[Bloat] BBR implementations, knobs to turn?

[erik.taraldsen at telenor.com]

Update:
The 5G router was connected to a new base station.  Now the limiting factor of throughput is the policer on the PGW in mobile core, not the radio link itself.  The SIM card used is limited to 30Mbit/s.  This scenario favours the new server.  I have attached graphs comparing radio link limited vs PGW policer results, and a zoomed in graph of the policer


We have Huawei RAN and Ericsson RAN, rate limited and not rate limited subscriptions, 4G and 5G access, and we are migrating to a new core with new PGW (policer).  Starting to be a bit of a matrix to set up tests for.


-Erik


________________________________________
Fra: Jesper Dangaard Brouer <brouer at redhat.com>
Sendt: 17. november 2020 16:07
Til: Taraldsen Erik; Priyaranjan Jha
Kopi: brouer at redhat.com; ncardwell at google.com; bloat at lists.bufferbloat.net
Emne: Re: [Bloat] BBR implementations, knobs to turn?

On Tue, 17 Nov 2020 10:05:24 +0000 <erik.taraldsen at telenor.com> wrote:

> Thank you for the response Neal

Yes. And it is impressive how many highly qualified people are on the
bufferbloat list.

> old_hw # uname -r
> 5.3.0-64-generic
> (Ubuntu 19.10 on xenon workstation, integrated network card, 1Gbit
> GPON access.  Used as proof of concept from the lab at work)
>
>
> new_hw # uname -r
> 4.18.0-193.19.1.el8_2.x86_64
> (Centos 8.2 on xenon rack server, discrete 10Gbit network card,
> 40Gbit server farm link (low utilization on link), intended as fully
> supported and run service.  Not possible to have newer kernel and
> still get service agreement in my organization)

Let me help out here.  The CentOS/RHEL8 kernels have a huge amount of
backports.  I've attached a patch/diff of net/ipv4/tcp_bbr.c changes
missing in RHEL8.

It looks like these patches are missing in CentOS/RHEL8:
 [1] https://git.kernel.org/torvalds/c/78dc70ebaa38aa3
 [2] https://git.kernel.org/torvalds/c/a87c83d5ee25cf7

Could missing patch [1] result in the issue Erik is seeing?
(It explicitly mentions improvements for WiFi...)

--
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer
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