[Cake] fq_codel_fast

[Dave Taht]

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....

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