_size(vscsi->req_vqs[0].vq); cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1; -- cgit v1.2.3-58-ga151