From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) (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 DFBBD3B29E; Mon, 7 Aug 2023 12:34:21 -0400 (EDT) Received: by mail-pj1-x1029.google.com with SMTP id 98e67ed59e1d1-26814e27a9eso2367052a91.0; Mon, 07 Aug 2023 09:34:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1691426061; x=1692030861; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=d+WtLhZSdYWdNIZZcLdlVp5vkvwuyPet1TyaeJMDY6w=; b=KNgpyGUutFOoptJWMJuLnFXGOPbFHwTS2CWG2WT0BVHhz1lEtUdK/2dabYBQn5Z/8z YzazQSp6bhEZvl+5Ozj4KbrF0oFwrpHBYApDM+4cNM52MYndc19vFNtrjDu6q5EhYYi+ 50OJXvUc8VNaJHgOZJ8B+a0TH9ubi9zIrArjXyElVxnHsXo5K7oIHGw8Mz63gkF76jgy 9MZ9HMI6E0fcMUDeEAX2xQ1JuVmcG7E14dWFYk2/AFH+SD9iqXFdub08E5j5s01u5W9J yi+xLx/ANmsyZedTOcXxscKfW2Gqw/5odr4eZs2WRL5XSLyVxntOflG8QgI7YvZhxedW rwHQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691426061; x=1692030861; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=d+WtLhZSdYWdNIZZcLdlVp5vkvwuyPet1TyaeJMDY6w=; b=ETVelffsqlPVriVYEXs2E1TZaB4xsC+t2Otz9k2bqo3tkmEMYDcsEKtwxLnzCUT7DW 8oDdYoOaAbd++FRHPf6xyc10WI69CisG1H0rLr55xH1i3cs5c3FVbSj79On4QC/tYHWx CF5hCwqDczhcAUqk70TI6PLI7Fq/YPVH5A2g5/Ptli+wOJz0oFjVN5qt580itxL/wR0i +VK+rJFMDJcgFxpud3kvCEJxnD2kUALWt9ZdmSn57RG10wd9txu4OgbXcEntyk+HBqJ9 fyeTsvwS7t1K4MW/a2rH9T6RULhTUbNbzc9lrVmDHPUaVbjERrh8buLTSEI5e3pvWSEf aGcA== X-Gm-Message-State: AOJu0Ywt8Zwmm9+bmTje3pPgxdb5usaJTXgvuc+ESUJux8LUVXVyblfh VqY8O3lEmNGmM0F8QNW7U4ZkP+9soCHreSEA7Ns= X-Google-Smtp-Source: AGHT+IGlBviKoqpCeOnk1SaT/wym33cYHAQZilInjkoTUQQ1psnjWpqDUeYKRhYbv27bY+GV1f3U3dve7Qthyz6636Q= X-Received: by 2002:a17:90b:4f84:b0:268:c29:52ad with SMTP id qe4-20020a17090b4f8400b002680c2952admr6865235pjb.13.1691426060611; Mon, 07 Aug 2023 09:34:20 -0700 (PDT) MIME-Version: 1.0 References: <6392cb1d-92e5-f289-c684-5850bf87df4a@kit.edu> <61DEDE16-34C9-430E-BEED-0D52E1F92132@gmx.de> In-Reply-To: <61DEDE16-34C9-430E-BEED-0D52E1F92132@gmx.de> From: Dave Taht Date: Mon, 7 Aug 2023 09:34:05 -0700 Message-ID: To: Sebastian Moeller Cc: "Bless, Roland (TM)" , bloat , codel@lists.bufferbloat.net Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Codel] [Bloat] slow start: small chunks can talk X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Aug 2023 16:34:22 -0000 In general these papers seem quite close to a couple ideas I have been working on for a few years, and getting close to publication on. I do not know what to do about it. Soliciting input here: https://www.linkedin.com/feed/update/urn:li:activity:7092544418255171585/ On Mon, Aug 7, 2023 at 3:18=E2=80=AFAM Sebastian Moeller = wrote: > > Hi Roland. > > > On Aug 7, 2023, at 10:48, Bless, Roland (TM) via Bloat wrote: > > > > Hi Dave, > > > > On 01.08.23 at 00:36 Dave Taht via Bloat wrote: > >> Promising approach: > >> https://ieeexplore.ieee.org/document/10188775 > > > > It's a pity that neither the authors nor the reviewers were aware of ea= rlier related work that you also sent here to the list: > > > > L. Guo and J. Y. B. Lee, "TCP-FLASH - A Fast Reacting TCP for Modern Ne= tworks," in IEEE Access, vol. 9, pp. 68861-68879, 2021, doi: 10.1109/ACCESS= .2021.3077612. > > Interesting link. This still uses essentially a packet-pair measu= ring method (send packet back2back, look at time difference in resulting AC= K packets to estimate bottleneck bandwidth in the forward direction). These= are still not robust or reliable... (parallel path, reordering, or simply = congestion on the reverse path, ACK filtering, ACK compression by GRO on th= e receiver end, ...). Now, well possible that packet-pair data, while not p= erfect, might still be good enough for the intended purpose... And even for= a traditional slow-start having an educated guess when to leave the expone= ntial growth phase could be helpful... > > More over, let's assume any of these (let's short circuit the pro= bing phase) will actually be deployed at scale; how will the network cope w= ith the much more aggressive ramp-up of such flows (essentially initial-win= dow as one batch the switch to estimated capacity once the bottleneck rate = is estimated). It is fun to see a single/few of such flows do the right thi= ng, but what about having the majority of flows use such methods? (Which wi= ll likely invalidate the bottleneck rate estimate quickly). > > I guess I might be too cautious here, but I personally see the ex= ponential ramp-up in more traditional slow-start already as pretty aggressi= ve and yet more adaptive to changing capacity than jumping to the estimated= capacity essentially cold (I have similar hesitation with the careful resu= me internet draft). > > Regards > Sebastian > > P.S.: "To tackle this problem, FLASH is designed to suppress > the AWnd constraint unless it is zero. This opportunistic > transmission technique, first proposed by Liu and Lee [6], > allows FLASH to send data beyond the AWnd limit up to > CWnd amount of packets inflight. " > > This is quite an euphemism "opportunistic transmission technique" for sim= ply ignoring parts of the protocol... > > P.P.S.: Dave's link is behind a pay-wall, so I have no idea about that pa= per beyond the abstract... but if they also relay on packet-pair bandwidth = estimates and an faster-than-slow-start ramp-up, I would expect similar iss= ues. > > > > > > > The fast launch phase and especially the CWnd-Compensated Bandwidth Est= imator (CCBE) are quite similar and a comparison of both approaches > > would have been interesting... > > > > Regards, > > Roland > > > > _______________________________________________ > > Bloat mailing list > > Bloat@lists.bufferbloat.net > > https://lists.bufferbloat.net/listinfo/bloat > --=20 Podcast: https://www.youtube.com/watch?v=3DbxmoBr4cBKg Dave T=C3=A4ht CSO, LibreQos