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author | Eric Dumazet <eric.dumazet@gmail.com> | 2009-11-12 07:44:25 (GMT) |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2009-11-14 04:46:55 (GMT) |
commit | eec4df9885f7822cdeca82577a25cac4598fa7cf (patch) | |
tree | 36295f78f105e3f69b571edb3b2feddaf99dfb73 /net/ipv4/devinet.c | |
parent | 342bde1b70c79bfc8509b017b3987f3c7541ff8e (diff) | |
download | linux-fsl-qoriq-eec4df9885f7822cdeca82577a25cac4598fa7cf.tar.xz |
ipv4: speedup inet_dump_ifaddr()
Stephen Hemminger a écrit :
> On Thu, 12 Nov 2009 15:11:36 +0100
> Eric Dumazet <eric.dumazet@gmail.com> 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 <eric.dumazet@gmail.com>
>
> 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 <eric.dumazet@gmail.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/devinet.c')
-rw-r--r-- | net/ipv4/devinet.c | 61 |
1 files changed, 38 insertions, 23 deletions
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index c2045f9..7620382 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; } |