From: Masami Hiramatsu <mhira...@kernel.org>
Date: Tue, 13 Feb 2018 01:29:03 +0900
> On Mon, 12 Feb 2018 00:08:46 -0500
> "Md. Islam" <misl...@kent.edu> wrote:
>> Recently tcp_probe kernel module has been replaced by trace_event. Old
>> tcp_probe had full=0 option where it only takes a snapshot only when
>> congestion window is changed. However I did not find such
>> functionality in trace_event.
> Yes, that seems broken to me. You should filter by using perf script or
> bpf. I'm not so clear about network stack, but it seems that cwnd can be
> set for each tcp connection. This means "current snd_cwnd" must be stored
> for each connection.
'bpf' is definitely the way to do custom stateful things like this.