Re: [PATCH bpf-next v4 0/2] Optimize bpf_redirect_map()/xdp_do_redirect()

On 2021-02-26 12:35, Toke Høiland-Jørgensen wrote:

Björn Töpel [off-list ref] writes:

quoted

Hi XDP-folks,

This two patch series contain two optimizations for the
bpf_redirect_map() helper and the xdp_do_redirect() function.

The bpf_redirect_map() optimization is about avoiding the map lookup
dispatching. Instead of having a switch-statement and selecting the
correct lookup function, we let bpf_redirect_map() be a map operation,
where each map has its own bpf_redirect_map() implementation. This way
the run-time lookup is avoided.

The xdp_do_redirect() patch restructures the code, so that the map
pointer indirection can be avoided.

Performance-wise I got 3% improvement for XSKMAP
(sample:xdpsock/rx-drop), and 4% (sample:xdp_redirect_map) on my
machine.

More details in each commit.

@Jesper/Toke I dropped your Acked-by: on the first patch, since there
were major restucturing. Please have another look! Thanks!

Will do! Did you update the performance numbers above after that change?

I did. The XSKMAP performance stayed the same (no surprise, since the
code was the same). However, for the DEVMAP the v4 got rid of a call, so
it *should* be a bit better, but for some reason it didn't show on my
machine.


Björn