From 3f80e08f40cdb308589a49077c87632fa4508b21 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 23 Oct 2018 11:54:16 -0700 Subject: tcp: add tcp_reset_xmit_timer() helper With EDT model, SRTT no longer is inflated by pacing delays. This means that RTO and some other xmit timers might be setup incorrectly. This is particularly visible with either : - Very small enforced pacing rates (SO_MAX_PACING_RATE) - Reduced rto (from the default 200 ms) This can lead to TCP flows aborts in the worst case, or spurious retransmits in other cases. For example, this session gets far more throughput than the requested 80kbit : $ netperf -H 127.0.0.2 -l 100 -- -q 10000 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 127.0.0.2 () port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 540000 262144 262144 104.00 2.66 With the fix : $ netperf -H 127.0.0.2 -l 100 -- -q 10000 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 127.0.0.2 () port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 540000 262144 262144 104.00 0.12 EDT allows for better control of rtx timers, since TCP has a better idea of the earliest departure time of each skb in the rtx queue. We only have to eventually add to the timer the difference of the EDT time with current time. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 188980c58f87..2868ef28ce52 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2979,8 +2979,8 @@ void tcp_rearm_rto(struct sock *sk) */ rto = usecs_to_jiffies(max_t(int, delta_us, 1)); } - inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, rto, - TCP_RTO_MAX); + tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS, rto, + TCP_RTO_MAX, tcp_rtx_queue_head(sk)); } } @@ -3255,8 +3255,8 @@ static void tcp_ack_probe(struct sock *sk) } else { unsigned long when = tcp_probe0_when(sk, TCP_RTO_MAX); - inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, - when, TCP_RTO_MAX); + tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, + when, TCP_RTO_MAX, NULL); } } -- cgit v1.2.3-59-g8ed1b