Power-saving/performance toggles for amdgpu

[Alex Deucher]

On Mon, Sep 7, 2020 at 10:30 AM Bastien Nocera <hadess at hadess.net> wrote:
>
> Hey,
>
> I'm currently working on a daemon that allows a UI that will eventually
> look like the power mode section in this mockup:
> https://gitlab.gnome.org/Teams/Design/settings-mockups/-/blob/master/power/power.png
>
> The daemon:
> https://gitlab.freedesktop.org/hadess/power-profiles-daemon
> The UI:
> https://gitlab.gnome.org/GNOME/gnome-control-center/-/merge_requests/816
>
> It might be interesting, on some systems, to nudge the GPU drivers
> in the direction wanted by the user, either enabling aggressive power-
> saving or allowing more power to be used for better temporary
> performance.
>
> I was wondering whether the tweaks
> in /sys/class/drm/card*/device/power_profile
> and /sys/class/drm/card*/device/power_method were things that this
> daemon could and should tweak, or whether it was present solely for
> debug purposes and shouldn't be needed even when high performance or
> power-saving is wanted:
> https://gitlab.freedesktop.org/hadess/power-profiles-daemon/-/issues/3
>
> Thanks in advance!
>

On older radeons (e.g., pre-GCN hardware), there were separate power
states for battery and AC, but these asics are supported by the radeon
kernel driver.  None of the hardware supported by amdgpu exposes
anything like that anymore.  The rest is mainly for profiling and
debugging.  For more information see the relevant kernel
documentation:
https://www.kernel.org/doc/html/latest/gpu/amdgpu.html#gpu-power-thermal-controls-and-monitoring
I don't think there is anything you'd want to tweak there.

Alex