From 7c28bd0b8ec4d128bd7660671d1b626b0abc471f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 24 Oct 2009 06:13:17 -0700 Subject: [PATCH] rtnetlink: speedup rtnl_dump_ifinfo() 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 Signed-off-by: David S. Miller --- include/net/net_namespace.h | 4 ++++ net/core/dev.c | 7 ++----- net/core/rtnetlink.c | 37 ++++++++++++++++++++++++------------- 3 files changed, 30 insertions(+), 18 deletions(-) diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 699410142bf..0addd45038a 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -28,6 +28,10 @@ struct ctl_table_header; struct net_generic; struct sock; + +#define NETDEV_HASHBITS 8 +#define NETDEV_HASHENTRIES (1 << NETDEV_HASHBITS) + struct net { atomic_t count; /* To decided when the network * namespace should be freed. diff --git a/net/core/dev.c b/net/core/dev.c index fa88dcd476d..e7bada1d5ed 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -193,18 +193,15 @@ static struct list_head ptype_all __read_mostly; /* Taps */ DEFINE_RWLOCK(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) { 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) { - return &net->dev_index_head[ifindex & ((1 << NETDEV_HASHBITS) - 1)]; + return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)]; } /* Device list insertion */ diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index ba13b0974a7..52ea418d530 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -682,22 +682,33 @@ nla_put_failure: static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb) { struct net *net = sock_net(skb->sk); - int idx; - int s_idx = cb->args[0]; + int h, s_h; + int idx = 0, s_idx; struct net_device *dev; - - idx = 0; - for_each_netdev(net, dev) { - 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) - break; + struct hlist_head *head; + struct hlist_node *node; + + s_h = cb->args[0]; + s_idx = cb->args[1]; + + for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) { + idx = 0; + head = &net->dev_index_head[h]; + hlist_for_each_entry(dev, node, head, index_hlist) { + 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: - idx++; + idx++; + } } - cb->args[0] = idx; +out: + cb->args[1] = idx; + cb->args[0] = h; return skb->len; } -- 2.41.0