netdev - Re: [PATCH v2 net-next] ipv6: Implement limits on Hop-by-Hop and Destination options

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Date:   Mon, 30 Oct 2017 19:52:36 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     tom@...ntonium.net, netdev@...r.kernel.org, rohit@...ntonium.net,
        weiwan@...gle.com
Subject: Re: [PATCH v2 net-next] ipv6: Implement limits on Hop-by-Hop and
 Destination options

On Tue, 2017-10-31 at 11:10 +0900, David Miller wrote:
> From: Tom Herbert <tom@...ntonium.net>
> Date: Mon, 30 Oct 2017 14:16:00 -0700
> 
> > I wrote a quick test program that floods a whole bunch of these
> > packets to a host and sure enough there is substantial time spent
> > in ip6_parse_tlv.
>  ...
> >   25.38%  [kernel]                    [k] __fib6_clean_all
> >   21.63%  [kernel]                    [k] ip6_parse_tlv
> 
> Yet the routing code still dominates the cost.

I am guessing the ip6_rt_max_size defaulting to 4096 needs to be
revisited, after all per-cpu added stuff.