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    Subject[patch 01/17] get_cycles() : kconfig HAVE_GET_CYCLES
    Create a new "HAVE_GET_CYCLES" architecture option to specify which
    architectures provide 64-bits TSC counters readable with get_cycles(). It's
    principally useful to only enable high-precision tracing code only on such
    architectures and don't even bother building it on architectures which lack such

    It also requires architectures to provide get_cycles_barrier() and

    I mainly use it for the "priority-sifting rwlock" latency tracing code, which
    traces worse-case latency induced by the locking. It also provides the basic
    changes needed for the LTTng timestamping infrastructure.

    Signed-off-by: Mathieu Desnoyers <>
    CC: David Miller <>
    CC: Linus Torvalds <>
    CC: Andrew Morton <>
    CC: Ingo Molnar <>
    CC: Peter Zijlstra <>
    CC: Thomas Gleixner <>
    CC: Steven Rostedt <>
    init/Kconfig | 10 ++++++++++
    1 file changed, 10 insertions(+)

    Index: linux.trees.git/init/Kconfig
    --- linux.trees.git.orig/init/Kconfig 2008-11-07 00:34:11.000000000 -0500
    +++ linux.trees.git/init/Kconfig 2008-11-12 17:58:05.000000000 -0500
    @@ -330,6 +330,16 @@ config CPUSETS

    +# Architectures with a 64-bits get_cycles() should select this.
    +# They should also define
    +# get_cycles_barrier() : instruction synchronization barrier if required
    +# get_cycles_rate() : cycle counter rate, in HZ. If 0, TSC are not synchronized
    +# across CPUs or their frequency may vary due to frequency scaling.
    +config HAVE_GET_CYCLES
    + def_bool n
    config GROUP_SCHED
    bool "Group CPU scheduler"
    depends on EXPERIMENTAL
    Mathieu Desnoyers
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68

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