netdev - Re: [PATCH bpf-next v2 1/1] bpf, lpm: make longest_prefix

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Date:   Thu, 22 Nov 2018 11:10:06 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Eric Dumazet <edumazet@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Vlad Dumitrescu <vladum@...gle.com>
Subject: Re: [PATCH bpf-next v2 1/1] bpf, lpm: make longest_prefix_match()
 faster

On 11/22/2018 06:39 AM, Eric Dumazet wrote:
> At LPC 2018 in Vancouver, Vlad Dumitrescu mentioned that longest_prefix_match()
> has a high cost [1].
> 
> One reason for that cost is a loop handling one byte at a time.
> 
> We can handle more bytes at a time, if enough attention is paid
> to endianness.
> 
> I was able to remove ~55 % of longest_prefix_match() cpu costs.
> 
> [1] https://linuxplumbersconf.org/event/2/contributions/88/attachments/76/87/lpc-bpf-2018-shaping.pdf
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Vlad Dumitrescu <vladum@...gle.com>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Daniel Borkmann <daniel@...earbox.net>

Looks good, applied to bpf-next, thanks!