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

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

> > >
> > > 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". ;-)
> 
> Since all fastpath APIs are not in bust in nature. IMO, rte_eth_fp_ops
> or so may be better.

I don't have any strong opinion about the name.
Whatever majority will decide is ok by me here.

> 
> >
> > > +
> > > +     /** 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 :

I don't think we need to anything special for 32-bit version here.
We have 16 pointers here in total right now,
on 32-bit systems it would fit into 64B anyway.

> >
> > __rte_cache_aligned for rxq to make sure 64B line?
> 
> __rte_cache_aligned_min for 128B CL systems.


> 
> >
> > > +     /** 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
> >