From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-x231.google.com (mail-qc0-x231.google.com [IPv6:2607:f8b0:400d:c01::231]) (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 DD63921F3ED; Thu, 16 Apr 2015 05:10:27 -0700 (PDT) Received: by qcpm10 with SMTP id m10so4705609qcp.3; Thu, 16 Apr 2015 05:10:26 -0700 (PDT) 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:content-transfer-encoding; bh=oiGycWi6a1bt+nr4TYM1qEvCWPAd4AvRXHxBfdkBs4o=; b=mbZEtFzMcfCeLNalL27P04jNDQc+JRTw3QIhwM+D1gbZF0gK+PXyPDL3TNJeC3Vgjg cLAubw9cklCktuPEEv8vBnQZpcZg++ALMQasymOu1DdFIdFZPScUMKm7IhTSWAZPIcaM Z9ebtAbAJh0XjkiDptDhasTeHhYLHRbzHzeZetEMkLSYOIX7HIRLItrvNmBRe78dowF1 suVxqhJ5O5LerU0lSiYxLqImYxMm9P1qi/WLVjHNabTvgSQaQAHtZQc+fdGeuyWqzmNZ IxUtcaxSxoQBjvDP2GLfn3WGXsma+7E6vJQnWy7Yf2Hc34VN88Mch2d+xGNNRat2dDuj A29A== MIME-Version: 1.0 X-Received: by 10.140.135.207 with SMTP id 198mr39019476qhh.71.1429186226377; Thu, 16 Apr 2015 05:10:26 -0700 (PDT) Received: by 10.140.48.11 with HTTP; Thu, 16 Apr 2015 05:10:26 -0700 (PDT) In-Reply-To: <91CCD5F5-5F5D-435D-9FD1-77BBEEC1E84E@gmail.com> References: <87twwg5m1u.fsf@toke.dk> <91CCD5F5-5F5D-435D-9FD1-77BBEEC1E84E@gmail.com> Date: Thu, 16 Apr 2015 22:10:26 +1000 Message-ID: From: Andrew McGregor To: Jonathan Morton Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: cake@lists.bufferbloat.net, =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= , "codel@lists.bufferbloat.net" Subject: Re: [Codel] [Cake] hard limit codel 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: Thu, 16 Apr 2015 12:10:56 -0000 Of course it fails at high RTT. Unfortunately, long RTTs are pretty common... for almost anything EXCEPT VIDEO. Video, on the other hand, is almost always served a) by application paced servers and b) over the shortest RTT available. So video isn't even a question for high-RTT evaluations. Even the upload stream from a VC client (not usually TCP at all in the first place) is not usually going half way round the world. On Thu, Apr 16, 2015 at 10:00 PM, Jonathan Morton w= rote: > >> On 16 Apr, 2015, at 14:50, Toke H=C3=B8iland-J=C3=B8rgensen wrote: >> >> I'll add, though, that I have seen the sentiment expressed here ("we >> need to limit the max delay of CoDel") in other contexts. And, well, >> delay spikes *is* a problem! > > Yes, they are. > > But in general AQM can=E2=80=99t be used to solve that problem without al= so suffering poor throughput; combining AQM with FQ *does* solve it. Just = like FQ is unfair to single flows competing against a swarm, but classifyin= g the swarm traffic into a separate traffic class fixes that problem too. > > Which of course is why cake uses AQM, FQ *and* Diffserv, all at once. > > The linked paper didn=E2=80=99t measure HLC against fq_codel, even though= they mention fq_codel. That=E2=80=99s a major shortcoming. > > - Jonathan Morton > > _______________________________________________ > Codel mailing list > Codel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/codel