Thank you very much for taking the time to write your response and link me to the resources.
I am planning on creating CDFs and have no intention of using average queue length as a primary statistic in my research. I am putting much more emphasis on end to end delays. That said, I am interested in taking sample measurements of instantaneous queue length, but am really looking for any queue-length statistics the AQMs may measure. Best, Ryan Doyle p.s. Thank you to everyone else that responded as well. I will be sure to look at all of the links, but can't respond to everything individually. > Date: Wed, 25 Feb 2015 10:24:45 -0800 > From: [email protected] > To: [email protected] > CC: [email protected] > Subject: Re: [aqm] Gathering Queue Length Statistics > > On Wed, Feb 25, 2015 at 9:53 AM, Ryan Doyle <[email protected]> wrote: > > Hello, > > > > I am a senior undergraduate student at the University of North Carolina at > > Chapel Hill and am studying the effectiveness of AQMs. I have set up a lab > > network and plan on running different sets of experiments with different > > AQMs. My router machines are running Linux kernel version 3.16.0. > > > > I am using the fq_codel, codel, and pie qdiscs for my research and am > > wondering if there is a way to collect statistics regarding the average > > queue length since a qdisc was enabled? I have looked at tc's "-s" flag for > > statistics, but they show nothing about queue length and I have been unable > > to find anything else that might help me get queue length statistics. > > Oh, god. I am getting incredibly sensitive about average queue length, > and I realize that that is not what you meant. But since not enough > people have seemingly read this or any of the related materials, here > it is again. > > http://www.pollere.net/Pdfdocs/QrantJul06.pdf > > And I of course always recommend van´s talk on the fountain model for > thinking about closed loop servo systems. > > http://www.bufferbloat.net/projects/cerowrt/wiki/Bloat-videos > > In the bufferbloat project... > > We have developed many tools that drive aqms hard, see netperf-wrapper > on github for that, which measures e2e delay without requiring any > tools on the routers inbetween. e2e delay in my mind is way more > important than average queue length. And you can derive the queue > length(s) from tcp timestamps in those netperf-wrapper tests, from > additional packet captures, if you must. > > If you absolutely MUST derive average queue length from the box, you > can poll the interface frequently with tc -s qdisc show as well as > with ifconfig- and parse out the number of packets and the number of > bytes. But you can do MUCH more valid statistical analysis than that, > with that sort of data set - and if you poll too frequently you will > heisenbug your tests, as those data collection calls take locks that > interfere with the path. and we have all sorts of advice about traps > for the unwary here: > > http://www.bufferbloat.net/projects/codel/wiki/Best_practices_for_benchmarking_Codel_and_FQ_Codel > > > Please use things like CDFs to see the range of delays, rather than > averages. It is what happens at above 90% of the range that makes > bufferbloat maddening to ordinary users. > > I am summarily rejecting any papers that I review that report average > queue length as if it meant anything. And for a few other reasons. You > have been warned. I really lost my temper after the last paper I > reviewed last weekend and the resulting flamage is all over the bloat > list and codel lists, and starts here: > > https://lists.bufferbloat.net/pipermail/codel/2015-February/000872.html > > > > Best, > > Ryan Doyle > > > > _______________________________________________ > > aqm mailing list > > [email protected] > > https://www.ietf.org/mailman/listinfo/aqm > > > > > > -- > Dave Täht > Let's make wifi fast, less jittery and reliable again! > > https://plus.google.com/u/0/107942175615993706558/posts/TVX3o84jjmb > > _______________________________________________ > aqm mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/aqm
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