Radeon Linux Driver Adds Option To Limit Number Of Enabled CUs

[phoronix]

Phoronix: Radeon Linux Driver Adds Option To Limit Number Of Enabled CUs

The RadeonSI Gallium3D and RADV Vulkan drivers within Mesa 22.0 have now added an override for controlling the number of enabled compute units (CUs) for the graphics processor...

https://www.phoronix.com/scan.php?page=news_item&px=Radeon-Limit-CUs

[brunosalezze]

This looks like a very cool benchmarking tool.

[apaulanthony]

Given rest of the article I assume the reference to AMD_CPU_MASK= environment variable is a typo

[Michael]

Given rest of the article I assume the reference to AMD_CPU_MASK= environment variable is a typo

Whoops yeah fixed, thanks., Habit of typing CPU more often than CU...

[Rabiator]

This looks like a very cool benchmarking tool.

It looks certainly helpful for developers. For the end user though, an easy to use underclocking/undervolting tool might be more valuable.
No offense to Marek Olšák intended of course. I understand we cannot have everything and perhaps the Mesa team needs this tool to proceed with some other issue.

Edit:
With a bit more time on Google, I found some articles about Patrick Schur's atitool. It might have been exactly what I was thinking about, but it seems to be no longer maintained. Any recommended alternatives?

[ms178]

There are good undervolting guides for AMD cards for setting up a script and systemd service, it is not as comfortable as having a GUI but once you store the values somewhere it is a copy and paste job and done in minutes. (Sidenote: Arch and derivatives fail to launch the service automatically but it works on other distros). But I'd welcome a way to change the fan profile that doesn't cost performance, tools which I tried came at a rather large performance cost.

[kiffmet]

Rabiator there is a sysfs interface for OC and UV, once you've set amdgpu.ppfeaturemask=0xfffd7fff
I configured my system to automatically execute a bash script that loads my OC/UV when logging in. You may also use CoreCtrl, radeon-profile or TuxClocker (all three of them are Qt based), WattmanGTK or rocm_smi (CLI, comes directly from AMD).
Refer to the ArchLinux Wiki for further information on how to set it up and which files to edit.

[M@GOid]

Maybe this is something for emulating the Steam Deck on other hardware. Or a way to increase battery life in portables. Or both.

[aufkrawall]

I don't think it's much more useful for anything but to test if render task performance properly scales with number of CUs. If it doesn't, the game or driver code probably does something in a non-optimal way. This then might be a hint for performance optimization potential.

[Spacefish]

Nice, now you can disable the CUs which generate GPU ring hangs?!