netdev - Re: [PATCH net-next v3 0/2] net: introduce and use route hint

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Date:   Tue, 19 Nov 2019 18:47:27 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     pabeni@...hat.com
Cc:     netdev@...r.kernel.org, willemdebruijn.kernel@...il.com,
        ecree@...arflare.com, dsahern@...il.com
Subject: Re: [PATCH net-next v3 0/2] net: introduce and use route hint

From: Paolo Abeni <pabeni@...hat.com>
Date: Tue, 19 Nov 2019 15:38:35 +0100

> This series leverages the listification infrastructure to avoid
> unnecessary route lookup on ingress packets. In absence of policy routing,
> packets with equal daddr will usually land on the same dst.
> 
> When processing packet bursts (lists) we can easily reference the previous
> dst entry. When we hit the 'same destination' condition we can avoid the
> route lookup, coping the already available dst.
> 
> Detailed performance numbers are available in the individual commit
> messages. Figures are slightly better then previous iteration because
> thanks to Willem's suggestion we additionally skip early demux when using
> the route hint.
> 
> v2 -> v3:
>  - use fib*_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
>  - fix potential race in ip6_list_rcv_finish()

To reiterate David A.'s feedback, having this depend upon
IP_MULTIPLE_TABLES being disabled is %100 a non-starter.

No distribution will benefit from these changes at all.