tracing: adding function timings to function profiler

If the function graph trace is enabled, the function profiler will
use it to take the timing of the functions.

 cat /debug/tracing/trace_stat/functions

  Function                               Hit    Time
  --------                               ---    ----
  mwait_idle                             127    183028.4 us
  schedule                                26    151997.7 us
  __schedule                              31    151975.1 us
  sys_wait4                                2    74080.53 us
  do_wait                                  2    74077.80 us
  sys_newlstat                           138    39929.16 us
  do_path_lookup                         179    39845.79 us
  vfs_lstat_fd                           138    39761.97 us
  user_path_at                           153    39469.58 us
  path_walk                              179    39435.76 us
  __link_path_walk                       189    39143.73 us
[...]

Note the times are skewed due to the function graph tracer not taking
into account schedules.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 89 insertions, 4 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 24dac448cdc9..a9ccd71fc922 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -33,7 +33,7 @@
 
 #include <asm/ftrace.h>
 
-#include "trace.h"
+#include "trace_output.h"
 #include "trace_stat.h"
 
 #define FTRACE_WARN_ON(cond)                    \
@@ -246,6 +246,9 @@ struct ftrace_profile {
         struct hlist_node               node;
         unsigned long                   ip;
         unsigned long                   counter;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        unsigned long long              time;
+#endif
 };
 
 struct ftrace_profile_page {
@@ -303,6 +306,22 @@ static void *function_stat_start(struct tracer_stat *trace)
         return function_stat_next(&profile_pages_start->records[0], 0);
 }
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/* function graph compares on total time */
+static int function_stat_cmp(void *p1, void *p2)
+{
+        struct ftrace_profile *a = p1;
+        struct ftrace_profile *b = p2;
+
+        if (a->time < b->time)
+                return -1;
+        if (a->time > b->time)
+                return 1;
+        else
+                return 0;
+}
+#else
+/* not function graph compares against hits */
 static int function_stat_cmp(void *p1, void *p2)
 {
         struct ftrace_profile *a = p1;
@@ -315,11 +334,17 @@ static int function_stat_cmp(void *p1, void *p2)
         else
                 return 0;
 }
+#endif
 
 static int function_stat_headers(struct seq_file *m)
 {
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        seq_printf(m, "  Function                               Hit    Time\n"
+                      "  --------                               ---    ----\n");
+#else
         seq_printf(m, "  Function                               Hit\n"
                       "  --------                               ---\n");
+#endif
         return 0;
 }
 
@@ -327,10 +352,25 @@ static int function_stat_show(struct seq_file *m, void *v)
 {
         struct ftrace_profile *rec = v;
         char str[KSYM_SYMBOL_LEN];
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        static struct trace_seq s;
+        static DEFINE_MUTEX(mutex);
+
+        mutex_lock(&mutex);
+        trace_seq_init(&s);
+        trace_print_graph_duration(rec->time, &s);
+#endif
 
         kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
+        seq_printf(m, "  %-30.30s  %10lu", str, rec->counter);
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        seq_printf(m, "    ");
+        trace_print_seq(m, &s);
+        mutex_unlock(&mutex);
+#endif
+        seq_putc(m, '\n');
 
-        seq_printf(m, "  %-30.30s  %10lu\n", str, rec->counter);
         return 0;
 }
 
@@ -534,11 +574,52 @@ function_profile_call(unsigned long ip, unsigned long parent_ip)
         local_irq_restore(flags);
 }
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+static int profile_graph_entry(struct ftrace_graph_ent *trace)
+{
+        function_profile_call(trace->func, 0);
+        return 1;
+}
+
+static void profile_graph_return(struct ftrace_graph_ret *trace)
+{
+        unsigned long flags;
+        struct ftrace_profile *rec;
+
+        local_irq_save(flags);
+        rec = ftrace_find_profiled_func(trace->func);
+        if (rec)
+                rec->time += trace->rettime - trace->calltime;
+        local_irq_restore(flags);
+}
+
+static int register_ftrace_profiler(void)
+{
+        return register_ftrace_graph(&profile_graph_return,
+                                     &profile_graph_entry);
+}
+
+static void unregister_ftrace_profiler(void)
+{
+        unregister_ftrace_graph();
+}
+#else
 static struct ftrace_ops ftrace_profile_ops __read_mostly =
 {
         .func = function_profile_call,
 };
 
+static int register_ftrace_profiler(void)
+{
+        return register_ftrace_function(&ftrace_profile_ops);
+}
+
+static void unregister_ftrace_profiler(void)
+{
+        unregister_ftrace_function(&ftrace_profile_ops);
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
 static ssize_t
 ftrace_profile_write(struct file *filp, const char __user *ubuf,
                      size_t cnt, loff_t *ppos)
@@ -570,11 +651,15 @@ ftrace_profile_write(struct file *filp, const char __user *ubuf,
                                 goto out;
                         }
 
-                        register_ftrace_function(&ftrace_profile_ops);
+                        ret = register_ftrace_profiler();
+                        if (ret < 0) {
+                                cnt = ret;
+                                goto out;
+                        }
                         ftrace_profile_enabled = 1;
                 } else {
                         ftrace_profile_enabled = 0;
-                        unregister_ftrace_function(&ftrace_profile_ops);
+                        unregister_ftrace_profiler();
                 }
         }
  out: