From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-il1-x130.google.com (mail-il1-x130.google.com [IPv6:2607:f8b0:4864:20::130]) (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 9FB8F3B29D for ; Fri, 3 Apr 2020 14:50:00 -0400 (EDT) Received: by mail-il1-x130.google.com with SMTP id p13so8316748ilp.3 for ; Fri, 03 Apr 2020 11:50:00 -0700 (PDT) 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 :content-transfer-encoding; bh=NAr3keceGlx3h8ZOq3OF/JvxP5SZEsb1zRZfinOlWzk=; b=eataFSB9rRUwsHUwOOpJjij+6X+id4wku7paJClZQxaWDQGKyH/Au6TYS/bPvqdNrh LJfD/UsWTVvaQCJEc7IB+3lPU7PZP+tcoY+zFutr9Qc7YjH4kIwu1a/c+qw1VdzMJZ2m 0K5mojnqdRGu7uIPD8p62+q3rxfhjfupzZaF+J1LFl4m7D0m6MVYsnczb6zptYnUGk5B LwYGoYa01RxlxIMrXat7RAW9QimEC9qNPCXTG8v1ZVY66ONYzV3UcsbDpbj7lUI0qVcn UgvEm6GNgi/BisSzN1QEvClHqsFv3zptEm4qMJ/0qAtiNT47/BdNpqDpaFFJuMaKY8a9 9gYg== 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:content-transfer-encoding; bh=NAr3keceGlx3h8ZOq3OF/JvxP5SZEsb1zRZfinOlWzk=; b=QKoqLl+PGcFySaCJzrSj9T0i2ihDwcH29pJJRalDRfVI7PS+Mcgker2WGJZbVZ0ZFI l7R1VeiSUi76e73gBnvevK4FJ7GsmkgAy8bnAY4z/Fau1zYt37+yTzh/2WKFXMM2mQtK hO/V4M17wTCcvGRg6w0XdPpX9067nzdiS1ToiH+gFrRNk4FHA8pIxwyquxCyM+cqd5e5 dUli6g2UAbOFAWQtKHG/r86OzlGG+tqm6o9ZEUjLKCv7PXSFFSlIT72LG5B4ZT+FlhnM HfQRkjJLd/tc0cAT9Tv+JkChPosLG37TDniC8O4wnfKyQ5M89sM5DpdCv+FW+JIbgz34 Adkw== X-Gm-Message-State: AGi0PuZ7Dj55ipuHRASKsfH/WkCyVzOCVBe93wc++ZoX1rHMB4kr9MRu X/KYcsSdDjQaQMm9ZBYC8W7jWIyOi5WrCjgT7T8= X-Google-Smtp-Source: APiQypIBeZ01PMKmqyEfpy/h2ml/Xg0d4O7EUK9vUGbmKX9DDjv5kRjD4EZF26flYVuH9dVRZBufVwQ7ZyIMNvKs4EI= X-Received: by 2002:a92:a312:: with SMTP id a18mr10250549ili.249.1585939800086; Fri, 03 Apr 2020 11:50:00 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Dave Taht Date: Fri, 3 Apr 2020 11:49:48 -0700 Message-ID: To: "Alexander E. Patrakov" , Cake List Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Cake] tc-cake(8) needs to explain a common mistake X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 03 Apr 2020 18:50:00 -0000 so nice to know cake has made it to russia!!! On Fri, Apr 3, 2020 at 11:46 AM Alexander E. Patrakov wrote: > > Hello, > > there is a recurring cargo cult pattern in many forums (e.g. OpenWRT): > people keep suggesting various overhead compensation parameters to > tc-cake without checking what's the bottleneck. They just assume that > it is always related to the link-layer technology of the connection. > > This assumption is mostly incorrect, and this needs to be explained in > the manual page to stop the cargo cult. E.g., here in Russia, in the > past year, I had a 1Gbit/s link (1000BASE-X) but they shaped my > connection down to 500 Mbit/s because that's the bandwidth that I paid > for. I.e. the link from my router to the ISP equipment was not the > bottleneck, it was the ISP's shaper. > > How about the following addition to the tc-cake(8) manual page, just > before "Manual Overhead Specification"? Feel free to edit. > > General considerations > ------------------------------- > > Do not blindly set the overhead compensation parameters to match the > internet connection link type and protocols running on it. Doing so > makes sense only if that link (and not something further in the path, > like the ISP's shaper) is indeed the bottleneck. > > Example 1: the ADSL modem connects at 18 Mbit/s, but the ISP further > throttles the speed to 15 Mbit/s because that's what the user pays > for, and does so with a shaper that has bufferbloat. Then, the "adsl" > keyword is likely not appropriate, because the ISP's shaper operates > on the IP level. The bandwidth needs to be set slightly below 15 > Mbit/s. > > Example 2: the ADSL modem connects at 18 Mbit/s, and the user pays for > "as fast as the modem can get" connection. Then, the "adsl" keyword is > relevant, and the bandwidth needs to be set to 18 Mbit/s. > > Example 3: the user has a 100BASE-TX Ethernet connection, and pays for > the full 100 Mbit/s bandwidth (i.e. there is no shaper further up). > Then, the "ethernet" keyword is relevant, and the bandwidth needs to > be set to 100 Mbit/s. > > -- > Alexander E. Patrakov > CV: http://pc.cd/PLz7 --=20 Make Music, Not War Dave T=C3=A4ht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-435-0729