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

Steven Rostedt
2009-02-23T17:13:50Z

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