[dpdk-dev,v2,1/6] ethdev: add descriptor status API

Message ID 1488902393-7237-2-git-send-email-olivier.matz@6wind.com (mailing list archive)
State Superseded, archived
Headers

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK

Commit Message

Olivier Matz March 7, 2017, 3:59 p.m. UTC
  Introduce a new API to get the status of a descriptor.

For Rx, it is almost similar to rx_descriptor_done API, except it
differentiates "used" descriptors (which are hold by the driver and not
returned to the hardware).

For Tx, it is a new API.

The descriptor_done() API, and probably the rx_queue_count() API could
be replaced by this new API as soon as it is implemented on all PMDs.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 doc/guides/nics/features/default.ini |   2 +
 lib/librte_ether/rte_ethdev.h        | 125 +++++++++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+)
  

Comments

Andrew Rybchenko March 9, 2017, 11:49 a.m. UTC | #1
On 03/07/2017 06:59 PM, Olivier Matz wrote:
> Introduce a new API to get the status of a descriptor.
>
> For Rx, it is almost similar to rx_descriptor_done API, except it
> differentiates "used" descriptors (which are hold by the driver and not
> returned to the hardware).
>
> For Tx, it is a new API.
>
> The descriptor_done() API, and probably the rx_queue_count() API could
> be replaced by this new API as soon as it is implemented on all PMDs.
>
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>   doc/guides/nics/features/default.ini |   2 +
>   lib/librte_ether/rte_ethdev.h        | 125 +++++++++++++++++++++++++++++++++++
>   2 files changed, 127 insertions(+)
>
> diff --git a/doc/guides/nics/features/default.ini b/doc/guides/nics/features/default.ini
> index 9e363ff..0e6a78d 100644
> --- a/doc/guides/nics/features/default.ini
> +++ b/doc/guides/nics/features/default.ini
> @@ -49,6 +49,8 @@ Inner L3 checksum    =
>   Inner L4 checksum    =
>   Packet type parsing  =
>   Timesync             =
> +Rx Descriptor Status =
> +Tx Descriptor Status =
>   Basic stats          =
>   Extended stats       =
>   Stats per queue      =
> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index 97f3e2d..904ecbe 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -1179,6 +1179,12 @@ typedef uint32_t (*eth_rx_queue_count_t)(struct rte_eth_dev *dev,
>   typedef int (*eth_rx_descriptor_done_t)(void *rxq, uint16_t offset);
>   /**< @internal Check DD bit of specific RX descriptor */
>   
> +typedef int (*eth_rx_descriptor_status_t)(void *rxq, uint16_t offset);
> +/**< @internal Check the status of a Rx descriptor */
> +
> +typedef int (*eth_tx_descriptor_status_t)(void *txq, uint16_t offset);
> +/**< @internal Check the status of a Tx descriptor */
> +
>   typedef int (*eth_fw_version_get_t)(struct rte_eth_dev *dev,
>   				     char *fw_version, size_t fw_size);
>   /**< @internal Get firmware information of an Ethernet device. */
> @@ -1483,6 +1489,10 @@ struct eth_dev_ops {
>   	eth_queue_release_t        rx_queue_release; /**< Release RX queue. */
>   	eth_rx_queue_count_t       rx_queue_count;/**< Get Rx queue count. */
>   	eth_rx_descriptor_done_t   rx_descriptor_done; /**< Check rxd DD bit. */
> +	eth_rx_descriptor_status_t rx_descriptor_status;
> +	/**< Check the status of a Rx descriptor. */
> +	eth_tx_descriptor_status_t tx_descriptor_status;
> +	/**< Check the status of a Tx descriptor. */
>   	eth_rx_enable_intr_t       rx_queue_intr_enable;  /**< Enable Rx queue interrupt. */
>   	eth_rx_disable_intr_t      rx_queue_intr_disable; /**< Disable Rx queue interrupt. */
>   	eth_tx_queue_setup_t       tx_queue_setup;/**< Set up device TX queue. */
> @@ -2768,6 +2778,121 @@ rte_eth_rx_descriptor_done(uint8_t port_id, uint16_t queue_id, uint16_t offset)
>   		dev->data->rx_queues[queue_id], offset);
>   }
>   
> +#define RTE_ETH_RX_DESC_AVAIL    0 /**< Desc available for hw. */
> +#define RTE_ETH_RX_DESC_DONE     1 /**< Desc done, filled by hw. */
> +#define RTE_ETH_RX_DESC_UNAVAIL  2 /**< Desc used by driver or hw. */
> +
> +/**
> + * Check the status of a Rx descriptor in the queue
> + *
> + * It should be called in a similar context than the Rx function:
> + * - on a dataplane core
> + * - not concurrently on the same queue
> + *
> + * Since it's a dataplane function, no check is performed on port_id and
> + * queue_id. The caller must therefore ensure that the port is enabled
> + * and the queue is configured and running.
> + *
> + * Note: accessing to a random descriptor in the ring may trigger cache
> + * misses and have a performance impact.
> + *
> + * @param port_id
> + *  A valid port identifier of the Ethernet device which.
> + * @param queue_id
> + *  A valid Rx queue identifier on this port.
> + * @param offset
> + *  The offset of the descriptor starting from tail (0 is the next
> + *  packet to be received by the driver).
> + *
> + * @return
> + *  - (RTE_ETH_RX_DESC_AVAIL): Descriptor is available for the hardware to
> + *    receive a packet.
> + *  - (RTE_ETH_RX_DESC_DONE): Descriptor is done, it is filled by hw, but
> + *    not yet processed by the driver (i.e. in the receive queue).
> + *  - (RTE_ETH_RX_DESC_UNAVAIL): Descriptor is unavailable, either hold by
> + *    the driver and not yet returned to hw, or reserved by the hw.
> + *  - (-EINVAL) bad descriptor offset.
> + *  - (-ENOTSUP) if the device does not support this function.
> + *  - (-ENODEV) bad port or queue (only if compiled with debug).
> + */
> +static inline int
> +rte_eth_rx_descriptor_status(uint8_t port_id, uint16_t queue_id,
> +	uint16_t offset)
> +{
> +	struct rte_eth_dev *dev;
> +	void *rxq;
> +
> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +#endif
> +	dev = &rte_eth_devices[port_id];
> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> +	if (queue_id >= dev->data->nb_rx_queues)
> +		return -ENODEV;
> +#endif
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_descriptor_status, -ENOTSUP);
> +	rxq = dev->data->rx_queues[queue_id];
> +
> +	return (*dev->dev_ops->rx_descriptor_status)(rxq, offset);
> +}
> +
> +#define RTE_ETH_TX_DESC_FULL    0 /**< Desc filled for hw, waiting xmit. */
> +#define RTE_ETH_TX_DESC_DONE    1 /**< Desc done, packet is transmitted. */
> +#define RTE_ETH_TX_DESC_UNAVAIL 2 /**< Desc used by driver or hw. */
> +
> +/**
> + * Check the status of a Tx descriptor in the queue.
> + *
> + * It should be called in a similar context than the Tx function:
> + * - on a dataplane core
> + * - not concurrently on the same queue
> + *
> + * Since it's a dataplane function, no check is performed on port_id and
> + * queue_id. The caller must therefore ensure that the port is enabled
> + * and the queue is configured and running.
> + *
> + * Note: accessing to a random descriptor in the ring may trigger cache
> + * misses and have a performance impact.
> + *
> + * @param port_id
> + *  A valid port identifier of the Ethernet device which.
> + * @param queue_id
> + *  A valid Tx queue identifier on this port.
> + * @param offset
> + *  The offset of the descriptor starting from tail (0 is the place where
> + *  the next packet will be send).
> + *
> + * @return
> + *  - (RTE_ETH_TX_DESC_FULL) Descriptor is being processed by the hw, i.e.
> + *    in the transmit queue.
> + *  - (RTE_ETH_TX_DESC_DONE) Hardware is done with this descriptor, it can
> + *    be reused by the driver.
> + *  - (RTE_ETH_TX_DESC_UNAVAIL): Descriptor is unavailable, reserved by the
> + *    driver or the hardware.
> + *  - (-EINVAL) bad descriptor offset.
> + *  - (-ENOTSUP) if the device does not support this function.
> + *  - (-ENODEV) bad port or queue (only if compiled with debug).
> + */
> +static inline int rte_eth_tx_descriptor_status(uint8_t port_id,
> +	uint16_t queue_id, uint16_t offset)
> +{
> +	struct rte_eth_dev *dev;
> +	void *txq;
> +
> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +#endif
> +	dev = &rte_eth_devices[port_id];
> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> +	if (queue_id >= dev->data->nb_tx_queues)
> +		return -ENODEV;
> +#endif
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->tx_descriptor_status, -ENOTSUP);
> +	txq = dev->data->tx_queues[queue_id];
> +
> +	return (*dev->dev_ops->tx_descriptor_status)(txq, offset);
> +}
> +
>   /**
>    * Send a burst of output packets on a transmit queue of an Ethernet device.
>    *

Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>
  
Qiming Yang March 21, 2017, 8:32 a.m. UTC | #2
Hi, Olivier
You need to add your new API in lib/librte_ether/rte_ether_version.map and doc/guides/rel_notes/release_17_05.rst

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier Matz
> Sent: Wednesday, March 8, 2017 12:00 AM
> To: dev@dpdk.org; thomas.monjalon@6wind.com; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>;
> Zhang, Helin <helin.zhang@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>;
> adrien.mazarguil@6wind.com; nelio.laranjeiro@6wind.com
> Cc: Yigit, Ferruh <ferruh.yigit@intel.com>; Richardson, Bruce
> <bruce.richardson@intel.com>; Venkatesan, Venky
> <venky.venkatesan@intel.com>; arybchenko@solarflare.com
> Subject: [dpdk-dev] [PATCH v2 1/6] ethdev: add descriptor status API
> 
> Introduce a new API to get the status of a descriptor.
> 
> For Rx, it is almost similar to rx_descriptor_done API, except it differentiates
> "used" descriptors (which are hold by the driver and not returned to the
> hardware).
> 
> For Tx, it is a new API.
> 
> The descriptor_done() API, and probably the rx_queue_count() API could be
> replaced by this new API as soon as it is implemented on all PMDs.
> 
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>  doc/guides/nics/features/default.ini |   2 +
>  lib/librte_ether/rte_ethdev.h        | 125
> +++++++++++++++++++++++++++++++++++
>  2 files changed, 127 insertions(+)
> 
> diff --git a/doc/guides/nics/features/default.ini
> b/doc/guides/nics/features/default.ini
> index 9e363ff..0e6a78d 100644
> --- a/doc/guides/nics/features/default.ini
> +++ b/doc/guides/nics/features/default.ini
> @@ -49,6 +49,8 @@ Inner L3 checksum    =
>  Inner L4 checksum    =
>  Packet type parsing  =
>  Timesync             =
> +Rx Descriptor Status =
> +Tx Descriptor Status =
>  Basic stats          =
>  Extended stats       =
>  Stats per queue      =
> diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> index 97f3e2d..904ecbe 100644
> --- a/lib/librte_ether/rte_ethdev.h
> +++ b/lib/librte_ether/rte_ethdev.h
> @@ -1179,6 +1179,12 @@ typedef uint32_t
> (*eth_rx_queue_count_t)(struct rte_eth_dev *dev,  typedef int
> (*eth_rx_descriptor_done_t)(void *rxq, uint16_t offset);  /**< @internal
> Check DD bit of specific RX descriptor */
> 
> +typedef int (*eth_rx_descriptor_status_t)(void *rxq, uint16_t offset);
> +/**< @internal Check the status of a Rx descriptor */
> +
> +typedef int (*eth_tx_descriptor_status_t)(void *txq, uint16_t offset);
> +/**< @internal Check the status of a Tx descriptor */
> +
>  typedef int (*eth_fw_version_get_t)(struct rte_eth_dev *dev,
>  				     char *fw_version, size_t fw_size);  /**<
> @internal Get firmware information of an Ethernet device. */ @@ -1483,6
> +1489,10 @@ struct eth_dev_ops {
>  	eth_queue_release_t        rx_queue_release; /**< Release RX queue.
> */
>  	eth_rx_queue_count_t       rx_queue_count;/**< Get Rx queue
> count. */
>  	eth_rx_descriptor_done_t   rx_descriptor_done; /**< Check rxd DD
> bit. */
> +	eth_rx_descriptor_status_t rx_descriptor_status;
> +	/**< Check the status of a Rx descriptor. */
> +	eth_tx_descriptor_status_t tx_descriptor_status;
> +	/**< Check the status of a Tx descriptor. */
>  	eth_rx_enable_intr_t       rx_queue_intr_enable;  /**< Enable Rx
> queue interrupt. */
>  	eth_rx_disable_intr_t      rx_queue_intr_disable; /**< Disable Rx
> queue interrupt. */
>  	eth_tx_queue_setup_t       tx_queue_setup;/**< Set up device TX
> queue. */
> @@ -2768,6 +2778,121 @@ rte_eth_rx_descriptor_done(uint8_t port_id,
> uint16_t queue_id, uint16_t offset)
>  		dev->data->rx_queues[queue_id], offset);  }
> 
> +#define RTE_ETH_RX_DESC_AVAIL    0 /**< Desc available for hw. */
> +#define RTE_ETH_RX_DESC_DONE     1 /**< Desc done, filled by hw. */
> +#define RTE_ETH_RX_DESC_UNAVAIL  2 /**< Desc used by driver or hw. */
> +
> +/**
> + * Check the status of a Rx descriptor in the queue
> + *
> + * It should be called in a similar context than the Rx function:
> + * - on a dataplane core
> + * - not concurrently on the same queue
> + *
> + * Since it's a dataplane function, no check is performed on port_id
> +and
> + * queue_id. The caller must therefore ensure that the port is enabled
> + * and the queue is configured and running.
> + *
> + * Note: accessing to a random descriptor in the ring may trigger cache
> + * misses and have a performance impact.
> + *
> + * @param port_id
> + *  A valid port identifier of the Ethernet device which.
> + * @param queue_id
> + *  A valid Rx queue identifier on this port.
> + * @param offset
> + *  The offset of the descriptor starting from tail (0 is the next
> + *  packet to be received by the driver).
> + *
> + * @return
> + *  - (RTE_ETH_RX_DESC_AVAIL): Descriptor is available for the hardware to
> + *    receive a packet.
> + *  - (RTE_ETH_RX_DESC_DONE): Descriptor is done, it is filled by hw, but
> + *    not yet processed by the driver (i.e. in the receive queue).
> + *  - (RTE_ETH_RX_DESC_UNAVAIL): Descriptor is unavailable, either hold by
> + *    the driver and not yet returned to hw, or reserved by the hw.
> + *  - (-EINVAL) bad descriptor offset.
> + *  - (-ENOTSUP) if the device does not support this function.
> + *  - (-ENODEV) bad port or queue (only if compiled with debug).
> + */
> +static inline int
> +rte_eth_rx_descriptor_status(uint8_t port_id, uint16_t queue_id,
> +	uint16_t offset)
> +{
> +	struct rte_eth_dev *dev;
> +	void *rxq;
> +
> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV); #endif
> +	dev = &rte_eth_devices[port_id];
> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> +	if (queue_id >= dev->data->nb_rx_queues)
> +		return -ENODEV;
> +#endif
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops-
> >rx_descriptor_status, -ENOTSUP);
> +	rxq = dev->data->rx_queues[queue_id];
> +
> +	return (*dev->dev_ops->rx_descriptor_status)(rxq, offset); }
> +
> +#define RTE_ETH_TX_DESC_FULL    0 /**< Desc filled for hw, waiting xmit.
> */
> +#define RTE_ETH_TX_DESC_DONE    1 /**< Desc done, packet is
> transmitted. */
> +#define RTE_ETH_TX_DESC_UNAVAIL 2 /**< Desc used by driver or hw. */
> +
> +/**
> + * Check the status of a Tx descriptor in the queue.
> + *
> + * It should be called in a similar context than the Tx function:
> + * - on a dataplane core
> + * - not concurrently on the same queue
> + *
> + * Since it's a dataplane function, no check is performed on port_id
> +and
> + * queue_id. The caller must therefore ensure that the port is enabled
> + * and the queue is configured and running.
> + *
> + * Note: accessing to a random descriptor in the ring may trigger cache
> + * misses and have a performance impact.
> + *
> + * @param port_id
> + *  A valid port identifier of the Ethernet device which.
> + * @param queue_id
> + *  A valid Tx queue identifier on this port.
> + * @param offset
> + *  The offset of the descriptor starting from tail (0 is the place
> +where
> + *  the next packet will be send).
> + *
> + * @return
> + *  - (RTE_ETH_TX_DESC_FULL) Descriptor is being processed by the hw, i.e.
> + *    in the transmit queue.
> + *  - (RTE_ETH_TX_DESC_DONE) Hardware is done with this descriptor, it
> can
> + *    be reused by the driver.
> + *  - (RTE_ETH_TX_DESC_UNAVAIL): Descriptor is unavailable, reserved by
> the
> + *    driver or the hardware.
> + *  - (-EINVAL) bad descriptor offset.
> + *  - (-ENOTSUP) if the device does not support this function.
> + *  - (-ENODEV) bad port or queue (only if compiled with debug).
> + */
> +static inline int rte_eth_tx_descriptor_status(uint8_t port_id,
> +	uint16_t queue_id, uint16_t offset)
> +{
> +	struct rte_eth_dev *dev;
> +	void *txq;
> +
> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV); #endif
> +	dev = &rte_eth_devices[port_id];
> +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> +	if (queue_id >= dev->data->nb_tx_queues)
> +		return -ENODEV;
> +#endif
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops-
> >tx_descriptor_status, -ENOTSUP);
> +	txq = dev->data->tx_queues[queue_id];
> +
> +	return (*dev->dev_ops->tx_descriptor_status)(txq, offset); }
> +
>  /**
>   * Send a burst of output packets on a transmit queue of an Ethernet device.
>   *
> --
> 2.8.1
  
Olivier Matz March 24, 2017, 12:49 p.m. UTC | #3
Hi Qiming,

On Tue, 21 Mar 2017 08:32:17 +0000, "Yang, Qiming" <qiming.yang@intel.com> wrote:
> Hi, Olivier
> You need to add your new API in lib/librte_ether/rte_ether_version.map and doc/guides/rel_notes/release_17_05.rst

About rte_ether_version.map, I don't think it's needed since
the functions are static inline. Did you noticed any issue?

