Intel Turbo Mode

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Hi,

is there a way in CentOS to find out if the Intel turbo mode will be used?

Using the ‘stress’ utility and checking the frequency with cpupower tells me that a CPU is running at it´s maximum frequency as reported by cpupower — and this frequency is less than the frequency it would run at if it used the turbo mode. All the other CPUs are at their minimum frequency. I have verified that turbo mode is enabled in the BIOS.

Is cpupower unable to report frequencies used in turbo mode despite it always says it gets its information from the hardware?

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“Didn’t work” is an error.

4 thoughts on - Intel Turbo Mode

  • It would seem that there are multiple ways to get the information you are looking for. I expect you have seen this already

    https://haypo.github.io/intel-cpus.html

    but I figured I would pass it on for others. They found that cpupower is less reliable in how it reports the data because of the values it gets them from.

    —
    Stephen J Smoogen.

  • Stephen John Smoogen writes:

    Thanks, I didn´t see that one yet. At least I noticed that cpupower says that turbo mode is available, and turbostat seems to indicate that CPUs sometimes run at higher frequencies like they would when in turbo mode.

    It´s strange that there is no tool to definitely figure this out, especially since RH seems to have done a lot of research into improving performance.

    —
    “Didn’t work” is an error.

  • My limited understanding is that it isn’t very reliable to show it and the Windows ones distort reality a lot (aka say you are in it when you aren’t actually in it) because they do a moving average to show what is going on so it doesn’t look as jagged as it really is. It is also not all that useful for general software needs. The CPU is going to be waiting a lot longer now for memory and io to catch up for most transactions.

    —
    Stephen J Smoogen.

  • Stephen John Smoogen writes:

    I guess the same could be said for turbostat because it show some computed frequency.

    Does it hurt anything when it waits faster? It might have the advantage that it doesn´t wait longer than it otherwise would and processes things somewhat faster when it finally does. For how long it takes until processing is finished, it doesn´t matter if the CPU waits longer when it still takes the same amount of time, and chances are it might not take as long.

    Or am I mistaken?

    Anyway, it seems to me as if there´s actually no way to figure out if the CPU is at turbo frequencies because it decides that for itself. But then, I have an E3-1230 V2 here, and even cpupower reports its turbo frequencies.

    —
    “Didn’t work” is an error.