Re: [PATCH 4/5 (resend)] net: Make ifindex generation per-net namespace (v2)

On Tue, 2012-08-07 at 16:37 +0400, Pavel Emelyanov wrote:

quoted

quoted

@@ -62,6 +62,7 @@ struct net {
 	struct sock 		*rtnl;			/* rtnetlink socket */
 	struct sock		*genl_sock;
 
+	int			ifindex;

could you place ifindex right after dev_base_seq : avoid two holes
and use the same cache line, dirtied in
list_netdevice()/unlist_netdevice()

Sure! Here it is:

From: Pavel Emelyanov <redacted>
Subject: [PATCH 4/5] net: Make ifindex generation per-net namespace

Strictly speaking this is only _really_ required for checkpoint-restore to
make loopback device always have the same index.

This change appears to be safe wrt "ifindex should be unique per-system"
concept, as all the ifindex usage is either already made per net namespace
of is explicitly limited with init_net only.

There are two cool side effects of this. The first one -- ifindices of
devices in container are always small, regardless of how many containers
we've started (and re-started) so far. The second one is -- we can speed
up the loopback ifidex access as shown in the next patch.

v2: Place ifindex right after dev_base_seq : avoid two holes and use the
    same cache line, dirtied in list_netdevice()/unlist_netdevice()

Signed-off-by: Pavel Emelyanov <redacted>
---

Acked-by: Eric Dumazet <edumazet@google.com>