[ovs-dev] [v13 03/12] dpif-netdev: Add function pointer for netdev input.

[Flavio Leitner]

Hello,

On Thu, Jun 17, 2021 at 05:18:16PM +0100, Cian Ferriter wrote:
> From: Harry van Haaren <harry.van.haaren at intel.com>
> 
> This commit adds a function pointer to the pmd thread data structure,
> giving the pmd thread flexibility in its dpif-input function choice.
> This allows choosing of the implementation based on ISA capabilities
> of the runtime CPU, leading to optimizations and higher performance.
> 
> Signed-off-by: Harry van Haaren <harry.van.haaren at intel.com>
> 
> ---
> 
> v13:
> - Minor code refactor to address review comments.
> ---
>  lib/dpif-netdev-private-thread.h | 13 +++++++++++++
>  lib/dpif-netdev.c                |  7 ++++++-
>  2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/dpif-netdev-private-thread.h b/lib/dpif-netdev-private-thread.h
> index 5e5308b96..0d674ab83 100644
> --- a/lib/dpif-netdev-private-thread.h
> +++ b/lib/dpif-netdev-private-thread.h
> @@ -47,6 +47,13 @@ struct dp_netdev_pmd_thread_ctx {
>      uint32_t emc_insert_min;
>  };
>  
> +/* Forward declaration for typedef. */
> +struct dp_netdev_pmd_thread;
> +
> +typedef void (*dp_netdev_input_func)(struct dp_netdev_pmd_thread *pmd,
> +                                     struct dp_packet_batch *packets,
> +                                     odp_port_t port_no);
> +
>  /* PMD: Poll modes drivers.  PMD accesses devices via polling to eliminate
>   * the performance overhead of interrupt processing.  Therefore netdev can
>   * not implement rx-wait for these devices.  dpif-netdev needs to poll
> @@ -101,6 +108,12 @@ struct dp_netdev_pmd_thread {
>      /* Current context of the PMD thread. */
>      struct dp_netdev_pmd_thread_ctx ctx;
>  
> +    /* Function pointer to call for dp_netdev_input() functionality. */
> +    dp_netdev_input_func netdev_input_func;
> +
> +    /* Pointer for per-DPIF implementation scratch space. */
> +    void *netdev_input_func_userdata;
> +

I see you need to switch the input function and the patch looks fine, but
the default function doesn't require netdev_input_func_userdata. I think
it would be better to add that in the next patch where it is actually
required.

fbl

>      struct seq *reload_seq;
>      uint64_t last_reload_seq;
>  
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index e913f4efc..e6486417e 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -4231,8 +4231,9 @@ dp_netdev_process_rxq_port(struct dp_netdev_pmd_thread *pmd,
>                  }
>              }
>          }
> +
>          /* Process packet batch. */
> -        dp_netdev_input(pmd, &batch, port_no);
> +        pmd->netdev_input_func(pmd, &batch, port_no);
>  
>          /* Assign processing cycles to rx queue. */
>          cycles = cycle_timer_stop(&pmd->perf_stats, &timer);
> @@ -6029,6 +6030,10 @@ dp_netdev_configure_pmd(struct dp_netdev_pmd_thread *pmd, struct dp_netdev *dp,
>      hmap_init(&pmd->tnl_port_cache);
>      hmap_init(&pmd->send_port_cache);
>      cmap_init(&pmd->tx_bonds);
> +
> +    /* Initialize the DPIF function pointer to the default scalar version. */
> +    pmd->netdev_input_func = dp_netdev_input;
> +
>      /* init the 'flow_cache' since there is no
>       * actual thread created for NON_PMD_CORE_ID. */
>      if (core_id == NON_PMD_CORE_ID) {
> -- 
> 2.32.0
> 
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-- 
fbl