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    SubjectRe: Unified tracing buffer
    Steven Rostedt wrote:
    > But, with that, with a global atomic counter, and the following trace:
    >
    > cpu 0: trace_point_a
    > cpu 1: trace_point_c
    > cpu 0: trace_point_b
    > cpu 1: trace_point_d
    >
    >
    > Could the event a really come after event d, even though we already hit
    > event b?

    yes, if event c is an interrupt event :-).

    cpu 0 cpu 1
    hit event d
    hit event a
    log event a
    irq event c
    log event c
    hit event b
    log event b
    log event d

    so, I think if we really need to order events, we have to stop
    irq right after hitting an event.

    Anyway, in most case, I think it works, but as accurate as
    synchronized-TSC if hardware supports it.

    Thank you,

    --
    Masami Hiramatsu

    Software Engineer
    Hitachi Computer Products (America) Inc.
    Software Solutions Division

    e-mail: mhiramat@redhat.com



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