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I have Intel Xeon Phi 7210 running CentOS 7 with kernel 3.10.0-514.el7.x86_64. I am comparing what frequency steps are available when I boot system into intel p-state vs when the system uses acpi cpufreq. I run sudo cpupower frequency-info to get following two logs.

Intel P-State

analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency:  Cannot determine or is not supported.
  hardware limits: 1000 MHz - 1.50 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 1.40 GHz and 1.40 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency: 1.30 GHz (asserted by call to hardware)
  boost state support:
    Supported: yes
    Active: yes

ACPI CPUFREQ

analyzing CPU 0:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 10.0 us
  hardware limits: 1000 MHz - 1.30 GHz
  available frequency steps:  1.30 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz
  available cpufreq governors: conservative userspace powersave ondemand performance
  current policy: frequency should be within 1000 MHz and 1.30 GHz.
                  The governor "conservative" may decide which speed to use
                  within this range.
  current CPU frequency: 1000 MHz (asserted by call to hardware)
  boost state support:
    Supported: yes
    Active: yes

Why does two different scaling drivers show different hardware frequency limits? For intel p-state, I see frequency limits from 1GHz to 1.5GHz and on other hand acpi cpufreq shows 1GHz to 1.3GHz.

As per datasheet, the above processor can run at 1.5GHz with turbo boost, is that the reason why it's not available for acpi cpufreq?

Any specific reason why this is the case?

Thanks.

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