From: Cong Wang <xiyou.wangc...@gmail.com> Date: Fri, 13 Oct 2017 13:03:16 -0700
> We need a real-time notification for tcp retransmission > for monitoring. > > Of course we could use ftrace to dynamically instrument this > kernel function too, however we can't retrieve the connection > information at the same time, for example perf-tools [1] reads > /proc/net/tcp for socket details, which is slow when we have > a lots of connections. > > Therefore, this patch adds a tracepoint for __tcp_retransmit_skb() > and exposes src/dst IP addresses and ports of the connection. > This also makes it easier to integrate into perf. > > Note, I expose both IPv4 and IPv6 addresses at the same time: > for a IPv4 socket, v4 mapped address is used as IPv6 addresses, > for a IPv6 socket, LOOPBACK4_IPV6 is already filled by kernel. > Also, add sk and skb pointers as they are useful for BPF. > > 1. https://github.com/brendangregg/perf-tools/blob/master/net/tcpretrans > > Cc: Eric Dumazet <eduma...@google.com> > Cc: Alexei Starovoitov <alexei.starovoi...@gmail.com> > Cc: Hannes Frederic Sowa <han...@stressinduktion.org> > Cc: Brendan Gregg <brendan.d.gr...@gmail.com> > Cc: Neal Cardwell <ncardw...@google.com> > Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com> Applied, thank you.