Re: [patch 06/16] Markers auto enable tracepoints (new API : trace_mark_tp())

KOSAKI Motohiro
2008-11-25T12:24:18Z

Hi

Sorry for very late responce.
However, if you do marker removing disucussion, I hope CC to Frank Eigler.
because SystemTap also use marker and tracepoint.
and this patch also improvement SystemTap marker support, I think.

IIRC, Currently, Systemtap also have marker/tracepoint on/off
syncronization problem.

> > Add a new API trace_mark_tp(), which declares a marker within a
> > tracepoint probe. When the marker is activated, the tracepoint is
> > automatically enabled.
> >
> > No branch test is used at the marker site, because it would be a
> > duplicate of the branch already present in the tracepoint.
> >
> > Impact: new API.
>
> i dont know.
>
> I was actually hoping for markers (the in-kernel API) to go away
> completely - and be replaced with tracepoints.
>
> Markers are the wrong design on several levels. They couple the kernel
> dynamically with unknown (to the kernel) entities - and that is
> causing complexity all around the place, clearly expressed in these
> patches of yours.
>
> Tracepoints are much more specific - typed and enumerated function
> call callback points in essence - with some politeness that allows
> external instrumentation entities to attach to those callbacks.
>
> Is there any usecase of markers that should not be converted to either
> tracepoints or to ftrace_printk() ?

Frank, Could you please read this thread and give us your comment?