From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-x22c.google.com (mail-we0-x22c.google.com [IPv6:2a00:1450:400c:c03::22c]) (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 4E93321F224; Tue, 29 Apr 2014 20:22:02 -0700 (PDT) Received: by mail-we0-f172.google.com with SMTP id u57so1093683wes.3 for ; Tue, 29 Apr 2014 20:22:00 -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=c53+Hx+6AyIxGWdvz4lK/FywyXdwbb8aRKbdwBGb4Bk=; b=WZEa7OXxcDoLAlz2reCvnYEGq7Qwx5tKBeIM4OKOLBY/JM2qVrN6vCcS1SrrRLvOGH HFhlFzWszNwk5w5T5zqLPgNRw2bpvYJTXlRw8FreD+gsDVWMhJM70hKvgFgsj1Zxm3HF 8WiSMNYgw8/t+gQwrihjekRkBPKvfp3MvurxIb98bT3R20OMjxUUwtugFYr9j2vDlAfz /MskjTDAMG9ObnSa1XsLmo+CgeIJqQDgyJV8YGEH2aBaCu+OpqEXRkb6YFc0iSiKMpuu dr3WEKU+MZ/hpZZFUCH7hjVPI4zNDo8H4OS1lQAfcH5SFXXnnBYnRJK3hwoIKtsrD6Kh 1Vqw== MIME-Version: 1.0 X-Received: by 10.180.198.46 with SMTP id iz14mr1353563wic.46.1398828120022; Tue, 29 Apr 2014 20:22:00 -0700 (PDT) Received: by 10.216.207.82 with HTTP; Tue, 29 Apr 2014 20:21:59 -0700 (PDT) In-Reply-To: <87bnvkkr2n.fsf@toke.dk> References: <4130D000-FE28-4A5E-B824-3371C1602472@cisco.com> <87bnvkkr2n.fsf@toke.dk> Date: Tue, 29 Apr 2014 20:21:59 -0700 Message-ID: From: Dave Taht To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: "Fred Baker \(fred\)" , "cerowrt-devel@lists.bufferbloat.net" , bloat , "aqm@ietf.org" Subject: Re: [Cerowrt-devel] [aqm] [Bloat] the side effects of 330ms lag in the real world X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Apr 2014 03:22:02 -0000 On Tue, Apr 29, 2014 at 10:01 AM, Toke H=C3=B8iland-J=C3=B8rgensen wrote: > Jim Gettys writes: > >> Now, if someone gives me real fiber to the home, with a real switch fabr= ic >> upstream, rather than gpon life might be somewhat better (if the switche= s aren't >> themselves overbuffered.... But so far, it isn't. > > As a data point for this, I have fibre to my apartment building and > ethernet into the apartment. I get .5 ms to my upstream gateway and > about 6 ms to Google. Still measured up to ~20 ms of bufferbloat while > running at 100 Mbps... > > http://files.toke.dk/bufferbloat/data/karlstad/cdf_comparison.png I need to note that what this wonderfully flat CDF for the measurement stream shows is that short flows under fq_codel leap to the head of the queue ever better as you get more and more bandwidth available. The background load flows not shown on this graph are experiencing 5-20ms worth of latency in each direction as per codel's algorithm. A better test (in progress) would measure typical voip behaviors.... > However, as that graph shows, it is quite possible to completely avoid > bufferbloat by deploying the right shaping. It does not "completely avoid bufferbloat", the fq_codel "fast queue" merely eliminates queuing delay for sparse flows, things like arp, syn, syn/ack, dns, ntp, etc, as well as the first packet of any flow that has not built up a queue yet. (which is, admittedly, quite a lot of bufferbloat reduction) The rest of the magic comes from codel. > And in that case fibre > *does* have a significant latency advantage. The best latency I've seen > to the upstream gateway on DSL has been ~12 ms. And reduced RTT =3D money. this piece states observed average RTTs at peak times were 17ms for fiber, 28ms for cable, and 44ms for DSL. http://www.igvita.com/2012/07/19/latency-the-new-web-performance-bottleneck= / I don't know if the underlying report measures baseline unloaded last mile = RTT. > > -Toke > > _______________________________________________ > aqm mailing list > aqm@ietf.org > https://www.ietf.org/mailman/listinfo/aqm > --=20 Dave T=C3=A4ht NSFW: https://w2.eff.org/Censorship/Internet_censorship_bills/russell_0296_= indecent.article