RX 480, Ryzen 1600X, tested on linux 4.10 and linux drm-next-4=
.12-wip, latest
upstream linux-firmware git. Same behavior on both kernels.
I recorded this video, showing umr top, sclk and mclk, while running the si=
mple
"Atlas Demo Scene" in the Destinations SteamVR app:
https://www.youtu=
be.com/watch?v=3DU_mceDSBF7o
With the "auto" setting the GPU power level is not set high enoug=
h for SteamVR
to render at the Vive's native 90 fps, so reprojection (interpolation to 90
fps) needs to kick in constantly.
Speculation time:
The SteamVR frametime graph shows the purple GPU load from the application
("Destinations") completely below the 11 ms which the application=
is probably
is probably targeting, so dpm has clocked the GPU fast enough for the
application to run at 90 fps. But then the application submits frames to the
SteamVR compositor which also takes some GPU time and pushes the "tota=
l" GPU
time taken to render one frame in the app and then display it in the compos=
itor
over the target 11 ms time.
Is this correct? Does dpm somehow analyze a per process GPU load? At least =
in
this case the GPU needs to clock fast enough to allow the application + the
SteamVR compositor to both render in under 11 ms per frame.