From 14dcbce77792e27a94adb242650c50809435af30 Mon Sep 17 00:00:00 2001 From: Alon Farchy Date: Tue, 5 Jul 2011 17:12:29 -0700 Subject: tracelevel module: Prioritize trace events This module lets subsystem authors prioritize ftrace events by calling tracelevel_register(...). High priority traces will be automatically enabled on boot. See tracelevel.h for more details Original-Change-Id: If03699e96c598bdcf93b9a9f73918ce7b0c750cb Reviewed-on: http://git-master/r/40290 Reviewed-by: Alon Farchy Tested-by: Alon Farchy Reviewed-by: Daniel Willemsen Tested-by: Daniel Solomon Tested-by: Simone Willett Rebase-Id: R49f59f81d61907f66fdf892130a1b4dc6575d40e --- Documentation/trace/tracelevel.txt | 42 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 Documentation/trace/tracelevel.txt (limited to 'Documentation/trace') diff --git a/Documentation/trace/tracelevel.txt b/Documentation/trace/tracelevel.txt new file mode 100644 index 000000000000..b282dd2b329b --- /dev/null +++ b/Documentation/trace/tracelevel.txt @@ -0,0 +1,42 @@ + 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); -- cgit v1.2.3