[Mesa-users] AMD Radeon Rx 580 on Linux is slow

[Jean-Dominique Frattini]

Good Morning,

I am looking for some help to find what could cause poor performances with
an AMD RX 580 graphic card on Linux.

First, what I am doing is rendering a scene about 74k triangles. Since I
got weird results, I did some tests to change how triangles are sent to GL.
Tests have been made with doing a single draw call with many triangles,
splitting a lot these draw calls (sending about 18k draw calls to GL), or
using glMultiDrawElements to regroup the many draw calls into a single
call. With these 3 methods I have almost the same result. Note that these
tests have been made using an own development project (closed-source).

I run this same tests on 4 different platforms:
P1: AMD Ryzen 7 1800X + AMD Rx 580 8 GB (free drivers) - Debian 10
P2: Intel Core I5 8300H + nVidia Geforce GTX 1060 6GB (nvidia drivers) -
Debian 10
P3: AMD FX 4170 + nVidia Geforce GTX 560 (nvidia drivers) - Debian 8
P4: Intel Atom Z36xxx (free drivers) - Debian 9

On P1, I reach about 67 images per second, a frame takes approximately 11
ms to be rendered, and could vary from 10 to 15 generally.
On P2, I reach about 240 images per second, a frame will take approximately
between 4 and 5 ms to be rendered.
On P3, I reach about 96 images per second, a frame will take approximately
10 ms to be rendered, and could vary from 7 to 11 ms generally.
On P4, I reach about 9 images per second, a frame will take approximately
between 100 and 110 ms.

On all systems vsync had been disabled.

glxgears tests reveal that P1 is still slower than P2 and P3 (vsync
disabled):

P1: average of 12800 FPS
P2: average of 17200 FPS
P3: average of 14200 FPS
P4: average of 3300 FPS

More information about P1:
OS: Debian Linux 10 (testing)
firmware for AMDGPU is up-to-date from Debian 10
OpenGL renderer: Radeon RX 580 Series (POLARIS10, DRM 3.26.0,
4.18.0-3-amd64, LLVM 7.0.1)
OpenGL vendor: X.Org
OpenGL version: 4.5 (Core Profile) Mesa 18.2.6
OpenGL Shading Language version: 4.50

Some more notes: building with or not debug do not show any differences for
P1 (not actually tested on other platforms). I also tried to disable OpenGL
debug extension, but I still have the same results. I also moved my CPU
scaling from on-demand to performance, but this also did not change things,
so I believe I am not CPU-bounded.

Any help would be appreciated. Please don't hesitate to ask for anything
you would believe relevant (dmesg outputs...) if you think this is
necessary.

Thanks.
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