netdev - Re: [PATCH net-next v4 3/5] ipv6: introduce and uses route look hints for list input.

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Date:   Thu, 21 Nov 2019 13:11:42 -0700
From:   David Ahern <dsahern@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Edward Cree <ecree@...arflare.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net-next v4 3/5] ipv6: introduce and uses route look hints
 for list input.

On 11/20/19 5:47 AM, Paolo Abeni wrote:
> When doing RX batch packet processing, we currently always repeat
> the route lookup for each ingress packet. When no custom rules are
> in place, and there aren't routes depending on source addresses,
> we know that packets with the same destination address will use
> the same dst.
> 
> This change tries to avoid per packet route lookup caching
> the destination address of the latest successful lookup, and
> reusing it for the next packet when the above conditions are
> in place. Ingress traffic for most servers should fit.
> 
> The measured performance delta under UDP flood vs a recvmmsg
> receiver is as follow:
> 
> vanilla		patched		delta
> Kpps		Kpps		%
> 1431		1674		+17
> 
> In the worst-case scenario - each packet has a different
> destination address - the performance delta is within noise
> range.
> 
...

> 
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>
> ---
>  net/ipv6/ip6_input.c | 26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)

Reviewed-by: David Ahern <dsahern@...il.com>