Ubuntu – Disabling Intel Turbo Boost in 12.04

12.04intelturbo-boost

I have a question concerning Intel Turbo Boost and the ability to disable it in Ubuntu 12.04. I wanted to disable Turbo Boost because it produced a lot of heat and I didn't find a need for it in Ubuntu (being so lightweight as it is compared to Windows). I found that by installing msr-tools and running modprobe msr and then:

wrmsr -p(PROCESSOR) 0x1a0 0x4000850089

Where PROCESSOR is the number of my CPU core allowed me to shut off Turbo Boost for that core. After appending msr into my etc/modules and the wrmsr lines into my rc.local I found I was able to shut off Turbo Boost at boot.

My question is: Is this method I've used safely disabling Turbo Boost, or should I attempt to find a different workaround.

I have an MSI-GE60 with no setting in the BIOS for Turbo Boost, so changing it like this appeared to be the only way.

Thanks to anyone who can help.

Best Answer

You could set the max CPU frequencies to a setting just under the turbo boost - attached is the code I use in rc.local

echo 1 > /sys/module/processor/parameters/ignore_ppc

for x in /sys/devices/system/cpu/cpu[0-3]/cpufreq/;do 
  echo 2501000 > $x/scaling_max_freq
done

In my system the speed of 250100 is a turbo speed, non-turbo being 2500000

Charles Green

Related Solutions

Intel Turbo Boost – How to Check if Turbo Boost is Working

11.04 runs the 2.6.38 kernel which is supposed to work well with Sandy Bridge CPUs.

You can open a terminal and run grep MHz /proc/cpuinfo. Then open a second terminal tab and run a loop like while :; do :; done. In the first terminal, run grep MHz /proc/cpuinfo again. You should see one of the cores has a higher frequency now:

$ grep MHz /proc/cpuinfo 
cpu MHz         : 1600.000
cpu MHz         : 1600.000
cpu MHz         : 1600.000
cpu MHz         : 1600.000
cpu MHz         : 1600.000
cpu MHz         : 3701.000
cpu MHz         : 1600.000
cpu MHz         : 1600.000

You can also try powertop and turbostat from the linux-tools-common package (run sudo modprobe msr before sudo turbostat). The Git version of i7z is supposed to work for Sandy Bridge (and it works for me with a desktop i7).

Ubuntu – Why is the Intel Turbo Boost Mode not running at maximum speed

Actually as you are running all 4 cores, the maximum frequency won't be achieved as specified. Intel specifies maximum turbo frequency for a single running core.

There are different maximum frequencies achieved for 1 active core and for 4 active cores (to prevent going over TDP) http://www.cpu-world.com/CPUs/Core_i5/Intel-Core%20i5-3210M%20(BGA)%20Mobile%20processor.html

e.g. thus you are getting around 2.9 ghz rather than 3.1

if you look in i7z there is a line specifying //// max multiplier achieved with 1/2/3/4 core. You cannot go above those multipliers if more than some number of cores are active.

also, inactive core need to be in C3 or higher states to allow the active core(s) to get into higher turbo levels.

Best Answer

Related Solutions

Intel Turbo Boost – How to Check if Turbo Boost is Working

Ubuntu – Why is the Intel Turbo Boost Mode not running at maximum speed

Related Question