Incorrect CPU Frequency From /proc/cpuinfo (Doc ID 729046.1)

Last updated on JUNE 02, 2009

Applies to:

Linux Kernel - Version: 4.4 to 5.3
This problem can occur on any platform.

Symptoms

There is Dual Core AMD Opteron(tm) Processor, with 2600 MHz CPU Frequency. But only 1000 MHz is shown through checking /proc/cpuinfo. 
# more /proc/cpuinfo
    processor       : 0
    vendor_id       : AuthenticAMD
    cpu family      : 15
    model           : 33
    model name      : Dual Core AMD Opteron(tm) Processor 885
    stepping        : 2
    cpu MHz         : 1000.000   <----incorrect CPU Frequency.
    cache size      : 1024 KB
    ...
However, dmidecode shows the correct CPU speed:
           ...
            Processor Information
                    Socket Designation: CPU 3
                    Type: Central Processor
                    Family: Opteron
                    Manufacturer: AMD
                    ID: 12 0F 02 00 FF FB 8B 17
                    Version: Dual Core AMD Opteron(tm) Processor 885
                    Voltage: 3.3 V 2.9 V
                    External Clock: 200 MHz
                    Max Speed: 2600 MHz
                    Current Speed: 2600 MHz  <------ The correct CPU Frequency.
                    Status: Populated, Enabled                    
            ...    

Cause

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