Title, basically. I’ve been tracking this problem for a while, here’s a reddit thread about it:
Long story short, some newer AMD chips have had bad performance in the last few kernels. The known workaround is to put amdgpu.dcdebugmask=0x10 in your kernel args. This fixes the lag, but also significantly increases power draw.
After a kernel update I usually try booting without that parameter to find out if it’s still necessary; today’s kernel seems to have finally fixed the problem. Here’s hoping it never comes back!
If you have hardware affected by this bug, and have been using the parameter as a workaround, you should try booting without amdgpu.dcdebugmask=0x10 and see if your problem is solved.
Fastfetch output for reference:
$ fastfetch -l none
user@host
-------------
OS: Bluefin (Version: 41.20250420 / FROM Fedora Silverblue 41) x86_64
Host: 21MCCTO1WW (ThinkPad T14 Gen 5)
Kernel: Linux 6.13.8-200.fc41.x86_64
Uptime: 23 mins
Packages: 2493 (rpm), 84 (flatpak), 215 (brew)
Shell: bash 5.2.32
Display (LEN414B): 2880x1800 @ 120 Hz (as 1440x900) in 14" [Built-in]
DE: GNOME 47.5
WM: Mutter (Wayland)
WM Theme: adw-gtk3-dark
Theme: adw-gtk3-dark [GTK2/3/4]
Icons: Papirus-Dark [GTK2/3/4]
Font: Inter (10pt) [GTK2/3/4]
Cursor: Bibata-Modern-Ice (24px)
Terminal: Ptyxis 47.12
Terminal Font: CommitMono (10pt)
CPU: AMD Ryzen 7 PRO 8840U (16) @ 5.13 GHz
GPU: AMD Phoenix3 [Integrated]
Memory: 6.33 GiB / 29.99 GiB (21%)
Swap: 0 B / 8.00 GiB (0%)
Disk (/sysroot): 97.93 GiB / 952.27 GiB (10%) - btrfs [Read-only]
Local IP (wlp2s0): 192.168.0.164/24
Battery (5B11H56418): 39% [Charging, AC Connected]
Locale: en_US.UTF-8
thank you, I spent a lot of time asking AI for ideas on how to troubleshoot this and I’m not sure if I was experiencing exactly this but at some point I started seeing stuttering about 5% of the time and it’s been gradually more and more unbearable.
But, the dcdebugmask setting wasn’t it (yes I’m using rpm-ostree kargs to set boot args, this should be called out in /etc/default/grub, IMO).
I have a RX6080XT factory overclocked card, which I think means that the memory clock (as seen in radeontop) is always 100%. I tried disabling freesync on my monitor, I tried various power management amdgpu driver flags. I enabled the gnome variable-refresh-rate experimental setting.. I checked the cable.. I updated bluefin from gts to stable.
I switched over to bazzite-gnome, seeing mention of gnome VRR patches, but that wasn’t it
KDE has the goods. So bazzite:stable. (even with bazzite-gnome having a newer amd-gpu-firmware package of 20250410-1.fc42 where as bazzite:stable has 20250311-1.fc42) . I also do not have this dcdebugmask setting now.
I don’t know if my issue was a combo of the card, a kernel regression, or gnome.
I guess I should try Aurora - I need incus and zfs
just want to mention one more thing: I used Nixola/VRRTest and glxgears to test this. I’m now seeing 239.9 FPS whereas I was seeing 220 FPS before, again don’t know when that degraded.