netdev - Re: Scaling 'ip addr add' (was Re: What's the right way to use a *large* number of source addresses?)

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Date:	Wed, 28 May 2014 13:18:55 -0400
From:	sowmini varadhan <sowmini05@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Jamal Hadi Salim <jhs@...atatu.com>,
	Niels Möller <nisse@...thpole.se>,
	netdev <netdev@...r.kernel.org>, Jonas Bonn <jonas@...thpole.se>,
	Jiri Pirko <jiri@...nulli.us>
Subject: Re: Scaling 'ip addr add' (was Re: What's the right way to use a
 *large* number of source addresses?)

On Wed, May 28, 2014 at 10:48 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:

> Following patch helps a lot
> (30 seconds to add 65536 addresses on lo interface instead of 52 seconds
> on my host)

I haven't had a chance to try out your patch yet (thanks for
the "dont do a del" caveat :-)) and I'm going to try it out now,
 but reading your info makes me
wonder- in this case all the addresses that are being added
are static Ipv4 addrs, i.e., they are clearly IFA_F_PERMANENT
addresses, so check_lifetime() should not have too much work
to do (other than to examine the ifa_flags and continue). So
why is this making such a big difference?

Alternatively, afaict check_lifetime() is only interested in
an !IFA_F_PERMANENT. So maybe __inet_insert_ifa should
only do the {inet_hash_insert(..); /* reset check_lifetime_work */}
when it added a !PERMANENT address? Would this break
something else? (I realize it may need more changes elsewhere,
if the PERMANENT flag is modified on the fly, I've not checked
for those yet)

--Sowmini
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