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| author | Rusty Russell <rusty@rustcorp.com.au> | 2014-03-19 17:08:24 +1030 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2014-03-24 12:20:18 +1030 |
| commit | fc4324b4597c4eb8907207e82f9a6acec84dd335 (patch) | |
| tree | e26df11a67a5eb36c29d08e57467e33692308e69 | |
| parent | b1ee30ae6ec4aa1e711bdab7e17d6c531e492294 (diff) | |
| download | linux-fc4324b4597c4eb8907207e82f9a6acec84dd335.tar.gz linux-fc4324b4597c4eb8907207e82f9a6acec84dd335.tar.bz2 linux-fc4324b4597c4eb8907207e82f9a6acec84dd335.zip | |
virtio-blk: base queue-depth on virtqueue ringsize or module param
Venkatash spake thus:
virtio-blk set the default queue depth to 64 requests, which was
insufficient for high-IOPS devices. Instead set the blk-queue depth to
the device's virtqueue depth divided by two (each I/O requires at least
two VQ entries).
But behold, Ted added a module parameter:
Also allow the queue depth to be something which can be set at module
load time or via a kernel boot-time parameter, for
testing/benchmarking purposes.
And I rewrote it substantially, mainly to take
VIRTIO_RING_F_INDIRECT_DESC into account.
As QEMU sets the vq size for PCI to 128, Venkatash's patch wouldn't
have made a change. This version does (since QEMU also offers
VIRTIO_RING_F_INDIRECT_DESC.
Inspired-by: "Theodore Ts'o" <tytso@mit.edu>
Based-on-the-true-story-of: Venkatesh Srinivas <venkateshs@google.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: virtio-dev@lists.oasis-open.org
Cc: virtualization@lists.linux-foundation.org
Cc: Frank Swiderski <fes@google.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
| -rw-r--r-- | drivers/block/virtio_blk.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index a2db9ed288f2..196222271a50 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -491,10 +491,11 @@ static struct blk_mq_ops virtio_mq_ops = { static struct blk_mq_reg virtio_mq_reg = { .ops = &virtio_mq_ops, .nr_hw_queues = 1, - .queue_depth = 64, + .queue_depth = 0, /* Set in virtblk_probe */ .numa_node = NUMA_NO_NODE, .flags = BLK_MQ_F_SHOULD_MERGE, }; +module_param_named(queue_depth, virtio_mq_reg.queue_depth, uint, 0444); static void virtblk_init_vbr(void *data, struct blk_mq_hw_ctx *hctx, struct request *rq, unsigned int nr) @@ -558,6 +559,13 @@ static int virtblk_probe(struct virtio_device *vdev) goto out_free_vq; } + /* Default queue sizing is to fill the ring. */ + if (!virtio_mq_reg.queue_depth) { + virtio_mq_reg.queue_depth = vblk->vq->num_free; + /* ... but without indirect descs, we use 2 descs per req */ + if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)) + virtio_mq_reg.queue_depth /= 2; + } virtio_mq_reg.cmd_size = sizeof(struct virtblk_req) + sizeof(struct scatterlist) * sg_elems; |