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How can I tell how fast the CPUs are running on a POWER8 server?

rated 0 times [ 4] [ 0] / answers: 1 / hits: 1406 / 3 Years ago, sun, may 23, 2021, 2:43:26

I'm running with Ubuntu 14.04 on a Power8 server.

Is there a way to tell how fast the processors are running?

How do I enable the tools that come with powerpc-utils and cpufreq ?

added....

ppc64_cpu reports

# ppc64_cpu --frequency

min:    3.693 GHz (cpu 159)

max:    3.693 GHz (cpu 1)

avg:    3.693 GHz

the output of 'cpufreq-info' shows (example for one core):

analyzing CPU 159:

  driver: powernv-cpufreq

  CPUs which run at the same hardware frequency: 152 153 154 155 156 157 158 159

  CPUs which need to have their frequency coordinated by software: 152 153 154 155 156 157 158 159

  maximum transition latency: 4294.55 ms.

  hardware limits: 2.06 GHz - 3.69 GHz

  available frequency steps: 3.69 GHz <clipped>, 2.09 GHz, 2.06 GHz

  available cpufreq governors: conservative, userspace, powersave, ondemand, performance

  current policy: frequency should be within 2.06 GHz and 3.69 GHz.

              The governor "ondemand" may decide which speed to use

              within this range.

  current CPU frequency is 2.06 GHz (asserted by call to hardware).

  cpufreq stats: 3.69 GHz:0.66%, 3.66 GHz:0.00%, 3.62 GHz:0.00% <clipped> 2.09 GHz:0.00%, 2.06 GHz:99.34%  (5)

Here we can see the CPU is still clocked at ~2GHz and the governor is "ondemand" so nothing has changed. This Ubuntu installation is fully up to date

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answered 3 Years ago oraoming · Accepted Answer

Yes, on Power /proc/cpuinfo shows the static "nominal" clock speed. The hardware also provides some frequency steppings above nominal that the cpufreq governors will include by default when running in OPAL firmware mode.

The reason 'ppc64_cpu --frequency' is showing different output is because that command reads some hardware counters and generates CPU activity to measure the frequency, therefore typically producing the max frequency of the system since the CPU utilization is increased while running the command.

The cpufreq method displays the actual frequency at that point in time, without bumping up the CPU utilization. So if the system is otherwise idle, cpufreq-info will show the lowest scaling frequency. This is the recommended method to check frequency of the host when running KVM guests since the PMU is shared between the host/guest(s) and the 'ppc64_cpu' method uses PMU hardware counters to measure frequency.