Intel P-State Gets More Cleanups & Optimizations

[phoronix]

Phoronix: Intel P-State Gets More Cleanups & Optimizations

Last week I wrote about Intel's Rafael Wysocki working on P-State improvements for Linux 4.12 and today he has published yet more clean-up and optimization patches for this Intel CPU frequency scaling driver alternative to ACPI CPUfreq...

http://www.phoronix.com/scan.php?page=news_item&px=Intel-P-State-Cleanups-March

[aufkrawall]

Is there any obvious reason to stay away from using schedutil governor?
It seems to be working well on my 2500k, gives better performance in Talos Principle Vulkan than pstate powersave and power consumption in idle is the same as with Windows 10 (I suspect read out clocks may be wrong with schedutil, but this would be a cosmetical issue).

[cj.wijtmans]

Is there any obvious reason to stay away from using schedutil governor?
It seems to be working well on my 2500k, gives better performance in Talos Principle Vulkan than pstate powersave and power consumption in idle is the same as with Windows 10 (I suspect read out clocks may be wrong with schedutil, but this would be a cosmetical issue).

better performance than powersave? duh?

[aufkrawall]

Was that irony?
Ofc pstate powersave isn't known for best performance, so schedutil might be a good choice.

In my test with Talos Principle Vulkan, ondemand btw. failed badly, it was even quite slower than pstate powersave. So probably schedutil would also be a good choice for Ryzen CPUs.

[cj.wijtmans]

I wouldnt know as i simply dont use cpufreq. I dont see why anyone would use it.

[aufkrawall]

And what governor you use instead..?

[geearf]

Is there any obvious reason to stay away from using schedutil governor?
It seems to be working well on my 2500k, gives better performance in Talos Principle Vulkan than pstate powersave and power consumption in idle is the same as with Windows 10 (I suspect read out clocks may be wrong with schedutil, but this would be a cosmetical issue).

I tried schedutil but it wasn't fast enough for my needs.
After talking with Rafael, he mentioned it's supposed to be a bit below ondemand.
In my tests I agree, I also found pstate powersave to perform better.

He also gave me a pstate patch, that for the first time since I got a haswell, allows me to use pstate powersave and see it scale! I really look forward to it being in 4.12!

[aufkrawall]

Did you try it with 4.10? It's definitely working well here in Talos Vulkan. I tried 720p, 1080p and 4k to test different GPU/CPU loads and it scored well in all three resolutions, unlike ondemand.

[geearf]

Did you try it with 4.10? It's definitely working well here in Talos Vulkan. I tried 720p, 1080p and 4k to test different GPU/CPU loads and it scored well in all three resolutions, unlike ondemand.

Yup my tests were on 4.10.
It might be a difference in CPU, I have a 4790k.

My test was not a benchmark, but running StarCraft 2 in wine. With cpufreq, anything below ondemand I get sound cracking every now and then, on powersave it's horrible and schedutil is no good enough. With ondemand or performance it's fine. With pstate enabled both governors are fine, with it passive, shedutil was still too slow.

[aufkrawall]

Gave SC2 a quick try in Wine staging, no sound cracking to report with schedutil.
Game shows some stuttering though, but also with cpufreq performance. Probably the typical non-optimal performance caused by Wine.