Re: [dpdk-dev] [PATCH v5 5/7] ethdev: make fast-path functions to use new flat array

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

On 10/7/21 2:27 PM, Konstantin Ananyev wrote:
> Rework fast-path ethdev functions to use rte_eth_fp_ops[].
> While it is an API/ABI breakage, this change is intended to be
> transparent for both users (no changes in user app is required) and
> PMD developers (no changes in PMD is required).
> One extra thing to note - RX/TX callback invocation will cause extra
> function call with these changes. That might cause some insignificant
> slowdown for code-path where RX/TX callbacks are heavily involved.

I'm sorry for nit picking here and below:

RX -> Rx, TX -> Tx everywhere above.

> 
> Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> ---
>  lib/ethdev/ethdev_private.c |  31 +++++
>  lib/ethdev/rte_ethdev.h     | 242 ++++++++++++++++++++++++++----------
>  lib/ethdev/version.map      |   3 +
>  3 files changed, 208 insertions(+), 68 deletions(-)
> 
> diff --git a/lib/ethdev/ethdev_private.c b/lib/ethdev/ethdev_private.c
> index 3eeda6e9f9..1222c6f84e 100644
> --- a/lib/ethdev/ethdev_private.c
> +++ b/lib/ethdev/ethdev_private.c
> @@ -226,3 +226,34 @@ eth_dev_fp_ops_setup(struct rte_eth_fp_ops *fpo,
>  	fpo->txq.data = dev->data->tx_queues;
>  	fpo->txq.clbk = (void **)(uintptr_t)dev->pre_tx_burst_cbs;
>  }
> +
> +uint16_t
> +rte_eth_call_rx_callbacks(uint16_t port_id, uint16_t queue_id,
> +	struct rte_mbuf **rx_pkts, uint16_t nb_rx, uint16_t nb_pkts,
> +	void *opaque)
> +{
> +	const struct rte_eth_rxtx_callback *cb = opaque;
> +
> +	while (cb != NULL) {
> +		nb_rx = cb->fn.rx(port_id, queue_id, rx_pkts, nb_rx,
> +				nb_pkts, cb->param);
> +		cb = cb->next;
> +	}
> +
> +	return nb_rx;
> +}
> +
> +uint16_t
> +rte_eth_call_tx_callbacks(uint16_t port_id, uint16_t queue_id,
> +	struct rte_mbuf **tx_pkts, uint16_t nb_pkts, void *opaque)
> +{
> +	const struct rte_eth_rxtx_callback *cb = opaque;
> +
> +	while (cb != NULL) {
> +		nb_pkts = cb->fn.tx(port_id, queue_id, tx_pkts, nb_pkts,
> +				cb->param);
> +		cb = cb->next;
> +	}
> +
> +	return nb_pkts;
> +}
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
> index cdd16d6e57..c0e1a40681 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -4904,6 +4904,33 @@ int rte_eth_representor_info_get(uint16_t port_id,
>  
>  #include <rte_ethdev_core.h>
>  
> +/**
> + * @internal
> + * Helper routine for eth driver rx_burst API.

rx -> Rx

> + * Should be called at exit from PMD's rte_eth_rx_bulk implementation.
> + * Does necessary post-processing - invokes RX callbacks if any, etc.

RX -> Rx

> + *
> + * @param port_id
> + *  The port identifier of the Ethernet device.
> + * @param queue_id
> + *  The index of the receive queue from which to retrieve input packets.

Isn't:
The index of the queue from which packets are received from?

> + * @param rx_pkts
> + *   The address of an array of pointers to *rte_mbuf* structures that
> + *   have been retrieved from the device.
> + * @param nb_pkts

Should be @param nb_rx

> + *   The number of packets that were retrieved from the device.
> + * @param nb_pkts
> + *   The number of elements in *rx_pkts* array.

@p should be used to refer to a paramter.

The description does not help to understand why both nb_rx and
nb_pkts are necessary. Isn't nb_pkts >= nb_rx and nb_rx
sufficient?

> + * @param opaque
> + *   Opaque pointer of RX queue callback related data.

RX -> Rx

> + *
> + * @return
> + *  The number of packets effectively supplied to the *rx_pkts* array.

@p should be used to refer to a parameter.

