netdev - Re: [PATCH net-next 2/2] xdp: Add devmap_idx map type for looking up devices by ifindex

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Message-ID: <87o975i1je.fsf@toke.dk>
Date:   Thu, 21 Feb 2019 16:50:13 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>, brouer@...hat.com
Subject: Re: [PATCH net-next 2/2] xdp: Add devmap_idx map type for looking up devices by ifindex

Jesper Dangaard Brouer <brouer@...hat.com> writes:

> On Thu, 21 Feb 2019 12:56:54 +0100
> Toke Høiland-Jørgensen <toke@...hat.com> wrote:
>
>> The default maps used by xdp_redirect() are changed to use the new map
>> type, which means that xdp_redirect() is no longer limited to ifindex < 64,
>> but instead to 64 total simultaneous interfaces per network namespace. This
>> also provides an easy way to compare the performance of devmap and
>> devmap_idx:
>> 
>> xdp_redirect_map (devmap): 8394560 pkt/s
>> xdp_redirect (devmap_idx): 8179480 pkt/s
>> 
>> Difference: 215080 pkt/s or 3.1 nanoseconds per packet.
>
> (1/8394560-1/8179480)*10^9 = -3.13239 ns
>
> But was the xdp_redirect_map code-path affected from patch 1/1? 
> (1/8412754-1/8394560)*10^9 = -0.2576 ns
>
> It doesn't look like any performance regression to xdp_redirect_map
> from these code changes :-)

Nope, the difference between the two patches is just random noise; the
numbers vary more between runs (or even between samples in the same
run), which is why I didn't mention that difference.

-Toke