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I'd like to install cpufreq modules on my server . I tried

sudo modprobe acpi-cpufreq

but got the error

FATAL: Error inserting acpi_cpufreq (/lib/modules/2.6.18-238.12.1.el5xen/kernel/arch/x86_64/kernel/cpufreq/acpi-cpufreq.ko): No such device

cat /proc/cpuinfo gives this

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 6
model name      :               Intel(R) Pentium(R) D CPU 3.20GHz
stepping        : 4
cpu MHz         : 3200.542
cache size      : 2048 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 6
wp              : yes
flags           : fpu tsc msr pae cx8 apic mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc pni vmx est cid cx16 lahf_lm
bogomips        : 8005.14
clflush size    : 64
cache_alignment : 128
address sizes   : 36 bits physical, 48 bits virtual
power management:

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 15
model           : 6
model name      :               Intel(R) Pentium(R) D CPU 3.20GHz
stepping        : 4
cpu MHz         : 3200.542
cache size      : 2048 KB
physical id     : 1
siblings        : 1
core id         : 0
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 6
wp              : yes
flags           : fpu tsc msr pae cx8 apic mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc pni vmx est cid cx16 lahf_lm
bogomips        : 8005.14
clflush size    : 64
cache_alignment : 128
address sizes   : 36 bits physical, 48 bits virtual
power management:

And uname -r gives 2.6.18-238.12.1.el5xen

ls /lib/modules/2.6.18-238.12.1.el5xen/kernel/arch/x86_64/kernel/cpufreq/

gives

acpi-cpufreq.ko  mperf.ko  powernow-k8.ko  speedstep-centrino.ko

Do I have everything required to install cpufreq ? Is my system compatible to have cpufreq ? If yes, what steps sshould I follow to install cpufreq ?

When I entered BIOS settings, I was not able to view option to change CPU performance settings either.

Kindly tell me what to do.

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we had trouble with Xen not allowing us to enable ACPI. When we switched away from the Xen kernel to plain Debian, it worked fine. So this ACPI issue can be specific to Xen or at least some versions of it. –  Jeff Atwood Jul 31 '12 at 9:46
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2 Answers

Check your bios settings - is there a 'speedstep' setting that is disabled? If so, enable it. Maybe the setting has another name? It's probably under the power saving bios settings somewhere.

Run dmesg right after trying to modprobe the module and see if any useful information is output there. Try running modprobe -v acpi-cpufreq, although I doubt that will be useful.

acpi-cpufreq certainly seems the correct module to use with your cpu.

Other than than my guess would be that your system doesn't actually support cpu frequency scaling.

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up vote 2 down vote accepted

I did dmesg|grep acpi and found that acpi was set to acpi=off in grub.conf, which I set it to acpi=on

It worked !

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1  
Nice! I totally forgot about checking your grub options. Glad you found that. –  Phil Hollenback Aug 18 '11 at 1:01
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