Does 2.6.26 provide nanosecond time to the user? - Kernel

This is a discussion on Does 2.6.26 provide nanosecond time to the user? - Kernel ; Im confused. (sorry I havent been following the linux-kernel mailing list on this) Does 2.6.26 use nanosecond time (1) internally? (2) provide it to the user? I see no way to turn it on/off in xconfig. Yet I do see ...

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Thread: Does 2.6.26 provide nanosecond time to the user?

  1. Does 2.6.26 provide nanosecond time to the user?

    Im confused.
    (sorry I havent been following the linux-kernel mailing list on this)

    Does 2.6.26 use nanosecond time
    (1) internally?
    (2) provide it to the user?

    I see no way to turn it on/off in xconfig.
    Yet I do see STA_NANO defined in sys/timex.h which is a good start.

    and IF it provides it to the user, what do I use to get nanosecond time.
    My search with man -k for timespec turns up
    sys_clock_getres
    and sys_clock_gettime

    or possibly clock_getres and clock_gettime, the man pages use both,
    but NONE of these entry points seem to exist in my system.

    Puzzled.


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    Reg.Clemens
    reg@dwf.com


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  2. Re: Does 2.6.26 provide nanosecond time to the user?

    Reg Clemens writes:

    > Im confused.
    > (sorry I havent been following the linux-kernel mailing list on this)
    >
    > Does 2.6.26 use nanosecond time
    > (1) internally?
    > (2) provide it to the user?
    >
    > I see no way to turn it on/off in xconfig.
    > Yet I do see STA_NANO defined in sys/timex.h which is a good start.
    >
    > and IF it provides it to the user, what do I use to get nanosecond time.
    > My search with man -k for timespec turns up
    > sys_clock_getres
    > and sys_clock_gettime
    >
    > or possibly clock_getres and clock_gettime, the man pages use both,
    > but NONE of these entry points seem to exist in my system.


    You might need to link with -lrt to get those functions.

    --
    Måns Rullgård
    mans@mansr.com

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  3. Re: Does 2.6.26 provide nanosecond time to the user?

    > Reg Clemens writes:
    >
    > > Im confused.
    > > (sorry I havent been following the linux-kernel mailing list on this)
    > >
    > > Does 2.6.26 use nanosecond time
    > > (1) internally?
    > > (2) provide it to the user?
    > >
    > > I see no way to turn it on/off in xconfig.
    > > Yet I do see STA_NANO defined in sys/timex.h which is a good start.
    > >
    > > and IF it provides it to the user, what do I use to get nanosecond time.
    > > My search with man -k for timespec turns up
    > > sys_clock_getres
    > > and sys_clock_gettime
    > >
    > > or possibly clock_getres and clock_gettime, the man pages use both,
    > > but NONE of these entry points seem to exist in my system.

    >
    > You might need to link with -lrt to get those functions.
    >

    Thanks, -lrt works fine, that answers that part of the question, how about
    the first question.

    --
    Reg.Clemens
    reg@dwf.com


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  4. Re: Does 2.6.26 provide nanosecond time to the user?

    Reg Clemens wrote:
    > Im confused.
    > (sorry I havent been following the linux-kernel mailing list on this)
    >
    > Does 2.6.26 use nanosecond time
    > (1) internally?
    > (2) provide it to the user?


    It's available to userspace via clock_gettime(), but whether it really
    is accurate to sub-microseconds will depend on the specific version of
    the kernel and hardware architecture being used.

    Chris
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  5. Re: Does 2.6.26 provide nanosecond time to the user?

    Reg Clemens wrote:

    > Thanks, -lrt works fine, that answers that part of the question, how about
    > the first question.


    The kernels use a variety of clocks internally. If the clocks are capable of
    nanosecond resolution then the results will be available via clock_gettime().



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