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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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11
kernel/trace/trace.h
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@ -595,6 +595,8 @@ static inline int ftrace_trace_task(struct task_struct *task)
static inline int ftrace_is_dead(void) { return 0; }
#endif
int ftrace_event_is_function(struct ftrace_event_call *call);
/*
* struct trace_parser - servers for reading the user input separated by spaces
* @cont: set if the input is not complete - no final space char was found
@ -832,4 +834,13 @@ extern const char *__stop___trace_bprintk_fmt[];
FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))
#include "trace_entries.h"
#ifdef CONFIG_PERF_EVENTS
#ifdef CONFIG_FUNCTION_TRACER
int perf_ftrace_event_register(struct ftrace_event_call *call,
enum trace_reg type, void *data);
#else
#define perf_ftrace_event_register NULL
#endif /* CONFIG_FUNCTION_TRACER */
#endif /* CONFIG_PERF_EVENTS */
#endif /* _LINUX_KERNEL_TRACE_H */