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

[Mathieu Desnoyers]

Hi,

Some early LTTng-UST adopters brought to my attention that the way
tracepoint loglevels are currently specified in LTTng-UST might be too
relax for its own good. If each application define their own loglevel
names/values, it will become difficult to use the loglevels to select
"trace verbosity" in a system-wide manner.

Now that I come to think of it, it might make sense to pre-define a set
of supported loglevels, similarly to syslog(3). However, given that
tracing sometimes targets debug levels that are more fine-grained than
in the case of logs, I would propose to split the "debug" loglevel into
sub-categories. The following loglevel names are just ideas, and
feedback is very welcome.

My current thought is to simply just allow these loglevels. I doubt that
letting application developers specify extra loglevels on top of this
would be that useful, and it would certainly be more confusing.

In the list below, lower numbers means "low verbosity", higher numbers
means "high verbosity, debug-style information".

based on syslog
http://linux.die.net/man/3/syslog
  SUSv2 and POSIX.1-2001. POSIX.1-2001

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

TRACE_PROCESS  8
information has process-level scope

TRACE_MODULE   9
information has module (executable/library) scope

TRACE_UNIT     10
information has compilation unit scope

TRACE_CLASS    11
information has class-level scope

TRACE_OBJECT   12
information has object-level scope

TRACE_FUNCTION 13
information has function-level scope

TRACE_PRINTF   14
tracepoint_printf message

TRACE_DEBUG    15
debug-level message

Thoughts ?

Thanks,

Mathieu


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