From bcdce7195e0eab55b37dbd53be53057f38006380 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 6 Oct 2009 17:28:29 -0700 Subject: net: speedup sk_wake_async() An incoming datagram must bring into cpu cache *lot* of cache lines, in particular : (other parts omitted (hash chains, ip route cache...)) On 32bit arches : offsetof(struct sock, sk_rcvbuf) =0x30 (read) offsetof(struct sock, sk_lock) =0x34 (rw) offsetof(struct sock, sk_sleep) =0x50 (read) offsetof(struct sock, sk_rmem_alloc) =0x64 (rw) offsetof(struct sock, sk_receive_queue)=0x74 (rw) offsetof(struct sock, sk_forward_alloc)=0x98 (rw) offsetof(struct sock, sk_callback_lock)=0xcc (rw) offsetof(struct sock, sk_drops) =0xd8 (read if we add dropcount support, rw if frame dropped) offsetof(struct sock, sk_filter) =0xf8 (read) offsetof(struct sock, sk_socket) =0x138 (read) offsetof(struct sock, sk_data_ready) =0x15c (read) We can avoid sk->sk_socket and socket->fasync_list referencing on sockets with no fasync() structures. (socket->fasync_list ptr is probably already in cache because it shares a cache line with socket->wait, ie location pointed by sk->sk_sleep) This avoids one cache line load per incoming packet for common cases (no fasync()) We can leave (or even move in a future patch) sk->sk_socket in a cold location Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/socket.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/socket.c') diff --git a/net/socket.c b/net/socket.c index 75655365b5fd..d53ad11558c3 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1100,11 +1100,14 @@ static int sock_fasync(int fd, struct file *filp, int on) fna->fa_next = sock->fasync_list; write_lock_bh(&sk->sk_callback_lock); sock->fasync_list = fna; + sock_set_flag(sk, SOCK_FASYNC); write_unlock_bh(&sk->sk_callback_lock); } else { if (fa != NULL) { write_lock_bh(&sk->sk_callback_lock); *prev = fa->fa_next; + if (!sock->fasync_list) + sock_reset_flag(sk, SOCK_FASYNC); write_unlock_bh(&sk->sk_callback_lock); kfree(fa); } -- cgit v1.2.3