linux-kernel - [PATCH 05/11] tools lib traceevent: Fix time stamp rounding issue

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Date:	Wed,  2 Mar 2016 19:16:40 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org, "Chaos.Chen" <rainboy1215@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 05/11] tools lib traceevent: Fix time stamp rounding issue

From: "Chaos.Chen" <rainboy1215@...il.com>

When rounding to microseconds, if the timestamp subsecond is between
.999999500 and .999999999, it is rounded to .1000000, when it should
instead increment the second counter due to the overflow.

For example, if the timestamp is 1234.999999501 instead of seeing:

  1235.000000

we see:

  1234.1000000

Signed-off-by: Chaos.Chen <rainboy1215@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Link: http://lkml.kernel.org/r/20160209204236.824426460@goodmis.org
[ fixed incrementing "secs" instead of decrementing it ]
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/lib/traceevent/event-parse.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 9a1e48afcf89..ce59f4891fa2 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -5429,6 +5429,11 @@ void pevent_print_event_time(struct pevent *pevent, struct trace_seq *s,
 			p = 9;
 		} else {
 			usecs = (nsecs + 500) / NSECS_PER_USEC;
+			/* To avoid usecs larger than 1 sec */
+			if (usecs >= 1000000) {
+				usecs -= 1000000;
+				secs++;
+			}
 			p = 6;
 		}
 
-- 
2.5.0