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ftrace, perf: Add support to use function tracepoint in perf

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Adding perf registration support for the ftrace function event,
so it is now possible to register it via perf interface.

The perf_event struct statically contains ftrace_ops as a handle
for function tracer. The function tracer is registered/unregistered
in open/close actions.

To be efficient, we enable/disable ftrace_ops each time the traced
process is scheduled in/out (via TRACE_REG_PERF_(ADD|DELL) handlers).
This way tracing is enabled only when the process is running.
Intentionally using this way instead of the event's hw state
PERF_HES_STOPPED, which would not disable the ftrace_ops.

It is now possible to use function trace within perf commands
like:

  perf record -e ftrace:function ls
  perf stat -e ftrace:function ls

Allowed only for root.

Link: http://lkml.kernel.org/r/1329317514-8131-6-git-send-email-jolsa@redhat.com

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jiri Olsa 2012-02-15 15:51:52 +01:00 • committed by Steven Rostedt
parent e59a0bff3e
commit ced39002f5
5 changed files with 109 additions and 2 deletions
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6
kernel/trace/trace_entries.h
View file

@ -55,7 +55,7 @@
/*
* Function trace entry - function address and parent function address:
*/
FTRACE_ENTRY(function, ftrace_entry,
FTRACE_ENTRY_REG(function, ftrace_entry,
TRACE_FN,
@ -64,7 +64,9 @@ FTRACE_ENTRY(function, ftrace_entry,
__field( unsigned long, parent_ip )
),
F_printk(" %lx <-- %lx", __entry->ip, __entry->parent_ip)
F_printk(" %lx <-- %lx", __entry->ip, __entry->parent_ip),
perf_ftrace_event_register
);
/* Function call entry */