[PATCHv3 1/2] tracing: graph output support for irqsoff tracer

Jiri Olsa
2010-03-26T12:32:11Z

hi,

when I was using irqsoff tracer, I thought it could be any use
to see the disabled IRQs flow output same way as function graph output.

The graph output is enabled by setting new 'display-graph' trace option
of irqsoff tracer.

wbr,
jirka

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
kernel/trace/trace.c | 31 ++++--
kernel/trace/trace.h | 10 ++
kernel/trace/trace_functions_graph.c | 15 ++-
kernel/trace/trace_irqsoff.c | 184 ++++++++++++++++++++++++++++++++--
4 files changed, 217 insertions(+), 23 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3ec2ee6..2229f5a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2058,6 +2058,23 @@ static enum print_line_t print_trace_line(struct trace_iterator *iter)
return print_trace_fmt(iter);
}

+void trace_default_header(struct seq_file *m)
+{
+ struct trace_iterator *iter = m->private;
+
+ if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
+ /* print nothing if the buffers are empty */
+ if (trace_empty(iter))
+ return;
+ print_trace_header(m, iter);
+ if (!(trace_flags & TRACE_ITER_VERBOSE))
+ print_lat_help_header(m);
+ } else {
+ if (!(trace_flags & TRACE_ITER_VERBOSE))
+ print_func_help_header(m);
+ }
+}
+
static int s_show(struct seq_file *m, void *v)
{
struct trace_iterator *iter = v;
@@ -2070,17 +2087,9 @@ static int s_show(struct seq_file *m, void *v)
}
if (iter->trace && iter->trace->print_header)
iter->trace->print_header(m);
- else if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
- /* print nothing if the buffers are empty */
- if (trace_empty(iter))
- return 0;
- print_trace_header(m, iter);
- if (!(trace_flags & TRACE_ITER_VERBOSE))
- print_lat_help_header(m);
- } else {
- if (!(trace_flags & TRACE_ITER_VERBOSE))
- print_func_help_header(m);
- }
+ else
+ trace_default_header(m);
+
} else if (iter->leftover) {
/*
* If we filled the seq_file buffer earlier, we
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2825ef2..42ad603 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -378,6 +378,7 @@ void trace_function(struct trace_array *tr,
unsigned long ip,
unsigned long parent_ip,
unsigned long flags, int pc);
+void trace_default_header(struct seq_file *m);

void trace_graph_return(struct ftrace_graph_ret *trace);
int trace_graph_entry(struct ftrace_graph_ent *trace);
@@ -492,8 +493,17 @@ extern int trace_clock_id;
/* Standard output formatting function used for function return traces */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
extern enum print_line_t print_graph_function(struct trace_iterator *iter);
+extern void print_graph_headers(struct seq_file *s);
extern enum print_line_t
trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);
+extern void graph_trace_open(struct trace_iterator *iter);
+extern void graph_trace_close(struct trace_iterator *iter);
+extern int __trace_graph_entry(struct trace_array *tr,
+ struct ftrace_graph_ent *trace,
+ unsigned long flags, int pc);
+extern void __trace_graph_return(struct trace_array *tr,
+ struct ftrace_graph_ret *trace,
+ unsigned long flags, int pc);

#ifdef CONFIG_DYNAMIC_FTRACE
/* TODO: make this variable */
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index e6989d9..d1b5d38 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -178,7 +178,7 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
return ret;
}

-static int __trace_graph_entry(struct trace_array *tr,
+int __trace_graph_entry(struct trace_array *tr,
struct ftrace_graph_ent *trace,
unsigned long flags,
int pc)
@@ -245,7 +245,7 @@ int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
return trace_graph_entry(trace);
}

-static void __trace_graph_return(struct trace_array *tr,
+void __trace_graph_return(struct trace_array *tr,
struct ftrace_graph_ret *trace,
unsigned long flags,
int pc)
@@ -1087,6 +1087,11 @@ print_graph_function(struct trace_iterator *iter)
trace_assign_type(field, entry);
return print_graph_return(&field->ret, s, entry, iter);
}
+ case TRACE_STACK:
+ case TRACE_FN:
+ /* dont trace stack and functions as comments */
+ return TRACE_TYPE_UNHANDLED;
+
default:
return print_graph_comment(s, entry, iter);
}
@@ -1116,7 +1121,7 @@ static void print_lat_header(struct seq_file *s)
seq_printf(s, "#%.*s|||| / \n", size, spaces);
}

-static void print_graph_headers(struct seq_file *s)
+void print_graph_headers(struct seq_file *s)
{
int lat = trace_flags & TRACE_ITER_LATENCY_FMT;

@@ -1152,7 +1157,7 @@ static void print_graph_headers(struct seq_file *s)
seq_printf(s, " | | | |\n");
}

-static void graph_trace_open(struct trace_iterator *iter)
+void graph_trace_open(struct trace_iterator *iter)
{
/* pid and depth on the last trace processed */
struct fgraph_data *data;
@@ -1187,7 +1192,7 @@ static void graph_trace_open(struct trace_iterator *iter)
pr_warning("function graph tracer: not enough memory\n");
}

-static void graph_trace_close(struct trace_iterator *iter)
+void graph_trace_close(struct trace_iterator *iter)
{
struct fgraph_data *data = iter->private;

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 2974bc7..2b67e35 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -34,6 +34,9 @@ static int trace_type __read_mostly;

static int save_lat_flag;

+static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
+static int start_irqsoff_tracer(struct trace_array *tr, int graph);
+
#ifdef CONFIG_PREEMPT_TRACER
static inline int
preempt_trace(void)
@@ -55,6 +58,23 @@ irq_trace(void)
# define irq_trace() (0)
#endif

