New Patches Allow More Easily Managing The AMD P-State Linux Driver

[phoronix]

Phoronix: New Patches Allow More Easily Managing The AMD P-State Linux Driver

Since the introduction of the AMD P-State driver to the mainline kernel, enthusiasts and gamers have been experimenting with the amd_pstate driver and some distributions like Ubuntu have went with using this driver in place of ACPI CPUFreq by default for Zen 2 and newer processors. Patches posted this week by AMD make it easier to switch between the AMD P-State driver and ACPI CPUFreq...

https://www.phoronix.com/news/AMD-P-State-Built-In-Options

[HD7950]

AMD P-State EPP driver really works as expected. I said bye bye to schedutil one month ago.

[ffs_]

Fine, I'll wait for another year and keep using ACPI CPUFreq + Performance governor until then.

[david-nk]

I feel like the scheduler doesn't matter much anymore. I use CPUFreq with the minimum frequency raised to 3 GHz from the default 400 MHz, which ensures a very responsive system. In the past you could not really do that since power draw would go up massively even when the system was idle, but that is no longer the case for modern CPUs. The power draw does not increase even by a single watt.

[ffs_]

I feel like the scheduler doesn't matter much anymore. I use CPUFreq with the minimum frequency raised to 3 GHz from the default 400 MHz, which ensures a very responsive system. In the past you could not really do that since power draw would go up massively even when the system was idle, but that is no longer the case for modern CPUs. The power draw does not increase even by a single watt.

That's true. Operating at high(er) frequencies doesn't mean that power draw is raising proportionately if there is no actual load.

[birdie]

AMD P-State EPP driver really works as expected. I said bye bye to schedutil one month ago.

It's a fucking bugfest and in idle it consumes more than the acpi driver. If that "works" for you, great. In the real world, that's fucking unacceptable.

Not to mention Windows users have been enjoying a featureful bug-free CPPC AMD CPU driver for over six years now (!) and in Linux we have fucking nothing yet.

Great open source support AMD is showing. So fucking great. No idea why open source fans love the company so much.

https://bugzilla.kernel.org/show_bug.cgi?id=215729

https://bugzilla.kernel.org/show_bug.cgi?id=215800

https://bugzilla.kernel.org/show_bug.cgi?id=215801

[birdie]

I feel like the scheduler doesn't matter much anymore. I use CPUFreq with the minimum frequency raised to 3 GHz from the default 400 MHz, which ensures a very responsive system. In the past you could not really do that since power draw would go up massively even when the system was idle, but that is no longer the case for modern CPUs. The power draw does not increase even by a single watt.

The scheduler matters when you need to limit your system power consumption because modern CPUs are so eager to jump to maximum performance states whenever there's any minimal load which could be undesirable in certain situations.

[birdie]

Fine, I'll wait for another year and keep using ACPI CPUFreq + Performance governor until then.

You may as well not use the CPU governor at all. Your system will be even faster. I don't understand why people bother with the CPU frequency subsystem when they switch to the performance governor.

Boot with module_blacklist=acpi-cpufreq intel_pstate=disable and you're good to go.

[V1tol]

No idea why open source fans love the company so much.

We love AMD mostly for opensource GPU support, not for the processors. Couple of months ago it was a single company producing both fast GPUs and good opensource drivers. And cpufreq vs AMD P-State makes almost no performance difference on my 5950X. The only difference I found is minimal frequency - 2.2GHz vs 400MHz, which I find as advantage of cpufreq from responsiveness perspective. Obviously energy consumption for desktop is not very important, especially when you have RX6800XT.

[ffs_]

You may as well not use the CPU governor at all. Your system will be even faster. I don't understand why people bother with the CPU frequency subsystem when they switch to the performance governor.

Boot with module_blacklist=acpi-cpufreq intel_pstate=disable and you're good to go.

Interesting. I'll try it out.