Calculating time in order of 0.1usec on x86 system - Kernel

This is a discussion on Calculating time in order of 0.1usec on x86 system - Kernel ; Hi, I need to calculate time spent by a function in order of less then a microsecond on x86 SMP platform. Current profiling tools and gettimeofday() are not sufficient. So I am using get_cycles() to get the CPU cycles. Now ...

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Thread: Calculating time in order of 0.1usec on x86 system

  1. Calculating time in order of 0.1usec on x86 system

    Hi,

    I need to calculate time spent by a function in order of less then a microsecond on x86 SMP platform.

    Current profiling tools and gettimeofday() are not sufficient.

    So I am using get_cycles() to get the CPU cycles.

    Now how do I convert it into the time interval?

    Do I have to divide it by "cpu_khz" variable? Or some other method?
    Is yes, what will be the unit of the result (time interval)? nsec/usec/msec?

    e.g. get_cycles()/cpu_khz (unit?)

    Or Is there more simpler method exist?

    Regards,
    Parav Pandit



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  2. Re: Calculating time in order of 0.1usec on x86 system

    I am getting my desired numbers.
    get_cycles()/cpu_khz gives the right time interval on x86 system.

    Parav



    --- On Tue, 9/30/08, Parav Pandit wrote:

    > From: Parav Pandit
    > Subject: Calculating time in order of 0.1usec on x86 system
    > To: "Linux kernel"
    > Date: Tuesday, September 30, 2008, 12:31 PM
    > Hi,
    >
    > I need to calculate time spent by a function in order of
    > less then a microsecond on x86 SMP platform.
    >
    > Current profiling tools and gettimeofday() are not
    > sufficient.
    >
    > So I am using get_cycles() to get the CPU cycles.
    >
    > Now how do I convert it into the time interval?
    >
    > Do I have to divide it by "cpu_khz" variable? Or
    > some other method?
    > Is yes, what will be the unit of the result (time
    > interval)? nsec/usec/msec?
    >
    > e.g. get_cycles()/cpu_khz (unit?)
    >
    > Or Is there more simpler method exist?
    >
    > Regards,
    > Parav Pandit
    >
    >
    >
    > --
    > To unsubscribe from this list: send the line
    > "unsubscribe linux-kernel" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at
    > http://vger.kernel.org/majordomo-info.html
    > Please read the FAQ at http://www.tux.org/lkml/




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