About release_17_05.rst, you are right, I can add some words about
this new feature.


Thanks,
Olivier


> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier Matz
> > Sent: Wednesday, March 8, 2017 12:00 AM
> > To: dev@dpdk.org; thomas.monjalon@6wind.com; Ananyev, Konstantin
> > <konstantin.ananyev@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>;
> > Zhang, Helin <helin.zhang@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>;
> > adrien.mazarguil@6wind.com; nelio.laranjeiro@6wind.com
> > Cc: Yigit, Ferruh <ferruh.yigit@intel.com>; Richardson, Bruce
> > <bruce.richardson@intel.com>; Venkatesan, Venky
> > <venky.venkatesan@intel.com>; arybchenko@solarflare.com
> > Subject: [dpdk-dev] [PATCH v2 1/6] ethdev: add descriptor status API
> > 
> > Introduce a new API to get the status of a descriptor.
> > 
> > For Rx, it is almost similar to rx_descriptor_done API, except it differentiates
> > "used" descriptors (which are hold by the driver and not returned to the
> > hardware).
> > 
> > For Tx, it is a new API.
> > 
> > The descriptor_done() API, and probably the rx_queue_count() API could be
> > replaced by this new API as soon as it is implemented on all PMDs.
> > 
> > Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> > ---
> >  doc/guides/nics/features/default.ini |   2 +
> >  lib/librte_ether/rte_ethdev.h        | 125
> > +++++++++++++++++++++++++++++++++++
> >  2 files changed, 127 insertions(+)
> > 
> > diff --git a/doc/guides/nics/features/default.ini
> > b/doc/guides/nics/features/default.ini
> > index 9e363ff..0e6a78d 100644
> > --- a/doc/guides/nics/features/default.ini
> > +++ b/doc/guides/nics/features/default.ini
> > @@ -49,6 +49,8 @@ Inner L3 checksum    =
> >  Inner L4 checksum    =
> >  Packet type parsing  =
> >  Timesync             =
> > +Rx Descriptor Status =
> > +Tx Descriptor Status =
> >  Basic stats          =
> >  Extended stats       =
> >  Stats per queue      =
> > diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
> > index 97f3e2d..904ecbe 100644
> > --- a/lib/librte_ether/rte_ethdev.h
> > +++ b/lib/librte_ether/rte_ethdev.h
> > @@ -1179,6 +1179,12 @@ typedef uint32_t
> > (*eth_rx_queue_count_t)(struct rte_eth_dev *dev,  typedef int
> > (*eth_rx_descriptor_done_t)(void *rxq, uint16_t offset);  /**< @internal
> > Check DD bit of specific RX descriptor */
> > 
> > +typedef int (*eth_rx_descriptor_status_t)(void *rxq, uint16_t offset);
> > +/**< @internal Check the status of a Rx descriptor */
> > +
> > +typedef int (*eth_tx_descriptor_status_t)(void *txq, uint16_t offset);
> > +/**< @internal Check the status of a Tx descriptor */
> > +
> >  typedef int (*eth_fw_version_get_t)(struct rte_eth_dev *dev,
> >  				     char *fw_version, size_t fw_size);  /**<
> > @internal Get firmware information of an Ethernet device. */ @@ -1483,6
> > +1489,10 @@ struct eth_dev_ops {
> >  	eth_queue_release_t        rx_queue_release; /**< Release RX queue.
> > */
> >  	eth_rx_queue_count_t       rx_queue_count;/**< Get Rx queue
> > count. */
> >  	eth_rx_descriptor_done_t   rx_descriptor_done; /**< Check rxd DD
> > bit. */
> > +	eth_rx_descriptor_status_t rx_descriptor_status;
> > +	/**< Check the status of a Rx descriptor. */
> > +	eth_tx_descriptor_status_t tx_descriptor_status;
> > +	/**< Check the status of a Tx descriptor. */
> >  	eth_rx_enable_intr_t       rx_queue_intr_enable;  /**< Enable Rx
> > queue interrupt. */
> >  	eth_rx_disable_intr_t      rx_queue_intr_disable; /**< Disable Rx
> > queue interrupt. */
> >  	eth_tx_queue_setup_t       tx_queue_setup;/**< Set up device TX
> > queue. */
> > @@ -2768,6 +2778,121 @@ rte_eth_rx_descriptor_done(uint8_t port_id,
> > uint16_t queue_id, uint16_t offset)
> >  		dev->data->rx_queues[queue_id], offset);  }
> > 
> > +#define RTE_ETH_RX_DESC_AVAIL    0 /**< Desc available for hw. */
> > +#define RTE_ETH_RX_DESC_DONE     1 /**< Desc done, filled by hw. */
> > +#define RTE_ETH_RX_DESC_UNAVAIL  2 /**< Desc used by driver or hw. */
> > +
> > +/**
> > + * Check the status of a Rx descriptor in the queue
> > + *
> > + * It should be called in a similar context than the Rx function:
> > + * - on a dataplane core
> > + * - not concurrently on the same queue
> > + *
> > + * Since it's a dataplane function, no check is performed on port_id
> > +and
