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[83.245.226.9]) by smtp.gmail.com with ESMTPSA id g18sm133495ljk.26.2019.03.19.20.42.20 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Mar 2019 20:42:20 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) From: Jonathan Morton In-Reply-To: <4D0CB5F2-93DD-4072-81C8-96F8ECAC870D@heistp.net> Date: Wed, 20 Mar 2019 05:42:19 +0200 Cc: ecn-sane@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <196CD487-B489-4C13-A13A-D005DE0457C5@gmail.com> References: <4D0CB5F2-93DD-4072-81C8-96F8ECAC870D@heistp.net> To: Pete Heist X-Mailer: Apple Mail (2.3445.9.1) Subject: Re: [Ecn-sane] cctrace prototype X-BeenThere: ecn-sane@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Discussion of explicit congestion notification's impact on the Internet List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Mar 2019 03:42:22 -0000 > On 20 Mar, 2019, at 2:41 am, Pete Heist wrote: >=20 > So I=E2=80=99m starting work on a tool to make congestion signal plots = in xplot.org format. It=E2=80=99s in Go for now and reads pcap files, = producing one plot for each flow of the timestamp vs signal proportion. = I=E2=80=99ll merge it to tcptrace later if needed, this is just faster = for getting it started. >=20 > Here are screenshots and xpl files of one flow from a 10 second, = 16-flow iperf upload with fq_codel_fast: >=20 > https://www.heistp.net/downloads/cctrace/ >=20 > For each point, right arrow is used for upstream and left for = downstream. >=20 > You can see that the SCE signals start sooner before CE takes over, = which could theoretically prevent CE with a cooperating TCP. Well, it's not *very* easy to see - but that is the idea in theory. It = might be easier to analyse such things (at this early stage of = development) with a single flow, or possibly a pair with staggered start = times. One thing I'm noticing is that the SCE rate drops off very sharply when = the CE marking rate rises, but the latter doesn't read higher than 50%. = Check your axis scale and your window average function for fenceposts. > It needs some work, and I=E2=80=99m not yet satisfied with the = windowing behavior. Choose a window size too low and the proportion = value is visibly quantized. Too high and changes aren=E2=80=99t well = reflected. I might be able to make a reasonable choice automatically = through. >=20 > Thoughts? Ok to discuss this on ecn-sane? >=20 > Also, feel free to imagine what else would help visualize CC = (different plot entirely? combined with throughput / RTT / TCP window?) = and I=E2=80=99ll try to make it happen... I'd like to see a sequence plot with the ECN codepoint indicated by = colour coding, and similarly for ECE/NS/CWR on the ack path. I'd also like to see a dynamic estimate of cwnd (or rather, in-flight = data), with similar colour coding and/or labelling, for correlation. - Jonathan Morton