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    SubjectRe: [PATCH] tracing/ftrace: add missing wake-up on some callsites

    On Mon, 23 Feb 2009, Frederic Weisbecker wrote:

    > On Mon, Feb 23, 2009 at 11:51:30AM -0500, Steven Rostedt wrote:
    > >
    > > On Mon, 23 Feb 2009, Frederic Weisbecker wrote:
    > > > >
    > > > > Perhaps we could add these callsites back, but we would need to update
    > > > > trace_wake_up.
    > > > >
    > > > > Have trace_wake_up set a flag instead, and add a tracepoint around the
    > > > > scheduler (outside the grabbing of runqueue locks), that will have a
    > > > > callback to the tracing code. That call back can perform the wakeups.
    > > > >
    > > > > How does that sound?
    > > >
    > > >
    > > > That sounds good but only for these particular tracers I guess.
    > >
    > > OK, what about making a trace_delay_wake_up()?
    >
    >
    > Which would send a delayed work to wake up?

    No, I was thinking that trace_delay_wake_up() would be called by these
    dangerous call sites. Then a per_cpu flag could be set. We could have a
    trace point in the scheduler code that is outside holding a runqueue lock,
    and this trace point would call a trace function that will clear the per
    cpu flag, and then call trace_wake_up().


    -- Steve



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