GPU under-volting and performance governors - AMD

jrwagh333 · November 15, 2018, 8:48pm

Using Ubuntu 18.04. I’m new to Linux so still learning.

My R9 290 isn’t giving me the performance I need compared to when I used windows - after asking here it seems to be an issue with drivers.

So I have decided to go for either an RX580 or RXVega 56.

My question is about under-volting and GPU guvners.

In windows it was just an easier slider ina GUI but I understand with Linux it’s a bit more technical.

Is anybody able to help or direct me to some info where I can learn?

If I go for the Vega then I heard it is a really good idea to undervolt - I just don’t have the first clue how to do it without EVGA Percision or MSI Afterburner

anotherriddle · November 15, 2018, 11:07pm

Unfortunately not my field of expertise, but I will link this (somewhat relevant) recent thread here:

How to overclock Vega on Linux...? GPU

I recently upgraded to a Vega 56 (specifically the MSI Air Boost Vega 56 “OC” edition.) Initial clock speeds under Windows were pretty weak; I was only hitting 1320MHz in demanding scenarios. Then following some advice from @thro I undervolted by 100mV and increased the power limit by +50%, and saw clock speeds jump to a high of 1580MHz. Keep in mind that the vendor set the clock speed target to 1622MHz, so technically I’m not overclocking… I started with Windows, because I’m familiar with stress tests, benchmarks and overclocking tools available on that platform. Now I’m trying to accomplish the same thing on Linux. I found a few scant articles on Phoronix about how to increase the power limit, but even manipulating the files in /sys/class/drm/card0/device/hwmon/hwmon0 will only let me lower the power limit, not raise it. So in Linux I’m still stuck at a 165 watt power limit. Any advice? Is this only possible with amdgpu-pro?

https://www.phoronix.com/scan.php?page=news_item&px=AMDGPU-OverDrive-Linux-4.15

TL;DR it’s not really supported but also not completely out of the question.

Zippy_Parmesian · November 15, 2018, 11:25pm

It was fixed by AMD on the 22nd of October. You should be able to do it in Overdrive. Unfortunately, you’ll need a very recent kernel to do it.

For those interested, this is the patch:

jrwagh333 · November 16, 2018, 9:35am

I didn’t know you could get AMD Overdrive on linux

Melcar · November 16, 2018, 5:03pm

Currently, the easiest way is by using AMD’s proprietary drivers. I stopped using those several years ago, so I have no idea about the specifics.
As far as open source drivers go, currently there is only frequency overclocking. Additionally, due to changes being made (AMD is set to implement Overdrive functionality on the kernel), overclocking is no longer as straight forward.
The only viable and same solution right now is to use the available radeon power profiles. This simply lets you switch between preset power profiles with default frequency ranges.