From 230140cffa7feae90ad50bf259db1fa07674f3a7 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 7 Nov 2007 02:40:20 -0800 Subject: [INET]: Remove per bucket rwlock in tcp/dccp ehash table. As done two years ago on IP route cache table (commit 22c047ccbc68fa8f3fa57f0e8f906479a062c426) , we can avoid using one lock per hash bucket for the huge TCP/DCCP hash tables. On a typical x86_64 platform, this saves about 2MB or 4MB of ram, for litle performance differences. (we hit a different cache line for the rwlock, but then the bucket cache line have a better sharing factor among cpus, since we dirty it less often). For netstat or ss commands that want a full scan of hash table, we perform fewer memory accesses. Using a 'small' table of hashed rwlocks should be more than enough to provide correct SMP concurrency between different buckets, without using too much memory. Sizing of this table depends on num_possible_cpus() and various CONFIG settings. This patch provides some locking abstraction that may ease a future work using a different model for TCP/DCCP table. Signed-off-by: Eric Dumazet Acked-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- net/ipv4/inet_timewait_sock.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'net/ipv4/inet_timewait_sock.c') diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c index 4e189e28f306..a60b99e0ebdc 100644 --- a/net/ipv4/inet_timewait_sock.c +++ b/net/ipv4/inet_timewait_sock.c @@ -20,16 +20,16 @@ static void __inet_twsk_kill(struct inet_timewait_sock *tw, struct inet_bind_hashbucket *bhead; struct inet_bind_bucket *tb; /* Unlink from established hashes. */ - struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, tw->tw_hash); + rwlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash); - write_lock(&ehead->lock); + write_lock(lock); if (hlist_unhashed(&tw->tw_node)) { - write_unlock(&ehead->lock); + write_unlock(lock); return; } __hlist_del(&tw->tw_node); sk_node_init(&tw->tw_node); - write_unlock(&ehead->lock); + write_unlock(lock); /* Disassociate with bind bucket. */ bhead = &hashinfo->bhash[inet_bhashfn(tw->tw_num, hashinfo->bhash_size)]; @@ -59,6 +59,7 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, const struct inet_sock *inet = inet_sk(sk); const struct inet_connection_sock *icsk = inet_csk(sk); struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash); + rwlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash); struct inet_bind_hashbucket *bhead; /* Step 1: Put TW into bind hash. Original socket stays there too. Note, that any socket with inet->num != 0 MUST be bound in @@ -71,7 +72,7 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, inet_twsk_add_bind_node(tw, &tw->tw_tb->owners); spin_unlock(&bhead->lock); - write_lock(&ehead->lock); + write_lock(lock); /* Step 2: Remove SK from established hash. */ if (__sk_del_node_init(sk)) @@ -81,7 +82,7 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, inet_twsk_add_node(tw, &ehead->twchain); atomic_inc(&tw->tw_refcnt); - write_unlock(&ehead->lock); + write_unlock(lock); } EXPORT_SYMBOL_GPL(__inet_twsk_hashdance); -- cgit v1.2.3-59-g8ed1b