CPU power limit settings do not take effect (overriden by MMIO RAPL / manual solution to bypass available).

[denisu14]

Hi,

I think I've found a bug on my laptop. Setting the CPU power limits through asusctl seems to work. The command succeeds and the value reads back fine but it has no actual effect on how much power the CPU draws.

Here's what I did: on AC in Performance mode, I ran asusctl armoury set ppt_pl1_spl 110 and ppt_pl2_sppt 135. Both the attribute and the kernel's current_value (/sys/class/firmware-attributes/asus-armoury/attributes/ppt_pl1_spl/current_value) reported the new numbers, so I assumed it worked. But when I put the CPU under a sustained all-core load and watched it with turbostat, it was still pinned at ~45 W long-term / ~90 W boost, exactly like before I changed anything.

After digging around, the limit that's actually being enforced is the MMIO RAPL one:

• /sys/class/powercap/intel-rapl-mmio:0/constraint_0/1_power_limit_uw stays at 45 W / 90 W no matter what ppt_* is set to.
• The MSR RAPL limit (intel-rapl:0) reads 175 W, so that's not it either.
• When I write 110 / 135 straight to those MMIO RAPL files myself, it works immediately sustained power jumped to ~95 W and held there.

I don't know much about ACPI so please let me know if there's a mistake in this bug report.

System: i9-13980HX, ROG Strix G814JZ, asusctl/asusd 6.3.7, kernel 7.0.12-arch1-1

Thanks!

[scardracs]

That's because asusctl only change the value into ACPI under /sys/class/firmware-attributes/asus-armoury/attributes/ but not into MMIO, which is why you have found that problem. I'll take a look into it and make a patch if possible