From 85bdf7db5b53cdcc7a901db12bcb3d0063e3866d Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 27 Nov 2018 14:42:02 -0800 Subject: [PATCH] tcp: make tcp_space() aware of socket backlog Jean-Louis Dupond reported poor iscsi TCP receive performance that we tracked to backlog drops. Apparently we fail to send window updates reflecting the fact that we are under stress. Note that we might lack a proper window increase when backlog is fully processed, since __release_sock() clears sk->sk_backlog.len _after_ all skbs have been processed. This should not matter in practice. If we had a significant load through socket backlog, we are in a dangerous situation. Reported-by: Jean-Louis Dupond Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Acked-by: Yuchung Cheng Tested-by: Jean-Louis Dupond Signed-off-by: David S. Miller --- include/net/tcp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 0c61bf0a06da..3b522259da7d 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1368,7 +1368,7 @@ static inline int tcp_win_from_space(const struct sock *sk, int space) /* Note: caller must be prepared to deal with negative returns */ static inline int tcp_space(const struct sock *sk) { - return tcp_win_from_space(sk, sk->sk_rcvbuf - + return tcp_win_from_space(sk, sk->sk_rcvbuf - sk->sk_backlog.len - atomic_read(&sk->sk_rmem_alloc)); } -- 2.30.2