On 2021/1/18 上午11:58, Joseph Qi wrote:
module parameter 'virtblk_queue_depth' was firstly introduced for
testing/benchmarking purposes described in commit fc4324b4597c
("virtio-blk: base queue-depth on virtqueue ringsize or module param").
Since we have different virtio-blk devices which have different
capabilities, it requires that we support per-device queue depth instead
of per-module. So defaultly use vq free elements if module parameter
'virtblk_queue_depth' is not set.

Signed-off-by: Joseph Qi <[email protected]>


Acked-by: Jason Wang <[email protected]>


---
  drivers/block/virtio_blk.c | 12 +++++++-----
  1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 145606d..f83a417 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -705,6 +705,7 @@ static int virtblk_probe(struct virtio_device *vdev)
        u32 v, blk_size, max_size, sg_elems, opt_io_size;
        u16 min_io_size;
        u8 physical_block_exp, alignment_offset;
+       unsigned int queue_depth;
if (!vdev->config->get) {
                dev_err(&vdev->dev, "%s failure: config access disabled\n",
@@ -755,17 +756,18 @@ static int virtblk_probe(struct virtio_device *vdev)
                goto out_free_vq;
        }
- /* Default queue sizing is to fill the ring. */
-       if (!virtblk_queue_depth) {
-               virtblk_queue_depth = vblk->vqs[0].vq->num_free;
+       if (likely(!virtblk_queue_depth)) {
+               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;
+                       queue_depth /= 2;
+       } else {
+               queue_depth = virtblk_queue_depth;
        }
memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
        vblk->tag_set.ops = &virtio_mq_ops;
-       vblk->tag_set.queue_depth = virtblk_queue_depth;
+       vblk->tag_set.queue_depth = queue_depth;
        vblk->tag_set.numa_node = NUMA_NO_NODE;
        vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
        vblk->tag_set.cmd_size =

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