> + */
> +uint16_t rte_eth_call_rx_callbacks(uint16_t port_id, uint16_t queue_id,
> +		struct rte_mbuf **rx_pkts, uint16_t nb_rx, uint16_t nb_pkts,
> +		void *opaque);
> +
>  /**
>   *
>   * Retrieve a burst of input packets from a receive queue of an Ethernet
> @@ -4995,23 +5022,37 @@ static inline uint16_t
>  rte_eth_rx_burst(uint16_t port_id, uint16_t queue_id,
>  		 struct rte_mbuf **rx_pkts, const uint16_t nb_pkts)
>  {
> -	struct rte_eth_dev *dev = &rte_eth_devices[port_id];
>  	uint16_t nb_rx;
> +	struct rte_eth_fp_ops *p;

p is typically a very bad name in a funcion with
many pointer variables etc. May be "fpo" as in previous
patch?

> +	void *cb, *qd;

Please, avoid variable, expecially pointers, declaration in
one line.

I'd suggest to use 'rxq' instead of 'qd'. The first paramter
of the rx_pkt_burst is 'rxq'.

Also 'cb' seems to be used under RTE_ETHDEV_RXTX_CALLBACKS
only. If so, it could be unused variable warning if
RTE_ETHDEV_RXTX_CALLBACKS is not defined.

> +
> +#ifdef RTE_ETHDEV_DEBUG_RX
> +	if (port_id >= RTE_MAX_ETHPORTS ||
> +			queue_id >= RTE_MAX_QUEUES_PER_PORT) {
> +		RTE_ETHDEV_LOG(ERR,
> +			"Invalid port_id=%u or queue_id=%u\n",
> +			port_id, queue_id);
> +		return 0;
> +	}
> +#endif
> +
> +	/* fetch pointer to queue data */
> +	p = &rte_eth_fp_ops[port_id];
> +	qd = p->rxq.data[queue_id];
>  
>  #ifdef RTE_ETHDEV_DEBUG_RX
>  	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, 0);
> -	RTE_FUNC_PTR_OR_ERR_RET(*dev->rx_pkt_burst, 0);
>  
> -	if (queue_id >= dev->data->nb_rx_queues) {
> -		RTE_ETHDEV_LOG(ERR, "Invalid RX queue_id=%u\n", queue_id);
> +	if (qd == NULL) {
> +		RTE_ETHDEV_LOG(ERR, "Invalid RX queue_id=%u for port_id=%u\n",

RX -> Rx

> +			queue_id, port_id);
>  		return 0;
>  	}
>  #endif
> -	nb_rx = (*dev->rx_pkt_burst)(dev->data->rx_queues[queue_id],
> -				     rx_pkts, nb_pkts);
> +
> +	nb_rx = p->rx_pkt_burst(qd, rx_pkts, nb_pkts);
>  
>  #ifdef RTE_ETHDEV_RXTX_CALLBACKS
> -	struct rte_eth_rxtx_callback *cb;
>  
>  	/* __ATOMIC_RELEASE memory order was used when the
>  	 * call back was inserted into the list.
> @@ -5019,16 +5060,10 @@ rte_eth_rx_burst(uint16_t port_id, uint16_t queue_id,
>  	 * cb and cb->fn/cb->next, __ATOMIC_ACQUIRE memory order is
>  	 * not required.
>  	 */
> -	cb = __atomic_load_n(&dev->post_rx_burst_cbs[queue_id],
> -				__ATOMIC_RELAXED);
> -
> -	if (unlikely(cb != NULL)) {
> -		do {
> -			nb_rx = cb->fn.rx(port_id, queue_id, rx_pkts, nb_rx,
> -						nb_pkts, cb->param);
> -			cb = cb->next;
> -		} while (cb != NULL);
> -	}
> +	cb = __atomic_load_n((void **)&p->rxq.clbk[queue_id], __ATOMIC_RELAXED);
> +	if (unlikely(cb != NULL))
> +		nb_rx = rte_eth_call_rx_callbacks(port_id, queue_id, rx_pkts,
> +				nb_rx, nb_pkts, cb);
>  #endif
>  
>  	rte_ethdev_trace_rx_burst(port_id, queue_id, (void **)rx_pkts, nb_rx);
> @@ -5051,16 +5086,27 @@ rte_eth_rx_burst(uint16_t port_id, uint16_t queue_id,
>  static inline int
>  rte_eth_rx_queue_count(uint16_t port_id, uint16_t queue_id)
>  {
> -	struct rte_eth_dev *dev;
> +	struct rte_eth_fp_ops *p;
> +	void *qd;

