tracing/function-graph-tracer: adjustments of the trace informations

Impact: increase the visual qualities of the call-graph-tracer output

This patch applies various trace output formatting changes:

 - CPU is now a decimal number, followed by a parenthesis.

 - Overhead is now on the second column (gives a good visibility)

 - Cost is now on the third column, can't exceed 9999.99 us. It is
   followed by a virtual line based on a "|" character.

 - Functions calls are now the last column on the right. This way, we
   haven't dynamic column (which flow is harder to follow) on its right.

 - CPU and Overhead have their own option flag. They are default-on but you
   can disable them easily:

      echo nofuncgraph-cpu > trace_options
      echo nofuncgraph-overhead > trace_options

TODO:

_ Refactoring of the thread switch output.
_ Give a default-off option to output the thread and its pid on each row.
_ Provide headers
_ ....

Here is an example of the new trace style:

0)           |             mutex_unlock() {
0)      0.639 us |           __mutex_unlock_slowpath();
0)      1.607 us |         }
0)           |             remove_wait_queue() {
0)      0.616 us |           _spin_lock_irqsave();
0)      0.616 us |           _spin_unlock_irqrestore();
0)      2.779 us |         }
0)      0.495 us |         n_tty_set_room();
0) ! 9999.999 us |       }
0)           |           tty_ldisc_deref() {
0)      0.615 us |         _spin_lock_irqsave();
0)      0.616 us |         _spin_unlock_irqrestore();
0)      2.793 us |       }
0)           |           current_fs_time() {
0)      0.488 us |         current_kernel_time();
0)      0.495 us |         timespec_trunc();
0)      2.486 us |       }
0) ! 9999.999 us |     }
0) ! 9999.999 us |   }
0) ! 9999.999 us | }
0)           |     sys_read() {
0)      0.796 us |   fget_light();
0)           |       vfs_read() {
0)           |         rw_verify_area() {
0)           |           security_file_permission() {
0)      0.488 us |         cap_file_permission();
0)      1.720 us |       }
0)      3.  4 us |     }
0)           |         tty_read() {
0)      0.488 us |       tty_paranoia_check();
0)           |           tty_ldisc_ref_wait() {
0)           |             tty_ldisc_try() {
0)      0.615 us |           _spin_lock_irqsave();
0)      0.615 us |           _spin_unlock_irqrestore();
0)      5.436 us |         }
0)      6.427 us |       }

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 93 insertions, 49 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index b958d60377b3..596a3ee43053 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -14,20 +14,25 @@
 #include "trace.h"
 
 #define TRACE_GRAPH_INDENT      2
-/* Spaces between function call and time duration */
-#define TRACE_GRAPH_TIMESPACE_ENTRY     "                    "
-/* Spaces between function call and closing braces */
-#define TRACE_GRAPH_TIMESPACE_RET       "                               "
 
+/* Flag options */
 #define TRACE_GRAPH_PRINT_OVERRUN       0x1
+#define TRACE_GRAPH_PRINT_CPU           0x2
+#define TRACE_GRAPH_PRINT_OVERHEAD      0x4
+
 static struct tracer_opt trace_opts[] = {
-        /* Display overruns or not */
-        { TRACER_OPT(overrun, TRACE_GRAPH_PRINT_OVERRUN) },
+        /* Display overruns ? */
+        { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
+        /* Display CPU ? */
+        { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
+        /* Display Overhead ? */
+        { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
         { } /* Empty entry */
 };
 
 static struct tracer_flags tracer_flags = {
-        .val = 0, /* Don't display overruns by default */
+        /* Don't display overruns by default */
+        .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD,
         .opts = trace_opts
 };
 
@@ -56,6 +61,36 @@ static void graph_trace_reset(struct trace_array *tr)
         unregister_ftrace_graph();
 }
 
+static inline int log10_cpu(int nb)
+{
+        if (nb / 100)
+                return 3;
+        if (nb / 10)
+                return 2;
+        return 1;
+}
+
+static enum print_line_t
+print_graph_cpu(struct trace_seq *s, int cpu)
+{
+        int i;
+        int ret;
+        int log10_this = log10_cpu(cpu);
+        int log10_all = log10_cpu(cpus_weight_nr(cpu_online_map));
+
+
+        for (i = 0; i < log10_all - log10_this; i++) {
+                ret = trace_seq_printf(s, " ");
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
+        ret = trace_seq_printf(s, "%d) ", cpu);
+        if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        return TRACE_TYPE_HANDLED;
+}
+
+
 /* If the pid changed since the last trace, output this event */
 static int verif_pid(struct trace_seq *s, pid_t pid, int cpu)
 {
@@ -67,8 +102,7 @@ static int verif_pid(struct trace_seq *s, pid_t pid, int cpu)
         last_pid[cpu] = pid;
         comm = trace_find_cmdline(pid);
 
