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how to control cpu freq

Hi!

I wanted to be able to change the cpu frequency and found out, that I have no idea how. :-) Under Suse I just had to enter "powersave" with some options, and it did all I wanted (at least under suse 9.2). Now I wanted to set the same thing up under debian, but don't get it to work correctly. I already installed acpid and cpudynd, but whenever I try to start acpid, it tells me:

Code:

acpid: can't open /proc/acpi/event: Device or resource busy

Entering "cpudynd", it says

Code:

cpudynd version 1.0 Copyright: Ricardo Galli <gallir@uib.es>

cpudynd: CPU frequency control disabled

Error: Nothing to do, exiting

When trying powernowd, it tells me

Code:

powernowd: PowerNow Daemon v0.90, (c) 2003-2004 John Clemens

powernowd: Found 1 cpu:

Couldn't open file: No such file or directory

Couldn't open file: No such file or directory

Couldn't open file: No such file or directory

couldn't open govn's file for writing: No such file or directory

Couldn't get per-cpu data: Illegal seek

PowerNowd encountered and error and could not start.

Please make sure that:

 - You are running a v2.5/v2.6 kernel or later

 - That you have sysfs mounted /sys

 - That you have the core cpufreq and cpufreq-userspace

  modules loaded into your kernel

 - That you have the cpufreq driver for your cpu loaded,

  and that it works. (check dmesg for errors)

If all of the above are true, and you still have problems,

please email the author: clemej@alum.rpi.edu

But since I am pretty new with setting up a system (As I mentioned above, I used Suse before, and there is not much "setting up a system" with it), that does not help me a lot. Maybe someone can help me with that issue and also tell me what daemon would be best to use (cpufreqd, cpudynd, powernowd).

My system is as follows:
Notebook: FSC Amilo M 7400
Debian sarge
Kernel 2.6.8-2

I hope that is all information that is needed to solve that problem, if not, just ask. Thanks,

ruh31

Quote:

- That you have the core cpufreq and cpufreq-userspace
modules loaded into your kernel
- That you have the cpufreq driver for your cpu loaded,
and that it works. (check dmesg for errors)

So do you have these modules loaded? Check with lsmod. Do you have /sys mounted?

What kind of processor do you have anyway?

I think that I have not loaded those modules. I get

Code:

$ lsmod

Module                  Size  Used by

i830                  78596  3

ipv6                  264644  8

ds                    18756  2

irtty_sir              9152  2

sir_dev                19244  1 irtty_sir

irda                  197120  2 irtty_sir,sir_dev

crc_ccitt              2144  1 irda

lp                    11176  0

af_packet              22568  2

snd_intel8x0m          20264  0

snd_intel8x0          36460  0

snd_ac97_codec        69988  2 snd_intel8x0m,snd_intel8x0

snd_pcm_oss            55080  0

snd_mixer_oss          20096  1 snd_pcm_oss

snd_pcm                98728  3 snd_intel8x0m,snd_intel8x0,snd_pcm_oss

snd_timer              25668  1 snd_pcm

snd_page_alloc        11752  3 snd_intel8x0m,snd_intel8x0,snd_pcm

gameport                4704  1 snd_intel8x0

snd_mpu401_uart        7968  1 snd_intel8x0

snd_rawmidi            25124  1 snd_mpu401_uart

snd_seq_device          8200  1 snd_rawmidi

snd                    57156  10 snd_intel8x0m,snd_intel8x0,snd_ac97_codec,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_timer,snd_mpu401_uart,snd_rawmidi,snd_seq_device

