On Tue, Jul 19, 2016 at 12:16:57PM -0700, Brenden Blanco wrote:
> Add a sample that rewrites and forwards packets out on the same
> interface. Observed single core forwarding performance of ~10Mpps.
>
> Since the mlx4 driver under test recycles every single packet page, the
> perf output shows almost exclusively just the ring management and bpf
> program work. Slowdowns are likely occurring due to cache misses.
long term we need to resurrect your prefetch patch. sux to leave
so much performance on the table.
> +static int parse_ipv4(void *data, u64 nh_off, void *data_end)
> +{
> + struct iphdr *iph = data + nh_off;
> +
> + if (iph + 1 > data_end)
> + return 0;
> + return iph->protocol;
> +}
> +
> +static int parse_ipv6(void *data, u64 nh_off, void *data_end)
> +{
> + struct ipv6hdr *ip6h = data + nh_off;
> +
> + if (ip6h + 1 > data_end)
> + return 0;
> + return ip6h->nexthdr;
> +}
...
> + if (h_proto == htons(ETH_P_IP))
> + index = parse_ipv4(data, nh_off, data_end);
> + else if (h_proto == htons(ETH_P_IPV6))
> + index = parse_ipv6(data, nh_off, data_end);
> + else
> + index = 0;
> +
> + value = bpf_map_lookup_elem(&dropcnt, &index);
> + if (value)
> + *value += 1;
> +
> + if (index == 17) {
not an obvious xdp example. if you'd have to respin for other
reasons please consider 'proto' name and IPPROTO_UDP here.
Acked-by: Alexei Starovoitov <a...@kernel.org>
