From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Emelyanov Subject: [PATCH 4/5 (resend)] net: Make ifindex generation per-net namespace (v2) Date: Tue, 07 Aug 2012 16:37:55 +0400 Message-ID: <50210C23.2070203@parallels.com> References: <501FD0F2.4040609@parallels.com> <501FD15F.70604@parallels.com> <5020F5C3.8010107@parallels.com> <1344341466.28967.78.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: David Miller , "Eric W. Biederman" , Linux Netdev List To: Eric Dumazet Return-path: Received: from mailhub.sw.ru ([195.214.232.25]:18984 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752630Ab2HGMiH (ORCPT ); Tue, 7 Aug 2012 08:38:07 -0400 In-Reply-To: <1344341466.28967.78.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: >> @@ -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 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 --- include/net/net_namespace.h | 1 + net/core/dev.c | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index ae1cd6c..6dc3db3 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -66,6 +66,7 @@ struct net { struct hlist_head *dev_name_head; struct hlist_head *dev_index_head; unsigned int dev_base_seq; /* protected by rtnl_mutex */ + int ifindex; /* core fib_rules */ struct list_head rules_ops; diff --git a/net/core/dev.c b/net/core/dev.c index 3ca300d..1f06df8 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5221,12 +5221,12 @@ int dev_ioctl(struct net *net, unsigned int cmd, void __user *arg) */ static int dev_new_index(struct net *net) { - static int ifindex; + int ifindex = net->ifindex; for (;;) { if (++ifindex <= 0) ifindex = 1; if (!__dev_get_by_index(net, ifindex)) - return ifindex; + return net->ifindex = ifindex; } } -- 1.7.6.5