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Linux: AMD Phenom II and AMD Athlon II CPU Change Frequency On All Logical Cores

I've AMD Athlon II processors based server and it does not change frequency on all logical cores under CentOS version 5.5 or RHEL Linux. How do I fix this problem?

The default CPU frequency scaling method uses powernow-k8 frequency driver module, and the ACPI data provided by BIOS, are not compatible with each other. It may not work at all to save power. To fix this problem Edit /etc/modprobe.conf file, enter:
# vi /etc/modprobe.conf
Append the following line:

options powernow-k8 preregister_acpi_perf=0

Save and close the file. It will work after reboot, however you can fix this for current setup by typing the following command as root user:
# /etc/init.d/ cpuspeed stop
# /sbin/rmmod powernow_k8
# /sbin/modprobe powernow-k8 preregister_acpi_perf=0
# /etc/init.d/cpuspeed start