[Ecn-sane] Fwd: [Cake] fq_codel_fast

[Dave Taht]

---------- Forwarded message ---------
From: Sebastian Moeller <moeller0 at gmx.de>
Date: Thu, Sep 6, 2018 at 10:25 AM
Subject: Re: [Cake] fq_codel_fast
To: Dave Täht <dave.taht at gmail.com>
Cc: Pete Heist <pete at heistp.net>, Cake List <cake at lists.bufferbloat.net>


Hi Dave,



> On Sep 6, 2018, at 19:22, Dave Taht <dave.taht at gmail.com> wrote:
>
> There was a very good paper or two (I think luca co-authored one) that
> showed that "active flows" were generally measured in the mid 200s in
> nearly any scenario. I agreed with that which was in part why I felt
> we could stick
> with 1024 queues, a direct mapped hash, and a couple collisions.
>
> cake can falsify that conclusion, or not - at least with ecn enabled,
> it does falsify it. I think. Can't remember the paper's name....

        I believe you are looking for (
https://team.inria.fr/rap/files/2013/12/KMOR04.pdf ):
"On the Scalability of Fair Queueing"

Best Regards
        Sebastian


>
> whether or not accepting 3x more delay as in this case is good,
> well... more measurements await via
> https://www.bufferbloat.net/projects/ecn-sane/wiki/ and the ecn-sane
> mailing list is now active.
>
> My original cake code dropped ecn on overload. I tended to think a
> little ecn a good thing.
>
>
> On Thu, Sep 6, 2018 at 10:10 AM Pete Heist <pete at heistp.net> wrote:
>>
>> Interesting, sounds like a good data point for the ECN debate. I wonder if that pathology happens at lower flow counts.
>>
>> I’ve been getting into FreeNet’s backhaul. Four of their backhaul links, the orange lines in the following map, are licensed spectrum full-duplex 100Mbit wireless links (not sure what tech, I’ll ask). I’ve so far not witnessed any bloat in these links because they seem to be over-provisioned based on the rates of the CPE connections, although that may change as AC is increasingly deployed.
>>
>> http://mapa.czfree.net/#lat=50.76176199690661&lng=15.06277084350586&zoom=13&autofilter=1&type=satellite&geolocate=98%7C114%7C111%7C117%7C109%7C111%7C118%7C115%7C107%7C97&node=6101&aponly=1&bbonly=1&actlink=1&actnode=1&tilt=0&heading=0&
>>
>> Active flow counts appear to be in the tens sometimes, probably not hundreds very often, from what I’ve witnessed so far...
>>
>> On Aug 30, 2018, at 8:24 PM, Dave Taht <dave.taht at gmail.com> wrote:
>>
>> This version does indeed work against net-next. I managed to break
>> myself because I'd been fiddling with flows 32 in some cases, and my
>> version
>> returns ENOTSUPP for that which sqm doesn't catch... and ohhh....
>> boy... htb with a 1000 packet fifo buffer fallback... SUCKS! :)
>>
>> As for profiling, once again I found myself distracted by the ecn
>> debate. Fitting ecn 500 flows through a 100mbit bottleneck results in
>> 1300 packets outstanding
>> 26 flows that can't start (presumably due to ecn fall back), and
>> without ecn, 450 packets outstanding 3 flows that can't start.
>>
>> On Wed, Aug 29, 2018 at 7:23 AM Dave Taht <dave.taht at gmail.com> wrote:
>>
>>
>> I'm presently compiling against net-next.
>> On Wed, Aug 29, 2018 at 1:12 AM Pete Heist <pete at heistp.net> wrote:
>>
>>
>>
>> On Aug 29, 2018, at 3:04 AM, Dave Taht <dave.taht at gmail.com> wrote:
>>
>> Anyway, this should be a drop in replacement (presently) for fq_codel,
>> that compiles out of tree and rips out almost everything I don't like.
>>
>> https://github.com/dtaht/fq_codel_fast
>>
>>
>> Cool…I’d give it a quick run but it doesn’t compile for me (attached). Kernel version?
>>
>> I think the tc filter thing really hurt us in cake.
>>
>>
>> It would be interesting to see how much. Jon also expressed concern and I’d been meaning to try some benchmarks before and after that change…
>>
>>
>>
>> --
>>
>> Dave Täht
>> CEO, TekLibre, LLC
>> http://www.teklibre.com
>> Tel: 1-669-226-2619
>>
>>
>>
>>
>> --
>>
>> Dave Täht
>> CEO, TekLibre, LLC
>> http://www.teklibre.com
>> Tel: 1-669-226-2619
>>
>>
>
>
> --
>
> Dave Täht
> CEO, TekLibre, LLC
> http://www.teklibre.com
> Tel: 1-669-226-2619
> _______________________________________________
> Cake mailing list
> Cake at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cake



-- 

Dave Täht
CEO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-669-226-2619