Subject: Re: [PATCH net-next 2/2] bpf: add bpf_redirect() helper

From: John Fastabend <[email-masked]>
Date: Tue, 15 Sep 2015 20:10:01 -0700

On 15-09-15 06:51 PM, Alexei Starovoitov wrote:
> Existing bpf_clone_redirect() helper clones skb before redirecting
> it to RX or TX of destination netdev.
> Introduce bpf_redirect() helper that does that without cloning.
> 
> Benchmarked with two hosts using 10G ixgbe NICs.
> One host is doing line rate pktgen.
> Another host is configured as:
> $ tc qdisc add dev $dev ingress
> $ tc filter add dev $dev root pref 10 u32 match u32 0 0 flowid 1:2 \
>    action bpf run object-file tcbpf1_kern.o section clone_redirect_xmit drop
> so it receives the packet on $dev and immediately xmits it on $dev + 1
> The section 'clone_redirect_xmit' in tcbpf1_kern.o file has the program
> that does bpf_clone_redirect() and performance is 2.0 Mpps
> 
> $ tc filter add dev $dev root pref 10 u32 match u32 0 0 flowid 1:2 \
>    action bpf run object-file tcbpf1_kern.o section redirect_xmit drop
> which is using bpf_redirect() - 2.4 Mpps
> 
> and using cls_bpf with integrated actions as:
> $ tc filter add dev $dev root pref 10 \
>   bpf run object-file tcbpf1_kern.o section redirect_xmit integ_act classid 1
> performance is 2.5 Mpps
> 
> To summarize:
> u32+act_bpf using clone_redirect - 2.0 Mpps
> u32+act_bpf using redirect - 2.4 Mpps
> cls_bpf using redirect - 2.5 Mpps
> 
> For comparison linux bridge in this setup is doing 2.1 Mpps
> and ixgbe rx + drop in ip_rcv - 7.8 Mpps
> 
> Signed-off-by: Alexei Starovoitov <[email-masked]>
> Acked-by: Daniel Borkmann <[email-masked]>
> ---

Nice, I like this. But just to be sure I read this correctly this will
only work on the ingress qdisc for now right? To get the tx side working
will require a bit more care.

Thanks,
.John