From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f171.google.com (mail-we0-f171.google.com [74.125.82.171]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 019D621F0B8; Tue, 15 May 2012 23:09:25 -0700 (PDT) Received: by wejx9 with SMTP id x9so423439wej.16 for ; Tue, 15 May 2012 23:09:24 -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=4MKEOXx602dvk54AXLiaDUi3U2tecI8DvFywQCnesv4=; b=YYHYtYq1pKkSHEETI/hwCKcnusnbheRUZL/UjRl8osdSfVOdyFS/CZoRG124nUmR5e RQ0t8gj7utbanHEyD+LY2XUWUKjrOYnnPu/+hSCpt/6r/iReZ6ee718nkQfdN6oAZ+hH ZW1W1Nsf/eKL1WBLkplee6cWWgmNzQxKYU06qPzyAFJuEeHMlnJwfw162FjCiA+c3Sh/ KA4Pw5k1Gzp6/oPXfzOCp54WMJsOp9u9akeop1xQUzxyw1SW1SWrUUbu/YB4PYyb1FIc 9yJnkONCjlw//yoMTmA0i4+zlpLmzEFGHnQfdM/rJ3VkYxa/QETbDRPzERTzYLIc0SVr mk+g== Received: by 10.180.83.196 with SMTP id s4mr4547195wiy.15.1337148564018; Tue, 15 May 2012 23:09:24 -0700 (PDT) Received: from [172.28.91.41] ([74.125.122.49]) by mx.google.com with ESMTPS id fo7sm47461807wib.9.2012.05.15.23.09.22 (version=SSLv3 cipher=OTHER); Tue, 15 May 2012 23:09:22 -0700 (PDT) From: Eric Dumazet To: Jonathan Morton In-Reply-To: References: <4FA9FDC0.9010600@superduper.net> Content-Type: text/plain; charset="UTF-8" Date: Wed, 16 May 2012 08:09:20 +0200 Message-ID: <1337148560.8512.1123.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Cc: codel@lists.bufferbloat.net, Kevin Gross , bloat Subject: Re: [Codel] [Bloat] The challenge 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: Wed, 16 May 2012 06:09:26 -0000 On Wed, 2012-05-16 at 08:55 +0300, Jonathan Morton wrote: > On 9 May, 2012, at 4:04 pm, Kevin Gross wrote: > > > From the paper (figure 7), you can see that CoDel still leaves spikes of buffer occupancy when network conditions change. These will still be disruptive to real-time traffic. Many networks that need QoS now will still need QoS. Networks that do not have QoS will be much more usable with CoDel. > > Combining AQM with FQ certainly seems like a good idea to me. I haven't had a chance to try the implementation of fq_codel which already exists yet, but it's compiled and just waiting for me to get around to it. If it works, then it should be an excellent default. fq_codel has no priority concepts. It's only Fair. But what is Fairness ? In the presence of elephant flows, you get more packets drops from elephant flows than from thin ones. If the elephant flow is the 'high priority' traffic, dropping packets from it is not what you wanted. pfifo_fast is able to have strict priority. If you want Codel and strict priority, you can use prio + codel (or prio + fq_codel)