p -> fpo, qd -> rxq

> +
> +	if (port_id >= RTE_MAX_ETHPORTS ||
> +			queue_id >= RTE_MAX_QUEUES_PER_PORT) {
> +		RTE_ETHDEV_LOG(ERR,
> +			"Invalid port_id=%u or queue_id=%u\n",
> +			port_id, queue_id);
> +		return -EINVAL;
> +	}
> +
> +	/* fetch pointer to queue data */
> +	p = &rte_eth_fp_ops[port_id];
> +	qd = p->rxq.data[queue_id];
>  
>  	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> -	dev = &rte_eth_devices[port_id];
> -	RTE_FUNC_PTR_OR_ERR_RET(*dev->rx_queue_count, -ENOTSUP);
> -	if (queue_id >= dev->data->nb_rx_queues ||
> -	    dev->data->rx_queues[queue_id] == NULL)
> +	RTE_FUNC_PTR_OR_ERR_RET(*p->rx_queue_count, -ENOTSUP);
> +	if (qd == NULL)
>  		return -EINVAL;
>  
> -	return (int)(*dev->rx_queue_count)(dev->data->rx_queues[queue_id]);
> +	return (int)(*p->rx_queue_count)(qd);
>  }
>  
>  /**@{@name Rx hardware descriptor states
> @@ -5108,21 +5154,30 @@ static inline int
>  rte_eth_rx_descriptor_status(uint16_t port_id, uint16_t queue_id,
>  	uint16_t offset)
>  {
> -	struct rte_eth_dev *dev;
> -	void *rxq;
> +	struct rte_eth_fp_ops *p;
> +	void *qd;

p -> fpo, qd -> rxq

>  
>  #ifdef RTE_ETHDEV_DEBUG_RX
> -	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +	if (port_id >= RTE_MAX_ETHPORTS ||
> +			queue_id >= RTE_MAX_QUEUES_PER_PORT) {
> +		RTE_ETHDEV_LOG(ERR,
> +			"Invalid port_id=%u or queue_id=%u\n",
> +			port_id, queue_id);
> +		return -EINVAL;
> +	}
>  #endif
> -	dev = &rte_eth_devices[port_id];
> +
> +	/* fetch pointer to queue data */
> +	p = &rte_eth_fp_ops[port_id];
> +	qd = p->rxq.data[queue_id];
> +
>  #ifdef RTE_ETHDEV_DEBUG_RX
> -	if (queue_id >= dev->data->nb_rx_queues)
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +	if (qd == NULL)
>  		return -ENODEV;
>  #endif
> -	RTE_FUNC_PTR_OR_ERR_RET(*dev->rx_descriptor_status, -ENOTSUP);
> -	rxq = dev->data->rx_queues[queue_id];
> -
> -	return (*dev->rx_descriptor_status)(rxq, offset);
> +	RTE_FUNC_PTR_OR_ERR_RET(*p->rx_descriptor_status, -ENOTSUP);
> +	return (*p->rx_descriptor_status)(qd, offset);
>  }
>  
>  /**@{@name Tx hardware descriptor states
> @@ -5169,23 +5224,54 @@ rte_eth_rx_descriptor_status(uint16_t port_id, uint16_t queue_id,
>  static inline int rte_eth_tx_descriptor_status(uint16_t port_id,
>  	uint16_t queue_id, uint16_t offset)
>  {
> -	struct rte_eth_dev *dev;
> -	void *txq;
> +	struct rte_eth_fp_ops *p;
> +	void *qd;

