From 6a27b656fc0210e976db362e1368c56db05c8f08 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 26 Jun 2014 17:41:48 +0800 Subject: [PATCH] block: virtio-blk: support multi virt queues per virtio-blk device Firstly this patch supports more than one virtual queues for virtio-blk device. Secondly this patch maps the virtual queue to blk-mq's hardware queue. With this approach, both scalability and performance can be improved. Signed-off-by: Ming Lei Acked-by: Michael S. Tsirkin Signed-off-by: Jens Axboe --- drivers/block/virtio_blk.c | 104 ++++++++++++++++++++++++++++++------- 1 file changed, 84 insertions(+), 20 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index f63d358f3d93..0a581400de0f 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -15,17 +15,22 @@ #include #define PART_BITS 4 +#define VQ_NAME_LEN 16 static int major; static DEFINE_IDA(vd_index_ida); static struct workqueue_struct *virtblk_wq; +struct virtio_blk_vq { + struct virtqueue *vq; + spinlock_t lock; + char name[VQ_NAME_LEN]; +} ____cacheline_aligned_in_smp; + struct virtio_blk { struct virtio_device *vdev; - struct virtqueue *vq; - spinlock_t vq_lock; /* The disk structure for the kernel. */ struct gendisk *disk; @@ -47,6 +52,10 @@ struct virtio_blk /* Ida index - used to track minor number allocations. */ int index; + + /* num of vqs */ + int num_vqs; + struct virtio_blk_vq *vqs; }; struct virtblk_req @@ -133,14 +142,15 @@ static void virtblk_done(struct virtqueue *vq) { struct virtio_blk *vblk = vq->vdev->priv; bool req_done = false; + int qid = vq->index; struct virtblk_req *vbr; unsigned long flags; unsigned int len; - spin_lock_irqsave(&vblk->vq_lock, flags); + spin_lock_irqsave(&vblk->vqs[qid].lock, flags); do { virtqueue_disable_cb(vq); - while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) { + while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) { blk_mq_complete_request(vbr->req); req_done = true; } @@ -151,7 +161,7 @@ static void virtblk_done(struct virtqueue *vq) /* In case queue is stopped waiting for more buffers. */ if (req_done) blk_mq_start_stopped_hw_queues(vblk->disk->queue, true); - spin_unlock_irqrestore(&vblk->vq_lock, flags); + spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags); } static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) @@ -160,6 +170,7 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) struct virtblk_req *vbr = blk_mq_rq_to_pdu(req); unsigned long flags; unsigned int num; + int qid = hctx->queue_num; const bool last = (req->cmd_flags & REQ_END) != 0; int err; bool notify = false; @@ -202,12 +213,12 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) vbr->out_hdr.type |= VIRTIO_BLK_T_IN; } - spin_lock_irqsave(&vblk->vq_lock, flags); - err = __virtblk_add_req(vblk->vq, vbr, vbr->sg, num); + spin_lock_irqsave(&vblk->vqs[qid].lock, flags); + err = __virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num); if (err) { - virtqueue_kick(vblk->vq); + virtqueue_kick(vblk->vqs[qid].vq); blk_mq_stop_hw_queue(hctx); - spin_unlock_irqrestore(&vblk->vq_lock, flags); + spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags); /* Out of mem doesn't actually happen, since we fall back * to direct descriptors */ if (err == -ENOMEM || err == -ENOSPC) @@ -215,12 +226,12 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) return BLK_MQ_RQ_QUEUE_ERROR; } - if (last && virtqueue_kick_prepare(vblk->vq)) + if (last && virtqueue_kick_prepare(vblk->vqs[qid].vq)) notify = true; - spin_unlock_irqrestore(&vblk->vq_lock, flags); + spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags); if (notify) - virtqueue_notify(vblk->vq); + virtqueue_notify(vblk->vqs[qid].vq); return BLK_MQ_RQ_QUEUE_OK; } @@ -377,12 +388,64 @@ static void virtblk_config_changed(struct virtio_device *vdev) static int init_vq(struct virtio_blk *vblk) { int err = 0; + int i; + vq_callback_t **callbacks; + const char **names; + struct virtqueue **vqs; + unsigned short num_vqs; + struct virtio_device *vdev = vblk->vdev; + + err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ, + struct virtio_blk_config, num_queues, + &num_vqs); + if (err) + num_vqs = 1; + + vblk->vqs = kmalloc(sizeof(*vblk->vqs) * num_vqs, GFP_KERNEL); + if (!vblk->vqs) { + err = -ENOMEM; + goto out; + } + + names = kmalloc(sizeof(*names) * num_vqs, GFP_KERNEL); + if (!names) + goto err_names; + + callbacks = kmalloc(sizeof(*callbacks) * num_vqs, GFP_KERNEL); + if (!callbacks) + goto err_callbacks; + + vqs = kmalloc(sizeof(*vqs) * num_vqs, GFP_KERNEL); + if (!vqs) + goto err_vqs; - /* We expect one virtqueue, for output. */ - vblk->vq = virtio_find_single_vq(vblk->vdev, virtblk_done, "requests"); - if (IS_ERR(vblk->vq)) - err = PTR_ERR(vblk->vq); + for (i = 0; i < num_vqs; i++) { + callbacks[i] = virtblk_done; + snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i); + names[i] = vblk->vqs[i].name; + } + + /* Discover virtqueues and write information to configuration. */ + err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names); + if (err) + goto err_find_vqs; + for (i = 0; i < num_vqs; i++) { + spin_lock_init(&vblk->vqs[i].lock); + vblk->vqs[i].vq = vqs[i]; + } + vblk->num_vqs = num_vqs; + + err_find_vqs: + kfree(vqs); + err_vqs: + kfree(callbacks); + err_callbacks: + kfree(names); + err_names: + if (err) + kfree(vblk->vqs); + out: return err; } @@ -551,7 +614,6 @@ static int virtblk_probe(struct virtio_device *vdev) err = init_vq(vblk); if (err) goto out_free_vblk; - spin_lock_init(&vblk->vq_lock); /* FIXME: How many partitions? How long is a piece of string? */ vblk->disk = alloc_disk(1 << PART_BITS); @@ -562,7 +624,7 @@ static int virtblk_probe(struct virtio_device *vdev) /* Default queue sizing is to fill the ring. */ if (!virtblk_queue_depth) { - virtblk_queue_depth = vblk->vq->num_free; + virtblk_queue_depth = vblk->vqs[0].vq->num_free; /* ... but without indirect descs, we use 2 descs per req */ if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)) virtblk_queue_depth /= 2; @@ -570,7 +632,6 @@ static int virtblk_probe(struct virtio_device *vdev) memset(&vblk->tag_set, 0, sizeof(vblk->tag_set)); vblk->tag_set.ops = &virtio_mq_ops; - vblk->tag_set.nr_hw_queues = 1; vblk->tag_set.queue_depth = virtblk_queue_depth; vblk->tag_set.numa_node = NUMA_NO_NODE; vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; @@ -578,6 +639,7 @@ static int virtblk_probe(struct virtio_device *vdev) sizeof(struct virtblk_req) + sizeof(struct scatterlist) * sg_elems; vblk->tag_set.driver_data = vblk; + vblk->tag_set.nr_hw_queues = vblk->num_vqs; err = blk_mq_alloc_tag_set(&vblk->tag_set); if (err) @@ -727,6 +789,7 @@ static void virtblk_remove(struct virtio_device *vdev) refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount); put_disk(vblk->disk); vdev->config->del_vqs(vdev); + kfree(vblk->vqs); kfree(vblk); /* Only free device id if we don't have any users */ @@ -777,7 +840,8 @@ static const struct virtio_device_id id_table[] = { static unsigned int features[] = { VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI, - VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE + VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE, + VIRTIO_BLK_F_MQ, }; static struct virtio_driver virtio_blk = { -- 2.39.2