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

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Date:   Fri, 26 Feb 2021 12:35:07 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Björn Töpel <bjorn.topel@...il.com>,
        ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Björn Töpel <bjorn.topel@...il.com>,
        bjorn.topel@...el.com, maciej.fijalkowski@...el.com,
        hawk@...nel.org, magnus.karlsson@...el.com,
        john.fastabend@...il.com, kuba@...nel.org, davem@...emloft.net
Subject: Re: [PATCH bpf-next v4 0/2] Optimize
 bpf_redirect_map()/xdp_do_redirect()

Björn Töpel <bjorn.topel@...il.com> writes:

> 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?

-Toke