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I'm looking to throttle my cpu through the ACPI. I've read up on it, but I keep receiving permission denied statements. I have 8 available throttling states. Here are the outcomes of my atttempts:

evan@evan-laptop:/proc/acpi/processor/CPU0$ echo 3 > /proc/acpi/processor/CPU0/throttling

bash: /proc/acpi/processor/CPU0/throttling: Permission denied

evan@evan-laptop:/proc/acpi/processor/CPU0$ sudo echo 3 > /proc/acpi/processor/CPU0/throttling

bash: /proc/acpi/processor/CPU0/throttling: Permission denied

EDIT: For reference, I am running Ubuntu Karmic with Intel Core Duo T2500 with ACPI enabled

share|improve this question
If you want to control it from terminal then also add info about your computer. It could be useful. uname -a, cat /proc/cpuinfo – Egon Dec 9 '09 at 20:57
up vote 1 down vote accepted

First do

cat /proc/acpi/processor/CPU0/throttling

Then use any of those states:

echo T4 > /proc/acpi/processor/CPU0/throttling

Also you can look in cat info if throttling is enabled.

share|improve this answer
Nope, not weird just more specific needs... – Egon Dec 9 '09 at 21:18
hmmm, thanks for looking into this. I had tried this too and tried again, but I get the same Permission Denied line. This is my first computer with Linux, so I'll search around for a little bit. – Evan Dec 9 '09 at 21:27
egon, I found out that the sudo only applies to the echo rather than the whole statement. if I just run it as a script from sudo or su to root (is there root on Ubuntu?) The problem is solved. It was definitely my newness to Linux that caused this particular problem – Evan Dec 10 '09 at 1:03
totally forgot about that... I was logged in as root... so yeah... :D – Egon Dec 10 '09 at 15:54
> cannot be used with sudo, tee can. just do echo T4 | sudo tee /proc/acpi/processor/CPU0/throttling – Steve Schnepp Aug 21 '10 at 10:44

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