From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x22f.google.com (mail-oi0-x22f.google.com [IPv6:2607:f8b0:4003:c06::22f]) (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 EB72821F327 for ; Mon, 20 Apr 2015 08:51:05 -0700 (PDT) Received: by oign205 with SMTP id n205so128662201oig.2 for ; Mon, 20 Apr 2015 08:51:04 -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=Ce1vjYnhi6Dd5xnKH+E6Q66Jzs4ZCHyWUWW1GegVMJc=; b=YmU0dnPWKGI113emDpsLVcSZGpAW8rBIF095IpvTc4MjFgP1s3wnpMPHHLU3+p5Eze tOSUT5unqyV3M1BcvAmQPvQmL+rGjT3Feh8ijXfdGfI7muJ5rCvBRxN67YHXuVWDYmOi L9WBSfmg0e9ld3uCnQiZypRyeiBFnV3SI/d02v0lDQZPj5TO6yciULZtyrzNdChVLpoD 5OvAyRl6SZrYXpVwbvXSzlx06yG2oOAgKExqHzUEKOtCPXwfsw2ug89K43aM6eHpx/fH 8U2wz+luj4V64ffOxaJeuvz+/FnS/9b2COSjfu9SpuGOcDi7mJrvnC1ML8AgsEzkZmDE PWiQ== MIME-Version: 1.0 X-Received: by 10.182.76.33 with SMTP id h1mr14161065obw.63.1429545064286; Mon, 20 Apr 2015 08:51:04 -0700 (PDT) Received: by 10.202.71.139 with HTTP; Mon, 20 Apr 2015 08:51:03 -0700 (PDT) In-Reply-To: References: <87wq18jmak.fsf@toke.dk> <87oamkjfhf.fsf@toke.dk> <87k2x8jcnw.fsf@toke.dk> Date: Mon, 20 Apr 2015 08:51:03 -0700 Message-ID: From: Dave Taht To: David Lang Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: bloat 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: Mon, 20 Apr 2015 15:51:34 -0000 1) I have 7 dual stack linode vm servers around the world you could use - they are in england, japan, newark, atlanta, california, and one other place. They are configured to use sch_fq (but I don't know what is on the bare metal), and have other analysis tools on them, but you would be welcome to use those. 2) There is a tcp socket option (something_lowat) which makes a big difference in the amount of stuff that gets buffered in the lower portions of the stack - would be useful in the server, and I think, but am not sure, it is turned on in a few of the latest browsers on some platforms. Stuart cheshire gave a talk about it recently that should end up on youtube soon. 3) I like smokeping's plotting facility for more clearly showing the range of outliers - 4) and do not cut things off at the 95 percentile, ever. 98% is more reasonable - but I still prefer cdf plots to capture the entire range of the data. The analogy I use here is what if your steering wheel failed to respond one time in 20 on your way to work - how long would you live? (and then, what if everyone's steering wheel failed one time in 20?) Another way of thinking about it is what if your voip call went to hell twice a minute? On Mon, Apr 20, 2015 at 7:51 AM, David Lang wrote: > On Mon, 20 Apr 2015, jb wrote: > >> 2. The test does not do latency pinging on 3G and GPRS >> because of a concern I had that with slower lines (a lot of 3G results a= re >> less than half a megabit) the pings would make the speed measured >> unreliable. And/or, a slow android phone would be being asked to do too >> much. I'll do some tests with and without pinging on a 56kbit shaped lin= e >> and see if there is a difference. If there is not, I can enable it. > > > remember that people can be testing from a laptop tethered to a phone. > >> 3. The graph of latency post-test is log X-axis at the moment >> because one spike can render the whole graph almost useless with axis >> scaling. What I might do is X-Axis breaking, and see if that looks ok. >> Alternatively, a two panel graph, one with 0-200ms axis, the other in fu= ll >> perspective. Or just live with the spike. Or scale to the 95% highest >> number and let the other 5% crop. There are tool-tips after all to show >> the >> actual numbers. > > > I think that showing the spike is significant because that latency spike > would impact the user. It's not false data. > > showing two graphs may be the way to go. > > I don't think showing the 95th percentile is right. Again it is throwing > away significant datapoints. > > I think summarizing the number as an average (with error bands) for each > category of the test would be useful. > > David Lang > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > --=20 Dave T=C3=A4ht Open Networking needs **Open Source Hardware** https://plus.google.com/u/0/+EricRaymond/posts/JqxCe2pFr67