soundcore              10336  1 snd

shpchp                101900  0

pciehp                99020  0

pci_hotplug            34640  2 shpchp,pciehp

intel_agp              22816  1

agpgart                34664  4 intel_agp

parport_pc            36900  1

parport                41800  2 lp,parport_pc

pcspkr                  3592  0

rtc                    12760  0

ehci_hcd              32004  0

usbhid                32224  0

eth1394                21576  0

uhci_hcd              33136  0

usbcore              119012  5 ehci_hcd,usbhid,uhci_hcd

b44                    22308  0

mii                    5120  1 b44

yenta_socket          21728  0

pcmcia_core            70868  2 ds,yenta_socket

ohci1394              35492  0

nls_iso8859_1          4032  1

nls_cp437              5696  2

capability              4520  0

commoncap              7232  1 capability

freq_table              4228  0

cpufreq_userspace      5272  0

ac                      4812  0

tsdev                  7392  0

battery                9388  0

mousedev              10476  1

button                  6296  0

joydev                  9984  0

fan                    3980  0

evdev                  9600  0

thermal                12656  0

processor              17264  1 thermal

sr_mod                17316  0

sbp2                  24392  0

scsi_mod              125228  2 sr_mod,sbp2

ieee1394              111512  3 eth1394,ohci1394,sbp2

psmouse                20360  0

ide_cd                42656  0

cdrom                  40732  2 sr_mod,ide_cd

vfat                  14656  1

fat                    46784  1 vfat

ntfs                  101940  1

ext2                  71848  0

ext3                  127240  1

jbd                    62616  1 ext3

mbcache                9348  2 ext2,ext3

ide_generic            1408  0

piix                  13440  1

ide_disk              19296  5

ide_core              139940  4 ide_cd,ide_generic,piix,ide_disk

unix                  28756  266

font                    8320  0

vesafb                  6656  0

cfbcopyarea            3872  1 vesafb

cfbimgblt              3040  1 vesafb

cfbfillrect            3776  1 vesafb

Moreover you said I should check dmesg for any errors. What exactly am I looking for in the messages that dmesg shows me. Should I post everything with "ACPI: ..." and "CPU: ..." here or is something else needed?

I am using a pentium M 1.7GHz processor (centrino). Hope you can help me!

Ok, well you have the cpufreq governor loaded there, it looks like you just need the modules for your cpu. I have done a little reading in /usr/src/linux/Documentation/cpu-freq and your processor is supported.

I don't have a centrino, so this is only best guess but it would seem you need to run:
"modprobe speedstep-centrino"

If this works then cd to /sys/devices/system/cpu/cpu0/cpufreq/
You should see files like:
cpuinfo_min_freq
cpuinfo_max_freq
etc...

Well, I tried what you said, but I get the following error message:

Code:

# modprobespeedstep-centrino

FATAL: Error inserting speedstep_centrino (/lib/modules/2.6.8-2-686/kernel/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.ko): No such device

What does this mean? By the way: Thanks a lot for your help!

I use cpu frequency scaling on my laptop (K6-3 processor).

You can lower cpu clock rate with both "CPU frequency scaling" and from ACPI with "CPU Throttling". I use CPU Frequency scaling. I suggest trying to use APM instead of ACPI... disable/remove the "acpid" and install "apmd". You might have to change BIOS settings also.

Anyways, to use "CPU frequency scaling" you need to have "cpufreq-userspace"-module loaded, and also a module specific for your processor:

Intel

* speedstep-centrino
* speedstep-ich (P4 Mobile)
* speedstep-smi

AMD

* powernow-k6
* powernow-k7
* powernow-k8

You can check "cat /proc/cpuinfo" to see which processor you have, and if it supports scaling. You can also see from it if the scaling works (it shows _current_ frequency). You can add appropriate modules to /etc/modules so that the load automatically.

You also need the "powernowd"-daemon (which you already had installed). It should work without problems.

I Google is correct, you should have a Pentium M processor - same as me (I have an IBM R40). What I did to get the frequency scaling to work in Debian was to:

In /etc/fstab add "sysfs /sys sysfs /defaults 0 0", if it's not there already. (The sysfs must be mounted.)

I recompiled the kernel with the following options (under Power management options, CPU Frequency scaling):

Default CPU Freq governor set to performance
'powersave' governor as a module
'userspace' governor for userspace frequency scaling into the kernel
CPU frequency table helpers into the kernel
Intel Enhanced SpeedStep into the kernel

Make sure the cpufreqd package is installed. Adjust /etc/cpufreqd.conf as needed.

With APM it wouldn't work unless the options above were compiled into the kernel. With APCI it seemed to work even when they were modules.

/TLV