https://bugs.kde.org/show_bug.cgi?id=524682
Bug ID: 524682
Summary: Overview effect fails to delete render time queries
("no context is current"), corrupting render-time
measurement
Classification: Plasma
Product: kwin
Version First 6.7.4
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: effects-overview
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Every invocation of the Overview effect (Meta+W) causes KWin to emit 2-4 copies
of:
kwin_wayland[PID]: Could not delete render time query because no context is
current
The messages appear immediately after the Overview QML component loads, and
recur on
every open/close cycle. Because these are the GL timer queries KWin uses to
measure
render time -- and render time feeds frame scheduling against vblank -- the
practical
effect is degraded frame pacing: stutter during ordinary compositing, and
KWin's own
showfps frame-time graph sticking at maximum until the output pipeline is torn
down
and rebuilt.
STEPS TO REPRODUCE
1. Log into a Plasma Wayland session.
2. In a terminal run: journalctl --user -f | grep --line-buffered "render time
query"
3. Press Meta+W to open Overview, then close it. Repeat several times.
OBSERVED RESULT
2-4 error lines are logged per invocation. Sample showing the correlation with
Overview's QML loading:
00:30:29 kwin_wayland[3030]:
qrc:/qt/qml/org/kde/kwin/overview/qml/Main.qml:851:5: QML Connections:
Implicitly defined onFoo properties in Connections are deprecated.
00:30:31 kwin_wayland[3030]: Could not delete render time query because no
context is current
00:30:31 kwin_wayland[3030]: Could not delete render time query because no
context is current
00:30:31 kwin_wayland[3030]: Could not delete render time query because no
context is current
00:30:56 kwin_wayland[3030]:
qrc:/qt/qml/org/kde/kwin/overview/qml/Main.qml:851:5: QML Connections: ...
00:30:57 kwin_wayland[3030]: Could not delete render time query because no
context is current
00:30:57 kwin_wayland[3030]: Could not delete render time query because no
context is current
00:30:57 kwin_wayland[3030]: Could not delete render time query because no
context is current
Setting overviewEnabled=false in kwinrc [Plugins] stops the errors entirely and
resolves the associated frame-time misbehaviour.
EXPECTED RESULT
Overview's teardown path should make the GL context current before deleting its
render time query objects, or defer deletion until a context is available. No
errors
should be logged and render-time measurement should remain valid.
INVESTIGATION -- WHAT HAS BEEN RULED OUT
This was originally suspected to be a multi-GPU context-management problem. It
is
not. The error reproduces identically in all three of the following
configurations:
1. Two GPUs present (AMD Raphael iGPU + NVIDIA RTX 5090), KWin managing both
("Atomic Mode Setting on GPU 0: true", "GPU 1: true").
2. Two GPUs present, KWin restricted to one via
Environment=KWIN_DRM_DEVICES=/dev/dri/card2 in a
plasma-kwin_wayland.service.d
drop-in. Confirmed GPU 0 only. Error rate unchanged.
3. Single GPU -- AMD iGPU disabled in firmware, so only the NVIDIA card exists
in
the system at all (/dev/dri contains only card1 and renderD128). Error rate
unchanged.
So the defect is in Overview's own GL context handling, independent of GPU
count.
Also of note: toggling HDR off/on on the affected output (which tears down and
rebuilds the output's pipeline) temporarily restores a sane frame-time reading,
consistent with the query objects being left in a bad state rather than the
compositor genuinely rendering slowly.
SOFTWARE / HARDWARE
Operating System: Fedora Linux 44
KDE Plasma Version: 6.7.4
KWin: kwin-6.7.4-2.fc44.x86_64
Qt Version: 6.11.1
Kernel Version: 7.1.9-200.fc44.x86_64
Graphics Platform: Wayland
Graphics Processor: NVIDIA GeForce RTX 5090
Driver: NVIDIA proprietary 610.57.04
CPU: AMD Ryzen 9 9950X3D
Displays at time of capture: LG 3440x1440@240Hz (HDR + WCG enabled) and a
second
2560x1440@120Hz panel rotated 270 degrees. The error reproduces regardless of
which
output is focused.
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