lscpu and Intel Turbo Boost

lscpu and Intel Turbo Boost

[Howard Lum]

I have a server with a Power Regulator control. When this is set for "OS Control Mode", the lscpu output reports CPU max MHz and CPU min MHz info. When the control is set to "Static High Performance", the lscpu output only reports "CPU MHz" and the value is the same as the CPU base frequency. Does this mean that the CPU is operating at the base frequency and is not using Intel Turbo Boost?

Howard Lum
Synamedia


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Re: lscpu and Intel Turbo Boost

[Karel Zak]

On Mon, Feb 01, 2021 at 02:16:41PM +0000, Howard Lum wrote:
> I have a server with a Power Regulator control. When this is set for
> "OS Control Mode", the lscpu output reports CPU max MHz and CPU min
> MHz info. When the control is set to "Static High Performance", the
> lscpu output only reports "CPU MHz" and the value is the same as the
> CPU base frequency. Does this mean that the CPU is operating at the
> base frequency and is not using Intel Turbo Boost?

"CPU MHz" is value from /proc/cpuinfo usually from the first CPU and
it's actual frequency of the processor. 

The next lscpu version will not show this value as it's useless to 
show frequency for the first CPU if you have more CPUs ...

And the min and max are read from

  /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_max_freq
  /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_min_freq

and describe frequency range.

Use grep "cpu MHz" /proc/cpuinfo to get the current frequencies, or in
the next lscpu version it will be possible use use "lscpu -eCPU,MHZ"
to get the same.

I have no clue about "Intel Turbo Boost" and how Linux report/use it,
but I guess that "cpu MHz" from /proc/cpuinfo is what kernel thinks
about the speed.

    Karel


-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com