[PATCH v4 1/3] ftrace: add tracepoint for timer

[PATCH v4 1/3] ftrace: add tracepoint for timer

[Xiao Guangrong]

This patch is modify from Mathieu's patch base on Ingo's suggestion, the
original patch can be found here:
	http://marc.info/?l=linux-kernel&m=123791201816247&w=2

Great thanks to Thomas for giving me so many valuable advices.

Those tracepoints are wanted and useful:
1: We can detect a timer's delay
2: We can monitor the lifecycle and behaviors of a timer

Thus they help in analysing and debuging.

Example ftrace output:
  insmod-1712  [000]   145.901459: timer_init: timer=d0ace4b4
  insmod-1712  [000]   145.901469: timer_start: timer=d0ace4b4 func=timer_fun expires=4294813629 timeout=199
  <idle>-0     [000]   146.100230: timer_cancel: timer=d0ace4b4
  <idle>-0     [000]   146.100233: timer_expire: timer=d0ace4b4 jiffies=4294813629
  <idle>-0     [000]   146.100627: timer_callback_done: func=d0ace4b4

We expect the timer expires at 4294813629, after 199 jiffies, actually the
timer expires at 4294813629, so it is delayed by 0 jiffies.
We also realize the timer's callback started at 146.100233, and it finished
at 146.100627, so it's taking 146.100627-146.100233=0.4ms.
 
Changelog:
v1->v2:
1: Add jiffies info into timer
2: Combine debugobjects and trace as Thomas's suggestion
v2->v3:
1: Remove function address from timer_expire and timer_cancel
   as Thomas's suggestion
2: Remove debug_and_trace_timer_expire() as Thomas's suggestion
3: Rename trace_timer_entry() and trace_timer_exit() to match this patch
v3->v4:
1: Rename debug_and_trace_*() to debug_*() as Peter Zijlstra's suggestion
2: Integrate Anton Blanchard's patch, which can been found at:
	http://marc.info/?l=linux-kernel&m=124331396919301&w=2

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 include/trace/events/timer.h |  134 ++++++++++++++++++++++++++++++++++++++++++
 kernel/timer.c               |   32 +++++++++-
 2 files changed, 162 insertions(+), 4 deletions(-)
 create mode 100644 include/trace/events/timer.h

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
new file mode 100644
index 0000000..a664afa
--- /dev/null
+++ b/include/trace/events/timer.h
@@ -0,0 +1,134 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM timer
+
+#if !defined(_TRACE_TIMER_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_TIMER_H
+
+#include <linux/tracepoint.h>
+#include <linux/timer.h>
+
+/**
+ * timer_init - called when the timer is initialized
+ * @timer: pointer to struct timer_list
+ **/
+TRACE_EVENT(timer_init,
+
+	TP_PROTO(struct timer_list *timer),
+
+	TP_ARGS(timer),
+
+	TP_STRUCT__entry(
+		__field( void *,	timer	)
+	),
+
+	TP_fast_assign(
+		__entry->timer	= timer;
+	),
+
+	TP_printk("timer=%p", __entry->timer)
+);
+
+/**
+ * timer_start - called when the timer is started
+ * @timer: pointer to struct timer_list
+ * @expires: the timer's expire time
+ **/
+TRACE_EVENT(timer_start,
+
+	TP_PROTO(struct timer_list *timer, unsigned long expires),
+
+	TP_ARGS(timer, expires),
+
+	TP_STRUCT__entry(
+		__field( void *,	timer		)
+		__field( void *,	function	)
+		__field( unsigned long,	expires		)
+		__field( int,		timeout		)
+	),
+
+	TP_fast_assign(
+		__entry->timer		= timer;
+		__entry->function	= timer->function;
+		__entry->expires	= expires;
+		__entry->timeout	= timer->expires - jiffies;
+	),
+
+	TP_printk("timer=%p func=%pf expires=%lu timeout=%d", __entry->timer,
+		  __entry->function, __entry->expires, __entry->timeout)
+);
+
+/**
+ * timer_expire - called immediately before the timer callback
+ * @timer: pointer to struct timer_list
+ *
+ * When used in combination with the timer_callback_done tracepoint we can
+ * determine the timer latency.
+ **/
+TRACE_EVENT(timer_expire,
+
+	TP_PROTO(struct timer_list *timer),
+
+	TP_ARGS(timer),
+
+	TP_STRUCT__entry(
+		__field( void *,	timer	)
+		__field( unsigned long,	jiffies	)
+	),
+
+	TP_fast_assign(
+		__entry->timer		= timer;
+		__entry->jiffies	= jiffies;
+	),
+
+	TP_printk("timer=%p jiffies=%lu", __entry->timer, __entry->jiffies)
+);
+
+/**
+ * timer_callback_done - called immediately after the timer callback returns
+ * @timer: pointer to struct timer_list
+ *
+ * When used in combination with the timer_expire tracepoint we can
+ * determine the timer latency.
+ **/
+TRACE_EVENT(timer_callback_done,
+
+	TP_PROTO(struct timer_list *timer),
+
+	TP_ARGS(timer),
+
+	TP_STRUCT__entry(
+		__field(void *,	timer	)
+	),
+
+	TP_fast_assign(
+		__entry->timer	= timer;
+	),
+
+	TP_printk("func=%p", __entry->timer)
+);
+
+/**
+ * timer_cancel - called when the timer is canceled
+ * @timer: pointer to struct timer_list
+ **/
+TRACE_EVENT(timer_cancel,
+
+	TP_PROTO(struct timer_list *timer),
+
+	TP_ARGS(timer),
+
+	TP_STRUCT__entry(
+		__field( void *,	timer	)
+	),
+
+	TP_fast_assign(
+		__entry->timer	= timer;
+	),
+
+	TP_printk("timer=%p", __entry->timer)
+);
+
+#endif /*  _TRACE_TIMER_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/timer.c b/kernel/timer.c
index a7f07d5..92ff6a7 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -46,6 +46,9 @@
 #include <asm/timex.h>
 #include <asm/io.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/timer.h>
+
 u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
 
