From 2bf90a57f0e682872c5cfb66ffa45e432bb9c7ae Mon Sep 17 00:00:00 2001 From: Philo Lu Date: Sun, 21 Apr 2024 12:20:09 +0800 Subject: [PATCH] tcp: update sacked after tracepoint in __tcp_retransmit_skb Marking TCP_SKB_CB(skb)->sacked with TCPCB_EVER_RETRANS after the traceopint (trace_tcp_retransmit_skb), then we can get the retransmission efficiency by counting skbs w/ and w/o TCPCB_EVER_RETRANS mark in this tracepoint. We have discussed to achieve this with BPF_SOCK_OPS in [0], and using tracepoint is thought to be a better solution. [0] https://lore.kernel.org/all/20240417124622.35333-1-lulie@linux.alibaba.com/ Signed-off-by: Philo Lu Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 99a1d88f7f47b..ce59e4499b66d 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3418,11 +3418,6 @@ start: err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); } - /* To avoid taking spuriously low RTT samples based on a timestamp - * for a transmit that never happened, always mark EVER_RETRANS - */ - TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; - if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG)) tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB, TCP_SKB_CB(skb)->seq, segs, err); @@ -3432,6 +3427,12 @@ start: } else if (err != -EBUSY) { NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL, segs); } + + /* To avoid taking spuriously low RTT samples based on a timestamp + * for a transmit that never happened, always mark EVER_RETRANS + */ + TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; + return err; } -- 2.30.2