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authorThomas Graf <tgraf@suug.ch>2014-08-02 13:47:45 +0400
committerDavid S. Miller <davem@davemloft.net>2014-08-03 06:49:38 +0400
commite341694e3eb57fcda9f1adc7bfea42fe080d8d7a (patch)
tree12ac538a44609b3075bfaf98999ba68d9ff575cc /net/netlink/diag.c
parent7e1e77636e36075ebf118298855268468f1028e8 (diff)
downloadlinux-e341694e3eb57fcda9f1adc7bfea42fe080d8d7a.tar.xz
netlink: Convert netlink_lookup() to use RCU protected hash table
Heavy Netlink users such as Open vSwitch spend a considerable amount of time in netlink_lookup() due to the read-lock on nl_table_lock. Use of RCU relieves the lock contention. Makes use of the new resizable hash table to avoid locking on the lookup. The hash table will grow if entries exceeds 75% of table size up to a total table size of 64K. It will automatically shrink if usage falls below 30%. Also splits nl_table_lock into a separate mutex to protect hash table mutations and allow synchronize_rcu() to sleep while waiting for readers during expansion and shrinking. Before: 9.16% kpktgend_0 [openvswitch] [k] masked_flow_lookup 6.42% kpktgend_0 [pktgen] [k] mod_cur_headers 6.26% kpktgend_0 [pktgen] [k] pktgen_thread_worker 6.23% kpktgend_0 [kernel.kallsyms] [k] memset 4.79% kpktgend_0 [kernel.kallsyms] [k] netlink_lookup 4.37% kpktgend_0 [kernel.kallsyms] [k] memcpy 3.60% kpktgend_0 [openvswitch] [k] ovs_flow_extract 2.69% kpktgend_0 [kernel.kallsyms] [k] jhash2 After: 15.26% kpktgend_0 [openvswitch] [k] masked_flow_lookup 8.12% kpktgend_0 [pktgen] [k] pktgen_thread_worker 7.92% kpktgend_0 [pktgen] [k] mod_cur_headers 5.11% kpktgend_0 [kernel.kallsyms] [k] memset 4.11% kpktgend_0 [openvswitch] [k] ovs_flow_extract 4.06% kpktgend_0 [kernel.kallsyms] [k] _raw_spin_lock 3.90% kpktgend_0 [kernel.kallsyms] [k] jhash2 [...] 0.67% kpktgend_0 [kernel.kallsyms] [k] netlink_lookup Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netlink/diag.c')
-rw-r--r--net/netlink/diag.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/net/netlink/diag.c b/net/netlink/diag.c
index 1af29624b92f..7301850eb56f 100644
--- a/net/netlink/diag.c
+++ b/net/netlink/diag.c
@@ -4,6 +4,7 @@
#include <linux/netlink.h>
#include <linux/sock_diag.h>
#include <linux/netlink_diag.h>
+#include <linux/rhashtable.h>
#include "af_netlink.h"
@@ -101,16 +102,20 @@ static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
int protocol, int s_num)
{
struct netlink_table *tbl = &nl_table[protocol];
- struct nl_portid_hash *hash = &tbl->hash;
+ struct rhashtable *ht = &tbl->hash;
+ const struct bucket_table *htbl = rht_dereference(ht->tbl, ht);
struct net *net = sock_net(skb->sk);
struct netlink_diag_req *req;
+ struct netlink_sock *nlsk;
struct sock *sk;
int ret = 0, num = 0, i;
req = nlmsg_data(cb->nlh);
- for (i = 0; i <= hash->mask; i++) {
- sk_for_each(sk, &hash->table[i]) {
+ for (i = 0; i < htbl->size; i++) {
+ rht_for_each_entry(nlsk, htbl->buckets[i], ht, node) {
+ sk = (struct sock *)nlsk;
+
if (!net_eq(sock_net(sk), net))
continue;
if (num < s_num) {