From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f43.google.com (mail-pb0-f43.google.com [209.85.160.43]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 48288201B52 for ; Sat, 1 Sep 2012 05:53:34 -0700 (PDT) Received: by pbbrq2 with SMTP id rq2so8581035pbb.16 for ; Sat, 01 Sep 2012 05:53:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; bh=uqWGdVSXJBme1FroD0vKV2R4KzdYvT8q9Mq7ywqzxAk=; b=r79MOF3dN+4Sx6VwCYRdg7IqkUPXgJxxlOY7dmtcfsKOCMQhVG2JdhnJsgFOcg+aGG F613FaBnfK/jMMwUJ1SlLHsphHUboi1cDxv51tjKOrkbymfTabKcUrj3r1cmvb2bnnc0 +l3zZMrNLqKIOyOLnh5TIuBZ6/EApvEKNYdg7xEw4E8hdm7Uxq+WL93auALgDETeiUqA 2ebmFjKPNZ+uKNxBRJc2doB30A+bbDX5nbbOixbHHJWnKHryJ7tJgAzu5LiuXe4jOYo6 0BoJri3r1dFfXDVpiMhMkiOpgTw72rbLqhNn9jFZxEf/+M/U/8We+p3yJ9A9yXA+hFt8 GbiA== Received: by 10.66.75.73 with SMTP id a9mr21379686paw.43.1346504013920; Sat, 01 Sep 2012 05:53:33 -0700 (PDT) Received: from [10.10.6.223] (0127ahost2.starwoodbroadband.com. [12.105.246.2]) by mx.google.com with ESMTPS id hc10sm5638102pbc.21.2012.09.01.05.53.32 (version=SSLv3 cipher=OTHER); Sat, 01 Sep 2012 05:53:33 -0700 (PDT) From: Eric Dumazet To: Dave Taht In-Reply-To: References: <1346396137.2586.301.camel@edumazet-glaptop> <5040DDE9.7030507@hp.com> <1346430207.7996.11.camel@edumazet-glaptop> Content-Type: text/plain; charset="UTF-8" Date: Sat, 01 Sep 2012 05:53:32 -0700 Message-ID: <1346504012.7996.68.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Cc: codel@lists.bufferbloat.net Subject: Re: [Codel] fq_codel : interval servo X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 01 Sep 2012 12:53:34 -0000 On Fri, 2012-08-31 at 09:59 -0700, Dave Taht wrote: > I realize that 10GigE and datacenter host based work is sexy and fun, > but getting stuff that runs well in today's 1-20Mbit environments is > my own priority, going up to 100Mbit, with something that can be > embedded in a SoC. The latest generation of SoCs all do QoS in > hardware... badly. Maybe 'datacenter' word was badly chosen and you obviously jumped on it, because it meant different things for you. Point was that when your machine has flows with quite different RTT, 1 ms on your local LAN, and 100 ms on different continent, current control law might clamp long distance communications, or have slow response time for the LAN traffic. The shortest path you have, the sooner you should drop packets because losses have much less impact on latencies. Yuchung idea sounds very good and my intuition is it will give tremendous results for standard linux qdisc setups ( a single qdisc per device) To get similar effects, you could use two (or more) fq codels per ethernet device. One fq_codel with interval = 1 or 5 ms for LAN communications One fq_codel with interval = 100 ms for other communications tc filters to select the right qdisc by destination addresses Then we are a bit far from codel spirit (no knob qdisc) I am pretty sure you noticed that if your ethernet adapter is only used for LAN communications, you have to setup codel interval to a much smaller value than the 100 ms default to get reasonably fast answer to congestion. Just make this automatic, because people dont want to think about it.