From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-x232.google.com (mail-ig0-x232.google.com [IPv6:2607:f8b0:4001:c05::232]) (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 DD1DE21F1E6 for ; Thu, 7 May 2015 06:14:51 -0700 (PDT) Received: by igbyr2 with SMTP id yr2so158818730igb.0 for ; Thu, 07 May 2015 06:14:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:content-type; bh=4PSJ2F4YFEDHsftWGex7lHRckYbuuwYpok2Z2qExt0k=; b=ngcQOLD42Zyap4tvQkhmJ+lvVImer1ae5R+N7JsCibeun9b6yqoiK3ZHxaCk7zpJNL 57Gxd2feRVNkA3o0VQVe/MYu7XRglD/Ro68mSVRgAyyARnj2c4dpEcUlj3QY5j2zDqix 1lwjo/4Lc6MLGLygyNhlv+8hmy6DTD9vaS/p8y4+0vuk2v8wf+tcNozTTB8KNq2hUsDj vrc4YI3Ns8P2FgKWNAyAR2tfh47aCqI5kzuhKU26fdoiyXCiZew6RF76Q81cgGbKlI9L WJ6VyySC/nu+wiuBq/gA4pX2Rouvp3F3Fe4dRbTHykr0kYVxogKD27752d9R9vLqwcdc e6bQ== MIME-Version: 1.0 X-Received: by 10.50.77.48 with SMTP id p16mr4322571igw.31.1431004490207; Thu, 07 May 2015 06:14:50 -0700 (PDT) Sender: justinbeech@gmail.com Received: by 10.50.107.42 with HTTP; Thu, 7 May 2015 06:14:49 -0700 (PDT) In-Reply-To: References: <2288B614-B415-4017-A842-76E8F5DFDE4C@gmx.de> <553B06CE.1050209@superduper.net> <14ceed3c818.27f7.e972a4f4d859b00521b2b659602cb2f9@superduper.net> <0C930D43-A05B-48E2-BC01-792CAA72CAD1@gmx.de> <5549A1B8.50005@superduper.net> <9CF0E173-2CE5-4950-84D1-44EAEF174882@gmx.de> Date: Thu, 7 May 2015 23:14:49 +1000 X-Google-Sender-Auth: s3bUZ90Y6btHR1oByLrRWGvb0r8 Message-ID: From: jb To: Mikael Abrahamsson , bloat Content-Type: multipart/alternative; boundary=047d7bdcaaa44f984705157db21d Subject: Re: [Bloat] DSLReports Speed Test has latency measurement built-in 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: Thu, 07 May 2015 13:15:21 -0000 --047d7bdcaaa44f984705157db21d Content-Type: text/plain; charset=UTF-8 I thought would be more sane too. I see mentioned online that PDV is a gaussian distribution (around mean) but it looks more like half a bell curve, with most numbers near the the lowest latency seen, and getting progressively worse with less frequency. At least for DSL connections on good ISPs that scenario seems more frequent. You "usually" get the best latency and "sometimes" get spikes or fuzz on top of it. by the way after I posted I discovered Firefox has an issue with this test so I had to block it with a message, my apologies if anyone wasted time trying it with FF. Hopefully i can figure out why. On Thu, May 7, 2015 at 9:44 PM, Mikael Abrahamsson wrote: > On Thu, 7 May 2015, jb wrote: > > There is a web socket based jitter tester now. It is very early stage but >> works ok. >> >> http://www.dslreports.com/speedtest?radar=1 >> >> So the latency displayed is the mean latency from a rolling 60 sample >> buffer, Minimum latency is also displayed. and the +/- PDV value is the >> mean difference between sequential pings in that same rolling buffer. It is >> quite similar to the std.dev actually (not shown). >> > > So I think there are two schools here, either you take average and display > + / - from that, but I think I prefer to take the lowest of the last 100 > samples (or something), and then display PDV from that "floor" value, ie > PDV can't ever be negative, it can only be positive. > > Apart from that, the above multi-place RTT test is really really nice, > thanks for doing this! > > > -- > Mikael Abrahamsson email: swmike@swm.pp.se > --047d7bdcaaa44f984705157db21d Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
I thought would be more sane too. I see mentioned online t= hat PDV is a=C2=A0
gaussian distribution (around mean) but it looks mor= e like half a bell curve, with most numbers near the the lowest latency see= n, and getting progressively worse with
less frequency.
At least for DSL connections on good ISPs that scenario seems more frequen= t.
You "usually" get the best latency and "sometim= es" get spikes or fuzz on top of it.

by the w= ay after I posted I discovered Firefox has an issue with this test so I had=
to block it with a message, my apologies if anyone wasted time t= rying it with FF.
Hopefully i can figure out why.

<= /div>

On Thu, May = 7, 2015 at 9:44 PM, Mikael Abrahamsson <swmike@swm.pp.se> wro= te:
On Thu, 7 May 2015, jb wrote:
There is a web socket based jitter tester now. It is very early stage but works ok.

http://www.dslreports.com/speedtest?radar=3D1

So the latency displayed is the mean latency from a rolling 60 sample buffe= r, Minimum latency is also displayed. and the +/- PDV value is the mean dif= ference between sequential pings in that same rolling buffer. It is quite s= imilar to the std.dev actually (not shown).

 So I think there are two schools here, either you take average and display = + / - from that, but I think I prefer to take the lowest of the last 100 sa= mples (or something), and then display PDV from that "floor" valu= e, ie PDV can't ever be negative, it can only be positive.

Apart from that, the above multi-place RTT test is really really nice, than= ks for doing this!


--
Mikael Abrahamsson=C2=A0 =C2=A0 email: swmike@swm.pp.se

--047d7bdcaaa44f984705157db21d--