Re: [aqm] Gathering Queue Length Statistics

grenville armitage <garmitage@swin.edu.au> Thu, 26 February 2015 04:19 UTC

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From: grenville armitage <garmitage@swin.edu.au>
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Subject: Re: [aqm] Gathering Queue Length Statistics
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On 02/26/2015 04:53, Ryan Doyle wrote:
	[..]
> 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.

Perhaps off on a tangent, but you might find http://caia.swin.edu.au/tools/spp/ a useful complement to your measurements. If you tcpdump the packets going in and out either side of your router, spp can take the two dump files and estimate the instantaneous RTT (itself a reflection of instantaneous queue depth) over time between said router ports. Use this to validate/contrast with RTT estimates you extract from TCP timestamps.

cheers,
gja