Re: [Kernel Bug 86261] Ipset add/restore slowed to a crawl in kernel 3.17 (and 3.17.1)

[Thomas Graf <tgraf@suug.ch>]

On 10/26/14 at 06:12pm, Jozsef Kadlecsik wrote:
> Hi Thomas,
> 
> According to my tests the slowdown in ipset (netlink) is caused by the 
> patch:
> 
> commit e341694e3eb57fcda9f1adc7bfea42fe080d8d7a
> Author: Thomas Graf <tgraf@suug.ch>
> Date:   Sat Aug 2 11:47:45 2014 +0200
> 
>     netlink: Convert netlink_lookup() to use RCU protected hash table
>     
> Running the test provided in the report below in a KVM guest, the times 
> spent in adding ~430 entries, saving, then restoring those

Hi Jozsef,

Thanks for tracking this down. I would assume that the following fix
addresses the ipset regression as well:

commit 78fd1d0ab072d4d9b5f0b7c14a1516665170b565
Author: Thomas Graf <tgraf@suug.ch>
Date:   Tue Oct 21 22:05:38 2014 +0200

    netlink: Re-add locking to netlink_lookup() and seq walker

    The synchronize_rcu() in netlink_release() introduces unacceptable
    latency. Reintroduce minimal lookup so we can drop the
    synchronize_rcu() until socket destruction has been RCUfied.

    Cc: David S. Miller <davem@davemloft.net>
    Cc: Eric Dumazet <eric.dumazet@gmail.com>
    Reported-by: Steinar H. Gunderson <sgunderson@bigfoot.com>
    Reported-and-tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
    Signed-off-by: Thomas Graf <tgraf@suug.ch>
    Signed-off-by: David S. Miller <davem@davemloft.net>