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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> 
> 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?

I copied it from comments from rte_eth_rx_burst().
I suppose it is just two ways to say the same thing.

> 
> > + * @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

Ack, will fix. 

> 
> > + *   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.

To be more precise you are talking about:
s/*rx_pkts*/@ rx_pkts/
?

> 
> 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?

Nope,  that's for callbacks call.
Will update the comment.
 
> > + * @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.

Here and in other places, I think local variable names and placement,
is just a matter of personal preference.

> 
> 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.

Good point, will move it back under #ifdef RTE_ETHDEV_RXTX_CALLBACKS.
 
> > +
> > +#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.

Ok, I am also fond of explicit comparisons :) 

 
> >  		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;
> >