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Commit cd7e7bd5 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Frederic Weisbecker
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tracing: Add kprobes event profiling interface 



Add profiling interfaces for each kprobes event. This interface provides
how many times each probe hit or missed.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it>
Cc: Roland McGrath <roland@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
LKML-Reference: <20090813203541.31965.8452.stgit@localhost.localdomain>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent ff50d991

Documentation/trace/kprobetrace.txt

+8 −0
Original line number Diff line number Diff line
@@ -70,6 +70,14 @@ filter: 
 names and field names for describing filters.





Event Profiling

---------------

 You can check the total number of probe hits and probe miss-hits via

/sys/kernel/debug/tracing/kprobe_profile.

 The first column is event name, the second is the number of probe hits,

the third is the number of probe miss-hits.





Usage examples

--------------

To add a probe as a new event, write a new definition to kprobe_events

kernel/trace/trace_kprobe.c

+43 −0
Original line number Diff line number Diff line
@@ -184,6 +184,7 @@ struct trace_probe { 
		struct kprobe		kp;

		struct kretprobe	rp;

	};

	unsigned long 		nhit;

	const char		*symbol;	/* symbol name */

	struct ftrace_event_call	call;

	struct trace_event		event;
@@ -781,6 +782,37 @@ static const struct file_operations kprobe_events_ops = { 
	.write		= probes_write,

};



/* Probes profiling interfaces */

static int probes_profile_seq_show(struct seq_file *m, void *v)

{

	struct trace_probe *tp = v;



	seq_printf(m, "  %-44s %15lu %15lu\n", tp->call.name, tp->nhit,

		   probe_is_return(tp) ? tp->rp.kp.nmissed : tp->kp.nmissed);



	return 0;

}



static const struct seq_operations profile_seq_op = {

	.start  = probes_seq_start,

	.next   = probes_seq_next,

	.stop   = probes_seq_stop,

	.show   = probes_profile_seq_show

};



static int profile_open(struct inode *inode, struct file *file)

{

	return seq_open(file, &profile_seq_op);

}



static const struct file_operations kprobe_profile_ops = {

	.owner          = THIS_MODULE,

	.open           = profile_open,

	.read           = seq_read,

	.llseek         = seq_lseek,

	.release        = seq_release,

};



/* Kprobe handler */

static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)

{
@@ -791,6 +823,8 @@ static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs) 
	unsigned long irq_flags;

	struct ftrace_event_call *call = &tp->call;



	tp->nhit++;



	local_save_flags(irq_flags);

	pc = preempt_count();
@@ -1140,9 +1174,18 @@ static __init int init_kprobe_trace(void) 
	entry = debugfs_create_file("kprobe_events", 0644, d_tracer,

				    NULL, &kprobe_events_ops);



	/* Event list interface */

	if (!entry)

		pr_warning("Could not create debugfs "

			   "'kprobe_events' entry\n");



	/* Profile interface */

	entry = debugfs_create_file("kprobe_profile", 0444, d_tracer,

				    NULL, &kprobe_profile_ops);



	if (!entry)

		pr_warning("Could not create debugfs "

			   "'kprobe_profile' entry\n");

	return 0;

}

fs_initcall(init_kprobe_trace);