Re: [PATCHv7 bpf-next 0/3] xdp: add a new helper for dev map multicast support

Hangbin Liu
2020-07-15T03:45:36Z

On Tue, Jul 14, 2020 at 11:12:59AM -0600, David Ahern wrote:
> >> with pktgen(pkt size 64) to compire with xdp_redirect_map(). Here is the
> >> test result(the veth peer has a dummy xdp program with XDP_DROP directly):
> >>
> >> Version | Test | Native | Generic
> >> 5.8 rc1 | xdp_redirect_map i40e->i40e | 10.0M | 1.9M
> >> 5.8 rc1 | xdp_redirect_map i40e->veth | 12.7M | 1.6M
> >> 5.8 rc1 + patch | xdp_redirect_map i40e->i40e | 10.0M | 1.9M
> >> 5.8 rc1 + patch | xdp_redirect_map i40e->veth | 12.3M | 1.6M
> >> 5.8 rc1 + patch | xdp_redirect_map_multi i40e->i40e | 7.2M | 1.5M
> >> 5.8 rc1 + patch | xdp_redirect_map_multi i40e->veth | 8.5M | 1.3M
> >> 5.8 rc1 + patch | xdp_redirect_map_multi i40e->i40e+veth | 3.0M | 0.98M
> >>
> >> The bpf_redirect_map_multi() is slower than bpf_redirect_map() as we loop
> >> the arrays and do clone skb/xdpf. The native path is slower than generic
> >> path as we send skbs by pktgen. So the result looks reasonable.
> >>
> >> Last but not least, thanks a lot to Jiri, Eelco, Toke and Jesper for
> >> suggestions and help on implementation.
> >>
> >> [0] https://xdp-project.net/#Handling-multicast
> >>
> >> v7: Fix helper flag check
> >> Limit the *ex_map* to use DEVMAP_HASH only and update function
> >> dev_in_exclude_map() to get better performance.
> >
> > Did it help? The performance numbers in the table above are the same as
> > in v6...
> >
>
> If there is only 1 entry in the exclude map, then the numbers should be
> about the same.

Yes, I didn't re-run the test. Because when do the testing, I use null exclude
map + flag BPF_F_EXCLUDE_INGRESS. So the perf number should have no difference
with last patch.

Thanks
Hangbin