Re: [dpdk-dev] [RFC v2 3/5] ethdev: copy ethdev 'burst' API into separate structure

["Wang, Haiyue" <haiyue.wang@intel.com>]

> -----Original Message-----
> From: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Sent: Wednesday, September 22, 2021 22:10
> To: dev@dpdk.org
> Cc: Li, Xiaoyun <xiaoyun.li@intel.com>; anoobj@marvell.com; jerinj@marvell.com;
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> <johndale@cisco.com>; hyonkim@cisco.com; Zhang, Qi Z <qi.z.zhang@intel.com>; Wang, Xiao W
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> mdr@ashroe.eu; Jayatheerthan, Jay <jay.jayatheerthan@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>
> Subject: [RFC v2 3/5] ethdev: copy ethdev 'burst' API into separate structure
> 
> Copy public function pointers (rx_pkt_burst(), etc.) and related
> pointers to internal data from rte_eth_dev structure into a separate flat
> array. We can keep it public to still use inline functions for 'fast' calls
> (like rte_eth_rx_burst(), etc.) to avoid/minimize slowdown.
> The intention is to make rte_eth_dev and related structures internal.
> That should allow future possible changes to core eth_dev strcutures
> to be transaprent to the user and help to avoid ABI/API breakages.
> 
> Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> ---
>  lib/ethdev/ethdev_private.c  | 53 ++++++++++++++++++++++++++++++++++++
>  lib/ethdev/ethdev_private.h  |  7 +++++
>  lib/ethdev/rte_ethdev.c      | 17 ++++++++++++
>  lib/ethdev/rte_ethdev_core.h | 45 ++++++++++++++++++++++++++++++
>  4 files changed, 122 insertions(+)
> 
> diff --git a/lib/ethdev/ethdev_private.c b/lib/ethdev/ethdev_private.c
> index 012cf73ca2..a1683da77b 100644
> --- a/lib/ethdev/ethdev_private.c
> +++ b/lib/ethdev/ethdev_private.c
> @@ -174,3 +174,56 @@ rte_eth_devargs_parse_representor_ports(char *str, void *data)
>  		RTE_LOG(ERR, EAL, "wrong representor format: %s\n", str);
>  	return str == NULL ? -1 : 0;
>  }
> +
> +static uint16_t
> +dummy_eth_rx_burst(__rte_unused void *rxq,
> +		__rte_unused struct rte_mbuf **rx_pkts,
> +		__rte_unused uint16_t nb_pkts)
> +{
> +	RTE_ETHDEV_LOG(ERR, "rx_pkt_burst for unconfigured port\n");
> +	rte_errno = ENOTSUP;
> +	return 0;
> +}
> +
> +static uint16_t
> +dummy_eth_tx_burst(__rte_unused void *txq,
> +		__rte_unused struct rte_mbuf **tx_pkts,
> +		__rte_unused uint16_t nb_pkts)
> +{
> +	RTE_ETHDEV_LOG(ERR, "tx_pkt_burst for unconfigured port\n");
> +	rte_errno = ENOTSUP;
> +	return 0;
> +}
> +
> +void
> +eth_dev_burst_api_reset(struct rte_eth_burst_api *rba)
> +{
> +	static void *dummy_data[RTE_MAX_QUEUES_PER_PORT];
> +	static const struct rte_eth_burst_api dummy_api = {
> +		.rx_pkt_burst = dummy_eth_rx_burst,
> +		.tx_pkt_burst = dummy_eth_tx_burst,
> +		.rxq = {.data = dummy_data, .clbk = dummy_data,},
> +		.txq = {.data = dummy_data, .clbk = dummy_data,},
> +	};
> +
> +	*rba = dummy_api;
> +}
> +
> +void
> +eth_dev_burst_api_setup(struct rte_eth_burst_api *rba,
> +		const struct rte_eth_dev *dev)
> +{
> +	rba->rx_pkt_burst = dev->rx_pkt_burst;
> +	rba->tx_pkt_burst = dev->tx_pkt_burst;
> +	rba->tx_pkt_prepare = dev->tx_pkt_prepare;
> +	rba->rx_queue_count = dev->rx_queue_count;
> +	rba->rx_descriptor_status = dev->rx_descriptor_status;
> +	rba->tx_descriptor_status = dev->tx_descriptor_status;
> +
> +	rba->rxq.data = dev->data->rx_queues;
> +	rba->rxq.clbk = (void **)(uintptr_t)dev->post_rx_burst_cbs;
> +
> +	rba->txq.data = dev->data->tx_queues;
> +	rba->txq.clbk = (void **)(uintptr_t)dev->pre_tx_burst_cbs;
> +}
> +
> diff --git a/lib/ethdev/ethdev_private.h b/lib/ethdev/ethdev_private.h
> index 9bb0879538..54921f4860 100644
> --- a/lib/ethdev/ethdev_private.h
> +++ b/lib/ethdev/ethdev_private.h
> @@ -30,6 +30,13 @@ eth_find_device(const struct rte_eth_dev *_start, rte_eth_cmp_t cmp,