p -> fpo, qd -> txq

>  
>  #ifdef RTE_ETHDEV_DEBUG_TX
> -	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +	if (port_id >= RTE_MAX_ETHPORTS ||
> +			queue_id >= RTE_MAX_QUEUES_PER_PORT) {
> +		RTE_ETHDEV_LOG(ERR,
> +			"Invalid port_id=%u or queue_id=%u\n",
> +			port_id, queue_id);
> +		return -EINVAL;
> +	}
>  #endif
> -	dev = &rte_eth_devices[port_id];
> +
> +	/* fetch pointer to queue data */
> +	p = &rte_eth_fp_ops[port_id];
> +	qd = p->txq.data[queue_id];
> +
>  #ifdef RTE_ETHDEV_DEBUG_TX
> -	if (queue_id >= dev->data->nb_tx_queues)
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +	if (qd == NULL)
>  		return -ENODEV;
>  #endif
> -	RTE_FUNC_PTR_OR_ERR_RET(*dev->tx_descriptor_status, -ENOTSUP);
> -	txq = dev->data->tx_queues[queue_id];
> -
> -	return (*dev->tx_descriptor_status)(txq, offset);
> +	RTE_FUNC_PTR_OR_ERR_RET(*p->tx_descriptor_status, -ENOTSUP);
> +	return (*p->tx_descriptor_status)(qd, offset);
>  }
>  
> +/**
> + * @internal
> + * Helper routine for eth driver tx_burst API.
> + * Should be called before entry PMD's rte_eth_tx_bulk implementation.
> + * Does necessary pre-processing - invokes TX callbacks if any, etc.

TX -> Tx

> + *
> + * @param port_id
> + *   The port identifier of the Ethernet device.
> + * @param queue_id
> + *   The index of the transmit queue through which output packets must be
> + *   sent.
> + * @param tx_pkts
> + *   The address of an array of *nb_pkts* pointers to *rte_mbuf* structures
> + *   which contain the output packets.

*nb_pkts* -> @p nb_pkts

> + * @param nb_pkts
> + *   The maximum number of packets to transmit.
> + * @return
> + *   The number of output packets to transmit.
> + */
> +uint16_t rte_eth_call_tx_callbacks(uint16_t port_id, uint16_t queue_id,
> +	struct rte_mbuf **tx_pkts, uint16_t nb_pkts, void *opaque);
> +
>  /**
>   * Send a burst of output packets on a transmit queue of an Ethernet device.
>   *
> @@ -5256,20 +5342,34 @@ static inline uint16_t
>  rte_eth_tx_burst(uint16_t port_id, uint16_t queue_id,
>  		 struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
>  {
> -	struct rte_eth_dev *dev = &rte_eth_devices[port_id];
> +	struct rte_eth_fp_ops *p;
> +	void *cb, *qd;

Same as above

> +
> +#ifdef RTE_ETHDEV_DEBUG_TX
> +	if (port_id >= RTE_MAX_ETHPORTS ||
> +			queue_id >= RTE_MAX_QUEUES_PER_PORT) {
> +		RTE_ETHDEV_LOG(ERR,
> +			"Invalid port_id=%u or queue_id=%u\n",
> +			port_id, queue_id);
> +		return 0;
> +	}
> +#endif
> +
> +	/* fetch pointer to queue data */
> +	p = &rte_eth_fp_ops[port_id];
> +	qd = p->txq.data[queue_id];
>  
>  #ifdef RTE_ETHDEV_DEBUG_TX
>  	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, 0);
> -	RTE_FUNC_PTR_OR_ERR_RET(*dev->tx_pkt_burst, 0);
>  
> -	if (queue_id >= dev->data->nb_tx_queues) {
> -		RTE_ETHDEV_LOG(ERR, "Invalid TX queue_id=%u\n", queue_id);
> +	if (qd == NULL) {
> +		RTE_ETHDEV_LOG(ERR, "Invalid TX queue_id=%u for port_id=%u\n",

TX -> Tx

> +			queue_id, port_id);
>  		return 0;
>  	}
>  #endif
>  
>  #ifdef RTE_ETHDEV_RXTX_CALLBACKS
> -	struct rte_eth_rxtx_callback *cb;
>  
>  	/* __ATOMIC_RELEASE memory order was used when the
>  	 * call back was inserted into the list.
> @@ -5277,21 +5377,16 @@ rte_eth_tx_burst(uint16_t port_id, uint16_t queue_id,
>  	 * cb and cb->fn/cb->next, __ATOMIC_ACQUIRE memory order is
>  	 * not required.
>  	 */
> -	cb = __atomic_load_n(&dev->pre_tx_burst_cbs[queue_id],
> -				__ATOMIC_RELAXED);
> -
> -	if (unlikely(cb != NULL)) {
> -		do {
> -			nb_pkts = cb->fn.tx(port_id, queue_id, tx_pkts, nb_pkts,
> -					cb->param);
> -			cb = cb->next;
> -		} while (cb != NULL);
> -	}
> +	cb = __atomic_load_n((void **)&p->txq.clbk[queue_id], __ATOMIC_RELAXED);
> +	if (unlikely(cb != NULL))
> +		nb_pkts = rte_eth_call_tx_callbacks(port_id, queue_id, tx_pkts,
> +				nb_pkts, cb);
>  #endif
>  
> -	rte_ethdev_trace_tx_burst(port_id, queue_id, (void **)tx_pkts,
> -		nb_pkts);
> -	return (*dev->tx_pkt_burst)(dev->data->tx_queues[queue_id], tx_pkts, nb_pkts);
> +	nb_pkts = p->tx_pkt_burst(qd, tx_pkts, nb_pkts);
> +
> +	rte_ethdev_trace_tx_burst(port_id, queue_id, (void **)tx_pkts, nb_pkts);
> +	return nb_pkts;
>  }
>  
>  /**
> @@ -5354,31 +5449,42 @@ static inline uint16_t
>  rte_eth_tx_prepare(uint16_t port_id, uint16_t queue_id,
>  		struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
>  {
> -	struct rte_eth_dev *dev;
> +	struct rte_eth_fp_ops *p;
> +	void *qd;

