[Cerowrt-devel] [Bloat] (no subject)

Wed May 15 04:30:51 EDT 2019

Hi Dave,

> On May 15, 2019, at 09:58, Dave Taht <dave.taht at gmail.com> wrote:
> 
> If it helps any: Nick Feamster and Jason Livingood just published "
> Internet Speed Measurement: Current Challenges and Future
> Recommendations " ( https://arxiv.org/pdf/1905.02334.pdf ) a few days
> ago, and outlines quite a few problems going forward at higher speeds.

	Excellent, will read (once time permits).

> I do wish the document had pointed out more clearly that router based
> measurements have problems also,

	+1, especially newer SoCs which implement power features can run into situations where depending on the load characteristics the CPUs throttle back (in frequency) and perfomance becomes quite choppy, which might not show up in bandwidth measurement but can really affect the experienced bufferbloat. I currently think it better for the load generation to be done by  different hosts than the DUT/de-bloater...

> with weaker cpus unable to source
> enough traffic for an accurate measurement, but I do hope this
> document has impact, and it's a good read, regardless.
> 
> Still, somehow getting it right at lower speeds is always on my mind.

	At lower speeds measuring the bandwidth is not that hard, since overloading the CPU and the server;s bandwidth gets less likely, no?

> I'd long ago hoped that DSL devices would adopt BQL, and that
> cablemodems would also, thus moving packet processing a little higher
> on the stack so more advanced algorithms like cake could take hold.

	Well, to make this happen we need to talk to modem manufacturers, so mostly intel/lantiq and broadcom I believe. I happen to have exact zero insiders in both companies in my "rolodex", but with in a group as diverse and expert as this list is, someone here must know someone that could get the word out inside those companies, no?
	For BQL on docsis modems though, I believe cablelabs might be the best route (not that BQL on a docsis modem will help a lot, given that we have, AFAICT, no open source OS running on a docsis modem, same seems true for GPON).

Best Regards
	Sebastian

> 
> On Wed, May 15, 2019 at 9:32 AM Sebastian Moeller <moeller0 at gmx.de> wrote:
>> 
>> Hi All,
>> 
>> 
>> I believe the following to be relevant to this discussion: https://apenwarr.ca/log/20180808
>> Where he discusses a similar idea including implementation albeit aimed at lower bandwidth and sans the automatic bandwidth tracking.
>> 
>> 
>>> On May 15, 2019, at 01:34, David P. Reed <dpreed at deepplum.com> wrote:
>>> 
>>> 
>>> Ideally, it would need to be self-configuring, though... I.e., something
>>> like the IQRouter auto-measuring of the upstream bandwidth to tune the
>>> shaper.
>> 
>> @Jonathan from your experience how tricky is it to get reliable speedtest endpoints and how reliable are they in practice. And do you do any sanitization, like take another measure immediate if the measured rate differs from the last by more than XX% or something like that?
>> 
>> 
>>> 
>>> Sure, seems like this is easy to code because there are exactly two ports to measure, they can even be labeled physically "up" and "down" to indicate their function.
>> 
>> IMHO the real challenge is automated measurements over the internet at Gbps speeds. It is not hard to get some test going (by e.g. tapping into ookla's fast net of confederated measurement endpoints) but getting something where the servers can reliably saturate 1Gbps+ seems somewhat trickier (last time I looked one required a 1Gbps connection to the server to participate in speedtest.net, obviously not really suited for measuring Gbps speeds).
>> In the EU there exists a mandate for national regulators to establish and/or endorse an anointed "official" speedtests, untended to keep ISP marketing honest, that come with stricter guarantees (e.g. the official German speedtest, breitbandmessung.de will only admit tests if the servers are having sufficient bandwidth reserves to actually saturate the link; the enduser is required to select the speed-tier giving them a strong hint about the required rates I believe).
>> For my back-burner toy project "per-packet-overhead estimation on arbitrary link technology" I am currently facing the same problem, I need a traffic sink and source that can reliably saturate my link so I can measure maximum achievable goodput, so if anybody in the list has ideas, I am all ears/eyes.
>> 
>>> 
>>> For reference, the GL.iNet routers are tiny and nicely packaged, and run
>>> OpenWrt; they do have one with Gbit ports[0], priced around $70. I very
>>> much doubt it can actually push a gigabit, though, but I haven't had a
>>> chance to test it. However, losing the WiFi, and getting a slightly
>>> beefier SoC in there will probably be doable without the price going
>>> over $100, no?
>>> 
>>> I assume the WiFi silicon is probably the most costly piece of intellectual property in the system. So yeah. Maybe with the right parts being available, one could aim at $50 or less, without sales channel markup. (Raspberry Pi ARM64 boards don't have GigE, and I think that might be because the GigE interfaces are a bit pricey. However, the ARM64 SoC's available are typically Celeron-class multicore systems. I don't know why there aren't more ARM64 systems on a chip with dual GigE, but I suspect searching for them would turn up some).
>> 
>> The turris MOX (https://www.turris.cz/en/specification/) might be a decent startimg point as it comes with one Gbethernet port and both a SGMII and a PCIe signals routed on a connector, they also have a 4 and an 8 port switch module, but for our purposes it might be possible to just create a small single Gb ethernet port board to get started.
>> 
>> Best Regards
>>        Sebastian
>> 
>>> 
>>> -Toke
>>> 
>>> [0] https://www.gl-inet.com/products/gl-ar750s/
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>>> Cerowrt-devel at lists.bufferbloat.net
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>> 
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> 
> 
> -- 
> 
> Dave Täht
> CTO, TekLibre, LLC
> http://www.teklibre.com
> Tel: 1-831-205-9740