From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?ISO-8859-2?Q?Micha=B3_Miros=B3aw?= <mirqus@gmail.com>
Subject: Re: [PATCH] veth: use batched device unregister
Date: Mon, 9 May 2011 08:56:26 +0200
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Cc: David Miller <davem@davemloft.net>, Alex Bligh <alex@alex.org.uk>,
	netdev@vger.kernel.org, Jesse Gross <jesse@nicira.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Ben Greear <greearb@candelatech.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
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2011/5/9 Eric Dumazet <eric.dumazet@gmail.com>:
> veth devices dont use the batched device unregisters yet.
>
> Since veth are a pair of devices, it makes sense to use a batch of tw=
o
> unregisters, this roughly divide dismantle time by two.
[...]
> --- a/drivers/net/veth.c
> +++ b/drivers/net/veth.c
> @@ -451,8 +451,16 @@ static void veth_dellink(struct net_device *dev,=
 struct list_head *head)
> =C2=A0 =C2=A0 =C2=A0 =C2=A0priv =3D netdev_priv(dev);
> =C2=A0 =C2=A0 =C2=A0 =C2=A0peer =3D priv->peer;
>
> - =C2=A0 =C2=A0 =C2=A0 unregister_netdevice_queue(dev, head);
> - =C2=A0 =C2=A0 =C2=A0 unregister_netdevice_queue(peer, head);
> + =C2=A0 =C2=A0 =C2=A0 if (head =3D=3D NULL) {
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 LIST_HEAD(list);
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 /* make a batch of=
 two devices to speedup unregister */
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 unregister_netdevi=
ce_queue(dev, &list);
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 unregister_netdevi=
ce_queue(peer, &list);
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 unregister_netdevi=
ce_many(&list);
> + =C2=A0 =C2=A0 =C2=A0 } else {
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 unregister_netdevi=
ce_queue(dev, head);
> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 unregister_netdevi=
ce_queue(peer, head);
> + =C2=A0 =C2=A0 =C2=A0 }

You could change dellink callers to always pass head !=3D NULL. As a
side effect, unregister_netdevice_queue() would do just what its name
suggests.

Best Regards,
Micha=C5=82 Miros=C5=82aw