 EXPORT_SYMBOL(jiffies_64);
@@ -520,6 +523,25 @@ static inline void debug_timer_activate(struct timer_list *timer) { }
 static inline void debug_timer_deactivate(struct timer_list *timer) { }
 #endif
 
+static inline void debug_init(struct timer_list *timer)
+{
+	debug_timer_init(timer);
+	trace_timer_init(timer);
+}
+
+static inline void
+debug_activate(struct timer_list *timer, unsigned long expires)
+{
+	debug_timer_activate(timer);
+	trace_timer_start(timer, expires);
+}
+
+static inline void debug_deactivate(struct timer_list *timer)
+{
+	debug_timer_deactivate(timer);
+	trace_timer_cancel(timer);
+}
+
 static void __init_timer(struct timer_list *timer,
 			 const char *name,
 			 struct lock_class_key *key)
@@ -548,7 +570,7 @@ void init_timer_key(struct timer_list *timer,
 		    const char *name,
 		    struct lock_class_key *key)
 {
-	debug_timer_init(timer);
+	debug_init(timer);
 	__init_timer(timer, name, key);
 }
 EXPORT_SYMBOL(init_timer_key);
@@ -567,7 +589,7 @@ static inline void detach_timer(struct timer_list *timer,
 {
 	struct list_head *entry = &timer->entry;
 
-	debug_timer_deactivate(timer);
+	debug_deactivate(timer);
 
 	__list_del(entry->prev, entry->next);
 	if (clear_pending)
@@ -628,7 +650,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
 			goto out_unlock;
 	}
 
-	debug_timer_activate(timer);
+	debug_activate(timer, expires);
 
 	new_base = __get_cpu_var(tvec_bases);
 
@@ -780,7 +802,7 @@ void add_timer_on(struct timer_list *timer, int cpu)
 	BUG_ON(timer_pending(timer) || !timer->function);
 	spin_lock_irqsave(&base->lock, flags);
 	timer_set_base(timer, base);
-	debug_timer_activate(timer);
+	debug_activate(timer, timer->expires);
 	internal_add_timer(base, timer);
 	/*
 	 * Check whether the other CPU is idle and needs to be
@@ -984,7 +1006,9 @@ static inline void __run_timers(struct tvec_base *base)
 				 */
 				lock_map_acquire(&lockdep_map);
 
+				trace_timer_expire(timer);
 				fn(data);
+				trace_timer_callback_done(timer);
 
 				lock_map_release(&lockdep_map);
 
-- 
1.6.1.2

[PATCH v4 2/3] ftrace: add tracepoint for hrtimer

[Xiao Guangrong]

Those tracepoints are wanted and useful:
1: We can detect a hrtimer's delay
2: We can monitor the lifecycle and behaviors of a hrtimer

Thus they help in analysing and debuging.

