From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-x12f.google.com (mail-lf1-x12f.google.com [IPv6:2a00:1450:4864:20::12f]) (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 F1D743B29E for ; Thu, 29 Aug 2019 04:02:45 -0400 (EDT) Received: by mail-lf1-x12f.google.com with SMTP id z21so1796096lfe.1 for ; Thu, 29 Aug 2019 01:02:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=diT3zHBmm4ro0PHRVjAUjVwtJnhQzOci+2rHJIbx2NU=; b=bGgbzwhIvZ22Rrdw48zjidv0x8D8xlYND4KIMQIh/knN/D/Ey8t1Aa+kmZmevOEQ0h VquRkigjCj8Uupf2ccXl9dpRmtosmGWVCBkPlaeatCjSWbUumWfyP9RQKL2ExBMxgymC BlcLMuYBL4nEJ4lhWb58VNbdjJ95uH/qd4l7zhe4hpp+O9bRTLdSO14dV1hL6HIrl2L+ 3f0/xjzCp+5LLGf4aOdFnOUCm/+Dw125BXkg6bywOomgaez523qTpNg5SsgZL2GGII8K Ea9fx7TU7ye1R5ELp8KOnF0GIpYXOTlF4DFoa6jeQOHS/DkFB/v/jw7uP4Zn3XTG87hs MpYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=diT3zHBmm4ro0PHRVjAUjVwtJnhQzOci+2rHJIbx2NU=; b=t8AvtVQXQW0RyWCKZmUgwdIr2gkJ/xvLEIO12AzW83i7OYZPvHQiRVQoLMnXrpMCuf telOY6UEhNGWbDjCMbLomWq3doZbSm30AEAs8FdotPf9S31fNwx4oXueokLFGhtOgkc8 efQGABhKig82MROY9KZLAzFaVsH5duBvz7vjeUGgLcEoSE5idc9Ilwq+rDiwYigDhHxU UXq09Z/NzMn6HCYGJgXpcTKPvekgSN3iVqeCMzPs2c1m65dFX8V1XavfufxDqQu4hL0d w8GP2z5nDQUt/pHZQNjET9FWdN0TnbyWyaPjOqNuEUZIURImmVxqbqG+8IBpPXfFhrLd LMkA== X-Gm-Message-State: APjAAAWASQgB4e7SwjZUE+m2pDBYH0qU7Fg+bwT9DtECfnqIaG8/Wrk2 1xw4p5ziQ1CH9P8d+huGTWw= X-Google-Smtp-Source: APXvYqxiHdp1sGquPdaoG7IMVcgpIGKvAkJory4SmR02BnlXTCXyUsmMs1X3i/OOwtpwUI2V829Ynw== X-Received: by 2002:a19:7715:: with SMTP id s21mr5148396lfc.98.1567065764952; Thu, 29 Aug 2019 01:02:44 -0700 (PDT) Received: from jonathartonsmbp.lan (83-245-237-193-nat-p.elisa-mobile.fi. [83.245.237.193]) by smtp.gmail.com with ESMTPSA id v27sm232282ljv.86.2019.08.29.01.02.43 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Aug 2019 01:02:43 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) From: Jonathan Morton In-Reply-To: Date: Thu, 29 Aug 2019 11:02:41 +0300 Cc: ECN-Sane Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Dave Taht X-Mailer: Apple Mail (2.3445.9.1) Subject: Re: [Ecn-sane] rfc3168 sec 6.1.2 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: Thu, 29 Aug 2019 08:02:46 -0000 > On 29 Aug, 2019, at 5:08 am, Dave Taht wrote: >=20 > It would explain a lot if this was not actually implemented in Linux. > I'm afraid to look. cwnd reduction is capped to 2. 1 should put you > in quickack mode AND to go lower seemingly it's supposed to > then rely on the retransmit timer. Nowadays the same effect can be obtained from the pacing timer. Just = set the CA scale factor to 50% to get an effective minimum cwnd of 1, or = lower still if needed. In most of our SCE testing, we're now setting the SS scale factor to = 100% (the default is 200%, which means the cwnd is sent over half an RTT = and the other half is idle) and the CA scale factor to 40% (default is = 120%, so the effective minimum cwnd is actually 2.4 from a packet-pair = standpoint). See the last substantive slide in the IETF-105 SCE deck. - Jonathan Morton=