AMD P-State Linux Driver Updated With Precision Boost Control, Other Fixes

[phoronix]

Phoronix: AMD P-State Linux Driver Updated With Precision Boost Control, Other Fixes

Back in Linux 5.17 the AMD P-State "amd_pstate" driver was introduced for Ryzen and EPYC systems as an alternative to the ACPU CPUFreq frequency scaling driver with an emphasis on delivering better power efficiency for modern AMD Zen 2 and newer systems. Since the mainlining there hasn't been too much change to this driver but now a new patch series has been sent out with some updates...

https://www.phoronix.com/scan.php?page=news_item&px=AMD-P-State-Precision-Boost

[Mitch]

I wonder if these enhancements will be backported for Steam Deck and if it already uses AMD P-State

[geearf]

How does it work with other schedulers? Is it ok to use this with BMQ/PDS or is it harmful?

[birdie]

For desktop CPUs, at least my 5800X, it's buggy as hell (these are three URLs/bugs), results in a higher power draw in idle and I'm not convinced it provides better performance. Looks like AMD doesn't care too much about this governor. It's especially upsetting to hear this from the lead developer, "I have no desktop Ryzen CPU to debug this". I mean AMD is flush with money and they cannot give a single CPU to their developer? Is this a freaking joke?

[cytomax55]

I wonder if these enhancements will be backported for Steam Deck and if it already uses AMD P-State

I wouldn't be surprised if Valve is funding this directly, I would be surprised if Valve wouldn't be using this as this would directly improve the experience of the steam deck

[muncrief]

I wonder if this will fix the Machine Check Errors and random reboots on Ryzen 3000 series CPUs. I was finally able to switch back to Linux as my primary OS a few weeks ago, and immediately began experiencing random reboots with my R7 3700X.

I'd been running Windows 10 for the last year and a half or so on the 3700X, and had run Linux on it for about a year before that, with no problems at all. But after some research I was shocked to learn that over the last few years the Linux kernel has been causing MCEs on various 3000 series CPUs, and that some kernel releases would seem to fix it, while others reintroduced the issue.

I further learned that the only solution right now was to buy a 5000 series CPU, so I had no choice but to purchase a new 5700X. By the way, while I waited for my new CPU I had to go back and run Windows 10 for a few days and it continued to work flawlessly, so it's highly doubtful that anything was wrong with the 3700X. In any case ever since I installed the 5700X Linux has worked flawlessly.

Now I just need to find someone who doesn't run Linux to buy my old 3700X.

[xnor]

Broken English in a commit message screenshot by Michael. Of course it's a bright white box on an otherwise dark-themed page.
Now all that is missing is changing the font to purple Comic Sans MS before taking the screenshot.

[intelfx]

So what is actually new here? Is this just about allowing software control of PB2, or are we talking about some new boost mode previously unavailable on Linux?

[birdie]

I wonder if this will fix the Machine Check Errors and random reboots on Ryzen 3000 series CPUs. I was finally able to switch back to Linux as my primary OS a few weeks ago, and immediately began experiencing random reboots with my R7 3700X.

I'd been running Windows 10 for the last year and a half or so on the 3700X, and had run Linux on it for about a year before that, with no problems at all. But after some research I was shocked to learn that over the last few years the Linux kernel has been causing MCEs on various 3000 series CPUs, and that some kernel releases would seem to fix it, while others reintroduced the issue.

I further learned that the only solution right now was to buy a 5000 series CPU, so I had no choice but to purchase a new 5700X. By the way, while I waited for my new CPU I had to go back and run Windows 10 for a few days and it continued to work flawlessly, so it's highly doubtful that anything was wrong with the 3700X. In any case ever since I installed the 5700X Linux has worked flawlessly.

Now I just need to find someone who doesn't run Linux to buy my old 3700X.

CPU governor is extremely unlikely to be the culprit. A faulty CPU is a lot more likely: Linux might be stressing different parts of your CPU or has different power management which is why you're getting those errors. Please try updating BIOS, and remove any overclocking/tuning if you have it.

I've used 3700X and 5800X each for over a year and a half, and I've had zero issues with them. The motherboard is the same. For the last one I have a slight overclock and undervolt as well. My only issue is that after all the BIOS updates 3700X idled around 11W while 5800X idles around 20W. Looks like something in 5800X in terms of power consumption/gating works worse than it did in 3700X. This is however shared by other Ryzen 5000X owners, so I accepted it.

AMD offers 3 years limited warranty for its CPUs, so I'd RMA it.

[birdie]

So what is actually new here? Is this just about allowing software control of PB2, or are we talking about some new boost mode previously unavailable on Linux?

amd-pstate is meant to provide better performance at a lower power envelope because it exposes proper CPU frequency controls (CPPC). The ACPI driver only knows about three frequencies 2200MHz, 2800MHz and 3800MHz.