From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-x135.google.com (mail-lf1-x135.google.com [IPv6:2a00:1450:4864:20::135]) (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 9C7C13BA8E for ; Sat, 1 Dec 2018 02:47:18 -0500 (EST) Received: by mail-lf1-x135.google.com with SMTP id p86so5721448lfg.5 for ; Fri, 30 Nov 2018 23:47:18 -0800 (PST) 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=mto+FvAFRmv8hswwVUlXyOjarnVQxruVz1RCRJzDrr4=; b=QGuhPeub0JtpW0CwMRVzHkHflVrkRGFKC3eF0NcgtaVk8jiuKuVN/g1LBfFXa5uN7K Veohe0UNWaRmGRgHRWMXAkPluV0G4FJDijxp+8PJeH2+/s3gD687tMk5MY6adVEyObkI w/BfJgv5GJhPhDsqUcZ1zno+qszC92QchN+edFQ+MA0o1n/amLda5KINGreAfbpDqXAr aImtsDYRzDrosxH528IE0eIpbenQatfYpz/Kd4+W120gpL8wSIqDJlDRlpOSm+R8utGH yhnmvibPuLRlsPtPhsgbIPa1jbPC1EZ6AcyMJP9C6ymU+SAIzRkgk9140PPNNvU8bBWh hNKw== 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=mto+FvAFRmv8hswwVUlXyOjarnVQxruVz1RCRJzDrr4=; b=bswB3VZhamZ4W+WzYuSmdIczOJqkuVVm2zdCG1gpaLAhPQ+ET6uSgnBv7VKwKbNJoE uNF2M/kYjB0kmRLbL9R2HM17Ltu4kiLxhQIdSOGdzLjILFQPfNyn++wi3XCeHuMVjXrH 2V7chCPmJvB5kLlWR1kW4ozKFT3CEBMO8Fjr4v1/D4G3/AJskqdxWIf/fFvXy9F46t3S XsdNrG8ioFmj4/eqOuvlb3fe4RQ68bp5MIPUla9Jj+RPqZjqMjiYKcV8kIyF2UHJ4pBE s+Bd0CTOfXMCILqfSjTPXpPq6FzqMr1gwQftqDNn4fGj0skyw6iV94mW5xwRvYsnAFzF W9Xw== X-Gm-Message-State: AA+aEWYmyY4kMm10Ya08qgpdX7sffwKp8eNYkm5efpeB1WKyV/dUO7Ul KDatiRy+/wOLJyQ2MwGDric= X-Google-Smtp-Source: AFSGD/UKLr5HjV+1bFFys35k8qADuwb35NbYzrJVHXA2C6/Er3UHSx+CXVZ0+CHTuZBVsjlPep9uOw== X-Received: by 2002:a19:4f0c:: with SMTP id d12mr5004150lfb.121.1543650437263; Fri, 30 Nov 2018 23:47:17 -0800 (PST) Received: from jonathartonsmbp.lan (83-245-236-220-nat-p.elisa-mobile.fi. [83.245.236.220]) by smtp.gmail.com with ESMTPSA id a2-v6sm1222789lji.13.2018.11.30.23.47.16 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 30 Nov 2018 23:47:16 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Subject: Re: monitoring queue length From: Jonathan Morton In-Reply-To: Date: Sat, 1 Dec 2018 09:47:15 +0200 Cc: bloat-devel@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <7ACB9F40-A42B-4807-85EF-10500F11E437@gmail.com> References: <3D0D58C0-B601-413B-B3EA-80C396E6187B@gmail.com> To: Azin Neishaboori X-Mailer: Apple Mail (2.3445.9.1) X-BeenThere: bloat-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Developers working on AQM, device drivers, and networking stacks" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 01 Dec 2018 07:47:18 -0000 > On 1 Dec, 2018, at 9:37 am, Azin Neishaboori = wrote: >=20 > So based on the dumbbell topology you described, I should see queue = buildup at the egress cellular interface of the router, right? Yes - but the actual cellular interface is on the far side of a = translation device, and so its queue is hidden from Linux. That's = unfortunately true of *every* 3G or LTE interface I've yet seen. Older = devices have a virtual serial PPP interface to the translator, newer = ones pretend to be Ethernet devices on the near side of the translator - = in both cases with much more bandwidth than the cellular interface = itself. This is actually quite a serious problem for people trying to improve = the quality of cellular Internet connections. All of the low-level = stuff that would be useful to experiment with is deliberately and = thoroughly hidden. If you put in an artificial bottleneck of 10Mbps on the outgoing = interface, you should be able to develop a queue there. You can use HTB = or HFSC, with the qdisc of your choice as a child on which the actual = queuing occurs. A better way to measure the impact of queuing in the raw device is to = observe the increase of latency when the link is loaded versus when it = is idle. I recommend using the Flent tool for that. - Jonathan Morton