From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-il1-x131.google.com (mail-il1-x131.google.com [IPv6:2607:f8b0:4864:20::131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 9BE603B2A4 for ; Sat, 4 Jan 2020 17:01:53 -0500 (EST) Received: by mail-il1-x131.google.com with SMTP id z12so2946054iln.11 for ; Sat, 04 Jan 2020 14:01:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=FOi+e/IRjpaMXMGbuG3IDbS2O43vDeBZ4VVD2LxXHUA=; b=X0RgcysNeTrERlSqkqUuImGUIFvwSANYB2DxHY37CiaA8Lau5kWklZDGohPUQnxxaR /7znrG0BQfrOnPpgtHASc1UJxXbzSs+bwew/+DgAM+HPcPr2dtrsFtNDOKfL8baKmuOX tkn8pBrh52sMOyIs0HPVPVVuSjnmK8YLYGevlmBC9WpeEcfBfhazSZiapVRfcMeKr2A1 lGwDpA5H5AJSB/ccTy8pJtb8mPtkS24RKRXXohBbDYJQ8zvBpLxShW3YT41xcDGj9IS9 NVZdHAW8H3xkz5P6Jgd8B6NKXQquhtSyvOrzko7/y4D61HR7X23ErsUYbKx2RvRXClQL LjaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=FOi+e/IRjpaMXMGbuG3IDbS2O43vDeBZ4VVD2LxXHUA=; b=Ouj0iuPS9U+mTbkQ8sCG0a3xNv2CEPqtwMJ4WNdUlXlVoP/liF+3nfwKvjTviCIwF4 pfmepYQ88AGqlqVaK5IR2Q9u3ff0I2IAcJubPE8sHH06wgdX2pER52Dt6CNBBuen5FK7 O7ir06h14MqjxNv8se+UNdqrJLhy/h9y2hp1EzHc2Xtp+MDQsgp34JBvlBdWEZevN6Pb X/+uNusLPZmRK+eGB8Z3iMqXfPA86d/4LUa/t+KVwTlK/dNcm1NlICQonb/+cZxAFzRE 8gdYtmFOIbiN87B+QSOBPIDHw+sEbQYEH1InF3sl66AARfMkVbWFtkbI1l2dQkhCz8Ol 1Gyw== X-Gm-Message-State: APjAAAUMC3f9JGhVyAAUfMtw8S4liyKedHfr60IhScru6TVaHDtJ+CAf 8kOCRUdK0wNdyZ7ZL1a3z1HnA8ljonKsvbpKQkySWeepwBY= X-Google-Smtp-Source: APXvYqz7T4jj4c9La9djPYHwMAzBS7rjo6KdBUSBelGpnENEmOhac+gRItfYGUYPmfLQ1N5/rRztbPDznI17a21AuL0= X-Received: by 2002:a92:cd0c:: with SMTP id z12mr84511566iln.45.1578175312967; Sat, 04 Jan 2020 14:01:52 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Dave Taht Date: Sat, 4 Jan 2020 14:01:42 -0800 Message-ID: To: ECN-Sane Cc: kaichen@cse.ust.hk, webai@microsoft.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Ecn-sane] comments: "Enabling ECN for Datacenter Networks with RTT Variations" 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: Sat, 04 Jan 2020 22:01:53 -0000 On Sun, Dec 29, 2019 at 8:02 PM Dave Taht wrote: > > this ecn# & codel in p4 paper had probably of most interest to me four po= ints: > > 1) Codel like algorithm on a tofino switch, implemented in p4 > 2) with some source code published... Not the p4 code, darn it... > unless I missed it? > but a detailed description of how they used the timestamp field was ne= at > 3 Honestly I'd never thought about how much rtt variation a dc had, > nor do I know if this model is correct > 3) Not really clear what parameters the used for codel For CoDel, the interval is set to 240=C2=B5s while target is set to 10=C2= =B5s. > https://resource.hpisys.com/seminar-papers/2019/paper/20191108_CoNEXT2019= _Enabling%20ECN%20for%20Datacenter%20Networks%20with%20RTT%20Variations.pdf > > "Despite being successful, prior ECN-based transports have an > important drawback: they adopt a fxed RTT value in calculating > instantaneous ECN marking threshold while overlooking the RTT > variations in practice. In this paper, we reveal that the current > practice of using a fxed high-percentile RTT for ECN threshold > calculation can lead to persistent queue buildups, signifcantly > increasing packet latency. On the other hand, directly adopting lower > percentile RTTs results in throughput degradation. To handle the > problem, we introduce ECN!, a simple yet efective solution to enable > ECN for RTT variations. At its heart, ECN! inherits the current > instantaneous ECN marking (based on a high-percentile RTT) to achieve > high throughput and burst tolerance, while further marking packets > (conservatively) upon detecting long-term queue buildups to eliminate > unnecessary queueing delay without degrading throughput. We implement > ECN! on a Barefoot Tofno switch" > > -- > Make Music, Not War > > Dave T=C3=A4ht > CTO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-831-435-0729 --=20 Make Music, Not War Dave T=C3=A4ht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-435-0729