On Fri, Dec 4, 2020 at 7:08 PM Hazem Mohamed Abuelfotoh abuehaze@amazon.com wrote:
Previously receiver buffer auto-tuning starts after receiving one advertised window amount of data.After the initial receiver buffer was raised by commit a337531b942b ("tcp: up initial rmem to 128KB and SYN rwin to around 64KB"),the receiver buffer may take too long for TCP autotuning to start raising the receiver buffer size. commit 041a14d26715 ("tcp: start receiver buffer autotuning sooner") tried to decrease the threshold at which TCP auto-tuning starts but it's doesn't work well in some environments where the receiver has large MTU (9001) configured specially within environments where RTT is high. To address this issue this patch is relying on RCV_MSS so auto-tuning can start early regardless the receiver configured MTU. Fixes: a337531b942b ("tcp: up initial rmem to 128KB and SYN rwin to around 64KB") Fixes: 041a14d26715 ("tcp: start receiver buffer autotuning sooner")Signed-off-by: Hazem Mohamed Abuelfotoh abuehaze@amazon.com
net/ipv4/tcp_input.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 389d1b340248..f0ffac9e937b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -504,13 +504,14 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb) static void tcp_init_buffer_space(struct sock *sk) { int tcp_app_win = sock_net(sk)->ipv4.sysctl_tcp_app_win;
struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); int maxwin; if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK)) tcp_sndbuf_expand(sk);
tp->rcvq_space.space = min_t(u32, tp->rcv_wnd, TCP_INIT_CWND * tp->advmss);
tp->rcvq_space.space = min_t(u32, tp->rcv_wnd, TCP_INIT_CWND * icsk->icsk_ack.rcv_mss);
So are you claiming icsk->icsk_ack.rcv_mss is related to MTU 9000 ?
RCV_MSS is not known until we receive actual packets... The initial value is somthing like 536 if I am not mistaken.
I think your patch does not match the changelog.
tcp_mstamp_refresh(tp); tp->rcvq_space.time = tp->tcp_mstamp; tp->rcvq_space.seq = tp->copied_seq;-- 2.16.6
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