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Message-ID: <4AE06D81.4050003@gmail.com>
Date: Thu, 22 Oct 2009 16:34:41 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: "David S. Miller" <davem@...emloft.net>
CC: Linux Netdev List <netdev@...r.kernel.org>,
Benjamin LaHaise <bcrl@...et.ca>
Subject: [PATCH net-next-2.6] 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 <eric.dumazet@...il.com>
---
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 6994101..0addd45 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 fa88dcd..e7bada1 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 ba13b09..52ea418 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;
}
--
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