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rtnetlink: speedup rtnl_dump_ifinfo()

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When handling large number of netdevice, rtnl_dump_ifinfo()
is very slow because it has O(N^2) complexity.

Instead of scanning one single list, we can use the 256 sub lists
of the dev_index hash table.

This considerably speedups "ip link" operations

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2009-10-24 06:13:17 -07:00
committed by David S. Miller
parent 8d5b2c084d
commit 7c28bd0b8e
3 changed files with 29 additions and 17 deletions
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4
include/net/net_namespace.h
View File

@@ -28,6 +28,10 @@ struct ctl_table_header;
struct net_generic; struct net_generic;
struct sock; struct sock;
#define NETDEV_HASHBITS 8
#define NETDEV_HASHENTRIES (1 << NETDEV_HASHBITS)
struct net { struct net {
atomic_t count; /* To decided when the network atomic_t count; /* To decided when the network
* namespace should be freed. * namespace should be freed.

7
net/core/dev.c
View File

@@ -193,18 +193,15 @@ static struct list_head ptype_all __read_mostly; /* Taps */
DEFINE_RWLOCK(dev_base_lock); DEFINE_RWLOCK(dev_base_lock);
EXPORT_SYMBOL(dev_base_lock); EXPORT_SYMBOL(dev_base_lock);
#define NETDEV_HASHBITS 8
#define NETDEV_HASHENTRIES (1 << NETDEV_HASHBITS)
static inline struct hlist_head *dev_name_hash(struct net *net, const char *name) static inline struct hlist_head *dev_name_hash(struct net *net, const char *name)
{ {
unsigned hash = full_name_hash(name, strnlen(name, IFNAMSIZ)); unsigned hash = full_name_hash(name, strnlen(name, IFNAMSIZ));
return &net->dev_name_head[hash & ((1 << NETDEV_HASHBITS) - 1)]; return &net->dev_name_head[hash & (NETDEV_HASHENTRIES - 1)];
} }
static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex) static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
{ {
return &net->dev_index_head[ifindex & ((1 << NETDEV_HASHBITS) - 1)]; return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)];
} }
/* Device list insertion */ /* Device list insertion */

35
net/core/rtnetlink.c
View File

@@ -682,22 +682,33 @@ nla_put_failure:
static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb) static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
{ {
struct net *net = sock_net(skb->sk); struct net *net = sock_net(skb->sk);
int idx; int h, s_h;
int s_idx = cb->args[0]; int idx = 0, s_idx;
struct net_device *dev; struct net_device *dev;
struct hlist_head *head;
struct hlist_node *node;
idx = 0; s_h = cb->args[0];
for_each_netdev(net, dev) { s_idx = cb->args[1];
if (idx < s_idx)
goto cont; for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
if (rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK, idx = 0;
NETLINK_CB(cb->skb).pid, head = &net->dev_index_head[h];
cb->nlh->nlmsg_seq, 0, NLM_F_MULTI) <= 0) hlist_for_each_entry(dev, node, head, index_hlist) {
break; if (idx < s_idx)
goto cont;
if (rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK,
NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, 0,
NLM_F_MULTI) <= 0)
goto out;
cont: cont:
idx++; idx++;
}
} }
cb->args[0] = idx; out:
cb->args[1] = idx;
cb->args[0] = h;
return skb->len; return skb->len;
} }