netdev - Re: [PATCH net-next v4 5/5] ipv4: use dst hint for ipv4 list receive

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Date:   Thu, 21 Nov 2019 14:16:03 -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 5/5] ipv4: use dst hint for ipv4 list receive

On 11/20/19 5:47 AM, Paolo Abeni wrote:
> This is alike the previous change, with some additional ipv4 specific
> quirk. Even when using the route hint we still have to do perform
> additional per packet checks about source address validity: a new
> helper is added to wrap them.
> 
> Hints are explicitly disabled if the destination is a local broadcast,
> that keeps the code simple and local broadcast are a slower path anyway.
> 
> UDP flood performances vs recvmmsg() receiver:
> 
> vanilla		patched		delta
> Kpps		Kpps		%
> 1683		1871		+11
> 
> In the worst case scenario - each packet has a different
> destination address - the performance delta is within noise
> range.
> 
> v3 -> v4:
>  - re-enable hints for forward
> 
> v2 -> v3:
>  - really fix build (sic) and hint usage check
>  - use fib4_has_custom_rules() helpers (David A.)
>  - add ip_extract_route_hint() helper (Edward C.)
>  - use prev skb as hint instead of copying data (Willem)
> 
> v1 -> v2:
>  - fix build issue with !CONFIG_IP_MULTIPLE_TABLES
> 
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>
> ---
>  include/net/route.h |  4 ++++
>  net/ipv4/ip_input.c | 35 +++++++++++++++++++++++++++++++----
>  net/ipv4/route.c    | 42 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 77 insertions(+), 4 deletions(-)
> 

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