Re: [dpdk-dev] [PATCH v2] net/virtio: add link speed tuning

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Ivan,

On 12/13/19 3:44 PM, Ivan Dyukov wrote:
> Some applications like pktgen use link_speed to calculate transmit
> rate. It limits outcome traffic to hardcoded 10G.
> 
> This patch makes link_speed configurable at compile time.
> 
> Signed-off-by: Ivan Dyukov <i.dyukov@samsung.com>
> ---
>  config/common_base                 |  1 +
>  config/meson.build                 |  1 +
>  drivers/net/vhost/rte_eth_vhost.c  |  2 +-
>  drivers/net/virtio/virtio_ethdev.c | 20 ++++++++++++++++----
>  4 files changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/config/common_base b/config/common_base
> index 7dec7ed45..8589ca4ec 100644
> --- a/config/common_base
> +++ b/config/common_base
> @@ -433,6 +433,7 @@ CONFIG_RTE_LIBRTE_AVP_DEBUG_BUFFERS=n
>  # Compile burst-oriented VIRTIO PMD driver
>  #
>  CONFIG_RTE_LIBRTE_VIRTIO_PMD=y
> +CONFIG_RTE_LIBRTE_VIRTIO_LINK_SPEED=10000
>  CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_RX=n
>  CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_TX=n
>  CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_DUMP=n
> diff --git a/config/meson.build b/config/meson.build
> index 364a8d739..78c30f334 100644
> --- a/config/meson.build
> +++ b/config/meson.build
> @@ -202,6 +202,7 @@ dpdk_conf.set('RTE_LIBEAL_USE_HPET', get_option('use_hpet'))
>  dpdk_conf.set('RTE_MAX_VFIO_GROUPS', 64)
>  dpdk_conf.set('RTE_DRIVER_MEMPOOL_BUCKET_SIZE_KB', 64)
>  dpdk_conf.set('RTE_LIBRTE_DPAA2_USE_PHYS_IOVA', true)
> +dpdk_conf.set('RTE_LIBRTE_VIRTIO_LINK_SPEED', 10000)
>  
>  
>  compile_time_cpuflags = []
> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
> index 46f01a7f4..38eaa5955 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -115,7 +115,7 @@ static struct internal_list_head internal_list =
>  static pthread_mutex_t internal_list_lock = PTHREAD_MUTEX_INITIALIZER;
>  
>  static struct rte_eth_link pmd_link = {
> -		.link_speed = 10000,
> +		.link_speed = RTE_LIBRTE_VIRTIO_LINK_SPEED,
>  		.link_duplex = ETH_LINK_FULL_DUPLEX,
>  		.link_status = ETH_LINK_DOWN
>  };
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 044eb10a7..948091cc2 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -2371,7 +2371,7 @@ virtio_dev_link_update(struct rte_eth_dev *dev, __rte_unused int wait_to_complet
>  
>  	memset(&link, 0, sizeof(link));
>  	link.link_duplex = ETH_LINK_FULL_DUPLEX;
> -	link.link_speed  = ETH_SPEED_NUM_10G;
> +	link.link_speed  = RTE_LIBRTE_VIRTIO_LINK_SPEED;
>  	link.link_autoneg = ETH_LINK_FIXED;
>  
>  	if (!hw->started) {
> @@ -2426,9 +2426,21 @@ virtio_dev_info_get(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
>  {
>  	uint64_t tso_mask, host_features;
>  	struct virtio_hw *hw = dev->data->dev_private;
> -
> -	dev_info->speed_capa = ETH_LINK_SPEED_10G; /* fake value */
> -
> +#if RTE_LIBRTE_VIRTIO_LINK_SPEED == ETH_LINK_SPEED_20G
> +	dev_info->speed_capa = ETH_LINK_SPEED_20G;
> +#elif RTE_LIBRTE_VIRTIO_LINK_SPEED == ETH_SPEED_NUM_25G
> +	dev_info->speed_capa = ETH_LINK_SPEED_25G;
> +#elif RTE_LIBRTE_VIRTIO_LINK_SPEED == ETH_SPEED_NUM_40G
> +	dev_info->speed_capa = ETH_LINK_SPEED_40G;
> +#elif RTE_LIBRTE_VIRTIO_LINK_SPEED == ETH_SPEED_NUM_50G
> +	dev_info->speed_capa = ETH_LINK_SPEED_50G;
> +#elif RTE_LIBRTE_VIRTIO_LINK_SPEED == ETH_SPEED_NUM_56G
> +	dev_info->speed_capa = ETH_LINK_SPEED_56G;
> +#elif RTE_LIBRTE_VIRTIO_LINK_SPEED == ETH_SPEED_NUM_100G
> +	dev_info->speed_capa = ETH_LINK_SPEED_100G;
> +#else
> +	dev_info->speed_capa = ETH_LINK_SPEED_10G;
> +#endif
>  	dev_info->max_rx_queues =
>  		RTE_MIN(hw->max_queue_pairs, VIRTIO_MAX_RX_QUEUES);
>  	dev_info->max_tx_queues =
> 

I think we may need toi extend the Virtio specification so that the
device can advertise the link speed.

Problem with your proposal is that it is build time only, so:
1. It won't be configurable when using distros DPDK package.
2. All the Virtio devices on a system will have the same value

While any Virtio spec update introduce link speed support, wouldn't it
be preferable to have this as a devarg?

Thanks,
Maxime