> > + * queue_id. The caller must therefore ensure that the port is enabled
> > + * and the queue is configured and running.
> > + *
> > + * Note: accessing to a random descriptor in the ring may trigger cache
> > + * misses and have a performance impact.
> > + *
> > + * @param port_id
> > + *  A valid port identifier of the Ethernet device which.
> > + * @param queue_id
> > + *  A valid Rx queue identifier on this port.
> > + * @param offset
> > + *  The offset of the descriptor starting from tail (0 is the next
> > + *  packet to be received by the driver).
> > + *
> > + * @return
> > + *  - (RTE_ETH_RX_DESC_AVAIL): Descriptor is available for the hardware to
> > + *    receive a packet.
> > + *  - (RTE_ETH_RX_DESC_DONE): Descriptor is done, it is filled by hw, but
> > + *    not yet processed by the driver (i.e. in the receive queue).
> > + *  - (RTE_ETH_RX_DESC_UNAVAIL): Descriptor is unavailable, either hold by
> > + *    the driver and not yet returned to hw, or reserved by the hw.
> > + *  - (-EINVAL) bad descriptor offset.
> > + *  - (-ENOTSUP) if the device does not support this function.
> > + *  - (-ENODEV) bad port or queue (only if compiled with debug).
> > + */
> > +static inline int
> > +rte_eth_rx_descriptor_status(uint8_t port_id, uint16_t queue_id,
> > +	uint16_t offset)
> > +{
> > +	struct rte_eth_dev *dev;
> > +	void *rxq;
> > +
> > +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV); #endif
> > +	dev = &rte_eth_devices[port_id];
> > +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > +	if (queue_id >= dev->data->nb_rx_queues)
> > +		return -ENODEV;
> > +#endif
> > +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops-  
> > >rx_descriptor_status, -ENOTSUP);  
> > +	rxq = dev->data->rx_queues[queue_id];
> > +
> > +	return (*dev->dev_ops->rx_descriptor_status)(rxq, offset); }
> > +
> > +#define RTE_ETH_TX_DESC_FULL    0 /**< Desc filled for hw, waiting xmit.
> > */
> > +#define RTE_ETH_TX_DESC_DONE    1 /**< Desc done, packet is
> > transmitted. */
> > +#define RTE_ETH_TX_DESC_UNAVAIL 2 /**< Desc used by driver or hw. */
> > +
> > +/**
> > + * Check the status of a Tx descriptor in the queue.
> > + *
> > + * It should be called in a similar context than the Tx function:
> > + * - on a dataplane core
> > + * - not concurrently on the same queue
> > + *
> > + * Since it's a dataplane function, no check is performed on port_id
> > +and
> > + * queue_id. The caller must therefore ensure that the port is enabled
> > + * and the queue is configured and running.
> > + *
> > + * Note: accessing to a random descriptor in the ring may trigger cache
> > + * misses and have a performance impact.
> > + *
> > + * @param port_id
> > + *  A valid port identifier of the Ethernet device which.
> > + * @param queue_id
> > + *  A valid Tx queue identifier on this port.
> > + * @param offset
> > + *  The offset of the descriptor starting from tail (0 is the place
> > +where
> > + *  the next packet will be send).
> > + *
> > + * @return
> > + *  - (RTE_ETH_TX_DESC_FULL) Descriptor is being processed by the hw, i.e.
> > + *    in the transmit queue.
> > + *  - (RTE_ETH_TX_DESC_DONE) Hardware is done with this descriptor, it
> > can
> > + *    be reused by the driver.
> > + *  - (RTE_ETH_TX_DESC_UNAVAIL): Descriptor is unavailable, reserved by
> > the
> > + *    driver or the hardware.
> > + *  - (-EINVAL) bad descriptor offset.
> > + *  - (-ENOTSUP) if the device does not support this function.
> > + *  - (-ENODEV) bad port or queue (only if compiled with debug).
> > + */
> > +static inline int rte_eth_tx_descriptor_status(uint8_t port_id,
> > +	uint16_t queue_id, uint16_t offset)
> > +{
> > +	struct rte_eth_dev *dev;
> > +	void *txq;
> > +
> > +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV); #endif
> > +	dev = &rte_eth_devices[port_id];
> > +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > +	if (queue_id >= dev->data->nb_tx_queues)
> > +		return -ENODEV;
> > +#endif
> > +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops-  
> > >tx_descriptor_status, -ENOTSUP);  
> > +	txq = dev->data->tx_queues[queue_id];
> > +
> > +	return (*dev->dev_ops->tx_descriptor_status)(txq, offset); }
> > +
> >  /**
> >   * Send a burst of output packets on a transmit queue of an Ethernet device.
> >   *
> > --
> > 2.8.1  
>
  
