[lttng-dev] [RFC] LTTng-UST loglevels

[Yannick Brosseau]

On 2012-02-06 18:01, Mathieu Desnoyers wrote:
>         TRACE_DEBUG_SYSTEM    = 7,
>         TRACE_DEBUG_PROGRAM   = 8,
>         TRACE_DEBUG_PROCESS   = 9,
>         TRACE_DEBUG_MODULE    = 10,
>         TRACE_DEBUG_UNIT      = 11,
>         TRACE_DEBUG_FUNCTION  = 12,
>         TRACE_DEBUG_LINE      = 13,  (default for TRACEPOINT_EVENT)
>         TRACE_DEBUG           = 14,  (default for trace_printf)
I still do not understand the difference and scope of theses level.
Normally a log and debug level is specified in term of its importance.
A "unit" or "function" is not an importance its a scope. Everything in a
programme is part of a line, function, unit or module. It does not
define how it's important.
> I'm not sure about the choices for defaults though. We might want to
> keep some room in the numbering for placing loglevels in between
> TRACE_DEBUG_LINE and TRACE_DEBUG, as well as below DEBUG. I'm not sure
> how to call those. These would be useful if we know for sure that a
> tracepoint is higher-throughput that the default TRACEPOINT_LOGLEVEL.
>
I don't understand this idea of default? Am I obligated to use the
loglevel?
If I do not define a loglevel it's because I do not want to use them. I
don't want to see a "default" loglevel associated to it.

To add to this last comment, having loglevel associated to the
tracepoint can really be confusing to a new user of a tracer. If the new
user try a tracer and see loglevel, he might thing this tool is just a
complex log manager, which is not really the case.  So I believe we
should put the emphasis on the *optional* characteristic of this
feature, and not advertise it in the default case.

Yannick