* [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr()
@ 2009-11-12 14:11 Eric Dumazet
2009-11-12 17:12 ` Stephen Hemminger
0 siblings, 1 reply; 6+ messages in thread
From: Eric Dumazet @ 2009-11-12 14:11 UTC (permalink / raw)
To: David S. Miller; +Cc: Linux Netdev List, Stephen Hemminger
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>
---
net/ipv4/devinet.c | 57 ++++++++++++++++++++++++++-----------------
1 files changed, 35 insertions(+), 22 deletions(-)
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index c2045f9..a74cb4e 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1174,39 +1174,52 @@ 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,
+ rcu_read_lock();
+ for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
+ idx = 0;
+ head = &net->dev_index_head[h];
+ 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;
- }
+ goto done;
+ }
cont:
- idx++;
+ idx++;
+ }
}
done:
- cb->args[0] = idx;
- cb->args[1] = ip_idx;
+ rcu_read_unlock();
+ cb->args[0] = h;
+ cb->args[1] = idx;
+ cb->args[2] = ip_idx;
return skb->len;
}
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr()
2009-11-12 14:11 [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr() Eric Dumazet
@ 2009-11-12 17:12 ` Stephen Hemminger
2009-11-12 17:44 ` Eric Dumazet
0 siblings, 1 reply; 6+ messages in thread
From: Stephen Hemminger @ 2009-11-12 17:12 UTC (permalink / raw)
To: Eric Dumazet; +Cc: David S. Miller, Linux Netdev List
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.
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr()
2009-11-12 17:12 ` Stephen Hemminger
@ 2009-11-12 17:44 ` Eric Dumazet
2009-11-12 19:12 ` Stephen Hemminger
2009-11-14 4:50 ` David Miller
0 siblings, 2 replies; 6+ messages in thread
From: Eric Dumazet @ 2009-11-12 17:44 UTC (permalink / raw)
To: Stephen Hemminger; +Cc: David S. Miller, Linux Netdev List
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>
---
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;
}
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr()
2009-11-12 17:44 ` Eric Dumazet
@ 2009-11-12 19:12 ` Stephen Hemminger
2009-11-12 19:14 ` Eric Dumazet
2009-11-14 4:50 ` David Miller
1 sibling, 1 reply; 6+ messages in thread
From: Stephen Hemminger @ 2009-11-12 19:12 UTC (permalink / raw)
To: Eric Dumazet; +Cc: David S. Miller, Linux Netdev List
On Thu, 12 Nov 2009 18:44:25 +0100
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> 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
One case where that might happen is:
modprobe dummy numdummies=10000
But dummy device should really be added with netlink, not at boot time.
--
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr()
2009-11-12 17:44 ` Eric Dumazet
2009-11-12 19:12 ` Stephen Hemminger
@ 2009-11-14 4:50 ` David Miller
1 sibling, 0 replies; 6+ messages in thread
From: David Miller @ 2009-11-14 4:50 UTC (permalink / raw)
To: eric.dumazet; +Cc: shemminger, netdev
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 12 Nov 2009 18:44:25 +0100
> [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>
Applied.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2009-11-14 4:49 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-11-12 14:11 [PATCH net-next-2.6] ipv4: speedup inet_dump_ifaddr() Eric Dumazet
2009-11-12 17:12 ` Stephen Hemminger
2009-11-12 17:44 ` Eric Dumazet
2009-11-12 19:12 ` Stephen Hemminger
2009-11-12 19:14 ` Eric Dumazet
2009-11-14 4:50 ` David Miller
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).