To start with, here’s the hardware I’m trying to get working in tandem:
-AMD Vega 56 (top PCI-E slot)
-AMD R7 250 (lowest 8x PCI-E slot)
-Asus Z-97 AR mobo
Running Pop!_OS 20.10
When I test with one GPU connected in their respective PCI-E slots, performance is excellent and rendering goes as smoothly as you can expect for their classes.
But for whatever reason, when connecting both at the same time, suddenly I get absurdly terrible performance on the poor little R7 250 if I either designate it as the “primary monitor” using the “Settings>Displays” tool in a spanned desktop, or disable the Vega 56 and attempt to use only the R7 250.
Talking like (exactly) 1 frame per second on a consistent basis.
While I can’t figure out how I’m supposed to offload GPU rendering in xrandr yet, the same thing happens if I turn off the Vega 56 using --output --off. ((I think the offloading problem is just me being dumb, my attempts at using the “–setprovider(…)” switches either don’t seem to do anything or throw an error–will post log if deemed important))
Mouse movement is always updating at the same time as Hz, but applications, DE/GUI elements, and the terminal are almost exclusively stuck updating at what seems to be exactly 1 frame per second, which really makes me near certain it’s a software issue. (The one exception is a video game called “Freedom Planet” that can escape this after some time and run full speed for some reason???)
For whatever reason, the inverse is true for the Vega 56 and it always performs wonderfully regardless of what I’m doing with the R7 250 or if it’s enabled/disabled.
Briefly testing in a live media session for Manjaro xfce seems to yield the same behavior, so I’m probably not getting Ubuntu’d or Gnome’d. Using the two GPUs in this manner works perfectly fine under Windows 10 20.04 as well, so I’m really thinking it’s not a hardware/UEFI issue.
I’m awfully sorry, but I may need some guidance as for how I’m supposed to report what mesa drivers I’m using or if this distro is even using x.org or wayland, how to set up or fetch some logging for system states, or similar such things if needed. I’m not really sure where I should be going or what I should be doing at this point tbh lol.
I kinda’ was hoping I could render on the beefy Vega 56 and output through the R7 250, so I want to get the two working in harmony ideally. To avoid any possible confusion, I am not attempting passthrough with VM–I simply have 2 GPUs in the PC and everything is running bare metal.
Thanks for helping a noob if you got this far lol