[RFC PATCH 2/2] block: virtio-blk: support multi virt queues per virtio-blk device
From: Ming Lei
Date: Fri Jun 13 2014 - 13:30:56 EST
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 problem can be improved.
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
---
drivers/block/virtio_blk.c | 75 ++++++++++++++++++++++++++++++++------------
1 file changed, 55 insertions(+), 20 deletions(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index f63d358..e0d077d 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -16,6 +16,8 @@
#define PART_BITS 4
+#define MAX_NUM_VQ 16
+
static int major;
static DEFINE_IDA(vd_index_ida);
@@ -24,8 +26,8 @@ static struct workqueue_struct *virtblk_wq;
struct virtio_blk
{
struct virtio_device *vdev;
- struct virtqueue *vq;
- spinlock_t vq_lock;
+ struct virtqueue *vq[MAX_NUM_VQ];
+ spinlock_t vq_lock[MAX_NUM_VQ];
/* The disk structure for the kernel. */
struct gendisk *disk;
@@ -47,6 +49,9 @@ struct virtio_blk
/* Ida index - used to track minor number allocations. */
int index;
+
+ /* num of vqs */
+ int num_vqs;
};
struct virtblk_req
@@ -133,14 +138,15 @@ 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->vq_lock[qid], flags);
do {
virtqueue_disable_cb(vq);
- while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
+ while ((vbr = virtqueue_get_buf(vblk->vq[qid], &len)) != NULL) {
blk_mq_complete_request(vbr->req);
req_done = true;
}
@@ -151,7 +157,7 @@ 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->vq_lock[qid], flags);
}
static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
@@ -160,6 +166,7 @@ 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 +209,12 @@ 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->vq_lock[qid], flags);
+ err = __virtblk_add_req(vblk->vq[qid], vbr, vbr->sg, num);
if (err) {
- virtqueue_kick(vblk->vq);
+ virtqueue_kick(vblk->vq[qid]);
blk_mq_stop_hw_queue(hctx);
- spin_unlock_irqrestore(&vblk->vq_lock, flags);
+ spin_unlock_irqrestore(&vblk->vq_lock[qid], flags);
/* Out of mem doesn't actually happen, since we fall back
* to direct descriptors */
if (err == -ENOMEM || err == -ENOSPC)
@@ -215,12 +222,12 @@ 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->vq[qid]))
notify = true;
- spin_unlock_irqrestore(&vblk->vq_lock, flags);
+ spin_unlock_irqrestore(&vblk->vq_lock[qid], flags);
if (notify)
- virtqueue_notify(vblk->vq);
+ virtqueue_notify(vblk->vq[qid]);
return BLK_MQ_RQ_QUEUE_OK;
}
@@ -377,12 +384,40 @@ 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[MAX_NUM_VQ];
+ const char *names[MAX_NUM_VQ];
+ unsigned short num_vqs;
+ struct virtio_device *vdev = vblk->vdev;
- /* 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);
+ if (virtio_has_feature(vdev, VIRTIO_BLK_F_MQ))
+ err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
+ struct virtio_blk_config, num_queues,
+ &num_vqs);
+ else
+ num_vqs = 1;
+
+ if (err)
+ goto out;
+ if (num_vqs > MAX_NUM_VQ)
+ num_vqs = MAX_NUM_VQ;
+
+ for (i = 0; i < num_vqs; i++) {
+ callbacks[i] = virtblk_done;
+ names[i] = "requests";
+ }
+
+ /* Discover virtqueues and write information to configuration. */
+ err = vdev->config->find_vqs(vdev, num_vqs, vblk->vq,
+ callbacks, names);
+ if (err)
+ goto out;
+
+ for (i = 0; i < num_vqs; i++)
+ spin_lock_init(&vblk->vq_lock[i]);
+ vblk->num_vqs = num_vqs;
+out:
return err;
}
@@ -551,7 +586,6 @@ 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 +596,7 @@ 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->vq[0]->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 +604,6 @@ 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 +611,7 @@ 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)
@@ -777,7 +811,8 @@ 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 = {
--
1.7.9.5
--
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