Arch Linux

Asbestbrezel

Member

Registered: 2014-07-27

Posts: 67

frequency limiting not working properly

Hello archers,

i wanted to limit the frequency of the i7-3520M.

I switched off the Turbomode, by setting /sys/devices/system/cpu/intel_pstate/no_turbo to "1". It works. But only when i do non-gpu-related things, like Browsing or stresstesting with mprime.
If it comes to gaming, for example Minecraft or Dota2 it uses the Turbo again and it scales up to 3,4ghz.

Same problem, with

cpupower frequency-set -u 2.2ghz

I monitor the frequency by using

watch grep \"cpu MHz\" /proc/cpuinfo

Don't know, how to fix that. I need some lower cpu-speed in games, because of throttling-problems with my ThinkPad x230.

Hope you can help. Greetings,
Marcel

sandm4n

Member

From: The Accumulator

Registered: 2014-01-17

Posts: 4

Website

Re: frequency limiting not working properly

I don't think cpupower is compatible with the new intel_pstate driver that governs the frequencies for CPUs >= Sandybridge. Fortunately intel_pstate provides /sys interfaces to manually throttle speeds:

ls /sys/devices/system/cpu/intel_pstate/

max_perf_pct  min_perf_pct  no_turbo 

max_perf_pct = max performance percent [not counting Turbo]
min_perf_pct = min performance percent

Your cpu = Intel Core i7-3520M @ 2.90GHz + Turbo upto 3.6GHz. You want 2.2 max.
Therefore:

2.2/2.9 * 100 =~ 75%

Thus:

echo 75 > /sys/devices/system/cpu/intel_pstate/max_perf_pct 

sets max performance to 75% ~ 2.2 GHz

Last edited by sandm4n (2014-07-27 22:20:33)

Asbestbrezel

Member

Registered: 2014-07-27

Posts: 67

Re: frequency limiting not working properly

I tried this before. I set it to 60%. Works fine on desktop, but if i play some games. 3,4ghz. Bam. No Mercy.

edit: it works, if intel_pstate is disabled completely.

Last edited by Asbestbrezel (2014-07-27 23:20:06)