tracing: Let tracepoints have data passed to tracepoint callbacks
[linux-2.6.git] / kernel / trace / ftrace.c
index 2404b59..6d2cb14 100644 (file)
@@ -264,6 +264,7 @@ struct ftrace_profile {
        unsigned long                   counter;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
        unsigned long long              time;
+       unsigned long long              time_squared;
 #endif
 };
 
@@ -366,9 +367,9 @@ static int function_stat_headers(struct seq_file *m)
 {
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
        seq_printf(m, "  Function                               "
-                  "Hit    Time            Avg\n"
+                  "Hit    Time            Avg             s^2\n"
                      "  --------                               "
-                  "---    ----            ---\n");
+                  "---    ----            ---             ---\n");
 #else
        seq_printf(m, "  Function                               Hit\n"
                      "  --------                               ---\n");
@@ -384,6 +385,7 @@ static int function_stat_show(struct seq_file *m, void *v)
        static DEFINE_MUTEX(mutex);
        static struct trace_seq s;
        unsigned long long avg;
+       unsigned long long stddev;
 #endif
 
        kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
@@ -394,11 +396,25 @@ static int function_stat_show(struct seq_file *m, void *v)
        avg = rec->time;
        do_div(avg, rec->counter);
 
+       /* Sample standard deviation (s^2) */
+       if (rec->counter <= 1)
+               stddev = 0;
+       else {
+               stddev = rec->time_squared - rec->counter * avg * avg;
+               /*
+                * Divide only 1000 for ns^2 -> us^2 conversion.
+                * trace_print_graph_duration will divide 1000 again.
+                */
+               do_div(stddev, (rec->counter - 1) * 1000);
+       }
+
        mutex_lock(&mutex);
        trace_seq_init(&s);
        trace_print_graph_duration(rec->time, &s);
        trace_seq_puts(&s, "    ");
        trace_print_graph_duration(avg, &s);
+       trace_seq_puts(&s, "    ");
+       trace_print_graph_duration(stddev, &s);
        trace_print_seq(m, &s);
        mutex_unlock(&mutex);
 #endif
@@ -650,6 +666,10 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
        if (!stat->hash || !ftrace_profile_enabled)
                goto out;
 
+       /* If the calltime was zero'd ignore it */
+       if (!trace->calltime)
+               goto out;
+
        calltime = trace->rettime - trace->calltime;
 
        if (!(trace_flags & TRACE_ITER_GRAPH_TIME)) {
@@ -668,8 +688,10 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
        }
 
        rec = ftrace_find_profiled_func(stat, trace->func);
-       if (rec)
+       if (rec) {
                rec->time += calltime;
+               rec->time_squared += calltime * calltime;
+       }
 
  out:
        local_irq_restore(flags);
@@ -3212,8 +3234,8 @@ free:
 }
 
 static void
-ftrace_graph_probe_sched_switch(struct rq *__rq, struct task_struct *prev,
-                               struct task_struct *next)
+ftrace_graph_probe_sched_switch(void *ignore,
+                       struct task_struct *prev, struct task_struct *next)
 {
        unsigned long long timestamp;
        int index;
@@ -3267,7 +3289,7 @@ static int start_graph_tracing(void)
        } while (ret == -EAGAIN);
 
        if (!ret) {
-               ret = register_trace_sched_switch(ftrace_graph_probe_sched_switch);
+               ret = register_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
                if (ret)
                        pr_info("ftrace_graph: Couldn't activate tracepoint"
                                " probe to kernel_sched_switch\n");
@@ -3339,11 +3361,11 @@ void unregister_ftrace_graph(void)
                goto out;
 
        ftrace_graph_active--;
-       unregister_trace_sched_switch(ftrace_graph_probe_sched_switch);
        ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
        ftrace_graph_entry = ftrace_graph_entry_stub;
        ftrace_shutdown(FTRACE_STOP_FUNC_RET);
        unregister_pm_notifier(&ftrace_suspend_notifier);
+       unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
 
  out:
        mutex_unlock(&ftrace_lock);