tcp: fix potential underestimation on rcv_rtt
When ms timestamp is used, current logic uses 1us in
tcp_rcv_rtt_update() when the real rcv_rtt is within 1 - 999us.
This could cause rcv_rtt underestimation.
Fix it by always using a min value of 1ms if ms timestamp is used.
Fixes: 645f4c6f2e
("tcp: switch rcv_rtt_est and rcvq_space to high resolution timestamps")
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
c009cb842f
commit
9ee11bd03c
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@ -508,9 +508,6 @@ static void tcp_rcv_rtt_update(struct tcp_sock *tp, u32 sample, int win_dep)
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u32 new_sample = tp->rcv_rtt_est.rtt_us;
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long m = sample;
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if (m == 0)
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m = 1;
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if (new_sample != 0) {
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/* If we sample in larger samples in the non-timestamp
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* case, we could grossly overestimate the RTT especially
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@ -547,6 +544,8 @@ static inline void tcp_rcv_rtt_measure(struct tcp_sock *tp)
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if (before(tp->rcv_nxt, tp->rcv_rtt_est.seq))
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return;
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delta_us = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcv_rtt_est.time);
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if (!delta_us)
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delta_us = 1;
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tcp_rcv_rtt_update(tp, delta_us, 1);
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new_measure:
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@ -563,8 +562,11 @@ static inline void tcp_rcv_rtt_measure_ts(struct sock *sk,
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(TCP_SKB_CB(skb)->end_seq -
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TCP_SKB_CB(skb)->seq >= inet_csk(sk)->icsk_ack.rcv_mss)) {
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u32 delta = tcp_time_stamp(tp) - tp->rx_opt.rcv_tsecr;
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u32 delta_us = delta * (USEC_PER_SEC / TCP_TS_HZ);
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u32 delta_us;
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if (!delta)
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delta = 1;
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delta_us = delta * (USEC_PER_SEC / TCP_TS_HZ);
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tcp_rcv_rtt_update(tp, delta_us, 0);
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}
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}
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