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) especially with high RTT
connections as in these environments rcvq_space.space will be the same
as rcv_wnd so TCP autotuning will never start because
sender can't send more than rcv_wnd size in one round trip.
To address this issue this patch is decreasing the initial
rcvq_space.space so TCP autotuning kicks in whenever the sender is
able to send more than 5360 bytes in one round trip regardless the
receiver's 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@xxxxxxxxxx>
---
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);
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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