+#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)
+
/*
* Sequence count - we record it when starting a measurement and
* skip the latency if the sequence has changed - some other section
@@ -108,6 +128,129 @@ static struct ftrace_ops trace_ops __read_mostly =
};
#endif /* CONFIG_FUNCTION_TRACER */

+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
+{
+ int cpu;
+
+ if (!(bit & TRACE_DISPLAY_GRAPH))
+ return -EINVAL;
+
+ if (!(is_graph() ^ set))
+ return 0;
+
+ stop_irqsoff_tracer(irqsoff_trace, !set);
+
+ for_each_possible_cpu(cpu)
+ per_cpu(tracing_cpu, cpu) = 0;
+
+ tracing_max_latency = 0;
+ tracing_reset_online_cpus(irqsoff_trace);
+
+ return start_irqsoff_tracer(irqsoff_trace, set);
+}
+
+static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
+{
+ struct trace_array *tr = irqsoff_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ long disabled;
+ int ret;
+ int cpu;
+ int pc;
+
+ cpu = raw_smp_processor_id();
+ if (likely(!per_cpu(tracing_cpu, cpu)))
+ return 0;
+
+ local_save_flags(flags);
+ /* slight chance to get a false positive on tracing_cpu */
+ if (!irqs_disabled_flags(flags))
+ return 0;
+
+ data = tr->data[cpu];
+ disabled = atomic_inc_return(&data->disabled);
+
+ if (likely(disabled == 1)) {
+ pc = preempt_count();
+ ret = __trace_graph_entry(tr, trace, flags, pc);
+ } else
+ ret = 0;
+
+ atomic_dec(&data->disabled);
+ return ret;
+}
+
+static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
+{
+ struct trace_array *tr = irqsoff_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ long disabled;
+ int cpu;
+ int pc;
+
+ cpu = raw_smp_processor_id();
+ if (likely(!per_cpu(tracing_cpu, cpu)))
+ return;
+
+ local_save_flags(flags);
+ /* slight chance to get a false positive on tracing_cpu */
+ if (!irqs_disabled_flags(flags))
+ return;
+
+ data = tr->data[cpu];
+ disabled = atomic_inc_return(&data->disabled);
+
+ if (likely(disabled == 1)) {
+ pc = preempt_count();
+ __trace_graph_return(tr, trace, flags, pc);
+ }
+
+ atomic_dec(&data->disabled);
+}
+
+static void irqsoff_trace_open(struct trace_iterator *iter)
+{
+ if (is_graph())
+ graph_trace_open(iter);
+
+}
+
+static void irqsoff_trace_close(struct trace_iterator *iter)
+{
+ if (iter->private)
+ graph_trace_close(iter);
+}
+
+static enum print_line_t
+irqsoff_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(iter);
+
+ return TRACE_TYPE_UNHANDLED;
+}
+
+void irqsoff_print_header(struct seq_file *s)
+{
+ if (is_graph())
+ print_graph_headers(s);
+ else
+ trace_default_header(s);
+}
+#else
+static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
+{
+ return -EINVAL;
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
/*
* Should this new latency be reported/recorded?
*/
@@ -347,19 +490,36 @@ void trace_preempt_off(unsigned long a0, unsigned long a1)
}
#endif /* CONFIG_PREEMPT_TRACER */

-static void start_irqsoff_tracer(struct trace_array *tr)
+static int start_irqsoff_tracer(struct trace_array *tr, int graph)
{
- register_ftrace_function(&trace_ops);
- if (tracing_is_enabled())
+ int ret = 0;
+
+ if (!graph)
+ ret = register_ftrace_function(&trace_ops);
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ else
+ ret = register_ftrace_graph(&irqsoff_graph_return,
+ &irqsoff_graph_entry);
+#endif
+
+ if (!ret && tracing_is_enabled())
tracer_enabled = 1;
else
tracer_enabled = 0;
+
+ return ret;
}

-static void stop_irqsoff_tracer(struct trace_array *tr)
+static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
{
tracer_enabled = 0;
- unregister_ftrace_function(&trace_ops);
+
+ if (!graph)
+ unregister_ftrace_function(&trace_ops);
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ else
+ unregister_ftrace_graph();
+#endif
}

static void __irqsoff_tracer_init(struct trace_array *tr)
@@ -372,12 +532,14 @@ static void __irqsoff_tracer_init(struct trace_array *tr)
/* make sure that the tracer is visible */
smp_wmb();
tracing_reset_online_cpus(tr);
- start_irqsoff_tracer(tr);
+
+ if (start_irqsoff_tracer(tr, is_graph()))
+ printk(KERN_ERR "failed to start irqsoff tracer\n");
}

static void irqsoff_tracer_reset(struct trace_array *tr)
{
- stop_irqsoff_tracer(tr);
+ stop_irqsoff_tracer(tr, is_graph());

if (!save_lat_flag)
trace_flags &= ~TRACE_ITER_LATENCY_FMT;
@@ -409,9 +571,17 @@ static struct tracer irqsoff_tracer __read_mostly =
.start = irqsoff_tracer_start,
.stop = irqsoff_tracer_stop,
.print_max = 1,
+ .print_header = irqsoff_print_header,
+ .print_line = irqsoff_print_line,
+ .flags = &tracer_flags,
+ .set_flag = irqsoff_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_irqsoff,
#endif
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ .open = irqsoff_trace_open,
+ .close = irqsoff_trace_close,
+#endif
};
# define register_irqsoff(trace) register_tracer(&trace)
#else
--
1.6.6.1