Re: [dpdk-dev] [PATCH] vhost: add support for dynamic vhost PMD creation

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 5/9/2016 10:31 PM, Yuanhan Liu wrote:
> On Thu, May 05, 2016 at 07:11:09PM +0100, Ferruh Yigit wrote:
>> Add rte_eth_from_vhost() API to create vhost PMD dynamically from
>> applications.
> 
> This sounds a good idea to me. It could be better if you name a good
> usage of it though.
> 
>>
>> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
>> ---
>>  drivers/net/vhost/rte_eth_vhost.c           | 117 ++++++++++++++++++++++++++++
>>  drivers/net/vhost/rte_eth_vhost.h           |  19 +++++
>>  drivers/net/vhost/rte_pmd_vhost_version.map |   7 ++
>>  3 files changed, 143 insertions(+)
>>
>> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
>> index 310cbef..c860ab8 100644
>> --- a/drivers/net/vhost/rte_eth_vhost.c
>> +++ b/drivers/net/vhost/rte_eth_vhost.c
>> @@ -796,6 +796,123 @@ error:
>>  	return -1;
>>  }
>>  
>> +static int
>> +rte_eth_from_vhost_create(const char *name, char *iface_name,
> 
> It's not a public function, so don't name it with prefix "rte_".
> 
>> +		const unsigned int numa_node, struct rte_mempool *mb_pool)
>> +{
>> +	struct rte_eth_dev_data *data = NULL;
>> +	struct rte_eth_dev *eth_dev = NULL;
>> +	struct pmd_internal *internal = NULL;
>> +	struct internal_list *list;
>> +	int nb_queues = 1;
>> +	uint16_t nb_rx_queues = nb_queues;
>> +	uint16_t nb_tx_queues = nb_queues;
>> +	struct vhost_queue *vq;
>> +	int i;
>> +
>> +	int port_id = eth_dev_vhost_create(name, iface_name, nb_queues,
>> +			numa_node);
>> +
>> +	if (port_id < 0)
>> +		return -1;
>> +
>> +	eth_dev = &rte_eth_devices[port_id];
>> +	data = eth_dev->data;
>> +	internal = data->dev_private;
>> +	list = find_internal_resource(internal->iface_name);
>> +
>> +	data->rx_queues = rte_zmalloc_socket(name,
>> +			sizeof(void *) * nb_rx_queues, 0, numa_node);
>> +	if (data->rx_queues == NULL)
>> +		goto error;
>> +
>> +	data->tx_queues = rte_zmalloc_socket(name,
>> +			sizeof(void *) * nb_tx_queues, 0, numa_node);
>> +	if (data->tx_queues == NULL)
>> +		goto error;
>> +
>> +	for (i = 0; i < nb_rx_queues; i++) {
>> +		vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
>> +				RTE_CACHE_LINE_SIZE, numa_node);
>> +		if (vq == NULL) {
>> +			RTE_LOG(ERR, PMD,
>> +				"Failed to allocate memory for rx queue\n");
>> +			goto error;
>> +		}
>> +		vq->mb_pool = mb_pool;
>> +		vq->virtqueue_id = i * VIRTIO_QNUM + VIRTIO_TXQ;
>> +		data->rx_queues[i] = vq;
>> +	}
> 
> I would invoke eth_rx_queue_setup() here, to remove the duplicated
> effort of queue allocation and initiation.
> 
>> +
>> +	for (i = 0; i < nb_tx_queues; i++) {
>> +		vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
>> +				RTE_CACHE_LINE_SIZE, numa_node);
>> +		if (vq == NULL) {
>> +			RTE_LOG(ERR, PMD,
>> +				"Failed to allocate memory for tx queue\n");
>> +			goto error;
>> +		}
>> +		vq->mb_pool = mb_pool;
> 
> Tx queue doesn't need a mbuf pool. And, ditto, call eth_tx_queue_setup()
> instead.
> 
> 
>> +int
>> +rte_eth_from_vhost(const char *name, char *iface_name,
>> +		const unsigned int numa_node, struct rte_mempool *mb_pool)
> 
> That would make this API be very limited. Assume we want to extend
> vhost pmd in future, we could easily do that by adding few more
> vdev options: you could reference my patch[0] to add client and
> reconnect option. But here you hardcode all stuff that are needed
> so far to create a vhost-pmd eth device; adding something new
> would imply an API breakage in future.
> 
> So, let the vdev options as the argument of this API? That could
> be friendly for future extension without breaking the API.
> 
> [0]: http://dpdk.org/dev/patchwork/patch/12608/
> 
>> +/**
>> + * API to create vhost PMD
>> + *
>> + * @param name
>> + *  Vhost device name
>> + * @param iface_name
>> + *  Vhost interface name
>> + * @param numa_node
>> + *  Socket id
>> + * @param mb_pool
>> + *  Memory pool
>> + *
>> + * @return
>> + *  - On success, port_id.
>> + *  - On failure, a negative value.
>> + */
> 
> Hmmm, too simple.
> 
> 	--yliu
> 

Hi Yuanhan,

Thank you for the review, I will send new version of the patch with
above issues addressed.

Thanks,
ferruh