On Tue, Nov 17, 2020 at 10:08 AM Jesper Dangaard Brouer <bro...@redhat.com> wrote: > > On Tue, 17 Nov 2020 10:05:24 +0000 <erik.tarald...@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...)
Thanks, Erik, for the detailed information. This is super-useful. And thanks, Jesper, for the patch analysis. Yes, I agree that missing patch [1] is likely the cause of the lower BBR throughout in the "new_hw" case. Since the "new_hw" is running an older kernel that's missing this important patch, it would be expected to have lower throughput in a workload like this. It's unfortunate that it's not possible to have a newer kernel on the newer hardware; it does seem in this case that this would probably do the trick. best, neal _______________________________________________ Bloat mailing list Bloat@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/bloat