https://bugs.kde.org/show_bug.cgi?id=470376
Bug ID: 470376
Summary: kscreenlocker uses discrete GPU when integrated GPU is
available.
Classification: Plasma
Product: kscreenlocker
Version: 5.27.5
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: plasma-b...@kde.org
Reporter: dmkoppel...@gmail.com
Target Milestone: ---
SUMMARY
I have a laptop with both an integrated and discrete GPU set up so
that the discrete GPU is only used by programs with certain
environment variables set (e.g, __NV_PRIME_RENDER_OFFLOAD). The intent
is to use the GPU only for graphics- or compute-intensive programs. At
other times the GPU is suspended, saving energy.
This works well most of the time, an exception is when the screen is
locked using kscreenlocker. While the screen is locked the discrete
GPU is active, wasting energy. This happens on AC, I have not tried it
on battery power.
It would be nice if kscreenlocker could avoid waking up the GPU so
that it remains suspended while the screen is locked.
STEPS TO REPRODUCE
1. Start with a system with both an integrated GPU and an NVidia
discrete GPU. Set up the system for render offloading.
2. Verify that discrete GPU is only being used where intended by
executing: cat /sys/devices/pciPATH-TO-GPU/power/runtime_status
(The file's contents is either "active" or "suspended".)
3. Wait for the screen to lock.
4. Check status by logging in from another system or unlock and cat
the runtime_status file.
OBSERVED RESULT
The contents of runtime_status was "active". After the GPU is
unlocked it returns to "suspended". (In my case the keyboard is
noticeably warm with the GPU running.)
EXPECTED RESULT
The contents of runtime_status is "suspended".
SOFTWARE/OS VERSION
This occurs on a Dell Precision 7680 (and 7560), both with integrated
and discrete (NVidia) GPUs.
Fedora 38
KDE 5.27.5
Qt: 5.15.9
KDE Frameworks: 5.106.0
NVIDIA binary drivers.
The problem occurs both under X11 and Wayland.
ADDITIONAL INFORMATION
Other programs, such as Chrome and kwin do not use the discrete GPU
(without the environment variables et). (Chrome, for example, uses the
discrete GPU only if started with __NV_PRIME_RENDER_OFFLOAD=1 set in
the environment.)
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