From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-x72a.google.com (mail-qk1-x72a.google.com [IPv6:2607:f8b0:4864:20::72a]) (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 76F8E3CB38; Wed, 4 Aug 2021 14:58:21 -0400 (EDT) Received: by mail-qk1-x72a.google.com with SMTP id t68so3760330qkf.8; Wed, 04 Aug 2021 11:58:21 -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 :cc; bh=aw/RKvBUXYnRV26Y4VDUoHFEx0m6OE4vyHajcN0iZJM=; b=UhvFPhTkrolFDGAD2LGPuHkET8DMQqBRldeRz3WkEkbEYEU4rXx619iM/8sBlwxvyJ kp8lKvKQTd1acJEm0NdMiwx9McE32+Z+5g6rRLlcXi1kq9LUu6WJ6julXIiSLZTpQyXe f/9fOLzfzvtINPARzHHoRi77zMIYvlejs/hdH3Q05Y/H2TWmr8SjAQ405mScFaPAVqgX zzSfB1eTWoGecmJk2QQIaFtEZBtfBtjRCOriCIsb6NsGtQ7uDMvqofdhyKvN05CTwhSB wqzDuClXRcf9z0BLL85LWXnljp5LWFNis5iuWrcFLDMjDC07zUiyFZjez2ux2kvU+Q2G +//g== 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:cc; bh=aw/RKvBUXYnRV26Y4VDUoHFEx0m6OE4vyHajcN0iZJM=; b=AJ+mhoCixuOVYi2GZIq/xdITk8NkG0sl600ZYldnd0Z/CtZdjR8bv8lmN/XMKrUKth vJMWtQWuMtE1oll43g64tcDorrDcYkFVVIQf0m7wYlxUmvu1SNc4rBUdZXPfdJZYLKE1 JifU1kCPIs2S9/eqRCITRuvHurtmEyht1mAzb3+24gbZ7GnkNb0zXoF7fL4QJ8OH9G1Q sUnodpJFrT9OgObF0Yk4NJ2k/3mkkZblSSL5k70ZuGJV0Ds0cytgqcO4wvnlQLeykQm7 EpEFpz9PO0PDJQxfgKjSbEmF3wTHz7gahxm9FMSJS8wB4C7JyeAIxdpx5ZGXIuUbbiKg F94Q== X-Gm-Message-State: AOAM5329c9mlbVwWMifXxyDtiSa1jgbX7GpS5YFAqAhZpW2dpK+ctWEA PrUf58rzXKYEwehac0VJBTNYSGpA9NRXBgXKsMw= X-Google-Smtp-Source: ABdhPJzOBPrtiKXWodg/fXh6j0Jau2Dse/to7f4Fd0S0fEablB7MhTzsQOLcDMNNXKwJ8n1Cn7lIttuMNCKHTICLcKo= X-Received: by 2002:ae9:e901:: with SMTP id x1mr901327qkf.360.1628103500957; Wed, 04 Aug 2021 11:58:20 -0700 (PDT) MIME-Version: 1.0 References: <058681B8-89EB-42ED-8E82-4048BA3C9504@cable.comcast.com> <649DC4B024D74B8BA6926ABFCD52DC79@SRA6> <5C65BC6E-1ABD-4432-B2CE-AC8BACDA363D@gmx.de> <87wnp1kqoj.wl-jch@irif.fr> In-Reply-To: <87wnp1kqoj.wl-jch@irif.fr> From: Jonathan Morton Date: Wed, 4 Aug 2021 21:58:09 +0300 Message-ID: To: Juliusz Chroboczek Cc: Mikael Abrahamsson , Sebastian Moeller , starlink@lists.bufferbloat.net, Mikael Abrahamsson via Bloat Content-Type: text/plain; charset="UTF-8" Subject: Re: [Starlink] [Bloat] Of interest: Comcast AQM Paper X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 Aug 2021 18:58:21 -0000 On Wed, 4 Aug 2021 at 21:31, Juliusz Chroboczek wrote: > A Cortex-A53 SoC at 1GHz with correctly designed Ethernet (i.e. not the > Raspberry Pi) can push 1Gbit from userspace without breaking a sweat. That was true of the earlier Raspberry Pis (eg. the Pi 3 uses a brace of Cortex-A53s) which use Ethernet chipsets attached over USB 2, but the Pi 4B has a directly integrated Ethernet port and two of the external USB ports are USB 3, giving enough bandwidth to attach a second GigE port. We have tested this in practice, and got full line rate throughput through Cake (though the CPU usage went up fairly sharply after about halfway). The Compute Module 4 exposes the same integrated Ethernet port, and a PCIe lane in place of the USB 3 chipset (the latter being attached to the former in the standard Pi 4B). This obviously allows attaching at least one real GigE port (with a free choice of PCIe-based chipset) at full line rate, without the intermediate step of USB. I think it would be reasonable to include a small Ethernet switch downstream of this, matching the connectivity of typical CPE on the LAN side. If a PCIe switch is inserted, then a choice of Mini-PCIe Wifi cards can be installed, with cables running to the normal array of external antennae, sidestepping the problem of USB Wifi dongles.