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Hi, I have a basic question: I'm using Linux (Ubuntu) and CPU I7. The current CPU frequency is 1200hz, the maximum CPU frequency is 2100hz. My Q is as follows: ...
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  1. #1
    Just Joined!
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    ACPI and Dynamic CPU Frequency


    Hi,

    I have a basic question:

    I'm using Linux (Ubuntu) and CPU I7.

    The current CPU frequency is 1200hz, the maximum CPU frequency is 2100hz.

    My Q is as follows:

    Does Linux (or the INTEL CPU's) increase the CPU frequency when the system is loaded ?

    (i.e when the total CPU's are 70% loaded (for example) , Does the OS (without the user interference) may increase the CPU freq from 1200 to the max freq 2100, in order to decrease the load on the CPU's ?) (and without the user interference) ?

    Thank's

  2. #2
    Linux Newbie
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    Sep 2007
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    The CPU scales up when needed and scales back down when not needed. There's nothing you hafta do. To see the system's policy/governor settings, open a terminal...

    Code:
    cpufreq-info

  3. #3
    Linux Guru Rubberman's Avatar
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    You will likely need to install the cpufrequtils package on your system to get the cpufreq-info command. I just tried it on my system (Scientific Linux 6.5) and had to install that package first, but it works great. Here is a snippet of the output:

    Code:
    analyzing CPU 6:
      driver: acpi-cpufreq
      CPUs which run at the same hardware frequency: 0 1 2 3 4 5 6 7
      CPUs which need to have their frequency coordinated by software: 0 1 2 3 4 5 6 7
      maximum transition latency: 10.0 us.
      hardware limits: 2.00 GHz - 3.00 GHz
      available frequency steps: 3.00 GHz, 2.66 GHz, 2.33 GHz, 2.00 GHz
      available cpufreq governors: ondemand, userspace, performance
      current policy: frequency should be within 2.00 GHz and 3.00 GHz.
                      The governor "ondemand" may decide which speed to use
                      within this range.
      current CPU frequency is 2.00 GHz.
    I have a dual quad-core system.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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