Rich I have a deep worry over this style of single point measurement - and hence speed - as an appropriate measure. We know, and have evidence, that throughput/utilisation is not a good proxy for the network delivering suitable quality of experience. We work with organisation (Telco’s, large system integrators etc) where we spend a lot of time having to “undo” the consequences of “maximising speed”. Just like there is more to life than work, there is more to QoE than speed.
For more specific comments see inline On 25 Jul 2014, at 13:09, Rich Brown <[email protected]> wrote: > Neil, > > Thanks for the note and the observations. My thoughts: > > 1) I note that speedof.me does seem to overstate the speed results. At my > home, it reports 5.98mbps down, and 638kbps up, while betterspeedtest.sh > shows 5.49/0.61 mbps. (speedtest.net gives numbers similar to the > betterspeedtest.net script.) > > 2) I think we're in agreement about the peak upload rate that you point out > is too high. Their measurement code runs in the browser. It seems likely that > the browser pumps out a few big packets before getting flow control > information, thus giving the impression that they can send at a higher rate. > This comports with the obvious decay that ramps toward the long-term rate. I think that its simpler than that, it is measuring the rate at which it can push packets out the interface - its real time rate is precisely that - it can not be the rate being reported by the far end, it can never exceed the limiting link. The long term average (if it is like other speed testers we’ve had to look into) is being measured at the TCP/IP SDU level by measuring the difference in time between the first and last timestamps of data stream and dividing that into the total data sent. Their “over-estimate” is because there are packets buffered in the CPE that have left the machine but not arrived at the far end. > > 3) But that long-term speed should be at or below the theoretical long-term > rate, not above it. Agreed, but in this case knowing the sync rate already defines that maximum. > > Two experiments for you to try: > > a) What does betterspeedtest.sh show? (It's in the latest CeroWrt, in > /usr/lib/CeroWrtScripts, or get it from github: > https://github.com/richb-hanover/CeroWrtScripts ) > > b) What does www.speedtest.net show? > > I will add your question (about the inaccuracy) to the note that I want to > send out to speedof.me this weekend. I will also ask that they include > min/max latency measurements to their test, and an option to send for > 10 > seconds to minimize any effect of PowerBoost... > > Best regards, > > Rich > > > > On Jul 25, 2014, at 5:10 AM, Neil Davies <[email protected]> wrote: > >> Rich >> >> You may want to check how accurate they are to start. >> >> I just ran a “speed test” on my line (which I have complete control and >> visibility over the various network elements) and it reports an average >> “speed” (in the up direction) that is in excess of the capacity of the line, >> it reports the maximum rate at nearly twice the best possible rate of the >> ADSL connection. >> >> Doesn’t matter how pretty it is, if its not accurate it is of no use. This >> is rather ironic as the web site claims it is the “smartest and most >> accurate”! >> >> Neil >> >> <speedof_me_14-07-25.png> >> >> PS pretty clear to me what mistake they’ve made in the measurement process - >> its to do with incorrect inference and hence missing the buffering effects. >> >> On 20 Jul 2014, at 14:19, Rich Brown <[email protected]> wrote: >> >>> Doc Searls >>> (http://blogs.law.harvard.edu/doc/2014/07/20/the-cliff-peronal-clouds-need-to-climb/) >>> mentioned in passing that he uses a new speed test website. I checked it >>> out, and it was very cool… >>> >>> www.speedof.me is an all-HTML5 website that seems to make accurate >>> measurements of the up and download speeds of your internet connection. >>> It’s also very attractive, and the real-time plots of the speed show >>> interesting info. (screen shot at: http://richb-hanover.com/speedof-me/) >>> >>> Now if we could get them to a) allow longer/bigger tests to circumvent >>> PowerBoost, and b) include a latency measurement so people could point out >>> their bufferbloated equipment. >>> >>> I'm going to send them a note. Anything else I should add? >>> >>> Rich >>> _______________________________________________ >>> Bloat mailing list >>> [email protected] >>> https://lists.bufferbloat.net/listinfo/bloat >> >
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