Björn Töpel <bjorn.topel@xxxxxxxxx> writes:
> From: Björn Töpel <bjorn.topel@xxxxxxxxx>
>
> In commit 43e74c0267a3 ("bpf_xdp_redirect_map: Perform map lookup in
> eBPF helper") the bpf_redirect_map() helper learned to do map lookup,
> which means that the explicit lookup in the XDP program for AF_XDP is
> not needed.
>
> This commit removes the map lookup, which simplifies the BPF code and
> improves the performance for the "rx_drop" [1] scenario with ~4%.
Nice, 4% is pretty good!
I wonder if the program needs to be backwards-compatible (with pre-5.3
kernels), though?
You can do that by something like this:
ret = bpf_redirect_map(&xsks_map, index, XDP_PASS);
if (ret > 0)
return ret;
if (bpf_map_lookup_elem(&xsks_map, &index))
return bpf_redirect_map(&xsks_map, index, 0);
return XDP_PASS;
This works because bpf_redirect_map() prior to 43e74c0267a3 will return
XDP_ABORTED on a non-0 flags value.
-Toke
