From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vc0-x22d.google.com (mail-vc0-x22d.google.com [IPv6:2607:f8b0:400c:c03::22d]) (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 B747721F2C5 for ; Wed, 25 Feb 2015 04:08:07 -0800 (PST) Received: by mail-vc0-f173.google.com with SMTP id hy4so1172690vcb.4 for ; Wed, 25 Feb 2015 04:08:06 -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=+V+ROREcU5BoTEEl/tpCnQZTp3q7Huue3Ckr10rp7rU=; b=Noeh7VSrBNKLNLTyP3tLqYq/LWWxS4OJS6p82AcOss684tKxV+JU9C+Z4VYBvNC0Cp OtsfgBODlnx6nucdMPxb9mS75q6n5sAgSbWzCrxbtYqTyxgmjCB2jeeFI9eQsSmLziQ0 3By0frWOK26nsZ4SD24fbQ6wQXuWsm2gBjCbz1HzAtZGFSKX1jF0Gzfc7Zvjt8YG5mGJ 9C5whNkaVmPU4LFsZ7joM+NLM2N9/1cdJYxMkq8fjirSFoFWL3F5ae5W7ZqQR6Q+PSok DZYNk81yVknfB0myGlkNp9prZ7HkULyEKsXJ0159s5I1s4swgUVQsphzxaeARs9Y5R+3 vnNw== MIME-Version: 1.0 X-Received: by 10.52.12.138 with SMTP id y10mr3590095vdb.35.1424866086012; Wed, 25 Feb 2015 04:08:06 -0800 (PST) Received: by 10.52.24.79 with HTTP; Wed, 25 Feb 2015 04:08:05 -0800 (PST) Received: by 10.52.24.79 with HTTP; Wed, 25 Feb 2015 04:08:05 -0800 (PST) In-Reply-To: <87k2z6fd3w.fsf@toke.dk> 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> <87k2z6fd3w.fsf@toke.dk> Date: Wed, 25 Feb 2015 14:08:05 +0200 Message-ID: From: Jonathan Morton To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Content-Type: multipart/alternative; boundary=485b397dd637e8cbec050fe87cb4 Cc: Alex Elsayed , 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: Wed, 25 Feb 2015 12:08:36 -0000 --485b397dd637e8cbec050fe87cb4 Content-Type: text/plain; charset=UTF-8 To add my tuppence to this discussion: I don't believe real world topologies and workloads are incompatible with academic experimentation. All you have to do is replicate the same workload and other conditions across each of the qdiscs you're testing, ie to change only the qdisc between test runs. That's the basis of the scientific method. Using a simplified topology and workload may well give you clearer and more understandable results from which you can more easily draw a conclusion for your paper. But that conclusion becomes correspondingly less relevant to practical applications and bleeding edge research, as others have explained. In the real world, I have a 3G connection shaped to half a megabit at the provider, occasionally limited to EDGE speeds at the tower depending on propagation conditions, typical idle latency 100ms, potential loaded latency the best part of a MINUTE. I'm not even sure what the upload bandwidth rate or topology is supposed to be. Packet loss is usually acceptably low, yet the horrible loaded latency means that I can't do more than one thing at a time on my phone; it even logs me out of Steam chat if I load a big web page, and it also takes time to drain the traffic out of the queue after I cancel something to do something else, or to do it a different way. Just now I wanted to watch an NTSB media briefing; Twitter tried to load a preview of the video just before I clicked the link to launch the proper YouTube app (which can do fullscreen); with the buffer thus filled, YouTube decided the network was broken and refused to load the video. In fact it left the navigation settings on the previous video I watched yesterday, so that when I hit retry, it loaded that video rather than the one I'd just clicked the link for. That's a real world workload, and a real world failure of epic proportions, and it didn't even need bidirectional traffic to trigger. - Jonathan Morton --485b397dd637e8cbec050fe87cb4 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

To add my tuppence to this discussion:

I don't believe real world topologies and workloads are = incompatible with academic experimentation. All you have to do is replicate= the same workload and other conditions across each of the qdiscs you'r= e testing, ie to change only the qdisc between test runs. That's the ba= sis of the scientific method.

Using a simplified topology and workload may well give you c= learer and more understandable results from which you can more easily draw = a conclusion for your paper. But that conclusion becomes correspondingly le= ss relevant to practical applications and bleeding edge research, as others= have explained.

In the real world, I have a 3G connection shaped to half a m= egabit at the provider, occasionally limited to EDGE speeds at the tower de= pending on propagation conditions, typical idle latency 100ms, potential lo= aded latency the best part of a MINUTE. I'm not even sure what the uplo= ad bandwidth rate or topology is supposed to be. Packet loss is usually acc= eptably low, yet the horrible loaded latency means that I can't do more= than one thing at a time on my phone; it even logs me out of Steam chat if= I load a big web page, and it also takes time to drain the traffic out of = the queue after I cancel something to do something else, or to do it a diff= erent way.

Just now I wanted to watch an NTSB media briefing; Twitter t= ried to load a preview of the video just before I clicked the link to launc= h the proper YouTube app (which can do fullscreen); with the buffer thus fi= lled, YouTube decided the network was broken and refused to load the video.= In fact it left the navigation settings on the previous video I watched ye= sterday, so that when I hit retry, it loaded that video rather than the one= I'd just clicked the link for. That's a real world workload, and a= real world failure of epic proportions, and it didn't even need bidire= ctional traffic to trigger.

- Jonathan Morton

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