Documentation/trace/tracelevel.txt

			 Tracelevel

		Documentation by Alon Farchy

1. Overview
===========

Tracelevel allows subsystem authors to add trace priorities to
their tracing events. High priority traces will be enabled
automatically at boot time.

This module is configured with CONFIG_TRACELEVEL.

2. Usage
=========

To give an event a priority, use the function tracelevel_register
at any time.

	tracelevel_register(my_event, level);

my_event corresponds directly to the event name as defined in the
event header file. Available levels are:

	TRACELEVEL_ERR 3
	TRACELEVEL_WARN 2
	TRACELEVEL_INFO 1
	TRACELEVEL_DEBUG 0

Any event registered at boot time as TRACELEVEL_ERR will be enabled
by default. The header also exposes the function tracelevel_set_level
to change the trace level at runtime. Any trace event registered with the
specified level or higher will be enabled with this call.

A userspace handle to tracelevel_set_level is available via the module
parameter 'level'. For example,

	echo 1 > /sys/module/tracelevel/parameters/level

Is logically equivalent to:

	tracelevel_set_level(TRACELEVEL_INFO);