[e2e] Codel and Wireless

Andrew Mcgregor andrewmcgr at google.com
Thu Dec 5 16:23:41 PST 2013

I'm running a fairly standard OpenWRT QoS config, with ingress and egress
shaping to prevent (too much) upstream queueing either in the network or in
the modem; I get about 22Mbps symmetric performance on this particular
setup, with reasonable latencies (I wouldn't be happy if I was FPS gaming,
but it's fine for everything else).  I don't remember the latency numbers
off the top of my head.  It's actually one of the better broadband
connections available in Australia, it's just a shame about the cost.

On 6 December 2013 11:16, Keith Winstein <keithw at mit.edu> wrote:

> On Thu, Dec 5, 2013 at 6:22 PM, Andrew Mcgregor <andrewmcgr at google.com>wrote:
>> By the way, fq_codel is not a combination of SFQ and CoDel, but something
>>  else.  The code deserves really close study to understand what is really
>> going on there, because there is a very interesting contribution in terms
>> of heuristically measuring whether flows are building queue in the qdisc
>> or
>> not.  Empirically, this works really well on user access links, including
>> LTE, by my own direct observation having run it on my home network's LTE
>> link for many months now.
> Andrew, I'd love to hear more about how you do this. Do you run fq_codel
> on the uplink or somehow also on the downlink? How do you prevent the LTE
> modem or baseband from buffering hundreds of kilobytes inside itself -- do
> you use an upstream traffic shaper (to prevent the LTE link from becoming
> the bottleneck) or something more sophisticated?
> Cheers,
> Keith

Andrew McGregor | SRE | andrewmcgr at google.com | +61 4 8143 7128

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