| Message ID | 20240421042009.28046-3-lulie@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 2bf90a57f0e682872c5cfb66ffa45e432bb9c7ae |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | tcp: update TCPCB_EVER_RETRANS after trace_tcp_retransmit_skb() | expand |
On Sun, Apr 21, 2024 at 6:20 AM Philo Lu <lulie@linux.alibaba.com> wrote: > > 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 <lulie@linux.alibaba.com> Reviewed-by: Eric Dumazet <edumazet@google.com>
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 61119d42b0fd2..e19e74e005c1b 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3390,11 +3390,6 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 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); @@ -3404,6 +3399,12 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) } 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; }
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 <lulie@linux.alibaba.com> --- net/ipv4/tcp_output.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)