On Tue, 26 Jun 2018 17:09:01 -0700
Song Liu <liu.song....@gmail.com> wrote:
> On Mon, Jun 25, 2018 at 7:27 AM, Jesper Dangaard Brouer
> <bro...@redhat.com> wrote:
> > XDP_TX requires also changing the MAC-addrs, else some hardware
> > may drop the TX packet before reaching the wire. This was
> > observed with driver mlx5.
> >
> > If xdp_rxq_info select --action XDP_TX the swapmac functionality
> > is activated. It is also possible to manually enable via cmdline
> > option --swapmac. This is practical if wanting to measure the
> > overhead of writing/updating payload for other action types.
> >
> > Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
> > Signed-off-by: Toke Høiland-Jørgensen <t...@toke.dk>
> > ---
[...]
> >
> > diff --git a/samples/bpf/xdp_rxq_info_kern.c
> > b/samples/bpf/xdp_rxq_info_kern.c
> > index 61af6210df2f..222a83eed1cb 100644
> > --- a/samples/bpf/xdp_rxq_info_kern.c
> > +++ b/samples/bpf/xdp_rxq_info_kern.c
> > @@ -21,6 +21,7 @@ struct config {
> > enum cfg_options_flags {
> > NO_TOUCH = 0x0U,
> > READ_MEM = 0x1U,
> > + SWAP_MAC = 0x2U,
> > };
[...]
> > @@ -98,7 +116,7 @@ int xdp_prognum0(struct xdp_md *ctx)
> > rxq_rec->issue++;
> >
> > /* Default: Don't touch packet data, only count packets */
> > - if (unlikely(config->options & READ_MEM)) {
> > + if (unlikely(config->options & (READ_MEM|SWAP_MAC))) {
> > struct ethhdr *eth = data;
> >
> > if (eth + 1 > data_end)
[...]
> > diff --git a/samples/bpf/xdp_rxq_info_user.c
> > b/samples/bpf/xdp_rxq_info_user.c
> > index 435485d4f49e..248a7eab9531 100644
[...]
> > @@ -119,6 +121,8 @@ static char* options2str(enum cfg_options_flags flag)
> > {
> > if (flag == NO_TOUCH)
> > return "no_touch";
> > + if (flag & SWAP_MAC)
> > + return "swapmac";
> > if (flag & READ_MEM)
> > return "read";
>
> I guess SWAP_MAC also reads the memory, so it "includes" READ_MEM?
True (see _kern side)
> It is OK for now. We may need to refactor this part when adding other
> flags in the future.
Sure, do remember that this is only a 'sample' program.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
