ring-buffer: Move the adding of the extended timestamp out of line

Requiring a extended time stamp is an uncommon occurrence, and it is
best to do it out of line when needed.

Add a noinline function that handles the extended timestamp and
have it called with an unlikely to completely move it out of the
fast path.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index ba8f25f..a78d4ee 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2396,6 +2396,29 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
        return NULL;
 }
 
+#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+static inline bool sched_clock_stable(void)
+{
+       return true;
+}
+#endif
+
+static noinline void
+rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
+                   struct rb_event_info *info)
+{
+       WARN_ONCE(info->delta > (1ULL << 59),
+                 KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
+                 (unsigned long long)info->delta,
+                 (unsigned long long)info->ts,
+                 (unsigned long long)cpu_buffer->write_stamp,
+                 sched_clock_stable() ? "" :
+                 "If you just came from a suspend/resume,\n"
+                 "please switch to the trace global clock:\n"
+                 "  echo global > /sys/kernel/debug/tracing/trace_clock\n");
+       info->add_timestamp = 1;
+}
+
 static struct ring_buffer_event *
 __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
                  struct rb_event_info *info)
@@ -2582,22 +2605,8 @@ rb_reserve_next_event(struct ring_buffer *buffer,
        /* Did the write stamp get updated already? */
        if (likely(info.ts >= cpu_buffer->write_stamp)) {
                info.delta = diff;
-               if (unlikely(test_time_stamp(info.delta))) {
-                       int local_clock_stable = 1;
-#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
-                       local_clock_stable = sched_clock_stable();
-#endif
-                       WARN_ONCE(info.delta > (1ULL << 59),
-                                 KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s",
-                                 (unsigned long long)info.delta,
-                                 (unsigned long long)info.ts,
-                                 (unsigned long long)cpu_buffer->write_stamp,
-                                 local_clock_stable ? "" :
-                                 "If you just came from a suspend/resume,\n"
-                                 "please switch to the trace global clock:\n"
-                                 "  echo global > /sys/kernel/debug/tracing/trace_clock\n");
-                       info.add_timestamp = 1;
-               }
+               if (unlikely(test_time_stamp(info.delta)))
+                       rb_handle_timestamp(cpu_buffer, &info);
        }
 
        event = __rb_reserve_next(cpu_buffer, &info);