From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-il1-x12b.google.com (mail-il1-x12b.google.com [IPv6:2607:f8b0:4864:20::12b]) (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 8A6E53B2A4 for ; Sun, 29 Dec 2019 23:03:07 -0500 (EST) Received: by mail-il1-x12b.google.com with SMTP id f5so26929585ilq.5 for ; Sun, 29 Dec 2019 20:03:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc :content-transfer-encoding; bh=b9giYyw4YNDEBQcALedVmAct3EhX2FvFSQTg4LGiM8M=; b=tsMKMvbRhHyGcO51CNOMRd2B2gBlzu1xFCqMhU6U3SU4KdfYD3x2DetJuCG7Opon34 /GcRYjyhP690bFmmuB+z4KBWXpvDeTSIxqRQwScU6wE7XRnpUUJDDwvl1MzTpRQS7MlF LtIvTAsz0qCXaSh2Do2ytmFUnJlCaCicUpjB/ScAwVdduDgQk78xOrmc5l2U5JKu5SHq lmQoUrBhswVAnRQScf0BlHkomab/ETlo8VDkXBMzPoyYTPgCsgRz9RIeSSIxVqypa3Dv pooIXyA/QQRIC569nIt6LnHnx8225niEBB4p5r4XTrAeZtO8wiyYrwgPo+MdZOJYylsi RB8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc :content-transfer-encoding; bh=b9giYyw4YNDEBQcALedVmAct3EhX2FvFSQTg4LGiM8M=; b=cTqp7Dcl69TWLV3jBTb08oAbfaz5X1XUClak/dPxZZoCSupOz3GOOmCSy1QHiAvD/4 UyBdKTeT4oPvBbLW7GOtQ/AtpWCwJsIoNImdH8m4cNFuh/vVGR8M80Hfu0GyvKvY/hS6 1BpHGIy0p78gXj0DLALbTV/6geu1gx8/zhSsmlwK1+kYLaaRCjdLgkrG6YafFKvUlRPY Zy2HvNFUOFx084n1pSlT7D4fG5JhyzsrQsgohZFR9iuu00oG6447b0oD8dDSqpseXAIV p4HoI1e2ifPIkbtu7JI/TGyOv58vFaJ0hFvoUIeqFZnwEgVNyTtsMlk5gxeX7ju+vjRV I+Mw== X-Gm-Message-State: APjAAAUtMzuHYBDWVR9jxJggOg/h/VxtU9+5/2VnqHZLn8FvMbeoCg4m MmoldqMcGesCV8j6ZL7G3WbMNyu1k4Da5OLACsRa1933S0o= X-Google-Smtp-Source: APXvYqyOlJK4ViLnueEIIbf9NfW1p0RRes0e2j6pfjd1YP5Aa5+zLN6ReUlCAiJuilrOpgCsOqeGidVLDKaQpFHKJG8= X-Received: by 2002:a92:cd0c:: with SMTP id z12mr58096444iln.45.1577678586642; Sun, 29 Dec 2019 20:03:06 -0800 (PST) MIME-Version: 1.0 From: Dave Taht Date: Sun, 29 Dec 2019 20:02:55 -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: [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: Mon, 30 Dec 2019 04:03:07 -0000 this ecn# & codel in p4 paper had probably of most interest to me four poin= ts: 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 neat 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 https://resource.hpisys.com/seminar-papers/2019/paper/20191108_CoNEXT2019_E= nabling%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" --=20 Make Music, Not War Dave T=C3=A4ht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-435-0729