Qiming Yang March 27, 2017, 1:28 a.m. UTC | #4
Hi, Olivier

> -----Original Message-----
> From: Olivier Matz [mailto:olivier.matz@6wind.com]
> Sent: Friday, March 24, 2017 8:49 PM
> To: Yang, Qiming <qiming.yang@intel.com>
> Cc: dev@dpdk.org; thomas.monjalon@6wind.com; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>;
> Zhang, Helin <helin.zhang@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>;
> adrien.mazarguil@6wind.com; nelio.laranjeiro@6wind.com; Yigit, Ferruh
> <ferruh.yigit@intel.com>; Richardson, Bruce <bruce.richardson@intel.com>;
> Venkatesan, Venky <venky.venkatesan@intel.com>;
> arybchenko@solarflare.com
> Subject: Re: [dpdk-dev] [PATCH v2 1/6] ethdev: add descriptor status API
> 
> Hi Qiming,
> 
> On Tue, 21 Mar 2017 08:32:17 +0000, "Yang, Qiming" <qiming.yang@intel.com>
> wrote:
> > Hi, Olivier
> > You need to add your new API in lib/librte_ether/rte_ether_version.map
> > and doc/guides/rel_notes/release_17_05.rst
> 
> About rte_ether_version.map, I don't think it's needed since the functions
> are static inline. Did you noticed any issue?
> 
That's OK, I didn't notice that the functions are static inline, sorry.

