Apple Catalina Appears to Introduce Massive Jitter

Thu Oct 29 18:14:25 UTC 2020

I was curious, so poked at this... my results from a macbook pro 2019
running Catalina 10.15.3

sudo /usr/local/sbin/mtr -r 10.200.200.200

Start: 2020-10-29T14:09:08-0400
HOST: bos-mp36c                   Loss%   Snt   Last   Avg  Best  Wrst StDev
  1.|-- 10.200.200.200             0.0%    10   11.9  63.7   9.0 340.2 104.1

sudo sysctl net.link.generic.system.hwcksum_tx=0
net.link.generic.system.hwcksum_tx: 1 -> 0
sudo sysctl net.link.generic.system.hwcksum_rx=0
net.link.generic.system.hwcksum_rx: 1 -> 0
sudo ifconfig en0 -rxcsum

sudo /usr/local/sbin/mtr -r 10.200.200.200

Start: 2020-10-29T14:09:43-0400
HOST: bos-mp36c                   Loss%   Snt   Last   Avg  Best  Wrst StDev
  1.|-- 10.200.200.200             0.0%    10   19.8  13.6   9.8  20.9   4.5

So, seems to make things better. =-)

On Thu, Oct 29, 2020 at 11:50 AM Mark Tinka <mark.tinka at seacom.com> wrote:

>
>
> On 10/29/20 16:08, J. Hellenthal wrote:
>
> > I believe I have seen the same thing with a Mid 2015 11,4 running
> catalina. Not diagnosing further because I could not find a reason for it
> fast enough and not sure if it really had an impact at the moment…. but
> could you try the following
> >
> >
> > sudo sysctl net.link.generic.system.hwcksum_tx=0
> > sudo sysctl net.link.generic.system.hwcksum_rx=0
> > sudo ifconfig en0 -rxcsum
>
> Thanks, I'll have a sniff.
>
> > If you have some specific tests to run I would be willing to run them
> here on Big Sur with the same laptop but I have nothing now that runs
> Catalina
>
> One of my mates found the same issue on Big Sur (beta) on a 2013 MacBook
> Pro.
>
> Just a simple mtr test to your local home router's IP address should,
> over wi-fi, should show you the jitter.
>
> Mark.
>
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