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

[santosh]

On Friday 30 June 2017 07:43 PM, Olivier Matz wrote:

> On Thu,  1 Jun 2017 13:35:59 +0530, Santosh Shukla <santosh.shukla at 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 at 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.

IMO: We should let application to decide on pool preference. Driver
only to advice his preferred or supported pool handle to application,
and its upto application to decide on pool selection scheme. 

> 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
>
Driver to advice his preferred pool to application. That's why out.

Thanks.

>
>> + * @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;