[ltt-dev] LLTng probes

[compudj@krystal.dyndns.org (Mathieu Desnoyers)]

* Jyotiswarup Raiturkar (Jyotiswarup.Raiturkar at arm.com) wrote:
> Hello
> 
>  
> 
> I'm looking at LTTng working inside the kernel, and trying to understand
> the instrumentation.
> 
>  
> 
> However, I am not able to see how the DEFINE_MARKER_TP() macros and
> other probe_* functions in kernel-trace.c are actually used . As I
> understand it, to make the actual trace, modules would have to call the
> probe_* functions; yet I'm not able to locate these calls.

The probes are connected to the tracepoints with:

kernel:marker.c: set_marker()

                     ret = tracepoint_probe_register_noupdate(
                                elem->tp_name,
                                elem->tp_cb);

Which is called when a marker is enabled. The markers are listed in a
table which is defined by the DEFINE_MARKER_TP() macros.

Thanks,

Mathieu

> 
>  
> 
> Thanks
> 
> Jyoti
> 
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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com