netdev - icmp6_send() is too expensive

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Message-ID: <CAL6e_pfLT9Q+Sz+e9L4DyzwatZAWmv+Kz_+HFPK3BOrpbua=wQ@mail.gmail.com>
Date:   Thu, 4 Oct 2018 15:02:39 -0400
From:   Jeff Barnhill <0xeffeff@...il.com>
To:     netdev@...r.kernel.org
Subject: icmp6_send() is too expensive

As mentioned here:
https://www.spinics.net/lists/netdev/msg505054.html

icmp6_send() can be expensive when there are a lot of devices and
anycast addresses. One solution I've prototyped is adding a global
hash table to store and allow more efficient searches for anycast
addresses.  This works and prevents the long delays I've seen when
many neighbors are invalidated in large numbers.

A colleague mentioned that another alternative may be to do something
like an rt6_lookup on the address and check for the RTF_ANYCAST flag.
This is much simpler, and I'm in the process of testing it now.

Is there any preference or recommendation as to which way to proceed
before I submit a patch?

Thanks,
Jeff