https://bugs.kde.org/show_bug.cgi?id=492319
Bug ID: 492319
Summary: On laptop with Radeon 780M GPU, 6.1.4 causes Triple
Buffering to produce graphical corruption in XWayland
apps and lag in all apps
Classification: Plasma
Product: kwin
Version: 6.1.4
Platform: Other
OS: Linux
Status: REPORTED
Keywords: regression
Severity: normal
Priority: NOR
Component: performance
Assignee: kwin-bugs-n...@kde.org
Reporter: n...@kde.org
Target Milestone: ---
SUMMARY
My wife has started to experience a series of annoying graphical glitches on
her laptop (2023 HP Pavilion Plus 14, 7840U CPU, Radeon 780M GPU, 2.8k OLED
screen @ 200% scale, Mesa 24.1.6, Kernel 6.10.6, amd-gpu-firmware-20240811)
that was introduced with the Plasma 6.1.4 update, and are resolved by disabling
triple buffering.
SYMPTOMS
Symptom 1: Starting from the moment the session is logged in, there is
transient graphical corruption manifesting in thin horizontal bands of static
that briefly flash across the screen while XWayland apps are focused and
visually updating. The issue is seen in:
- Krita (Native Fedora package)
- Steam (Native Fedora package)
- Ungoogled Chromium (Flatpak)
Symptom 2: All apps on the system begin to graphically lag, with the lag
getting progressively worse the longer the system is used for. Specific
examples:
- Typed keystrokes in any app (including native Wayland KDE apps) will not be
shown on the screen for a few milliseconds.
- Drawn strokes in Krita will lag behind the pen.
- YouTube videos playing in either Ungoogled Chromium (XWayland, Flatpak) or
Firefox (Native Fedora packaging, Wayland) will begin to skip frames and the
audio will start to stutter. The effect is much worse in Ungoogled Chromium,
though it manifests to an extent in Firefox as well
Symptom 3: `radeontop` shows that VRAM is over-subscribed: from the moment the
session is logged in, it says it's at over 100% VRAM usage. typically about
110%. As apps are opened and used, this will rise to 120% or so.
While any of these issues are manifesting, the system feels relatively cool to
the touch and the fans are not going crazy. CPU, main memory, and storage
resources are not being stressed. Only the GPU appears to be stressed.
SOLUTION
We discovered that setting KWIN_DRM_DISABLE_TRIPLE_BUFFERING=1 fixes all of the
above issues. Notably, for symptom 3, the VRAM usage on boot goes down to only
about 90%, which still seems much too high and may be worth separately
debugging. This might have been caused by the changes that fixed Bug 488843,
which were released in Plasma 6.1.4.
OTHER SOLUTIONS ATTEMPTED
We previously tried rolling back the kernel, mesa, and amd-gpu-firmware to
significantly older versions, but to no effect. Only disabling triple buffering
helps.
--
You are receiving this mail because:
You are watching all bug changes.
