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

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
LKML-Reference: <1285243253-7372-4-git-send-email-jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Jiri Olsa authored and Steven Rostedt committed Oct 18, 2010
1 parent 0a77262 commit 7495a5b
Showing 1 changed file with 221 additions and 10 deletions.
231 changes: 221 additions & 10 deletions kernel/trace/trace_sched_wakeup.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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?
*/
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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:
Expand All @@ -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);
Expand Down Expand Up @@ -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,
};

Expand All @@ -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,
};

Expand Down

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