From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964997AbeBLQcS (ORCPT ); Mon, 12 Feb 2018 11:32:18 -0500 Received: from shards.monkeyblade.net ([184.105.139.130]:54544 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964902AbeBLQcR (ORCPT ); Mon, 12 Feb 2018 11:32:17 -0500 Date: Mon, 12 Feb 2018 11:32:15 -0500 (EST) Message-Id: <20180212.113215.529432620125895990.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) From: David Miller In-Reply-To: <20180213012903.ef6b0efe5b896994ef8fc713@kernel.org> References: <20180213012903.ef6b0efe5b896994ef8fc713@kernel.org> X-Mailer: Mew version 6.7 on Emacs 25.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu Date: Tue, 13 Feb 2018 01:29:03 +0900 > On Mon, 12 Feb 2018 00:08:46 -0500 > "Md. Islam" 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 Recently tcp_probe kernel module has been replaced by trace_event.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.