From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vc0-x22e.google.com (mail-vc0-x22e.google.com [IPv6:2607:f8b0:400c:c03::22e]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 6ADE721F237 for ; Thu, 26 Feb 2015 03:34:10 -0800 (PST) Received: by mail-vc0-f174.google.com with SMTP id id10so3699049vcb.5 for ; Thu, 26 Feb 2015 03:34:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=gJL801XGsP5GY7hWm6c9NdcVLi9pbyrq/IflH+2rktA=; b=VYR7pI1YEQMU7S5+oWGPJ3xKYkyGHdU+1A/HdqytLu5sUxvDfhHyyeP8LdGjuCoFQS +nYV76gAq873hPVHf3mYW22znYbjG23/izhhqlUguBn4lbO2Bani2u6TL/rLFxOq4FM3 2JLNfPIuGZbJTlfCdG12VQEOZ1qcC9lDwOBwdOXXrUuUlrl6oM0nI/l1uIYhLNUDGZQN XwuXgCzURhaqZxN+Ht1SfNQGF22mQGzHuBXKUtxYlIByEijnHmF2xHbXcdJo/oe07LGH RveHrM0L/po3E/JRBdIVY4OcBw82Ma3qvbqk2xhcfv8esHxsEkSRj3JE7Jhv6qmsO/5p N/2g== MIME-Version: 1.0 X-Received: by 10.52.12.138 with SMTP id y10mr8200853vdb.35.1424950449854; Thu, 26 Feb 2015 03:34:09 -0800 (PST) Received: by 10.52.24.79 with HTTP; Thu, 26 Feb 2015 03:34:09 -0800 (PST) Received: by 10.52.24.79 with HTTP; Thu, 26 Feb 2015 03:34:09 -0800 (PST) In-Reply-To: References: <201502250806.t1P86o5N011632@bagheera.jungle.bt.co.uk> <4A80D1F9-F4A1-4D14-AC75-958C5A2E8168@gmx.de> <3F47B274-B0E4-44F2-A434-E3C9F7D5D041@ifi.uio.no> <87twyaffv3.fsf@toke.dk> <87pp8yfe0s.fsf@toke.dk> <54EEE0D2.1060606@orange.com> Date: Thu, 26 Feb 2015 13:34:09 +0200 Message-ID: From: Jonathan Morton To: Sebastian Moeller Content-Type: multipart/alternative; boundary=485b397dd63762ddc3050ffc2114 Cc: bloat Subject: Re: [Bloat] RED against bufferbloat X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Feb 2015 11:34:39 -0000 --485b397dd63762ddc3050ffc2114 Content-Type: text/plain; charset=UTF-8 > But do we know whether mobile phone SOCs actually make good routers? Many of them probably don't, due to limited off chip I/O bandwidth, but their CPU cores would be useful in an SoC which did have such bandwidth. The BCM2435/6 used in the Raspberry Pi/2 is a classic example of such a phone SoC; its I/O is very flexible and its GPU remarkably powerful (really it is a GPU with a vestigial CPU hanging off the side), but the only high bandwidth off-chip interfaces are HDMI and USB 2, so it can just about handle Fast Ethernet but doesn't have a hope of reliably sustaining low latency at full line rate. However it does demonstrate that a quad Cortex A7 CPU cluster is now very cheap to implement. One of those integrated with a couple of GMACs and a couple of PCIe lanes for Wi-Fi would make a good router SoC. While I'm on the subject, I think the whole concept of web configurators is wrong-headed. Give the box a little LCD and let the user plug a USB keyboard in. Security problems solved (well, reduced a lot) at a stroke. - Jonathan Morton --485b397dd63762ddc3050ffc2114 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

> But do we know whether mobile phone SOCs actually make = good routers?

Many of them probably don't, due to limited off chip I/O= bandwidth, but their CPU cores would be useful in an SoC which did have su= ch bandwidth.

The BCM2435/6 used in the Raspberry Pi/2 is a classic exampl= e of such a phone SoC; its I/O is very flexible and its GPU remarkably powe= rful (really it is a GPU with a vestigial CPU hanging off the side), but th= e only high bandwidth off-chip interfaces are HDMI and USB 2, so it can jus= t about handle Fast Ethernet but doesn't have a hope of reliably sustai= ning low latency at full line rate.

However it does demonstrate that a quad Cortex A7 CPU cluste= r is now very cheap to implement. One of those integrated with a couple of = GMACs and a couple of PCIe lanes for Wi-Fi would make a good router SoC.

While I'm on the subject, I think the whole concept of w= eb configurators is wrong-headed. Give the box a little LCD and let the use= r plug a USB keyboard in. Security problems solved (well, reduced a lot) at= a stroke.

- Jonathan Morton

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