diff options
| author | Tom Zanussi <tom.zanussi@linux.intel.com> | 2016-03-03 12:54:52 -0600 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2016-04-19 12:19:01 -0400 |
| commit | 69a0200c2e25d61c50091549d00cfeb426c258f5 (patch) | |
| tree | ceff2e294f7247446e1a35344dc55ddf9b2a21a8 /kernel/trace/trace.c | |
| parent | 316961988b5ec71bbf4b2ad447662770349aec13 (diff) | |
tracing: Add hist trigger support for stacktraces as keys
It's often useful to be able to use a stacktrace as a hash key, for
keeping a count of the number of times a particular call path resulted
in a trace event, for instance. Add a special key named 'stacktrace'
which can be used as key in a 'keys=' param for this purpose:
# echo hist:keys=stacktrace ... \
[ if filter] > event/trigger
Link: http://lkml.kernel.org/r/87515e90b3785232a874a12156174635a348edb1.1457029949.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>
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0dd23c5b1c34..2238bfde799b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3843,14 +3843,14 @@ static const char readme_msg[] = "\t table using the key(s) and value(s) named, and the value of a\n" "\t sum called 'hitcount' is incremented. Keys and values\n" "\t correspond to fields in the event's format description. Keys\n" - "\t can be any field. Compound keys consisting of up to two\n" - "\t fields can be specified by the 'keys' keyword. Values must\n" - "\t correspond to numeric fields. Sort keys consisting of up to\n" - "\t two fields can be specified using the 'sort' keyword. The\n" - "\t sort direction can be modified by appending '.descending' or\n" - "\t '.ascending' to a sort field. The 'size' parameter can be\n" - "\t used to specify more or fewer than the default 2048 entries\n" - "\t for the hashtable size.\n\n" + "\t can be any field, or the special string 'stacktrace'.\n" + "\t Compound keys consisting of up to two fields can be specified\n" + "\t by the 'keys' keyword. Values must correspond to numeric\n" + "\t fields. Sort keys consisting of up to two fields can be\n" + "\t specified using the 'sort' keyword. The sort direction can\n" + "\t be modified by appending '.descending' or '.ascending' to a\n" + "\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" |