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Commit 7495a5be authored by Jiri Olsa's avatar Jiri Olsa Committed by Steven Rostedt
Browse files

tracing: Graph support for wakeup tracer 



Add function graph support for wakeup latency tracer.
The graph output is enabled by setting the 'display-graph'
trace option.

Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
LKML-Reference: <1285243253-7372-4-git-send-email-jolsa@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 0a772620

kernel/trace/trace_sched_wakeup.c

+221 −10
Original line number Diff line number Diff line
@@ -31,13 +31,33 @@ static int wakeup_rt; 
static arch_spinlock_t wakeup_lock =

	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;



static void wakeup_reset(struct trace_array *tr);

static void __wakeup_reset(struct trace_array *tr);

static int wakeup_graph_entry(struct ftrace_graph_ent *trace);

static void wakeup_graph_return(struct ftrace_graph_ret *trace);



static int save_lat_flag;



#define TRACE_DISPLAY_GRAPH     1



static struct tracer_opt trace_opts[] = {

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

	/* display latency trace as call graph */

	{ TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },

#endif

	{ } /* Empty entry */

};



static struct tracer_flags tracer_flags = {

	.val  = 0,

	.opts = trace_opts,

};



#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)



#ifdef CONFIG_FUNCTION_TRACER

/*

 * irqsoff uses its own tracer function to keep the overhead down:

 * wakeup uses its own tracer function to keep the overhead down:

 */

static void

wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
@@ -80,8 +100,191 @@ static struct ftrace_ops trace_ops __read_mostly = 
{

	.func = wakeup_tracer_call,

};



static int start_func_tracer(int graph)

{

	int ret;



	if (!graph)

		ret = register_ftrace_function(&trace_ops);

	else

		ret = register_ftrace_graph(&wakeup_graph_return,

					    &wakeup_graph_entry);



	if (!ret && tracing_is_enabled())

		tracer_enabled = 1;

	else

		tracer_enabled = 0;



	return ret;

}



static void stop_func_tracer(int graph)

{

	tracer_enabled = 0;



	if (!graph)

		unregister_ftrace_function(&trace_ops);

	else

		unregister_ftrace_graph();

}



#endif /* CONFIG_FUNCTION_TRACER */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

static int wakeup_set_flag(u32 old_flags, u32 bit, int set)

{



	if (!(bit & TRACE_DISPLAY_GRAPH))

		return -EINVAL;



	if (!(is_graph() ^ set))

		return 0;



	stop_func_tracer(!set);



	wakeup_reset(wakeup_trace);

	tracing_max_latency = 0;



	return start_func_tracer(set);

}



static int wakeup_graph_entry(struct ftrace_graph_ent *trace)

{

	struct trace_array *tr = wakeup_trace;

	struct trace_array_cpu *data;

	unsigned long flags;

	long disabled;

	int cpu, pc, ret = 0;



	if (likely(!wakeup_task))

		return 0;



	pc = preempt_count();

	preempt_disable_notrace();



	cpu = raw_smp_processor_id();

	if (cpu != wakeup_current_cpu)

		goto out_enable;



	data = tr->data[cpu];

	disabled = atomic_inc_return(&data->disabled);

	if (unlikely(disabled != 1))

		goto out;



	local_save_flags(flags);

	ret = __trace_graph_entry(tr, trace, flags, pc);



out:

	atomic_dec(&data->disabled);



out_enable:

	preempt_enable_notrace();

	return ret;

}



static void wakeup_graph_return(struct ftrace_graph_ret *trace)

{

	struct trace_array *tr = wakeup_trace;

	struct trace_array_cpu *data;

	unsigned long flags;

	long disabled;

	int cpu, pc;



	if (likely(!wakeup_task))

		return;



	pc = preempt_count();

	preempt_disable_notrace();



	cpu = raw_smp_processor_id();

	if (cpu != wakeup_current_cpu)

		goto out_enable;



	data = tr->data[cpu];

	disabled = atomic_inc_return(&data->disabled);

	if (unlikely(disabled != 1))

		goto out;



	local_save_flags(flags);

	__trace_graph_return(tr, trace, flags, pc);



out:

	atomic_dec(&data->disabled);



out_enable:

	preempt_enable_notrace();

	return;

}



static void wakeup_trace_open(struct trace_iterator *iter)

{

	if (is_graph())

		graph_trace_open(iter);