p->fpo, qd->txq

>  
>  #ifdef RTE_ETHDEV_DEBUG_TX
> -	if (!rte_eth_dev_is_valid_port(port_id)) {
> -		RTE_ETHDEV_LOG(ERR, "Invalid TX port_id=%u\n", port_id);
> +	if (port_id >= RTE_MAX_ETHPORTS ||
> +			queue_id >= RTE_MAX_QUEUES_PER_PORT) {
> +		RTE_ETHDEV_LOG(ERR,
> +			"Invalid port_id=%u or queue_id=%u\n",
> +			port_id, queue_id);
>  		rte_errno = ENODEV;
>  		return 0;
>  	}
>  #endif
>  
> -	dev = &rte_eth_devices[port_id];
> +	/* fetch pointer to queue data */
> +	p = &rte_eth_fp_ops[port_id];
> +	qd = p->txq.data[queue_id];
>  
>  #ifdef RTE_ETHDEV_DEBUG_TX
> -	if (queue_id >= dev->data->nb_tx_queues) {
> -		RTE_ETHDEV_LOG(ERR, "Invalid TX queue_id=%u\n", queue_id);
> +	if (!rte_eth_dev_is_valid_port(port_id)) {
> +		RTE_ETHDEV_LOG(ERR, "Invalid TX port_id=%u\n", port_id);

TX -> Tx

> +		rte_errno = ENODEV;
> +		return 0;
> +	}
> +	if (qd == NULL) {
> +		RTE_ETHDEV_LOG(ERR, "Invalid TX queue_id=%u for port_id=%u\n",

TX -> Tx

> +			queue_id, port_id);
>  		rte_errno = EINVAL;
>  		return 0;
>  	}
>  #endif
>  
> -	if (!dev->tx_pkt_prepare)
> +	if (!p->tx_pkt_prepare)

Please, change it to compare vs NULL since you touch the line.
Just to be consistent with DPDK coding style and lines above.

>  		return nb_pkts;
>  
> -	return (*dev->tx_pkt_prepare)(dev->data->tx_queues[queue_id],
> -			tx_pkts, nb_pkts);
> +	return p->tx_pkt_prepare(qd, tx_pkts, nb_pkts);
>  }
>  
>  #else
> diff --git a/lib/ethdev/version.map b/lib/ethdev/version.map
> index 904bce6ea1..79e62dcf61 100644
> --- a/lib/ethdev/version.map
> +++ b/lib/ethdev/version.map
> @@ -7,6 +7,8 @@ DPDK_22 {
>  	rte_eth_allmulticast_disable;
>  	rte_eth_allmulticast_enable;
>  	rte_eth_allmulticast_get;
> +	rte_eth_call_rx_callbacks;
> +	rte_eth_call_tx_callbacks;
>  	rte_eth_dev_adjust_nb_rx_tx_desc;
>  	rte_eth_dev_callback_register;
>  	rte_eth_dev_callback_unregister;
> @@ -76,6 +78,7 @@ DPDK_22 {
>  	rte_eth_find_next_of;
>  	rte_eth_find_next_owned_by;
>  	rte_eth_find_next_sibling;
> +	rte_eth_fp_ops;
>  	rte_eth_iterator_cleanup;
>  	rte_eth_iterator_init;
>  	rte_eth_iterator_next;
>