[Bug 256594] AMD Ryzen CPU stutter (responsiveness lag)

From: <bugzilla-noreply_at_freebsd.org>
Date: Sun, 25 Dec 2022 14:53:01 UTC

--- Comment #11 from crest@rlwinm.de ---
If you're still stuck try breakout out into the loader prompt by pressing
escape during the 10 second countdown in the bootloader menu. On the loader
prompt type:

    set kern.sched.steal_thresh=0

To persist this you can put this line into /boot/loader.conf to apply as early
as possible:


To apply it slightly later you can add the same line to /etc/sysctl.conf as
initially reported in this thread.

The stutter wasn't bad enough during installation on my personal workstation
which als moonlights as a gaming rig (AMD Ryzen 9 3950X, 32GB DDR4-3600 RAM,
RTX 3090 GPU). It just felt slightly off at the vt(4) console. I couldn't place
it at the time. With Xorg and the Nvidia driver loaded the system was still
fast when compiling etc., but felt very sluggish and lots of tearing in i3.
Supposedly smooth scrolling in browsers etc. was nothing of the sort. To get a
pleasant desktop experience without tearing I also had to force the Nvidia
driver to use a less efficient form of composition which increased idle power
consumption by ~10W, because it keeps the GPU from staying in the lowest power
state even when just editing source code in urxvt and gvim.

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