[PATCH v4 3/3] tracing: add additional marks to signal very large delay

[byungchul . park]

From: Byungchul Park <byungchul.park@xxxxxxx>

Currently, some tracers tracing latency print "!" or "+" just after time
to signal overhead, depending on the interval between events. Even it is
usually enough to do that, we sometimes need to be signaled for bigger
interval than 100 micro seconds.

Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
---
 Documentation/trace/ftrace.txt |    8 +++++---
 kernel/trace/trace_output.c    |   23 ++++++++++++++++++-----
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index f827e2f..64efb3e 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -680,9 +680,11 @@ The above is mostly meaningful for kernel developers.
 	 needs to be fixed to be only relative to the same CPU.
 	 The marks are determined by the difference between this
 	 current trace and the next trace.
-	  '!' - greater than preempt_mark_thresh (default 100)
-	  '+' - greater than 1 microsecond
-	  ' ' - less than or equal to 1 microsecond.
+	  '$' - greater than 1 second
+	  '#' - greater than 1000 microsecond
+	  '!' - greater than 100 microsecond
+	  '+' - greater than 10 microsecond
+	  ' ' - less than or equal to 10 microsecond.
 
   The rest is the same as the 'trace' file.
 
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index c6977d5..3fd3017 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -124,7 +124,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
 
 	if (ret == (const char *)(trace_seq_buffer_ptr(p)))
 		trace_seq_printf(p, "0x%lx", val);
-		
+
 	trace_seq_putc(p, 0);
 
 	return ret;
@@ -471,7 +471,21 @@ lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
 	return trace_print_lat_fmt(s, entry);
 }
 
-static unsigned long preempt_mark_thresh_us = 100;
+#undef MARK
+#define MARK(v, s) {.val = v, .sym = s}
+static const struct trace_mark mark[] = {
+	MARK(1000000000ULL	, '$'), /* 1 sec */
+	MARK(1000000ULL		, '#'), /* 1000 usecs */
+	MARK(100000ULL		, '!'), /* 100 usecs */
+	MARK(10000ULL		, '+'), /* 10 usecs */
+	MARK(0ULL		, ' '), /* 0 usecs */
+};
+#undef MARK
+
+static inline char find_trace_mark(unsigned long long d)
+{
+	return trace_duration_mark(d, mark, ARRAY_SIZE(mark));
+}
 
 static int
 lat_print_timestamp(struct trace_iterator *iter, u64 next_ts)
@@ -506,8 +520,7 @@ lat_print_timestamp(struct trace_iterator *iter, u64 next_ts)
 		return trace_seq_printf(
 				s, " %4lldus%c: ",
 				abs_ts,
-				rel_ts > preempt_mark_thresh_us ? '!' :
-				  rel_ts > 1 ? '+' : ' ');
+				find_trace_mark(rel_ts * NSEC_PER_USEC));
 	} else { /* !verbose && !in_ns */
 		return trace_seq_printf(s, " %4lld: ", abs_ts);
 	}
@@ -692,7 +705,7 @@ int register_ftrace_event(struct trace_event *event)
 				goto out;
 
 		} else {
-			
+
 			event->type = next_event_type++;
 			list = &ftrace_event_list;
 		}
-- 
1.7.9.5

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