> About release_17_05.rst, you are right, I can add some words about this new
> feature.
> 
> 
> Thanks,
> Olivier
> 
> 
> >
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Olivier Matz
> > > Sent: Wednesday, March 8, 2017 12:00 AM
> > > To: dev@dpdk.org; thomas.monjalon@6wind.com; Ananyev, Konstantin
> > > <konstantin.ananyev@intel.com>; Lu, Wenzhuo
> <wenzhuo.lu@intel.com>;
> > > Zhang, Helin <helin.zhang@intel.com>; Wu, Jingjing
> > > <jingjing.wu@intel.com>; adrien.mazarguil@6wind.com;
> > > nelio.laranjeiro@6wind.com
> > > Cc: Yigit, Ferruh <ferruh.yigit@intel.com>; Richardson, Bruce
> > > <bruce.richardson@intel.com>; Venkatesan, Venky
> > > <venky.venkatesan@intel.com>; arybchenko@solarflare.com
> > > Subject: [dpdk-dev] [PATCH v2 1/6] ethdev: add descriptor status API
> > >
> > > Introduce a new API to get the status of a descriptor.
> > >
> > > For Rx, it is almost similar to rx_descriptor_done API, except it
> > > differentiates "used" descriptors (which are hold by the driver and
> > > not returned to the hardware).
> > >
> > > For Tx, it is a new API.
> > >
> > > The descriptor_done() API, and probably the rx_queue_count() API
> > > could be replaced by this new API as soon as it is implemented on all
> PMDs.
> > >
> > > Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> > > ---
> > >  doc/guides/nics/features/default.ini |   2 +
> > >  lib/librte_ether/rte_ethdev.h        | 125
> > > +++++++++++++++++++++++++++++++++++
> > >  2 files changed, 127 insertions(+)
> > >
> > > diff --git a/doc/guides/nics/features/default.ini
> > > b/doc/guides/nics/features/default.ini
> > > index 9e363ff..0e6a78d 100644
> > > --- a/doc/guides/nics/features/default.ini
> > > +++ b/doc/guides/nics/features/default.ini
> > > @@ -49,6 +49,8 @@ Inner L3 checksum    =
> > >  Inner L4 checksum    =
> > >  Packet type parsing  =
> > >  Timesync             =
> > > +Rx Descriptor Status =
> > > +Tx Descriptor Status =
> > >  Basic stats          =
> > >  Extended stats       =
> > >  Stats per queue      =
> > > diff --git a/lib/librte_ether/rte_ethdev.h
> > > b/lib/librte_ether/rte_ethdev.h index 97f3e2d..904ecbe 100644
> > > --- a/lib/librte_ether/rte_ethdev.h
> > > +++ b/lib/librte_ether/rte_ethdev.h
> > > @@ -1179,6 +1179,12 @@ typedef uint32_t
> > > (*eth_rx_queue_count_t)(struct rte_eth_dev *dev,  typedef int
> > > (*eth_rx_descriptor_done_t)(void *rxq, uint16_t offset);  /**<
> > > @internal Check DD bit of specific RX descriptor */
> > >
> > > +typedef int (*eth_rx_descriptor_status_t)(void *rxq, uint16_t
> > > +offset); /**< @internal Check the status of a Rx descriptor */
> > > +
> > > +typedef int (*eth_tx_descriptor_status_t)(void *txq, uint16_t
> > > +offset); /**< @internal Check the status of a Tx descriptor */
> > > +
> > >  typedef int (*eth_fw_version_get_t)(struct rte_eth_dev *dev,
> > >  				     char *fw_version, size_t fw_size);  /**<
> @internal Get
> > > firmware information of an Ethernet device. */ @@ -1483,6
> > > +1489,10 @@ struct eth_dev_ops {
> > >  	eth_queue_release_t        rx_queue_release; /**< Release RX queue.
> > > */
> > >  	eth_rx_queue_count_t       rx_queue_count;/**< Get Rx queue
> > > count. */
> > >  	eth_rx_descriptor_done_t   rx_descriptor_done; /**< Check rxd DD
> > > bit. */
> > > +	eth_rx_descriptor_status_t rx_descriptor_status;
> > > +	/**< Check the status of a Rx descriptor. */
> > > +	eth_tx_descriptor_status_t tx_descriptor_status;
> > > +	/**< Check the status of a Tx descriptor. */
> > >  	eth_rx_enable_intr_t       rx_queue_intr_enable;  /**< Enable Rx
> > > queue interrupt. */
> > >  	eth_rx_disable_intr_t      rx_queue_intr_disable; /**< Disable Rx
> > > queue interrupt. */
> > >  	eth_tx_queue_setup_t       tx_queue_setup;/**< Set up device TX
> > > queue. */
> > > @@ -2768,6 +2778,121 @@ rte_eth_rx_descriptor_done(uint8_t port_id,
> > > uint16_t queue_id, uint16_t offset)
> > >  		dev->data->rx_queues[queue_id], offset);  }
> > >
> > > +#define RTE_ETH_RX_DESC_AVAIL    0 /**< Desc available for hw. */
> > > +#define RTE_ETH_RX_DESC_DONE     1 /**< Desc done, filled by hw. */
> > > +#define RTE_ETH_RX_DESC_UNAVAIL  2 /**< Desc used by driver or hw.
> > > +*/
> > > +
> > > +/**
> > > + * Check the status of a Rx descriptor in the queue
> > > + *
> > > + * It should be called in a similar context than the Rx function:
> > > + * - on a dataplane core
> > > + * - not concurrently on the same queue
> > > + *
> > > + * Since it's a dataplane function, no check is performed on
> > > +port_id and
> > > + * queue_id. The caller must therefore ensure that the port is