Great thanks to Thomas for giving me so many valuable advices.

Example ftrace output:
  insmod-1824  [001]   606.749538: hrtimer_init: timer=d0ae04c0 clockid=CLOCK_REALTIME mode=HRTIMER_MODE_ABS
  insmod-1824  [001]   606.749614: hrtimer_start: timer=d0ae04c0 func=hrtimer_fun expires=1246707447252299435ns softexpires=1246707447252299435ns
  <idle>-0     [001]   606.754372: hrtimer_cancel: timer=d0ae04c0
  <idle>-0     [001]   606.754374: hrtimer_expire: timer=d0ae04c0 now=1246707447257141331ns
  <idle>-0     [001]   606.754430: hrtimer_callback_done: timer=d0ae04c0
 
We expect the hrtimer expires at 1246707447252299435ns, actually the
hrtimer expires at 1246707447257141331ns, so it is delayed by
1246707447257141331-1246707447252299435=4841896ns.
We also realize the hrtimer's callback started at 606.754374, and it
finished at 606.754430, so it's taking 606.754430-606.754374=0.05ms.

Changelog:
v1->v2:
1: Remove ktime_to_ns() in TP_fast_assign()
2: Combine debugobjects and trace as Thomas's suggestion
v2->v3:
1: Remove function address from hrtimer_expire and hrtimer_cancel
   as Thomas's suggestion
2: Remove debug_and_trace_hrtimer_expire() as Thomas's suggestion
3: Rename trace_hrtimer_entry() and trace_hrtimer_exit() to match this patch
v3->v4:
1: Rename debug_and_trace_*() to debug_*() as Peter Zijlstra's suggestion
2: Move trace_hrtimer_expire() to __run_hrtimer() in order to calculate
   exacts timer latency as Peter Zijlstra's suggestion
3: Integrate Anton Blanchard's patch, which can been found at:
	http://marc.info/?l=linux-kernel&m=124331396919301&w=2

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 include/trace/events/timer.h |  133 ++++++++++++++++++++++++++++++++++++++++++
 kernel/hrtimer.c             |   34 +++++++++--
 2 files changed, 162 insertions(+), 5 deletions(-)

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index a664afa..dd2f133 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -128,6 +128,139 @@ TRACE_EVENT(timer_cancel,
 	TP_printk("timer=%p", __entry->timer)
 );
 
