Re: [dpdk-dev] [PATCH v4 4/7] ethdev: make burst functions to use new flat array

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

> >
> > Rework 'fast' burst 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.
> >
> > 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      |   5 +
> >  3 files changed, 210 insertions(+), 68 deletions(-)
> >
> > diff --git a/lib/ethdev/ethdev_private.c b/lib/ethdev/ethdev_private.c
> > index 3eeda6e9f9..27d29b2ac6 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_rx_epilog(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;
> > +}
> 
> This helper name is ambiguous.
> Maybe the intent was to have a generic place holder for updates in
> future releases.

Yes, that was the intent.
We have array of opaque pointers (one per queue).
So I thought some generic name would be better - who knows
how we would need to change this function and its parameters in future.
 
> But in this series, __rte_eth_rx_epilog is invoked only if a rx
> callback is registered, under #ifdef RTE_ETHDEV_RXTX_CALLBACKS.

Hmm, yes it implies that we'll do callback underneath :)
 
> I'd prefer we call it a spade, i.e. rte_eth_call_rx_callbacks,

If there are no objections from other people - I am ok to rename it.

> and it
> does not need to be advertised as internal.

About internal vs public, I think Ferruh proposed the same.
I am not really fond of it as:
if we'll declare it public, we will have obligations to support it in future releases.
Plus it might encourage users to use it on its own, which I don't think is a right thing to do.

> 
> 
> > +
> > +uint16_t
> > +__rte_eth_tx_prolog(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;
> > +}
> 
> Idem, rte_eth_call_tx_callbacks.
> 
> 
> --
> David Marchand