>  /* Parse devargs value for representor parameter. */
>  int rte_eth_devargs_parse_representor_ports(char *str, void *data);
> 
> +/* reset eth 'burst' API to dummy values */
> +void eth_dev_burst_api_reset(struct rte_eth_burst_api *rba);
> +
> +/* setup eth 'burst' API to ethdev values */
> +void eth_dev_burst_api_setup(struct rte_eth_burst_api *rba,
> +		const struct rte_eth_dev *dev);
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> index 424bc260fa..5904bb7bae 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -44,6 +44,9 @@
>  static const char *MZ_RTE_ETH_DEV_DATA = "rte_eth_dev_data";
>  struct rte_eth_dev rte_eth_devices[RTE_MAX_ETHPORTS];
> 
> +/* public 'fast/burst' API */
> +struct rte_eth_burst_api rte_eth_burst_api[RTE_MAX_ETHPORTS];
> +
>  /* spinlock for eth device callbacks */
>  static rte_spinlock_t eth_dev_cb_lock = RTE_SPINLOCK_INITIALIZER;
> 
> @@ -1788,6 +1791,9 @@ rte_eth_dev_start(uint16_t port_id)
>  		(*dev->dev_ops->link_update)(dev, 0);
>  	}
> 
> +	/* expose selection of PMD rx/tx function */
> +	eth_dev_burst_api_setup(rte_eth_burst_api + port_id, dev);
> +
>  	rte_ethdev_trace_start(port_id);
>  	return 0;
>  }
> @@ -1810,6 +1816,9 @@ rte_eth_dev_stop(uint16_t port_id)
>  		return 0;
>  	}
> 
> +	/* point rx/tx functions to dummy ones */
> +	eth_dev_burst_api_reset(rte_eth_burst_api + port_id);
> +
>  	dev->data->dev_started = 0;
>  	ret = (*dev->dev_ops->dev_stop)(dev);
>  	rte_ethdev_trace_stop(port_id, ret);
> @@ -4568,6 +4577,14 @@ rte_eth_mirror_rule_reset(uint16_t port_id, uint8_t rule_id)
>  	return eth_err(port_id, (*dev->dev_ops->mirror_rule_reset)(dev, rule_id));
>  }
> 
> +RTE_INIT(eth_dev_init_burst_api)
> +{
> +	uint32_t i;
> +
> +	for (i = 0; i != RTE_DIM(rte_eth_burst_api); i++)
> +		eth_dev_burst_api_reset(rte_eth_burst_api + i);
> +}
> +
>  RTE_INIT(eth_dev_init_cb_lists)
>  {
>  	uint16_t i;
> diff --git a/lib/ethdev/rte_ethdev_core.h b/lib/ethdev/rte_ethdev_core.h
> index 00f27c643a..da6de5de43 100644
> --- a/lib/ethdev/rte_ethdev_core.h
> +++ b/lib/ethdev/rte_ethdev_core.h
> @@ -53,6 +53,51 @@ typedef int (*eth_rx_descriptor_status_t)(void *rxq, uint16_t offset);
>  typedef int (*eth_tx_descriptor_status_t)(void *txq, uint16_t offset);
>  /**< @internal Check the status of a Tx descriptor */
> 
> +/**
> + * @internal
> + * Structure used to hold opaque pointernals to internal ethdev RX/TXi
> + * queues data.
> + * The main purpose to expose these pointers at all - allow compiler
> + * to fetch this data for 'fast' ethdev inline functions in advance.
> + */
> +struct rte_ethdev_qdata {
> +	void **data;
> +	/**< points to array of internal queue data pointers */
> +	void **clbk;
> +	/**< points to array of queue callback data pointers */
> +};
> +
> +/**
> + * @internal
> + * 'fast' ethdev funcions and related data are hold in a flat array.
> + * one entry per ethdev.
> + */
> +struct rte_eth_burst_api {

'ops' is better ? Like "struct rte_eth_burst_ops". ;-)

> +
> +	/** first 64B line */
> +	eth_rx_burst_t rx_pkt_burst;
> +	/**< PMD receive function. */
> +	eth_tx_burst_t tx_pkt_burst;
> +	/**< PMD transmit function. */
> +	eth_tx_prep_t tx_pkt_prepare;
> +	/**< PMD transmit prepare function. */
> +	eth_rx_queue_count_t rx_queue_count;
> +	/**< Get the number of used RX descriptors. */
> +	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. */
> +	uintptr_t reserved[2];
> +

How about 32 bit system ? Does it need something like :

__rte_cache_aligned for rxq to make sure 64B line?

> +	/** second 64B line */
> +	struct rte_ethdev_qdata rxq;
> +	struct rte_ethdev_qdata txq;
> +	uintptr_t reserved2[4];
> +
> +} __rte_cache_aligned;
> +
> +extern struct rte_eth_burst_api rte_eth_burst_api[RTE_MAX_ETHPORTS];
> +
> 
>  /**
>   * @internal
> --
> 2.26.3