Re: [dpdk-dev] [PATCH 2/2] ether/ethdev: Allow pmd to advertise preferred pool capability

[Olivier Matz <olivier.matz@6wind.com>]

On Thu,  1 Jun 2017 13:35:59 +0530, Santosh Shukla <santosh.shukla@caviumnetworks.com> wrote:
> Platform with two different NICs like external PCI NIC and
> Integrated NIC, May want to use their preferred pool handle.
> Right now there is no way that two different NICs on same board,
> Could use their choice of a pool.
> Both NICs forced to use same pool, Which is statically configured
> by setting CONFIG_RTE_MEMPOOL_DEFAULT_OPS=<pool-name>.
> 
> So Introducing get_preferred_pool() API. Which allows PMD driver
> to advertise their pool capability to Application.
> Based on that hint, Application creates separate pool for
> That driver.
> 
> Signed-off-by: Santosh Shukla <santosh.shukla@caviumnetworks.com>
> ---
>  lib/librte_ether/rte_ethdev.c          | 16 ++++++++++++++++
>  lib/librte_ether/rte_ethdev.h          | 21 +++++++++++++++++++++
>  lib/librte_ether/rte_ether_version.map |  7 +++++++
>  3 files changed, 44 insertions(+)
> 
> diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
> index 83898a8f7..4068a05b1 100644
> --- a/lib/librte_ether/rte_ethdev.c
> +++ b/lib/librte_ether/rte_ethdev.c
> @@ -3472,3 +3472,19 @@ rte_eth_dev_l2_tunnel_offload_set(uint8_t port_id,
>  				-ENOTSUP);
>  	return (*dev->dev_ops->l2_tunnel_offload_set)(dev, l2_tunnel, mask, en);
>  }
> +
> +int
> +rte_eth_dev_get_preferred_pool(uint8_t port_id, const char *pool)
> +{
> +	struct rte_eth_dev *dev;
> +
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +
> +	dev = &rte_eth_devices[port_id];
> +
> +	if (*dev->dev_ops->get_preferred_pool == NULL) {
> +		pool = RTE_MBUF_DEFAULT_MEMPOOL_OPS;
> +		return 0;
> +	}
> +	return (*dev->dev_ops->get_preferred_pool)(dev, pool);
> +}

Instead of this, what about:

/*
 * Return values:
 *   - -ENOTSUP: error, pool type is not supported
 *   - on success, return the priority of the mempool (0 = highest)
 */
int
rte_eth_dev_pool_ops_supported(uint8_t port_id, const char *pool)

By default, always return 0 (i.e. all pools are supported).

With this API, we can announce several supported pools (not only
one preferred), and order them by preference.

I also wonder if we should use a ops_index instead of a pool name
for the second argument.



> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index 0f38b45f8..8e5b06af7 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -1381,6 +1381,10 @@ typedef int (*eth_l2_tunnel_offload_set_t)
>  	 uint8_t en);
>  /**< @internal enable/disable the l2 tunnel offload functions */
>  
> +typedef int (*eth_get_preferred_pool_t)(struct rte_eth_dev *dev,
> +						const char *pool);
> +/**< @internal Get preferred pool handler for a device */
> +
>  #ifdef RTE_NIC_BYPASS
>  
>  enum {
> @@ -1573,6 +1577,8 @@ struct eth_dev_ops {
>  	/**< Get extended device statistic values by ID. */
>  	eth_xstats_get_names_by_id_t xstats_get_names_by_id;
>  	/**< Get name of extended device statistics by ID. */
> +	eth_get_preferred_pool_t get_preferred_pool;
> +	/**< Get preferred pool handler for a device */
>  };
>  
>  /**
> @@ -4607,6 +4613,21 @@ rte_eth_dev_get_port_by_name(const char *name, uint8_t *port_id);
>  int
>  rte_eth_dev_get_name_by_port(uint8_t port_id, char *name);
>  
> +/**
> + * Get preferred pool handle for a device
> + *
> + * @param port_id
> + *   port identifier of the device
> + * @param [out] pool
> + *   Preferred pool handle for this device.
> + *   Pool len shouldn't more than 256B. Allocated by pmd driver.

[out] ??
I don't get why it is allocated by the driver



> + * @return
> + *   - (0) if successful.
> + *   - (-EINVAL) on failure.
> + */
> +int
> +rte_eth_dev_get_preferred_pool(uint8_t port_id, const char *pool);
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/lib/librte_ether/rte_ether_version.map b/lib/librte_ether/rte_ether_version.map
> index d6726bb1b..819fe800e 100644
> --- a/lib/librte_ether/rte_ether_version.map
> +++ b/lib/librte_ether/rte_ether_version.map
> @@ -156,3 +156,10 @@ DPDK_17.05 {
>  	rte_eth_xstats_get_names_by_id;
>  
>  } DPDK_17.02;
> +
> +DPDK_17.08 {
> +	global:
> +
> +	rte_eth_dev_get_preferred_pool;
> +
> +} DPDK_17.05;