On Mon, Jun 05, 2017 at 10:41:56AM -0500, Eric Blake wrote:
> On 06/05/2017 10:38 AM, Michael S. Tsirkin wrote:
> > On Mon, Jun 05, 2017 at 04:57:29PM +0800, Wei Wang wrote:
> >> This patch enables the virtio-net tx queue size to be configurable
> >> between 256 and 1024 by the user. The queue size specified by the
> >> user should be power of 2. If "tx_queue_size" is not offered by the
> >> user, the default queue size, 1024, will be used.
> >>
>
> >> + if (n->net_conf.tx_queue_size < VIRTIO_NET_TX_QUEUE_MIN_SIZE ||
> >> + n->net_conf.tx_queue_size > VIRTQUEUE_MAX_SIZE ||
> >> + (n->net_conf.tx_queue_size & (n->net_conf.tx_queue_size - 1))) {
> >
> > Pls use is_power_of_2.
> >
> >> + error_setg(errp, "Invalid tx_queue_size (= %" PRIu16 "), "
> >> + "must be a power of 2 between %d and %d.",
>
> No trailing '.' in error_setg() messages, please.
>
> >> + n->net_conf.tx_queue_size,
> >> VIRTIO_NET_TX_QUEUE_MIN_SIZE,
> >> + VIRTQUEUE_MAX_SIZE);
> >
> > I think management will need a way to discover the limits for
> > this value. Not sure how. Cc QAPI maintainers.
>
> Is this something that can be documented? Or is it a runtime-variable
> limit, where you will need to query the limit on a per-machine basis?
> Given that it looks like compile-time documentation, I'm leaning towards
> documentation being sufficient.
We are likely to change the limits with time. E.g.
VIRTIO_NET_TX_QUEUE_MIN_SIZE is arbitrary.
> --
> Eric Blake, Principal Software Engineer
> Red Hat, Inc. +1-919-301-3266
> Virtualization: qemu.org | libvirt.org
>
