From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cyrill Gorcunov <gorcunov@gmail.com>
Subject: Re: [RFC] net: ipv4 -- Introduce ifa limit per net
Date: Sat, 5 Mar 2016 18:57:14 +0300
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To: David Miller <davem@davemloft.net>
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On Fri, Mar 04, 2016 at 11:11:09PM -0500, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Fri, 04 Mar 2016 16:08:30 -0800
> 
> > __inet_del_ifa() should probably take into account in_dev->dead (no
> > promotion, no list scan...)
> 
> Indeed, that is the real problem:

Well, tried it out. Indeed it partially released the contention
but with patch applied I stuck with

Samples: 20K of event 'cpu-clock', Event count (approx.): 4647374938
Overhead  Shared Object        Symbol
  19.27%  [kernel]             [k] __local_bh_enable_ip
  15.97%  [kernel]             [k] lock_acquire
  15.12%  [kernel]             [k] fib_del_ifaddr
  11.66%  [kernel]             [k] lock_release
   7.57%  [kernel]             [k] lock_is_held
   5.35%  [kernel]             [k] lock_acquired
   3.26%  [kernel]             [k] _raw_spin_unlock_irqrestore
   3.04%  [kernel]             [k] __local_bh_disable_ip
   2.10%  [kernel]             [k] _raw_spin_unlock_irq
   1.54%  [kernel]             [k] native_save_fl
   1.37%  [kernel]             [k] ___might_sleep
   0.90%  [kernel]             [k] do_raw_spin_trylock
   0.83%  [kernel]             [k] nf_ct_iterate_cleanup
   0.77%  [kernel]             [k] debug_lockdep_rcu_enabled
   0.62%  [kernel]             [k] tick_nohz_idle_enter
   0.61%  [kernel]             [k] _raw_spin_lock
   0.58%  [kernel]             [k] __slab_alloc.isra.43.constprop.47
   0.42%  [kernel]             [k] get_parent_ip
   0.40%  [kernel]             [k] preempt_count_sub
   0.36%  [kernel]             [k] native_save_fl
   0.34%  [kernel]             [k] _raw_spin_unlock
   0.31%  [kernel]             [k] do_raw_spin_unlock

and until everything get cleaned up I couldn't connect
to the node via ssh. I continue playing with patch maybe
I find some other optimization paths. Thanks!