netdev - Re: [PATCH bpf-next v4 1/2] bpf, xdp: make bpf_redirect

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Date:   Fri, 26 Feb 2021 12:40:33 +0100
From:   Björn Töpel <bjorn.topel@...el.com>
To:     Toke Høiland-Jørgensen <toke@...hat.com>,
        Björn Töpel <bjorn.topel@...il.com>,
        ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     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 1/2] bpf, xdp: make bpf_redirect_map() a map
 operation

On 2021-02-26 12:37, Toke Høiland-Jørgensen wrote:
> Björn Töpel <bjorn.topel@...il.com> writes:
> 
>> From: Björn Töpel <bjorn.topel@...el.com>
>>
>> Currently the bpf_redirect_map() implementation dispatches to the
>> correct map-lookup function via a switch-statement. To avoid the
>> dispatching, this change adds bpf_redirect_map() as a map
>> operation. Each map provides its bpf_redirect_map() version, and
>> correct function is automatically selected by the BPF verifier.
>>
>> A nice side-effect of the code movement is that the map lookup
>> functions are now local to the map implementation files, which removes
>> one additional function call.
>>
>> Signed-off-by: Björn Töpel <bjorn.topel@...el.com>
> 
> Nice! I agree that this is a much nicer approach! :)
> 
> (That last paragraph above is why I asked if you updated the performance
> numbers in the cover letter; removing an additional function call should
> affect those, right?)
>

Yeah, it should. Let me spend some more time benchmarking on the DEVMAP
scenario.

@Jesper Do you have a CPUMAP benchmark that you can point me to? I just
did functional testing for CPUMAP

> Acked-by: Toke Høiland-Jørgensen <toke@...hat.com>
> 

Thank you!


Björn