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    Subject[RFC patch 00/15] Tracer Timestamping
    Hi,

    Starting with the bottom of my LTTng patchset
    (git://git.kernel.org/pub/scm/linux/kernel/git/compudj/linux-2.6-lttng.git)
    I post as RFC the timestamping infrastructure I have been using for a while in
    the tracer. It integrates get_cycles() standardization following David Miller's
    comments I did more recently.

    It also deals with 32 -> 64 bits timestamp counter extension with a RCU-style
    algorithm, which is especially useful on MIPS and SuperH architectures.

    There is also a TSC synchronization test within this patchset to detect
    unsynchronized TSCs. See comments in this specific patch to figure out the
    difference between the current x86 tsc_sync.c and the one I propose in this
    patch.

    It also provides an architecture-agnostic fallback in case there is no
    timestamp counter available : basically, it's
    (jiffies << 13) | atomically_incremented_counter (if there are more than 8192
    events per jiffy, time will still be monotonic, but will increment faster than
    the actual system frequency).

    Comments are welcome. Note that this is only the beginning of the patchset. I
    plan to submit the event ID allocation/portable event typing aimed at exporting
    the data to userspace and buffering mechanism as soon as I integrate a core
    version of the LTTV userspace tools to the kernel build tree. Other than that, I
    currently have a tracer which fulfills most of the requirements expressed
    earlier. I just fear that if I release only the kernel part without foolproof
    binary-to-ascii trace decoder within the kernel, people might be a bit reluctant
    to fetch a separate userspace package.

    Mathieu

    --
    Mathieu Desnoyers
    Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68


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