From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH net-next-2.6] net: dont hold rtnl mutex during netlink
 dump callbacks
Date: Thu, 28 Apr 2011 17:53:50 +0200
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	 <20110428084337.6b54603e@nehalam>
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Cc: David Miller <davem@davemloft.net>,
	Patrick McHardy <kaber@trash.net>,
	netdev <netdev@vger.kernel.org>,
	Remi Denis-Courmont <remi.denis-courmont@nokia.com>
To: Stephen Hemminger <shemminger@vyatta.com>
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Le jeudi 28 avril 2011 =C3=A0 08:43 -0700, Stephen Hemminger a =C3=A9cr=
it :
> On Thu, 28 Apr 2011 10:56:07 +0200
> Eric Dumazet <eric.dumazet@gmail.com> wrote:
>=20
> > Four years ago, Patrick made a change to hold rtnl mutex during net=
link
> > dump callbacks.
> >=20
> > I believe it was a wrong move. This slows down concurrent dumps, ma=
king
> > good old /proc/net/ files faster than rtnetlink in some situations.
> >=20
> > This occurred to me because one "ip link show dev ..." was _very_ s=
low
> > on a workload adding/removing network devices in background.
> >=20
> > All dump callbacks are able to use RCU locking now, so this patch d=
oes
> > roughly a revert of commits :
> >=20
> > 1c2d670f366 : [RTNETLINK]: Hold rtnl_mutex during netlink dump call=
backs
> > 6313c1e0992 : [RTNETLINK]: Remove unnecessary locking in dump callb=
acks
> >=20
> > This let writers fight for rtnl mutex and readers going full speed.
> >=20
> > It also takes care of phonet : phonet_route_get() is now called fro=
m rcu
> > read section. I renamed it to phonet_route_get_rcu()
> >=20
> > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> > Cc: Patrick McHardy <kaber@trash.net>
> > Cc: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
>=20
> Acked-by: Stephen Hemminger <shemminger@vyatta.com>
>=20

Thanks for reviewing Stephen=20