From eec4df9885f7822cdeca82577a25cac4598fa7cf Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 12 Nov 2009 07:44:25 +0000 Subject: [PATCH] ipv4: speedup inet_dump_ifaddr() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Stephen Hemminger a écrit : > On Thu, 12 Nov 2009 15:11:36 +0100 > Eric Dumazet wrote: > >> When handling large number of netdevices, inet_dump_ifaddr() >> is very slow because it has O(N^2) complexity. >> >> Instead of scanning one single list, we can use the NETDEV_HASHENTRIES >> sub lists of the dev_index hash table, and RCU lookups. >> >> Signed-off-by: Eric Dumazet > > You might be able to make RCU critical section smaller by moving > it into loop. > Indeed. But we dump at most one skb (<= 8192 bytes ?), so rcu_read_lock holding time is small, unless we meet many netdevices without addresses. I wonder if its really common... Thanks [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr() When handling large number of netdevices, inet_dump_ifaddr() is very slow because it has O(N2) complexity. Instead of scanning one single list, we can use the NETDEV_HASHENTRIES sub lists of the dev_index hash table, and RCU lookups. Signed-off-by: Eric Dumazet Acked-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/ipv4/devinet.c | 61 +++++++++++++++++++++++++++++----------------- 1 file changed, 38 insertions(+), 23 deletions(-) diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index c2045f9615d..7620382058a 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1174,39 +1174,54 @@ nla_put_failure: static int inet_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb) { struct net *net = sock_net(skb->sk); - int idx, ip_idx; + int h, s_h; + int idx, s_idx; + int ip_idx, s_ip_idx; struct net_device *dev; struct in_device *in_dev; struct in_ifaddr *ifa; - int s_ip_idx, s_idx = cb->args[0]; + struct hlist_head *head; + struct hlist_node *node; - s_ip_idx = ip_idx = cb->args[1]; - idx = 0; - for_each_netdev(net, dev) { - if (idx < s_idx) - goto cont; - if (idx > s_idx) - s_ip_idx = 0; - in_dev = __in_dev_get_rtnl(dev); - if (!in_dev) - goto cont; + s_h = cb->args[0]; + s_idx = idx = cb->args[1]; + s_ip_idx = ip_idx = cb->args[2]; - for (ifa = in_dev->ifa_list, ip_idx = 0; ifa; - ifa = ifa->ifa_next, ip_idx++) { - if (ip_idx < s_ip_idx) - continue; - if (inet_fill_ifaddr(skb, ifa, NETLINK_CB(cb->skb).pid, + for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) { + idx = 0; + head = &net->dev_index_head[h]; + rcu_read_lock(); + hlist_for_each_entry_rcu(dev, node, head, index_hlist) { + if (idx < s_idx) + goto cont; + if (idx > s_idx) + s_ip_idx = 0; + in_dev = __in_dev_get_rcu(dev); + if (!in_dev) + goto cont; + + for (ifa = in_dev->ifa_list, ip_idx = 0; ifa; + ifa = ifa->ifa_next, ip_idx++) { + if (ip_idx < s_ip_idx) + continue; + if (inet_fill_ifaddr(skb, ifa, + NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq, - RTM_NEWADDR, NLM_F_MULTI) <= 0) - goto done; - } + RTM_NEWADDR, NLM_F_MULTI) <= 0) { + rcu_read_unlock(); + goto done; + } + } cont: - idx++; + idx++; + } + rcu_read_unlock(); } done: - cb->args[0] = idx; - cb->args[1] = ip_idx; + cb->args[0] = h; + cb->args[1] = idx; + cb->args[2] = ip_idx; return skb->len; }