[lttng-dev] [LTTng-UST RFC] Tracepoint Loglevels Specification

[Mathieu Desnoyers]

* Alexandre Montplaisir (alexandre.montplaisir at polymtl.ca) wrote:
> On 12-02-02 10:56 AM, Mathieu Desnoyers wrote:
> > [...]
> >
> > Indeed, as we dig further down within a process, we have to use static
> > compile-time/link-time entities to specify a smaller granularity.
> >
> > The reason why I propose these entities rather than more free-form
> > "major/minor" is because I think we really need to impose pre-defined
> > loglevels that will allow selection of verbosity across the entire
> > system (all applications) in a pre-defined way. If the semantic is too
> > loose, then we miss the ability to let users know what is happening when
> > they select "minor" instead of "major", because these identifiers do not
> > map to anything concrete for the user.
> 
> But then again, this granularity will be just as good as the people who
> use it when instrumenting their programs.
> 
> Looking at this quickly, I think 15 different levels is too much. It
> should be limited to 5 imo. (less is more!) I understand you want to
> pre-define stuff for the user's sake, but in practice I doubt this will
> be used as intended. Some (few) programmers will use everything
> correctly and religiously, some others will only use 1-3, some will only
> use TRACE_DEBUG, and so on, so it would be just as hard, if not harder,
> for the end users trying to make sense out of it.
> 

Given those are now hardcoded (there are only these levels available), I
seriously doubt that developers and teams who want to use it in a large
system (and who are willing to design their loglevels accordingly) will
enjoy it if we limit them to 3-4 levels because joe developper is not
going to use that.

I think mapping all the syslog loglevel is good, because we can then map
logs directly into the trace. But then we necessarily need more detail
within the debugging levels, because tracing is not logging.

Thanks for your feedback,

Mathieu


> > I changed the detailed part of the list this morning, removing "object"
> > and "class". New list:
> >
> >  * TRACE_EMERG    0
> >  * system is unusable
> >  *
> >  * TRACE_ALERT    1
> >  * action must be taken immediately
> >  *
> >  * TRACE_CRIT     2
> >  * critical conditions
> >  *
> >  * TRACE_ERR      3
> >  * error conditions
> >  *
> >  * TRACE_WARNING  4
> >  * warning conditions
> >  *
> >  * TRACE_NOTICE   5
> >  * normal, but significant, condition
> >  *
> >  * TRACE_INFO     6
> >  * informational message
> >  *
> >  * TRACE_SYSTEM   7
> >  * information has system-level scope (set of programs)
> >  *
> >  * TRACE_PROGRAM  8
> >  * information has program-level scope (set of processes)
> >  *
> >  * TRACE_PROCESS  9
> >  * information has process-level scope (set of modules)
> >  *
> >  * TRACE_MODULE   10
> >  * information has module (executable/library) scope (set of units)
> >  *
> >  * TRACE_UNIT     11
> >  * information has compilation unit scope (set of functions)
> >  *
> >  * TRACE_FUNCTION 12
> >  * information has function-level scope
> >  *
> >  * TRACE_DEFAULT  13
> >  * default trace loglevel (TRACEPOINT_EVENT default)
> >  *
> >  * TRACE_VERBOSE  14
> >  * verbose information
> >  *
> >  * TRACE_DEBUG    15
> >  * debug-level message (trace_printf default)
> >
> > Thoughts ?
> >
> > Mathieu
> >
> 
> 
> -- 
> Alexandre Montplaisir
> DORSAL lab,
> École Polytechnique de Montréal
> 

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