[dpdk-dev] [PATCH v2 2/2] ethdev: allow pmd to advertise pool handle

[Santosh Shukla]

Now that dpdk supports more than one mempool drivers and
each mempool driver works best for specific PMD, example:
- sw ring based mempool for Intel PMD drivers
- dpaa2 HW mempool manager for dpaa2 PMD driver.
- fpa HW mempool manager for Octeontx PMD driver.

Application like to know `preferred mempool vs PMD driver`
information in advance before port setup.

Introducing rte_eth_dev_get_preferred_pool_ops() API,
which allows PMD driver to advertise their pool capability to application.

Application side programing sequence would be:

char pref_mempool[RTE_MEMPOOL_OPS_NAMESIZE];
rte_eth_dev_get_preferred_pool_ops(ethdev_port_id, pref_mempoolx /*out*/);
rte_mempool_create_empty();
rte_mempool_set_ops_byname( , pref_memppol, );
rte_mempool_populate_default();

Signed-off-by: Santosh Shukla <santosh.shukla at caviumnetworks.com>
---
v1 --> v2:
- Renamed _get_preferred_pool to _get_preferred_pool_ops().
Per v1 review feedback, Olivier suggested to rename api
to rte_eth_dev_pool_ops_supported(), considering that 2nd param
for that api will return pool handle 'priority' for that port.
However, per v1 [1], we're opting for approach 1) where
ethdev API returns _preferred_ pool handle to application and Its upto
application to decide on policy - whether application wants to create
pool with received preferred pool handle or not. For more discussion details
on this topic refer [1].

[1] http://dpdk.org/dev/patchwork/patch/24944/

- Removed const qualifier from _get_preferred_pool_ops() param.
- Updated API description and changes return val from -EINVAL to _ENOTSUP
	(suggested by Olivier)

 lib/librte_ether/rte_ethdev.c          | 18 ++++++++++++++++++
 lib/librte_ether/rte_ethdev.h          | 21 +++++++++++++++++++++
 lib/librte_ether/rte_ether_version.map |  1 +
 3 files changed, 40 insertions(+)

diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
index a1b744704..3ac87f617 100644
--- a/lib/librte_ether/rte_ethdev.c
+++ b/lib/librte_ether/rte_ethdev.c
@@ -3415,3 +3415,21 @@ rte_eth_dev_adjust_nb_rx_tx_desc(uint8_t port_id,
 
 	return 0;
 }
+
+int
+rte_eth_dev_get_preferred_pool_ops(uint8_t port_id, char *pool)
+{
+	struct rte_eth_dev *dev;
+	const char *tmp;
+
+	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
+
+	dev = &rte_eth_devices[port_id];
+
+	if (*dev->dev_ops->get_preferred_pool_ops == NULL) {
+		tmp = rte_eal_mbuf_default_mempool_ops();
+		snprintf(pool, RTE_MBUF_POOL_OPS_NAMESIZE, "%s", tmp);
+		return 0;
+	}
+	return (*dev->dev_ops->get_preferred_pool_ops)(dev, pool);
+}
diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
index 55fda9583..d27e34e2e 100644
--- a/lib/librte_ether/rte_ethdev.h
+++ b/lib/librte_ether/rte_ethdev.h
@@ -1425,6 +1425,10 @@ typedef int (*eth_get_dcb_info)(struct rte_eth_dev *dev,
 				 struct rte_eth_dcb_info *dcb_info);
 /**< @internal Get dcb information on an Ethernet device */
 
+typedef int (*eth_get_preferred_pool_ops_t)(struct rte_eth_dev *dev,
+						char *pool);
+/**< @internal Get preferred pool handle for port */
+
 /**
  * @internal A structure containing the functions exported by an Ethernet driver.
  */
@@ -1544,6 +1548,8 @@ struct eth_dev_ops {
 
 	eth_tm_ops_get_t tm_ops_get;
 	/**< Get Traffic Management (TM) operations. */
+	eth_get_preferred_pool_ops_t get_preferred_pool_ops;
+	/**< Get preferred pool handle for port */
 };
 
 /**
@@ -4435,6 +4441,21 @@ int rte_eth_dev_adjust_nb_rx_tx_desc(uint8_t port_id,
 				     uint16_t *nb_rx_desc,
 				     uint16_t *nb_tx_desc);
 
+/**
+ * Get preferred pool handle for port
+ *
+ * @param port_id
+ *   port identifier of the device
+ * @param [out] pool
+ *   Preferred pool handle for this port.
+ *   Maximum length of preferred pool handle is RTE_MBUF_POOL_OPS_NAMESIZE.
+ * @return
+ *   - (0) if successful.
+ *   - (-ENOTSUP, -ENODEV or -EINVAL) on failure.
+ */
+int
+rte_eth_dev_get_preferred_pool_ops(uint8_t port_id, char *pool);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/librte_ether/rte_ether_version.map b/lib/librte_ether/rte_ether_version.map
index 42837285e..ac35da6f8 100644
--- a/lib/librte_ether/rte_ether_version.map
+++ b/lib/librte_ether/rte_ether_version.map
@@ -185,5 +185,6 @@ DPDK_17.08 {
 	rte_tm_shared_wred_context_delete;
 	rte_tm_wred_profile_add;
 	rte_tm_wred_profile_delete;
+	rte_eth_dev_get_preferred_pool_ops;
 
 } DPDK_17.05;
-- 
2.11.0