[CentOS-virt] No cpu throttling for Xeon E5405?

Fri May 22 21:57:19 UTC 2009
Dennis J. <dennisml at conversis.de>

we bought some machines with 2 x quad core Xeon E5405 processors and 
installed centos 5.3 on them. My problem is that I can't get the cpuspeed 
service to work. No driver seems to claim responsibility for the throttling 
and the fallback "modprobe acpi_cpufreq" in the cpuspeed init script just 
yields a "No such device" message. According to the acpi information the 
CPUs should support this just fine:

cat /proc/acpi/processor/CPU0/info:
processor id:            0
acpi id:                 0
bus mastering control:   yes
power management:        no
throttling control:      yes
limit interface:         yes

cat /proc/acpi/processor/CPU0/throttling:
state count:             8
active state:            T0
    *T0:                  00%
     T1:                  12%
     T2:                  25%
     T3:                  37%
     T4:                  50%
     T5:                  62%
     T6:                  75%
     T7:                  87%

At least half of the cores aren't really used at the moment under non-peak 
load so we are wasting quite a bit of power with this. Any idea on how to 
get this working?