Messages in this thread | | | Subject | Re: [PATCH] virtio-blk: make the queue depth the max supportable by the hypervisor | From | Konrad Rzeszutek Wilk <> | Date | Sat, 15 Mar 2014 06:57:01 -0400 |
| |
On March 14, 2014 11:34:31 PM EDT, Theodore Ts'o <tytso@mit.edu> wrote: >The current virtio block sets a queue depth of 64, which is >insufficient for very fast devices. It has been demonstrated that >with a high IOPS device, using a queue depth of 256 can double the >IOPS which can be sustained. > >As suggested by Venkatash Srinivas, set the queue depth by default to >be one half the the device's virtqueue, which is the maximum queue >depth that can be supported by the channel to the host OS (each I/O >request requires at least two VQ entries). > >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. > >Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> >Signed-off-by: Venkatesh Srinivas <venkateshs@google.com> >Cc: Rusty Russell <rusty@rustcorp.com.au> >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> >--- > >This is a combination of my patch and Vekatash's patch. I agree that >setting the default automatically is better than requiring the user to >set the value by hand. > > drivers/block/virtio_blk.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > >diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c >index 6a680d4..0f70c01 100644 >--- a/drivers/block/virtio_blk.c >+++ b/drivers/block/virtio_blk.c >@@ -481,6 +481,9 @@ static struct blk_mq_ops virtio_mq_ops = { > .free_hctx = blk_mq_free_single_hw_queue, > }; > >+static int queue_depth = -1; >+module_param(queue_depth, int, 0444);
?
>+ > static struct blk_mq_reg virtio_mq_reg = { > .ops = &virtio_mq_ops, > .nr_hw_queues = 1, >@@ -551,9 +554,14 @@ static int virtblk_probe(struct virtio_device >*vdev) > goto out_free_vq; > } > >+ virtio_mq_reg.queue_depth = queue_depth > 0 ? queue_depth : >+ (vblk->vq->num_free / 2); > virtio_mq_reg.cmd_size = > sizeof(struct virtblk_req) + > sizeof(struct scatterlist) * sg_elems; >+ virtblk_name_format("vd", index, vblk->disk->disk_name, >DISK_NAME_LEN); >+ pr_info("%s: using queue depth %d\n", vblk->disk->disk_name, >+ virtio_mq_reg.queue_depth);
Isn't that visible from sysfs? > > q = vblk->disk->queue = blk_mq_init_queue(&virtio_mq_reg, vblk); > if (!q) { >@@ -565,8 +573,6 @@ static int virtblk_probe(struct virtio_device >*vdev) > > q->queuedata = vblk; > >- virtblk_name_format("vd", index, vblk->disk->disk_name, >DISK_NAME_LEN); >- > vblk->disk->major = major; > vblk->disk->first_minor = index_to_minor(index); > vblk->disk->private_data = vblk;
| |