[Bloat] BBR implementations, knobs to turn?

[Jesper Dangaard Brouer]

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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