One component of tracking perf_clock timestamps to time-of-day is
updates to xtime by a user or ntpd. To that end this patch adds
tracepoints to the timekeeping code as suggested by Thomas:
https://lkml.org/lkml/2011/3/2/186
v2: use timekeeping_get_ns to retrieve nsec component
Signed-off-by: David Ahern <dsah...@gmail.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: John Stultz <johns...@us.ibm.com>
Cc: Steven Rostedt <rost...@goodmis.org>
---
include/trace/events/timekeeping.h | 51 ++++++++++++++++++++++++++++++++++++
kernel/time/timekeeping.c | 11 ++++++++
2 files changed, 62 insertions(+)
create mode 100644 include/trace/events/timekeeping.h
diff --git a/include/trace/events/timekeeping.h
b/include/trace/events/timekeeping.h
new file mode 100644
index 0000000..ff7a631
--- /dev/null
+++ b/include/trace/events/timekeeping.h
@@ -0,0 +1,51 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM timekeeping
+
+#if !defined(_TRACE_TIMEKEEP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_TIMEKEEP_H
+
+#include <linux/tracepoint.h>
+#include <linux/time.h>
+
+DECLARE_EVENT_CLASS(xtime_template,
+
+ TP_PROTO(u64 sec, u64 nsec),
+
+ TP_ARGS(sec, nsec),
+
+ TP_STRUCT__entry(
+ __field( u64, sec)
+ __field( u64, nsec)
+ ),
+
+ TP_fast_assign(
+ __entry->sec = sec;
+ __entry->nsec = nsec;
+ ),
+
+ TP_printk("sec=%Lu nsec=%Lu", __entry->sec, __entry->nsec)
+);
+
+DEFINE_EVENT(xtime_template, do_settimeofday,
+ TP_PROTO(u64 sec, u64 nsec),
+ TP_ARGS(sec, nsec));
+
+DEFINE_EVENT(xtime_template, timekeeping_inject_offset,
+ TP_PROTO(u64 sec, u64 nsec),
+ TP_ARGS(sec, nsec));
+
+DEFINE_EVENT(xtime_template, timekeeping_inject_sleeptime,
+ TP_PROTO(u64 sec, u64 nsec),
+ TP_ARGS(sec, nsec));
+
+DEFINE_EVENT(xtime_template, timekeeping_resume,
+ TP_PROTO(u64 sec, u64 nsec),
+ TP_ARGS(sec, nsec));
+
+DEFINE_EVENT(xtime_template, change_clocksource,
+ TP_PROTO(u64 sec, u64 nsec),
+ TP_ARGS(sec, nsec));
+#endif /* _TRACE_TIMEKEEP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 9a0bc98..0ce45ec 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -23,6 +23,8 @@
#include <linux/stop_machine.h>
#include <linux/pvclock_gtod.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/timekeeping.h>
static struct timekeeper timekeeper;
@@ -462,6 +464,8 @@ int do_settimeofday(const struct timespec *tv)
timekeeping_update(tk, true);
+ trace_do_settimeofday(tk->xtime_sec, timekeeping_get_ns(tk));
+
write_sequnlock_irqrestore(&tk->lock, flags);
/* signal hrtimers about time change */
@@ -504,6 +508,8 @@ int timekeeping_inject_offset(struct timespec *ts)
error: /* even if we error out, we forwarded the time, so call update */
timekeeping_update(tk, true);
+ trace_timekeeping_inject_offset(tk->xtime_sec, timekeeping_get_ns(tk));
+
write_sequnlock_irqrestore(&tk->lock, flags);
/* signal hrtimers about time change */
@@ -536,6 +542,7 @@ static int change_clocksource(void *data)
old->disable(old);
}
timekeeping_update(tk, true);
+ trace_change_clocksource(tk->xtime_sec, timekeeping_get_ns(tk));
write_sequnlock_irqrestore(&tk->lock, flags);
@@ -772,6 +779,9 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
timekeeping_update(tk, true);
+ trace_timekeeping_inject_sleeptime(tk->xtime_sec,
+ timekeeping_get_ns(tk));
+
write_sequnlock_irqrestore(&tk->lock, flags);
/* signal hrtimers about time change */
@@ -807,6 +817,7 @@ static void timekeeping_resume(void)
tk->ntp_error = 0;
timekeeping_suspended = 0;
timekeeping_update(tk, false);
+ trace_timekeeping_resume(tk->xtime_sec, timekeeping_get_ns(tk));
write_sequnlock_irqrestore(&tk->lock, flags);
touch_softlockup_watchdog();
