On Thursday 26 March 2009 15:27:49 Victor Jimenez wrote:
> Hello,
>
> we are considering to buy a system with an AMD Opteron 2384 processor.
> We want to conduct some experiments with dynamic voltage frequency
> scaling (DVFS).
>
> It seems the chips supports DVFS per core, so one core can be running at
> frequency X and the other core can do it at frequency Y. However, we are
> not sure how to access all the actuators to change frequency/voltage.
>
> Is cpufreq from Linux kernel supporting this? I could only find support
> for K8 microarchitectures and a patch to read the temperatures for K10
> microarchitecture (e.g., Opteron 2384). However, we are not sure whether
> is it possible to perform DVFS for K10 microarchitecture using cpufreq.
>
> Does anyone know anything about this? Any plans to support K10 in
> cpufreq?
powernow-k8.c also fully supports K10 processors.
All code embedded into:
if (cpu_family == CPU_HW_PSTATE)
is for K10 processors.
It might have made sense to provide a separate driver, but this would have
caused some extra grief in userspace.
If we have automatic driver loading depending on different processor types
and features at some time, it might be an improvement to split out
powernow-k10.c, not sure whether it's worth it.
Back to your question:
DVFS is fully supported for K10.
Look into
/sys/devices/system/cpu/cpu0/cpufreq
for details.
If you compile with:
CONFIG_CPU_FREQ_STAT=m
and load the cpufreq_stats module you get a detailed statistic about which
cpufreq state has been used how often and how long here:
/sys/devices/system/cpu/cpu0/cpufreq/stats/
unload and reload cpufreq_stats to refresh the values (if you want to dive
in deeper).
Thomas
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