tracing: Add support for multiple hist triggers per event
Allow users to define any number of hist triggers per trace event.
Any number of hist triggers may be added for a given event, which may
differ by key, value, or filter.
Reading the event's 'hist' file will display the output of all the
hist triggers defined on an event concatenated in the order they were
defined.
Link: http://lkml.kernel.org/r/48a0c8dd34c344571de880fb35e211c6d9a28961.1457029949.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8430145..e89b2ed 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3856,9 +3856,11 @@
"\t sort field. The 'size' parameter can be used to specify more\n"
"\t or fewer than the default 2048 entries for the hashtable size.\n\n"
"\t Reading the 'hist' file for the event will dump the hash\n"
- "\t table in its entirety to stdout. The default format used to\n"
- "\t display a given field can be modified by appending any of the\n"
- "\t following modifiers to the field name, as applicable:\n\n"
+ "\t table in its entirety to stdout. If there are multiple hist\n"
+ "\t triggers attached to an event, there will be a table for each\n"
+ "\t trigger in the output. The default format used to display a\n"
+ "\t given field can be modified by appending any of the following\n"
+ "\t modifiers to the field name, as applicable:\n\n"
"\t .hex display a number as a hex value\n"
"\t .sym display an address as a symbol\n"
"\t .sym-offset display an address as a symbol and offset\n"