> > > +enabled
> > > + * and the queue is configured and running.
> > > + *
> > > + * Note: accessing to a random descriptor in the ring may trigger
> > > +cache
> > > + * misses and have a performance impact.
> > > + *
> > > + * @param port_id
> > > + *  A valid port identifier of the Ethernet device which.
> > > + * @param queue_id
> > > + *  A valid Rx queue identifier on this port.
> > > + * @param offset
> > > + *  The offset of the descriptor starting from tail (0 is the next
> > > + *  packet to be received by the driver).
> > > + *
> > > + * @return
> > > + *  - (RTE_ETH_RX_DESC_AVAIL): Descriptor is available for the
> hardware to
> > > + *    receive a packet.
> > > + *  - (RTE_ETH_RX_DESC_DONE): Descriptor is done, it is filled by hw, but
> > > + *    not yet processed by the driver (i.e. in the receive queue).
> > > + *  - (RTE_ETH_RX_DESC_UNAVAIL): Descriptor is unavailable, either
> hold by
> > > + *    the driver and not yet returned to hw, or reserved by the hw.
> > > + *  - (-EINVAL) bad descriptor offset.
> > > + *  - (-ENOTSUP) if the device does not support this function.
> > > + *  - (-ENODEV) bad port or queue (only if compiled with debug).
> > > + */
> > > +static inline int
> > > +rte_eth_rx_descriptor_status(uint8_t port_id, uint16_t queue_id,
> > > +	uint16_t offset)
> > > +{
> > > +	struct rte_eth_dev *dev;
> > > +	void *rxq;
> > > +
> > > +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > > +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV); #endif
> > > +	dev = &rte_eth_devices[port_id];
> > > +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > > +	if (queue_id >= dev->data->nb_rx_queues)
> > > +		return -ENODEV;
> > > +#endif
> > > +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops-
> > > >rx_descriptor_status, -ENOTSUP);
> > > +	rxq = dev->data->rx_queues[queue_id];
> > > +
> > > +	return (*dev->dev_ops->rx_descriptor_status)(rxq, offset); }
> > > +
> > > +#define RTE_ETH_TX_DESC_FULL    0 /**< Desc filled for hw, waiting
> xmit.
> > > */
> > > +#define RTE_ETH_TX_DESC_DONE    1 /**< Desc done, packet is
> > > transmitted. */
> > > +#define RTE_ETH_TX_DESC_UNAVAIL 2 /**< Desc used by driver or hw.
> > > +*/
> > > +
> > > +/**
> > > + * Check the status of a Tx descriptor in the queue.
> > > + *
> > > + * It should be called in a similar context than the Tx function:
> > > + * - on a dataplane core
> > > + * - not concurrently on the same queue
> > > + *
> > > + * Since it's a dataplane function, no check is performed on
> > > +port_id and
> > > + * queue_id. The caller must therefore ensure that the port is
> > > +enabled
> > > + * and the queue is configured and running.
> > > + *
> > > + * Note: accessing to a random descriptor in the ring may trigger
> > > +cache
> > > + * misses and have a performance impact.
> > > + *
> > > + * @param port_id
> > > + *  A valid port identifier of the Ethernet device which.
> > > + * @param queue_id
> > > + *  A valid Tx queue identifier on this port.
> > > + * @param offset
> > > + *  The offset of the descriptor starting from tail (0 is the place
> > > +where
> > > + *  the next packet will be send).
> > > + *
> > > + * @return
> > > + *  - (RTE_ETH_TX_DESC_FULL) Descriptor is being processed by the hw,
> i.e.
> > > + *    in the transmit queue.
> > > + *  - (RTE_ETH_TX_DESC_DONE) Hardware is done with this descriptor,
> > > +it
> > > can
> > > + *    be reused by the driver.
> > > + *  - (RTE_ETH_TX_DESC_UNAVAIL): Descriptor is unavailable,
> > > + reserved by
> > > the
> > > + *    driver or the hardware.
> > > + *  - (-EINVAL) bad descriptor offset.
> > > + *  - (-ENOTSUP) if the device does not support this function.
> > > + *  - (-ENODEV) bad port or queue (only if compiled with debug).
> > > + */
> > > +static inline int rte_eth_tx_descriptor_status(uint8_t port_id,
> > > +	uint16_t queue_id, uint16_t offset) {
> > > +	struct rte_eth_dev *dev;
> > > +	void *txq;
> > > +
> > > +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > > +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV); #endif
> > > +	dev = &rte_eth_devices[port_id];
> > > +#ifdef RTE_LIBRTE_ETHDEV_DEBUG
> > > +	if (queue_id >= dev->data->nb_tx_queues)
> > > +		return -ENODEV;
> > > +#endif
> > > +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops-
> > > >tx_descriptor_status, -ENOTSUP);
> > > +	txq = dev->data->tx_queues[queue_id];
> > > +
> > > +	return (*dev->dev_ops->tx_descriptor_status)(txq, offset); }
> > > +
> > >  /**
> > >   * Send a burst of output packets on a transmit queue of an Ethernet
> device.
> > >   *
> > > --
> > > 2.8.1
> >
  

