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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 <ming.lei@canonical.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei 2014-06-26 17:41:48 +08:00 committed by Jens Axboe
parent cb553215d5
commit 6a27b656fc
1 changed files with 84 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

104
drivers/block/virtio_blk.c
View File

@ -15,17 +15,22 @@
#include <linux/numa.h>
#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;
/* 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);
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;
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 = {