diff options
author | Alon Farchy <afarchy@nvidia.com> | 2011-07-05 17:12:29 -0700 |
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committer | Dan Willemsen <dwillemsen@nvidia.com> | 2011-08-22 16:52:44 -0700 |
commit | dd25d94499c206553523c2b6715b5d69078b72d2 (patch) | |
tree | 33d53bc4cb2901c90c01d91f08ce0cac181dfeda /Documentation | |
parent | 8ff24586278ca7d1f54647de3b3bc19e1fd2d4a2 (diff) |
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 <afarchy@nvidia.com>
Tested-by: Alon Farchy <afarchy@nvidia.com>
Reviewed-by: Daniel Willemsen <dwillemsen@nvidia.com>
Tested-by: Daniel Solomon <daniels@nvidia.com>
Tested-by: Simone Willett <swillett@nvidia.com>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/trace/tracelevel.txt | 42 |
1 files changed, 42 insertions, 0 deletions
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); |