Patch

diff --git a/doc/guides/nics/features/default.ini b/doc/guides/nics/features/default.ini
index 9e363ff..0e6a78d 100644
--- a/doc/guides/nics/features/default.ini
+++ b/doc/guides/nics/features/default.ini
@@ -49,6 +49,8 @@  Inner L3 checksum    =
 Inner L4 checksum    =
 Packet type parsing  =
 Timesync             =
+Rx Descriptor Status =
+Tx Descriptor Status =
 Basic stats          =
 Extended stats       =
 Stats per queue      =
diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
index 97f3e2d..904ecbe 100644
--- a/lib/librte_ether/rte_ethdev.h
+++ b/lib/librte_ether/rte_ethdev.h
@@ -1179,6 +1179,12 @@  typedef uint32_t (*eth_rx_queue_count_t)(struct rte_eth_dev *dev,
 typedef int (*eth_rx_descriptor_done_t)(void *rxq, uint16_t offset);
 /**< @internal Check DD bit of specific RX descriptor */
 
+typedef int (*eth_rx_descriptor_status_t)(void *rxq, uint16_t offset);
+/**< @internal Check the status of a Rx descriptor */
+
+typedef int (*eth_tx_descriptor_status_t)(void *txq, uint16_t offset);
+/**< @internal Check the status of a Tx descriptor */
+
 typedef int (*eth_fw_version_get_t)(struct rte_eth_dev *dev,
 				     char *fw_version, size_t fw_size);
 /**< @internal Get firmware information of an Ethernet device. */
@@ -1483,6 +1489,10 @@  struct eth_dev_ops {
 	eth_queue_release_t        rx_queue_release; /**< Release RX queue. */
 	eth_rx_queue_count_t       rx_queue_count;/**< Get Rx queue count. */
 	eth_rx_descriptor_done_t   rx_descriptor_done; /**< Check rxd DD bit. */
+	eth_rx_descriptor_status_t rx_descriptor_status;
+	/**< Check the status of a Rx descriptor. */
+	eth_tx_descriptor_status_t tx_descriptor_status;
+	/**< Check the status of a Tx descriptor. */
 	eth_rx_enable_intr_t       rx_queue_intr_enable;  /**< Enable Rx queue interrupt. */
 	eth_rx_disable_intr_t      rx_queue_intr_disable; /**< Disable Rx queue interrupt. */
 	eth_tx_queue_setup_t       tx_queue_setup;/**< Set up device TX queue. */
@@ -2768,6 +2778,121 @@  rte_eth_rx_descriptor_done(uint8_t port_id, uint16_t queue_id, uint16_t offset)
 		dev->data->rx_queues[queue_id], offset);
 }
 
+#define RTE_ETH_RX_DESC_AVAIL    0 /**< Desc available for hw. */
+#define RTE_ETH_RX_DESC_DONE     1 /**< Desc done, filled by hw. */
+#define RTE_ETH_RX_DESC_UNAVAIL  2 /**< Desc used by driver or hw. */
+
+/**
+ * Check the status of a Rx descriptor in the queue
+ *
+ * It should be called in a similar context than the Rx function:
+ * - on a dataplane core
+ * - not concurrently on the same queue
+ *
+ * Since it's a dataplane function, no check is performed on port_id and
+ * queue_id. The caller must therefore ensure that the port is enabled
+ * and the queue is configured and running.
+ *
+ * Note: accessing to a random descriptor in the ring may trigger cache
+ * misses and have a performance impact.
+ *
+ * @param port_id
+ *  A valid port identifier of the Ethernet device which.
+ * @param queue_id
+ *  A valid Rx queue identifier on this port.
+ * @param offset
+ *  The offset of the descriptor starting from tail (0 is the next
+ *  packet to be received by the driver).
+ *
+ * @return
+ *  - (RTE_ETH_RX_DESC_AVAIL): Descriptor is available for the hardware to
+ *    receive a packet.
+ *  - (RTE_ETH_RX_DESC_DONE): Descriptor is done, it is filled by hw, but
+ *    not yet processed by the driver (i.e. in the receive queue).
+ *  - (RTE_ETH_RX_DESC_UNAVAIL): Descriptor is unavailable, either hold by
+ *    the driver and not yet returned to hw, or reserved by the hw.
+ *  - (-EINVAL) bad descriptor offset.
+ *  - (-ENOTSUP) if the device does not support this function.
+ *  - (-ENODEV) bad port or queue (only if compiled with debug).
+ */
+static inline int
+rte_eth_rx_descriptor_status(uint8_t port_id, uint16_t queue_id,
+	uint16_t offset)
+{
+	struct rte_eth_dev *dev;
+	void *rxq;
+
+#ifdef RTE_LIBRTE_ETHDEV_DEBUG
+	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
+#endif
+	dev = &rte_eth_devices[port_id];
+#ifdef RTE_LIBRTE_ETHDEV_DEBUG
+	if (queue_id >= dev->data->nb_rx_queues)
+		return -ENODEV;
+#endif
+	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rx_descriptor_status, -ENOTSUP);
+	rxq = dev->data->rx_queues[queue_id];
+
+	return (*dev->dev_ops->rx_descriptor_status)(rxq, offset);
+}
+
+#define RTE_ETH_TX_DESC_FULL    0 /**< Desc filled for hw, waiting xmit. */
+#define RTE_ETH_TX_DESC_DONE    1 /**< Desc done, packet is transmitted. */
+#define RTE_ETH_TX_DESC_UNAVAIL 2 /**< Desc used by driver or hw. */
+
+/**
+ * Check the status of a Tx descriptor in the queue.
+ *
+ * It should be called in a similar context than the Tx function:
+ * - on a dataplane core
+ * - not concurrently on the same queue
+ *
+ * Since it's a dataplane function, no check is performed on port_id and
+ * queue_id. The caller must therefore ensure that the port is enabled
+ * and the queue is configured and running.
+ *
+ * Note: accessing to a random descriptor in the ring may trigger cache
+ * misses and have a performance impact.
+ *
+ * @param port_id
+ *  A valid port identifier of the Ethernet device which.
+ * @param queue_id
+ *  A valid Tx queue identifier on this port.
+ * @param offset
+ *  The offset of the descriptor starting from tail (0 is the place where
+ *  the next packet will be send).
+ *
+ * @return
+ *  - (RTE_ETH_TX_DESC_FULL) Descriptor is being processed by the hw, i.e.
+ *    in the transmit queue.
+ *  - (RTE_ETH_TX_DESC_DONE) Hardware is done with this descriptor, it can
+ *    be reused by the driver.
+ *  - (RTE_ETH_TX_DESC_UNAVAIL): Descriptor is unavailable, reserved by the
+ *    driver or the hardware.
+ *  - (-EINVAL) bad descriptor offset.
+ *  - (-ENOTSUP) if the device does not support this function.
+ *  - (-ENODEV) bad port or queue (only if compiled with debug).
+ */
+static inline int rte_eth_tx_descriptor_status(uint8_t port_id,
+	uint16_t queue_id, uint16_t offset)
+{
+	struct rte_eth_dev *dev;
+	void *txq;
+
+#ifdef RTE_LIBRTE_ETHDEV_DEBUG
+	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
+#endif
+	dev = &rte_eth_devices[port_id];
+#ifdef RTE_LIBRTE_ETHDEV_DEBUG
+	if (queue_id >= dev->data->nb_tx_queues)
+		return -ENODEV;
+#endif
+	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->tx_descriptor_status, -ENOTSUP);
+	txq = dev->data->tx_queues[queue_id];
+
+	return (*dev->dev_ops->tx_descriptor_status)(txq, offset);
+}
+
 /**
  * Send a burst of output packets on a transmit queue of an Ethernet device.
  *