From 9317bb69824ec8d078b0b786b6971aedb0af3d4f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 25 Apr 2016 10:39:32 -0700 Subject: [PATCH] net: SOCKWQ_ASYNC_NOSPACE optimizations SOCKWQ_ASYNC_NOSPACE is tested in sock_wake_async() so that a SIGIO signal is sent when needed. tcp_sendmsg() clears the bit. tcp_poll() sets the bit when stream is not writeable. We can avoid two atomic operations by first checking if socket is actually interested in the FASYNC business (most sockets in real applications do not use AIO, but select()/poll()/epoll()) This also removes one cache line miss to access sk->sk_wq->flags in tcp_sendmsg() Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/sock.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/net/sock.h b/include/net/sock.h index d63b8494124e..0f48aad9f8e8 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1940,11 +1940,17 @@ static inline unsigned long sock_wspace(struct sock *sk) */ static inline void sk_set_bit(int nr, struct sock *sk) { + if (nr == SOCKWQ_ASYNC_NOSPACE && !sock_flag(sk, SOCK_FASYNC)) + return; + set_bit(nr, &sk->sk_wq_raw->flags); } static inline void sk_clear_bit(int nr, struct sock *sk) { + if (nr == SOCKWQ_ASYNC_NOSPACE && !sock_flag(sk, SOCK_FASYNC)) + return; + clear_bit(nr, &sk->sk_wq_raw->flags); }