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net: Convert TCP & DCCP hash tables to use RCU / hlist_nulls

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RCU was added to UDP lookups, using a fast infrastructure :
- sockets kmem_cache use SLAB_DESTROY_BY_RCU and dont pay the
  price of call_rcu() at freeing time.
- hlist_nulls permits to use few memory barriers.

This patch uses same infrastructure for TCP/DCCP established
and timewait sockets.

Thanks to SLAB_DESTROY_BY_RCU, no slowdown for applications
using short lived TCP connections. A followup patch, converting
rwlocks to spinlocks will even speedup this case.

__inet_lookup_established() is pretty fast now we dont have to
dirty a contended cache line (read_lock/read_unlock)

Only established and timewait hashtable are converted to RCU
(bind table and listen table are still using traditional locking)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2008-11-16 19:40:17 -08:00
committed by David S. Miller
parent 88ab1932ea
commit 3ab5aee7fe
13 changed files with 152 additions and 85 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
net/ipv4/tcp_ipv4.c
View File

@@ -1857,16 +1857,16 @@ EXPORT_SYMBOL(tcp_v4_destroy_sock);
#ifdef CONFIG_PROC_FS
/* Proc filesystem TCP sock list dumping. */
static inline struct inet_timewait_sock *tw_head(struct hlist_head *head)
static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
{
return hlist_empty(head) ? NULL :
return hlist_nulls_empty(head) ? NULL :
list_entry(head->first, struct inet_timewait_sock, tw_node);
}
static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
{
return tw->tw_node.next ?
hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
return !is_a_nulls(tw->tw_node.next) ?
hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
}
static void *listening_get_next(struct seq_file *seq, void *cur)
@@ -1954,8 +1954,8 @@ static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
static inline int empty_bucket(struct tcp_iter_state *st)
{
return hlist_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
hlist_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
}
static void *established_get_first(struct seq_file *seq)
@@ -1966,7 +1966,7 @@ static void *established_get_first(struct seq_file *seq)
for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
struct sock *sk;
struct hlist_node *node;
struct hlist_nulls_node *node;
struct inet_timewait_sock *tw;
rwlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
@@ -1975,7 +1975,7 @@ static void *established_get_first(struct seq_file *seq)
continue;
read_lock_bh(lock);
sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
if (sk->sk_family != st->family ||
!net_eq(sock_net(sk), net)) {
continue;
@@ -2004,7 +2004,7 @@ static void *established_get_next(struct seq_file *seq, void *cur)
{
struct sock *sk = cur;
struct inet_timewait_sock *tw;
struct hlist_node *node;
struct hlist_nulls_node *node;
struct tcp_iter_state *st = seq->private;
struct net *net = seq_file_net(seq);
@@ -2032,11 +2032,11 @@ get_tw:
return NULL;
read_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
} else
sk = sk_next(sk);
sk = sk_nulls_next(sk);
sk_for_each_from(sk, node) {
sk_nulls_for_each_from(sk, node) {
if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
goto found;
}
@@ -2375,6 +2375,7 @@ struct proto tcp_prot = {
.sysctl_rmem = sysctl_tcp_rmem,
.max_header = MAX_TCP_HEADER,
.obj_size = sizeof(struct tcp_sock),
.slab_flags = SLAB_DESTROY_BY_RCU,
.twsk_prot = &tcp_timewait_sock_ops,
.rsk_prot = &tcp_request_sock_ops,
.h.hashinfo = &tcp_hashinfo,