}



static void wakeup_trace_close(struct trace_iterator *iter)

{

	if (iter->private)

		graph_trace_close(iter);

}



#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC)



static enum print_line_t wakeup_print_line(struct trace_iterator *iter)

{

	/*

	 * In graph mode call the graph tracer output function,

	 * otherwise go with the TRACE_FN event handler

	 */

	if (is_graph())

		return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);



	return TRACE_TYPE_UNHANDLED;

}



static void wakeup_print_header(struct seq_file *s)

{

	if (is_graph())

		print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);

	else

		trace_default_header(s);

}



static void

__trace_function(struct trace_array *tr,

		 unsigned long ip, unsigned long parent_ip,

		 unsigned long flags, int pc)

{

	if (is_graph())

		trace_graph_function(tr, ip, parent_ip, flags, pc);

	else

		trace_function(tr, ip, parent_ip, flags, pc);

}

#else

#define __trace_function trace_function



static int wakeup_set_flag(u32 old_flags, u32 bit, int set)

{

	return -EINVAL;

}



static int wakeup_graph_entry(struct ftrace_graph_ent *trace)

{

	return -1;

}



static enum print_line_t wakeup_print_line(struct trace_iterator *iter)

{

	return TRACE_TYPE_UNHANDLED;

}



static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }

static void wakeup_print_header(struct seq_file *s) { }

static void wakeup_trace_open(struct trace_iterator *iter) { }

static void wakeup_trace_close(struct trace_iterator *iter) { }

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



/*

 * Should this new latency be reported/recorded?

 */
@@ -152,7 +355,7 @@ probe_wakeup_sched_switch(void *ignore, 
	/* The task we are waiting for is waking up */

	data = wakeup_trace->data[wakeup_cpu];



	trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);

	__trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);

	tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);



	T0 = data->preempt_timestamp;
@@ -252,7 +455,7 @@ probe_wakeup(void *ignore, struct task_struct *p, int success) 
	 * is not called by an assembly function  (where as schedule is)

	 * it should be safe to use it here.

	 */

	trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);

	__trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);



out_locked:

	arch_spin_unlock(&wakeup_lock);
@@ -303,12 +506,8 @@ static void start_wakeup_tracer(struct trace_array *tr) 
	 */

	smp_wmb();



	register_ftrace_function(&trace_ops);



	if (tracing_is_enabled())

		tracer_enabled = 1;

	else

		tracer_enabled = 0;

	if (start_func_tracer(is_graph()))

		printk(KERN_ERR "failed to start wakeup tracer\n");



	return;

fail_deprobe_wake_new:
@@ -320,7 +519,7 @@ static void start_wakeup_tracer(struct trace_array *tr) 
static void stop_wakeup_tracer(struct trace_array *tr)

{

	tracer_enabled = 0;

	unregister_ftrace_function(&trace_ops);

	stop_func_tracer(is_graph());

	unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);

	unregister_trace_sched_wakeup_new(probe_wakeup, NULL);

	unregister_trace_sched_wakeup(probe_wakeup, NULL);
@@ -379,9 +578,15 @@ static struct tracer wakeup_tracer __read_mostly = 
	.start		= wakeup_tracer_start,

	.stop		= wakeup_tracer_stop,

	.print_max	= 1,

	.print_header	= wakeup_print_header,

	.print_line	= wakeup_print_line,

	.flags		= &tracer_flags,

	.set_flag	= wakeup_set_flag,

#ifdef CONFIG_FTRACE_SELFTEST

	.selftest    = trace_selftest_startup_wakeup,

#endif

	.open		= wakeup_trace_open,

	.close		= wakeup_trace_close,

	.use_max_tr	= 1,

};
@@ -394,9 +599,15 @@ static struct tracer wakeup_rt_tracer __read_mostly = 
	.stop		= wakeup_tracer_stop,

	.wait_pipe	= poll_wait_pipe,

	.print_max	= 1,

	.print_header	= wakeup_print_header,

	.print_line	= wakeup_print_line,

	.flags		= &tracer_flags,

	.set_flag	= wakeup_set_flag,

#ifdef CONFIG_FTRACE_SELFTEST

	.selftest    = trace_selftest_startup_wakeup,

#endif

	.open		= wakeup_trace_open,

	.close		= wakeup_trace_close,

	.use_max_tr	= 1,

};