Re: [dpdk-dev] [PATCH v2 06/15] app/testpmd: add common fwd wrapper function

[Jerin Jacob <jerinjacobk@gmail.com>]

On Wed, Aug 11, 2021 at 7:35 PM Xueming Li <xuemingl@nvidia.com> wrote:
>
> From: Xiaoyu Min <jackmin@nvidia.com>
>
> Added an inline common wrapper function for all fwd engines
> which do the following in common:
>
> 1. get_start_cycles
> 2. rte_eth_rx_burst(...,nb_pkt_per_burst)
> 3. if rxq_share do forward_shared_rxq(), otherwise do fwd directly
> 4. get_end_cycle
>
> Signed-off-by: Xiaoyu Min <jackmin@nvidia.com>
> ---
>  app/test-pmd/testpmd.h | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/app/test-pmd/testpmd.h b/app/test-pmd/testpmd.h
> index 13141dfed9..b685ac48d6 100644
> --- a/app/test-pmd/testpmd.h
> +++ b/app/test-pmd/testpmd.h
> @@ -1022,6 +1022,30 @@ void add_tx_dynf_callback(portid_t portid);
>  void remove_tx_dynf_callback(portid_t portid);
>  int update_jumbo_frame_offload(portid_t portid);
>
> +static inline void
> +do_burst_fwd(struct fwd_stream *fs, packet_fwd_cb fwd)
> +{
> +       struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
> +       uint16_t nb_rx;
> +       uint64_t start_tsc = 0;
> +
> +       get_start_cycles(&start_tsc);
> +
> +       /*
> +        * Receive a burst of packets and forward them.
> +        */
> +       nb_rx = rte_eth_rx_burst(fs->rx_port, fs->rx_queue,
> +                       pkts_burst, nb_pkt_per_burst);
> +       inc_rx_burst_stats(fs, nb_rx);
> +       if (unlikely(nb_rx == 0))
> +               return;
> +       if (unlikely(rxq_share > 0))

See below. It reads a global memory.

> +               forward_shared_rxq(fs, nb_rx, pkts_burst, fwd);
> +       else
> +               (*fwd)(fs, nb_rx, pkts_burst);

New function pointer in fastpath.

IMO, We should not create performance regression for the existing
forward engine.
Can we have a new forward engine just for shared memory testing?

> +       get_end_cycles(fs, start_tsc);
> +}
> +
>  /*
>   * Work-around of a compilation error with ICC on invocations of the
>   * rte_be_to_cpu_16() function.
> --
> 2.25.1
>