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tcp: skip big rtt sample if receive queue is not empty

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tcp_rcv_rtt_update() role is to keep an estimation
of RTT (tp->rcv_rtt_est.rtt_us) for receivers.

If an application is too slow to drain the TCP receive
queue, it is better to leave the RTT estimation small,
so that tcp_rcv_space_adjust() does not inflate
tp->rcvq_space.space and sk->sk_rcvbuf.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250513193919.1089692-9-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet
2025-05-13 19:39:16 +00:00
committed by Jakub Kicinski
parent b879dcb1ae
commit a00f135cd9
1 changed files with 3 additions and 0 deletions
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3
net/ipv4/tcp_input.c
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@@ -682,6 +682,9 @@ static void tcp_rcv_rtt_update(struct tcp_sock *tp, u32 sample, int win_dep)
*/
if (win_dep)
return;
/* Do not use this sample if receive queue is not empty. */
if (tp->rcv_nxt != tp->copied_seq)
return;
new_sample = old_sample - (old_sample >> 3) + sample;
}