From bcdce7195e0eab55b37dbd53be53057f38006380 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 6 Oct 2009 17:28:29 -0700 Subject: [PATCH] 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 --- include/net/sock.h | 3 ++- net/socket.c | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/include/net/sock.h b/include/net/sock.h index 1621935aad5..98398bdec57 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -504,6 +504,7 @@ enum sock_flags { SOCK_TIMESTAMPING_SOFTWARE, /* %SOF_TIMESTAMPING_SOFTWARE */ SOCK_TIMESTAMPING_RAW_HARDWARE, /* %SOF_TIMESTAMPING_RAW_HARDWARE */ SOCK_TIMESTAMPING_SYS_HARDWARE, /* %SOF_TIMESTAMPING_SYS_HARDWARE */ + SOCK_FASYNC, /* fasync() active */ }; static inline void sock_copy_flags(struct sock *nsk, struct sock *osk) @@ -1396,7 +1397,7 @@ static inline unsigned long sock_wspace(struct sock *sk) static inline void sk_wake_async(struct sock *sk, int how, int band) { - if (sk->sk_socket && sk->sk_socket->fasync_list) + if (sock_flag(sk, SOCK_FASYNC)) sock_wake_async(sk->sk_socket, how, band); } diff --git a/net/socket.c b/net/socket.c index 75655365b5f..d53ad11558c 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); }