OpenGL performance reduced on Raspbian Stretch

[Tommi]

Originally reported here:
https://www.raspberrypi.org/forums/viewtopic.php?f=66&t=191791

Basically, OpenGL performance is reduced by Stretch update when compared to older Jessie release.

Jessie used Mesa 13.0.0 release, Stretch use Mesa 13.0.6 release.

quote from user:

"Running 'glxgears -info' on Raspbian Jessie is reporting around 180 frames-per-second rendering speed but the same on Stretch is reporting only about 45 FPS, or a quarter of the speed! This is on the same hardware (a Raspberry Pi 3 with HDMI output), in both cases with the 'experimental' VC4 GL Driver disabled."

# glxinfo output for Jessie and Stretch

Jessie:

name of display: :0.0
display: :0 screen: 0
direct rendering: Yes
server glx vendor string: SGI
server glx version string: 1.4
client glx vendor string: Mesa Project and SGI
client glx version string: 1.4
GLX version: 1.4
OpenGL vendor string: VMware, Inc.
OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 3.9, 128 bits)
OpenGL core profile version string: 3.3 (Core Profile) Mesa 13.0.0
OpenGL core profile shading language version string: 3.30
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL version string: 3.0 Mesa 13.0.0
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL ES profile version string: OpenGL ES 3.0 Mesa 13.0.0
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00

Stretch:

name of display: :0.0
display: :0 screen: 0
direct rendering: Yes
server glx vendor string: SGI
server glx version string: 1.4
client glx vendor string: Mesa Project and SGI
client glx version string: 1.4
GLX version: 1.4
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: VMware, Inc. (0xffffffff)
    Device: llvmpipe (LLVM 3.9, 128 bits) (0xffffffff)
    Version: 13.0.6
    Accelerated: no
    Video memory: 927MB
    Unified memory: no
    Preferred profile: core (0x1)
    Max core profile version: 3.3
    Max compat profile version: 3.0
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.0
OpenGL vendor string: VMware, Inc.
OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 3.9, 128 bits)
OpenGL core profile version string: 3.3 (Core Profile) Mesa 13.0.6
OpenGL core profile shading language version string: 3.30
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL version string: 3.0 Mesa 13.0.6
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL ES profile version string: OpenGL ES 3.0 Mesa 13.0.6
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00

Note: llvmpipe is being used on both Jessie and Stretch releases (not VC4)

CPU load:
Jessie: ~180 fps, CPU load ~50% (CPU meter in task bar) ~180% ('top' command), colours correct.
Stretch: ~45 fps, CPU load ~70% (CPU meter) ~260% ('top'), colours incorrect.

[Jernej Jakob (jjakob)]

Can confirm the bug in Stretch. glxgears reports 45fps because it is using llvmpipe instead of VC4.
When enabling the GL driver via raspi-config, raspi-config should remove/disable /usr/share/X11/xorg.xonf.d/99-fbturbo.conf (e.g. rename it to disable it), but it does not, which results in Xorg not using the GL driver. A manual workaround is renaming this file manually (don't forget to rename it back when disabling the GL driver or you'll get no video!).
So this is IMO at least a bug in raspi-config.
Why jessie gives 180fps in glxgears even when using llvmpipe, I have no idea. llvmpipe is software rendered, it's not VC4 which is hardware rendered.

[Jernej Jakob (jjakob)]

I opened an issue at https://github.com/RPi-Distro/raspi-config/issues/78