netdev - Re: [PATCH v2 net-next 0/4] batch calls to fib_flush and arp

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Date:	Fri, 5 Feb 2016 14:37:57 -0800
From:	Salam Noureddine <noureddine@...sta.com>
To:	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jiri Pirko <jiri@...lanox.com>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Julian Anastasov <ja@....bg>,
	Network Development <netdev@...r.kernel.org>
Cc:	Salam Noureddine <noureddine@...sta.com>
Subject: Re: [PATCH v2 net-next 0/4] batch calls to fib_flush and arp_ifdown

Forgot to mention the rtnl_lock hold time gain with these changes.

I got the following benchmark results on one of our switches.
Without this patch, deleting 1k interfaces with 100k routes in the fib held
the rtnl_lock for 13 seconds. With the patch, rtnl_lock hold time went down
to 5 seconds. The gain is even more pronounced with 512k routes in the FIB.
In this case, without the patch, rtnl_lock was held for 36 seconds and with
the patch it was held for 5.5 seconds.

On Thu, Feb 4, 2016 at 3:35 PM, Salam Noureddine <noureddine@...sta.com> wrote:
> Added changes suggested by Julian Anastasov in version 2.
>
> fib_flush walks the whole fib in a net_namespace and is called for
> each net_device being closed or unregistered. This can be very expensive
> when dealing with 100k or more routes in the fib and removal of a lot
> of interfaces. These four patches deal with this issue by calling fib_flush
> just once for each net namespace and introduce a new function arp_ifdown_all
> that does a similar optimization for the neighbour table.
>
> The benchmark tests were run on linux-3.18.
>
> Salam Noureddine (4):
>   net: add event_list to struct net and provide utility functions
>   net: dev: add batching to net_device notifiers
>   net: core: introduce neigh_ifdown_all for all down interfaces
>   net: fib: avoid calling fib_flush for each device when doing batch
>     close     and unregister
>
>  include/linux/netdevice.h   |  2 ++
>  include/net/arp.h           |  1 +
>  include/net/neighbour.h     |  1 +
>  include/net/net_namespace.h | 22 +++++++++++++++++++++
>  include/net/netns/ipv4.h    |  1 +
>  net/core/dev.c              | 48 ++++++++++++++++++++++++++++++++++++++++-----
>  net/core/neighbour.c        | 38 ++++++++++++++++++++++++++++-------
>  net/core/net_namespace.c    |  1 +
>  net/ipv4/arp.c              |  4 ++++
>  net/ipv4/fib_frontend.c     | 16 +++++++++++++--
>  10 files changed, 120 insertions(+), 14 deletions(-)
>
> --
> 1.8.1.4
>