[PATCH v2 1/2] ftrace: add tracepoint for xtime

Zhaolei
2009-09-16T05:24:54Z

From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>

This patch can trace current xtime and wall_to_monotonic. Then user can
use ctime() to convert them to wall time which is easier to be understood,
especially for flight-recorder which need to get trace event from a kernel
dump file.

Example of ftrace output:
<idle>-0 [000] 20118.489849: gtod_update_xtime: xtime=1243265589.999999824 wall_to_monotonic=3051713268.744158739
<...>-4020 [001] 20118.489855: sys_open(filename: bf9e66e0, flags: 98800, mode: bf9e66e0)
<...>-4020 [001] 20118.489873: sys_open -> 0xffffffec

ctime(1243265590) = date:Mon May 25 11:33:10 2009
So we can realize the task with pid 4020 open a file at
Mon May 25 11:33:10 2009

Changelog:
v1->v2: Rebased by Zhao Lei <zhaolei@cn.fujitsu.com>

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
include/trace/events/xtime.h | 38 ++++++++++++++++++++++++++++++++++++++
kernel/time/ntp.c | 4 ++++
kernel/time/timekeeping.c | 6 ++++++
3 files changed, 48 insertions(+), 0 deletions(-)
create mode 100644 include/trace/events/xtime.h

diff --git a/include/trace/events/xtime.h b/include/trace/events/xtime.h
new file mode 100644
index 0000000..398e679
--- /dev/null
+++ b/include/trace/events/xtime.h
@@ -0,0 +1,38 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM xtime
+
+#if !defined(_TRACE_XTIME_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_XTIME_H
+
+#include <linux/time.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(gtod_update_xtime,
+
+ TP_PROTO(struct timespec *xtime, struct timespec *wall_to_monotonic),
+
+ TP_ARGS(xtime, wall_to_monotonic),
+
+ TP_STRUCT__entry(
+ __field( long, xtime_sec )
+ __field( long, xtime_nsec )
+ __field( long, wall_to_monotonic_sec )
+ __field( long, wall_to_monotonic_nsec )
+ ),
+
+ TP_fast_assign(
+ __entry->xtime_sec = xtime->tv_sec;
+ __entry->xtime_nsec = xtime->tv_nsec;
+ __entry->wall_to_monotonic_sec = wall_to_monotonic->tv_sec;
+ __entry->wall_to_monotonic_nsec = wall_to_monotonic->tv_nsec;
+ ),
+
+ TP_printk("xtime=%ld.%09ld wall_to_monotonic=%ld.%09ld",
+ __entry->xtime_sec, __entry->xtime_nsec,
+ __entry->wall_to_monotonic_sec, __entry->wall_to_monotonic_nsec)
+);
+
+#endif /* _TRACE_XTIME_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 4800f93..fc2f13a 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -15,6 +15,8 @@
#include <linux/time.h>
#include <linux/mm.h>

+#include <trace/events/xtime.h>
+
/*
* NTP timekeeping variables:
*/
@@ -218,6 +220,8 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
break;
}

+ trace_gtod_update_xtime(&xtime, &wall_to_monotonic);
+
write_sequnlock(&xtime_lock);

return res;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index fb0f46f..42b220f 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -20,6 +20,9 @@
#include <linux/tick.h>
#include <linux/stop_machine.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/xtime.h>
+
/* Structure holding internal timekeeping values. */
struct timekeeper {
/* Current clocksource used for timekeeping. */
@@ -338,6 +341,8 @@ int do_settimeofday(struct timespec *tv)

update_vsyscall(&xtime, timekeeper.clock);

+ trace_gtod_update_xtime(&xtime, &wall_to_monotonic);
+
write_sequnlock_irqrestore(&xtime_lock, flags);

/* signal hrtimers about time change */
@@ -811,6 +816,7 @@ void update_wall_time(void)

/* check to see if there is a new clocksource to use */
update_vsyscall(&xtime, timekeeper.clock);
+ trace_gtod_update_xtime(&xtime, &wall_to_monotonic);
}

/**
--
1.5.5.3