From: David Miller <davem@davemloft.net>
To: mhiramat@kernel.org
Cc: mislam4@kent.edu, tom.zanussi@linux.intel.com,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
stephen@networkplumber.org, mathieu.desnoyers@polymtl.ca,
rostedt@goodmis.org
Subject: Re: [PATCH net-next] trace_events_filter: conditional trace event (tcp_probe full=0)
Date: Mon, 12 Feb 2018 11:32:15 -0500 (EST) [thread overview]
Message-ID: <20180212.113215.529432620125895990.davem@davemloft.net> (raw)
In-Reply-To: <20180213012903.ef6b0efe5b896994ef8fc713@kernel.org>
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Tue, 13 Feb 2018 01:29:03 +0900
> On Mon, 12 Feb 2018 00:08:46 -0500
> "Md. Islam" <mislam4@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 Recently tcp_probe kernel module has been replaced by trace_event.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.
next prev parent reply other threads:[~2018-02-12 16:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-12 5:08 [PATCH net-next] trace_events_filter: conditional trace event (tcp_probe full=0) Md. Islam
2018-02-12 16:29 ` Masami Hiramatsu
2018-02-12 16:32 ` David Miller [this message]
2018-02-13 5:54 ` Md. Islam
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