From: Wei Wang Date: Thu, 26 Apr 2018 16:58:10 +0000 (-0700) Subject: tcp: remove mss check in tcp_select_initial_window() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c36207bd8774768fcb1de27bd06f3cd866db2421;p=linux.git tcp: remove mss check in tcp_select_initial_window() In tcp_select_initial_window(), we only set rcv_wnd to tcp_default_init_rwnd() if current mss > (1 << wscale). Otherwise, rcv_wnd is kept at the full receive space of the socket which is a value way larger than tcp_default_init_rwnd(). With larger initial rcv_wnd value, receive buffer autotuning logic takes longer to kick in and increase the receive buffer. In a TCP throughput test where receiver has rmem[2] set to 125MB (wscale is 11), we see the connection gets recvbuf limited at the beginning of the connection and gets less throughput overall. Signed-off-by: Wei Wang Acked-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Acked-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 95feffb6d53f8..d07c0dcc99aaa 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -229,11 +229,9 @@ void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, } } - if (mss > (1 << *rcv_wscale)) { - if (!init_rcv_wnd) /* Use default unless specified otherwise */ - init_rcv_wnd = tcp_default_init_rwnd(mss); - *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); - } + if (!init_rcv_wnd) /* Use default unless specified otherwise */ + init_rcv_wnd = tcp_default_init_rwnd(mss); + *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); /* Set the clamp no higher than max representable value */ (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp);