Re: [PATCH v2 2/7] lib_vhost: Support multiple queues in virtio dev

[Panu Matilainen <pmatilai@redhat.com>]

On 06/10/2015 08:52 AM, Ouyang Changchun wrote:
> Each virtio device could have multiple queues, say 2 or 4, at most 8.
> Enabling this feature allows virtio device/port on guest has the ability to
> use different vCPU to receive/transmit packets from/to each queue.
>
> In multiple queues mode, virtio device readiness means all queues of
> this virtio device are ready, cleanup/destroy a virtio device also
> requires clearing all queues belong to it.
>
> Changes in v2:
>    - remove the q_num_set api
>    - add the qp_num_get api
>    - determine the queue pair num from qemu message
>    - rework for reset owner message handler
>    - dynamically alloc mem for dev virtqueue
>    - queue pair num could be 0x8000
>    - fix checkpatch errors
>
> Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
> ---
>   lib/librte_vhost/rte_virtio_net.h             |  10 +-
>   lib/librte_vhost/vhost-net.h                  |   1 +
>   lib/librte_vhost/vhost_rxtx.c                 |  32 ++---
>   lib/librte_vhost/vhost_user/vhost-net-user.c  |   4 +-
>   lib/librte_vhost/vhost_user/virtio-net-user.c |  76 +++++++++---
>   lib/librte_vhost/vhost_user/virtio-net-user.h |   2 +
>   lib/librte_vhost/virtio-net.c                 | 161 +++++++++++++++++---------
>   7 files changed, 197 insertions(+), 89 deletions(-)
>
> diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h
> index 5d38185..92b4bfa 100644
> --- a/lib/librte_vhost/rte_virtio_net.h
> +++ b/lib/librte_vhost/rte_virtio_net.h
> @@ -59,7 +59,6 @@ struct rte_mbuf;
>   /* Backend value set by guest. */
>   #define VIRTIO_DEV_STOPPED -1
>
> -
>   /* Enum for virtqueue management. */
>   enum {VIRTIO_RXQ, VIRTIO_TXQ, VIRTIO_QNUM};
>
> @@ -96,13 +95,14 @@ struct vhost_virtqueue {
>    * Device structure contains all configuration information relating to the device.
>    */
>   struct virtio_net {
> -	struct vhost_virtqueue	*virtqueue[VIRTIO_QNUM];	/**< Contains all virtqueue information. */
>   	struct virtio_memory	*mem;		/**< QEMU memory and memory region information. */
> +	struct vhost_virtqueue	**virtqueue;    /**< Contains all virtqueue information. */
>   	uint64_t		features;	/**< Negotiated feature set. */
>   	uint64_t		device_fh;	/**< device identifier. */
>   	uint32_t		flags;		/**< Device flags. Only used to check if device is running on data core. */
>   #define IF_NAME_SZ (PATH_MAX > IFNAMSIZ ? PATH_MAX : IFNAMSIZ)
>   	char			ifname[IF_NAME_SZ];	/**< Name of the tap device or socket path. */
> +	uint32_t                num_virt_queues;
>   	void			*priv;		/**< private context */
>   } __rte_cache_aligned;
>
> @@ -220,4 +220,10 @@ uint16_t rte_vhost_enqueue_burst(struct virtio_net *dev, uint16_t queue_id,
>   uint16_t rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
>   	struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count);
>

Unfortunately this is an ABI break, NAK. Ditto for other changes to 
struct virtio_net in patch 3/7 in this series. See 
http://dpdk.org/browse/dpdk/tree/doc/guides/rel_notes/abi.rst for the 
ABI policy.

There's plenty of discussion around the ABI going on at the moment, 
including this thread: http://dpdk.org/ml/archives/dev/2015-June/018456.html

	- Panu -