Arch Linux

p90

Member

Registered: 2013-06-07

Posts: 21

Pentium M 1.7Ghz is only run at 800Mhz?

Hi,

I am an owner of an Amilo M1437G laptop with an Intel Pentium M 1.7Ghz.

As my laptop was running very slowly, I noticed that my cpu apparently is only run at 800Mhz instead of 1.7Ghz.
I had no power tools (like cpupower) installed at first but dmesg says it found a 800Mhz processor at boot
and /proc/cpuinfo always states that is running at 800Mhz as well.

My next step was to check with dmidecode.
It also says that the current clock speed is 800Mhz and even if I put high load on my laptop, it will always stay at 800Mhz.
dmidecode also states the maximum speed correctly (1.7Ghz).

At this point, I was pretty confused and tried to install cpupower and take a look what is going on here.
Installing cpupower was no problem but loading the kernel module had a nasty surprise.
I could not load the recommended acpi_cpufreq (no device found) but only the p4-clockmod kernel driver.
And as if things could not get worse, p4-clockmo decided that my maximum frequency should be 600Mhz and my lowest frequency should be 75Mhz.
Consequently, my cpu was running at a reported speed of 600Mhz. I also tried the 75Mhz but besides more lag, it seems to do what it did promise.

I am using the normal arch kernel (so 3.15.7-1) so I guess I cannot have been hit by this bug here: https://bugzilla.kernel.org/show_bug.cgi?id=73781

Has anyone any idea what is going on here?
I do not even want any frequency scaling (even if it would be nice) but only my stock 1.7Ghz back.

With best regards,

p90 on a very slow laptop

nem

Member

Registered: 2009-12-15

Posts: 46

Re: Pentium M 1.7Ghz is only run at 800Mhz?

get the speedstep-centrino package from aur and speedstepping should work.
speedstepping with this specific cpu-family is not supported by cpufreq due to some missing bios features as far as i know. support for these old cpus was dropped from the arch-kernel.

regards,
nem

Last edited by nem (2014-07-30 23:03:23)

p90

Member

Registered: 2013-06-07

Posts: 21

Re: Pentium M 1.7Ghz is only run at 800Mhz?

Hi,

I tried the speedstep-centrino package but I get the same response as the acpi_cpufreq module: ERROR could not insert , No such device

So I am still running on 800Mhz.

nem

Member

Registered: 2009-12-15

Posts: 46

Re: Pentium M 1.7Ghz is only run at 800Mhz?

did you run 'depmod' as root after you installed the module? if not, modprobing doesn't work.

also, to automatically load the module at boot:

$ echo "speedstep-centrino" > /etc/module-load.d/speedstep-centrino.conf

Last edited by nem (2014-07-30 23:58:31)

p90

Member

Registered: 2013-06-07

Posts: 21

Re: Pentium M 1.7Ghz is only run at 800Mhz?

Hi, I ran depmod and also rebooted my system.
Still, speedstep-centrino does not load on a modprobe.

basica

Member

From: Australia

Registered: 2012-10-31

Posts: 217

Re: Pentium M 1.7Ghz is only run at 800Mhz?

I realize I might be stating the obvious, but have you ensured you did not have scaling disabled in your BIOS?

Last edited by basica (2014-07-31 06:54:26)

p90

Member

Registered: 2013-06-07

Posts: 21

Re: Pentium M 1.7Ghz is only run at 800Mhz?

Hi,

there is no option in my bios to disable stepstep and it worked some time ago (I even had frequency scaling with p4-clockmod but this was a year ago)
so it should be working.

Gusar

Member

Registered: 2009-08-25

Posts: 3,607

Re: Pentium M 1.7Ghz is only run at 800Mhz?

I even had frequency scaling with p4-clockmod but this was a year ago

No you didn't. p4-clockmod does clock modulation, not frequency scaling. Totally different thing.

Your best course of action is to try older kernels, to figure out which one worked and which doesn't. Then preferably do a bisect to find the exact commit which broke things.

p90

Member

Registered: 2013-06-07

Posts: 21

Re: Pentium M 1.7Ghz is only run at 800Mhz?

@Gusar
You are right, sorry for this mistake

I finally got it to work.
Diggin threw some old acpi-cpufreq kernel bugs I found a comment by a user who had the same laptop as mine.
It seems that the bios sometimes messes up the acpi tables leading to acpi_cpufreq not loading anymore.
After reseting my bios, acpi_cpufreq was loading again!
Now I have my full 1.7Ghz back.

Thanks to everybody who was trying to help me with this!

FiX

Member

Registered: 2011-12-17

Posts: 8

Re: Pentium M 1.7Ghz is only run at 800Mhz?

Same issue on Dell E7440 Laptop with i7-4600U (Haswell) CPU.
I tried to restart or power cycle the laptop but it doesn't help. CPU is still at the lowest point.