-        return trace_seq_printf(s, "\nCPU[%03d] "
-                                    " ------------8<---------- thread %s-%d"
+        return trace_seq_printf(s, "\n------------8<---------- thread %s-%d"
                                     " ------------8<----------\n\n",
                                     cpu, comm, pid);
 }
@@ -86,7 +120,7 @@ trace_branch_is_leaf(struct trace_iterator *iter,
         if (!ring_iter)
                 return false;
 
-        event = ring_buffer_iter_peek(iter->buffer_iter[iter->cpu], NULL);
+        event = ring_buffer_iter_peek(ring_iter, NULL);
 
         if (!event)
                 return false;
@@ -108,7 +142,7 @@ static inline int
 print_graph_duration(unsigned long long duration, struct trace_seq *s)
 {
         unsigned long nsecs_rem = do_div(duration, 1000);
-        return trace_seq_printf(s, "+ %llu.%lu us\n", duration, nsecs_rem);
+        return trace_seq_printf(s, "%4llu.%3lu us | ", duration, nsecs_rem);
 }
 
 /* Signal a overhead of time execution to the output */
@@ -136,8 +170,8 @@ print_graph_entry_leaf(struct trace_iterator *iter,
         struct ring_buffer_event *event;
         struct ftrace_graph_ent *call;
         unsigned long long duration;
-        int i;
         int ret;
+        int i;
 
         event = ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
         ret_entry = ring_buffer_event_data(event);
@@ -145,8 +179,19 @@ print_graph_entry_leaf(struct trace_iterator *iter,
         call = &entry->graph_ent;
         duration = graph_ret->rettime - graph_ret->calltime;
 
+        /* Must not exceed 8 characters: 9999.999 us */
+        if (duration > 10000000ULL)
+                duration = 9999999ULL;
+
         /* Overhead */
-        ret = print_graph_overhead(duration, s);
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
+                ret = print_graph_overhead(duration, s);
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
+
+        /* Duration */
+        ret = print_graph_duration(duration, s);
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -161,16 +206,7 @@ print_graph_entry_leaf(struct trace_iterator *iter,
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
-        ret = trace_seq_printf(s, "();");
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
-
-        /* Duration */
-        ret = trace_seq_printf(s, TRACE_GRAPH_TIMESPACE_ENTRY);
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
-
-        ret = print_graph_duration(duration, s);
+        ret = trace_seq_printf(s, "();\n");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -186,9 +222,14 @@ print_graph_entry_nested(struct ftrace_graph_ent_entry *entry,
         struct ftrace_graph_ent *call = &entry->graph_ent;
 
         /* No overhead */
-        ret = trace_seq_printf(s, "  ");
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
+                ret = trace_seq_printf(s, "  ");
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
+
+        /* No time */
+        ret = trace_seq_printf(s, "        |     ");
 
         /* Function */
         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
@@ -201,12 +242,7 @@ print_graph_entry_nested(struct ftrace_graph_ent_entry *entry,
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
-        ret = trace_seq_printf(s, "() {");
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
-
-        /* No duration to print at this state */
-        ret = trace_seq_printf(s, TRACE_GRAPH_TIMESPACE_ENTRY "-\n");
+        ret = trace_seq_printf(s, "() {\n");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -220,12 +256,16 @@ print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
         int ret;
         struct trace_entry *ent = iter->ent;
 
+        /* Pid */
         if (!verif_pid(s, ent->pid, cpu))
                 return TRACE_TYPE_PARTIAL_LINE;
 
-        ret = trace_seq_printf(s, "CPU[%03d] ", cpu);
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
+        /* Cpu */
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
+                ret = print_graph_cpu(s, cpu);
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
 
         if (trace_branch_is_leaf(iter, field))
                 return print_graph_entry_leaf(iter, field, s);
@@ -242,17 +282,30 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
         int ret;
         unsigned long long duration = trace->rettime - trace->calltime;
 
+        /* Must not exceed 8 characters: xxxx.yyy us */
+        if (duration > 10000000ULL)
+                duration = 9999999ULL;
+
         /* Pid */
         if (!verif_pid(s, ent->pid, cpu))
                 return TRACE_TYPE_PARTIAL_LINE;
 
         /* Cpu */
-        ret = trace_seq_printf(s, "CPU[%03d] ", cpu);
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
+                ret = print_graph_cpu(s, cpu);
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
 
         /* Overhead */
-        ret = print_graph_overhead(duration, s);
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
+                ret = print_graph_overhead(duration, s);
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
+
+        /* Duration */
+        ret = print_graph_duration(duration, s);
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
 
@@ -263,16 +316,7 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
                         return TRACE_TYPE_PARTIAL_LINE;
         }
 
-        ret = trace_seq_printf(s, "} ");
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
-
-        /* Duration */
-        ret = trace_seq_printf(s, TRACE_GRAPH_TIMESPACE_RET);
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
-
-        ret = print_graph_duration(duration, s);
+        ret = trace_seq_printf(s, "}\n");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;