tracing: Support string type key properly
The string in a trace event is usually recorded as dynamic array which is variable length. But current hist code only support fixed length array so it cannot support most strings. This patch fixes it by checking filter_type of the field and get proper pointer with it. With this, it can get a histogram of exec() based on filenames like below: # cd /sys/kernel/tracing/events/sched/sched_process_exec # cat 'hist:key=filename' > trigger # ps PID TTY TIME CMD 1 ? 00:00:00 init 29 ? 00:00:00 sh 38 ? 00:00:00 ps # ls enable filter format hist id trigger # cat hist # trigger info: hist:keys=filename:vals=hitcount:sort=hitcount:size=2048 [active] { filename: /usr/bin/ps } hitcount: 1 { filename: /usr/bin/ls } hitcount: 1 { filename: /usr/bin/cat } hitcount: 1 Totals: Hits: 3 Entries: 3 Dropped: 0 Link: http://lkml.kernel.org/r/610180d6df0cfdf11ee205452f3b241dea657233.1457029949.git.tom.zanussi@linux.intel.com Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by:Namhyung Kim <namhyung@kernel.org> Tested-by:
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> [ Added (unsigned long) typecast to fix compile warning ] Signed-off-by:
Steven Rostedt <rostedt@goodmis.org>
parent
69a0200c