CPU Clock Frequency

[sozie]

Hello everyone,

I noticed recently with (hwinfo) that the frequency in KVMs at the processor level was different from the frequency on the host machine.

Here is an example in a KVM:

01: None 00.0: 10103 CPU
  [Created at cpu.465]
  Unique ID: rdCR.j8NaKXDZtZ6
  Hardware Class: cpu
  Arch: X86-64
  Vendor: "GenuineIntel"
  Model: 6.62.4 "Intel(R) Xeon(R) CPU E5-2680 v2 @ 2.80GHz"
  Features: fpu,vme,de,pse,tsc,msr,pae,mce,cx8,apic,sep,mtrr,pge,mca,cmov,pat,pse36,clflush,mmx,fxsr,sse,sse2,ss,ht,syscall,nx,pdpe1gb,rdtscp,lm,constant_tsc,arch_perfmon,rep_good,nopl,xtopology,cpuid,tsc_ks
  Clock: 2793 MHz
  BogoMips: 5586.53
  Cache: 16384 kb
  Units/Processor: 2
  Config Status: cfg=new, avail=yes, need=no, active=unknown

And now this is what I got back in the host machine :

40: None 27.0: 10103 CPU
  [Created at cpu.465]
  Unique ID: qeTn.j8NaKXDZtZ6
  Hardware Class: cpu
  Arch: X86-64
  Vendor: "GenuineIntel"
  Model: 6.62.4 "Intel(R) Xeon(R) CPU E5-2680 v2 @ 2.80GHz"
  Features: fpu,vme,de,pse,tsc,msr,pae,mce,cx8,apic,sep,mtrr,pge,mca,cmov,pat,pse36,clflush,dts,acpi,mmx,fxsr,sse,sse2,ss,ht,tm,pbe,syscall,nx,pdpe1gb,rdtscp,lm,constant_tsc,arch_perfmon,pebs,bts,rep_good,nd
  Clock: 3600 MHz
  BogoMips: 5588.59
  Cache: 25600 kb
  Units/Processor: 32
  Config Status: cfg=new, avail=yes, need=no, active=unknown

On the CPU configuration side of the interface, I have selected "CPU HOST".

If someone has an idea to make the frequency the same in two sides, I'm a taker!

Thanks a lot!
Rémi.

 

[Dunuin]

The VMs frequency doesn't really matter as your VM won't see a real physical CPU. As long as yoru hosts CPU clocks high everything is fine, no matter what the VM is reporting.

 

[apoc]

CPU E5-2680 v2 @ 2.80GHz

That is your CPU and your base clock rate.
What your host reports is likely the turboboost clock which to my experience always can vary.

See here:
https://ark.intel.com/content/www/d...n-processor-e52680-v2-25m-cache-2-80-ghz.html

So technically the VM can run on a core which just runst at base clock speed, hence there is nothing wrong with what you see.

 

[sozie]

Hello to all,

Thank you for your answers. It's true that I should have done a test directly to check the frequency and not rely on HWINFO's "claims".

Have a nice day !
Rémi