Messages in this thread | | | Date | Wed, 25 Nov 2015 18:12:43 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH 1/2] ftrace: Add separate handler for ftrace:function event |
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On Wed, Nov 25, 2015 at 12:02:57PM -0500, Steven Rostedt wrote: > On Wed, 25 Nov 2015 17:50:57 +0100 > Jiri Olsa <jolsa@redhat.com> wrote: > > > > This seems redundant. I never understood the control_ops that perf uses > > > in the function tracing infrastructure. Why can't you just register the > > > event->ops and have that ops set the filtering? Then the ftrace > > > infrastructure will only call that event handler for the functions its > > > filtered on. Then you don't need to do it again. Right now ftrace > > > already does that with the generic "control_ops" that perf uses, but > > > now you are doing it again. Seems rather pointless. > > > > well thats exactly what we are doing.. but as all ops > > share single callback we need to find the proper event > > this callback was triggered for > > The ftrace_ops has a "private" field for the user to set. Could you > make that point back to the event that allocated the ftrace_ops? > Then the callback function could easily get the event that matches the > ftrace_ops.
aaah did not see this one ;-) that will do.. nice
> > > > > currently we use tracepoint callback (perf_tp_event) > > where the proper event is found based on the event->filter > > > > however this is not the case for ftrace:function because > > filter will not change the event->filter, but the ops filter > > Yeah, I'm trying to figure out the paths here. I would love to remove > the control_ops as that complicates the function tracing code a bit > more than I would like it to be.
perf is using the control interface to enable and disable function tracing any time the process (and its events) is scheduled in/out
sched_in(event) -> ftrace_function_local_enable(&event->ftrace_ops) sched_out(event) -> ftrace_function_local_disable(&event->ftrace_ops)
> > I just crashed function tracing by function tracing perf doing function > tracing :-) I'm currently debugging that (and adding more code to help > debug things like this).
;-)
jirka
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