+/**
+ * hrtimer_init - called when the hrtimer is initialized
+ * @timer: pointer to struct hrtimer
+ * @clockid: the hrtimer's clock
+ * @mode: the hrtimer's mode
+ **/
+TRACE_EVENT(hrtimer_init,
+
+	TP_PROTO(struct hrtimer *timer, clockid_t clockid, enum hrtimer_mode mode),
+
+	TP_ARGS(timer, clockid, mode),
+
+	TP_STRUCT__entry(
+		__field( void *,		timer		)
+		__field( clockid_t,		clockid		)
+		__field( enum hrtimer_mode,	mode		)
+	),
+
+	TP_fast_assign(
+		__entry->timer		= timer;
+		__entry->clockid	= clockid;
+		__entry->mode		= mode;
+	),
+
+	TP_printk("timer=%p clockid=%s mode=%s", __entry->timer,
+		  __entry->clockid == CLOCK_REALTIME ?
+			"CLOCK_REALTIME" : "CLOCK_MONOTONIC",
+		  __entry->mode == HRTIMER_MODE_ABS ?
+			"HRTIMER_MODE_ABS" : "HRTIMER_MODE_REL")
+);
+
+/**
+ * hrtimer_start - called when the hrtimer is started
+ * @timer: pointer to struct hrtimer
+ **/
+TRACE_EVENT(hrtimer_start,
+
+	TP_PROTO(struct hrtimer *timer),
+
+	TP_ARGS(timer),
+
+	TP_STRUCT__entry(
+		__field( void *,	timer		)
+		__field( void *,	function	)
+		__field( s64,		expires		)
+		__field( s64,		softexpires	)
+	),
+
+	TP_fast_assign(
+		__entry->timer		= timer;
+		__entry->function	= timer->function;
+		__entry->expires	= hrtimer_get_expires(timer).tv64;
+		__entry->softexpires	= hrtimer_get_softexpires(timer).tv64;
+	),
+
+	TP_printk("timer=%p func=%pf expires=%lluns softexpires=%lluns",
+		  __entry->timer, __entry->function,
+		 (unsigned long long)__entry->expires,
+		 (unsigned long long)__entry->softexpires)
+);
+
+/**
+ * htimmer_expire - called immediately before the hrtimer callback
+ * @timer: pointer to struct hrtimer
+ *
+ * When used in combination with the hrtimer_callback_done tracepoint we can
+ * determine the high res timer latency.
+ **/
+TRACE_EVENT(hrtimer_expire,
+
+	TP_PROTO(struct hrtimer *timer),
+
+	TP_ARGS(timer),
+
+	TP_STRUCT__entry(
+		__field( void *,	timer	)
+		__field( s64,		now	)
+	),
+
+	TP_fast_assign(
+		__entry->timer	= timer;
+		__entry->now	= timer->base->get_time().tv64;
+	),
+
+	TP_printk("timer=%p now=%lluns", __entry->timer,
+		 (unsigned long long)__entry->now)
+ );
+
+ /**
+  * hrtimer_callback_done - called immediately after the hrtimer callback returns
+  * @timer: pointer to struct hrtimer
+  *
+  * When used in combination with the hrtimer_expire tracepoint we can
+  * determine the high res timer latency.
+  **/
+TRACE_EVENT(hrtimer_callback_done,
+
+	TP_PROTO(struct hrtimer *timer),
+
+	TP_ARGS(timer),
+
+	TP_STRUCT__entry(
+		__field( void *,	timer	)
+	),
+
+	TP_fast_assign(
+		__entry->timer	= timer;
+	),
+
+	TP_printk("timer=%p", __entry->timer)
+);
+
+/**
+ * hrtimer_cancel - called when the hrtimer is canceled
+ * @timer: pointer to struct hrtimer
+ **/
+TRACE_EVENT(hrtimer_cancel,
+
+	TP_PROTO(struct hrtimer *timer),
+
+	TP_ARGS(timer),
+
+	TP_STRUCT__entry(
+		__field( void *,	timer	)
+	),
+
+	TP_fast_assign(
+		__entry->timer	= timer;
+	),
+
+	TP_printk("timer=%p", __entry->timer)
+);
+
 #endif /*  _TRACE_TIMER_H */
 
 /* This part must be outside protection */
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index e2f91ec..f05c7a1 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -48,6 +48,8 @@
 
 #include <asm/uaccess.h>
 
+#include <trace/events/timer.h>
+
 /*
  * The timer bases:
  *
@@ -441,6 +443,26 @@ static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
 #endif
 
+static inline void
+debug_init(struct hrtimer *timer, clockid_t clockid,
+	   enum hrtimer_mode mode)
+{
+	debug_hrtimer_init(timer);
+	trace_hrtimer_init(timer, clockid, mode);
+}
+
+static inline void debug_activate(struct hrtimer *timer)
+{
+	debug_hrtimer_activate(timer);
+	trace_hrtimer_start(timer);
+}
+
+static inline void debug_deactivate(struct hrtimer *timer)
+{
+	debug_hrtimer_deactivate(timer);
+	trace_hrtimer_cancel(timer);
+}
+
 /* High resolution timer related functions */
 #ifdef CONFIG_HIGH_RES_TIMERS
 
@@ -797,7 +819,7 @@ static int enqueue_hrtimer(struct hrtimer *timer,
 	struct hrtimer *entry;
 	int leftmost = 1;
 
-	debug_hrtimer_activate(timer);
+	debug_activate(timer);
 
 	/*
 	 * Find the right place in the rbtree:
@@ -883,7 +905,7 @@ remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
 		 * reprogramming happens in the interrupt handler. This is a
 		 * rare case and less expensive than a smp call.
 		 */
-		debug_hrtimer_deactivate(timer);
+		debug_deactivate(timer);
 		timer_stats_hrtimer_clear_start_info(timer);
 		reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
 		__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE,
@@ -1116,7 +1138,7 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 		  enum hrtimer_mode mode)
 {
-	debug_hrtimer_init(timer);
+	debug_init(timer, clock_id, mode);
 	__hrtimer_init(timer, clock_id, mode);
 }
 EXPORT_SYMBOL_GPL(hrtimer_init);
@@ -1149,7 +1171,7 @@ static void __run_hrtimer(struct hrtimer *timer)
 
 	WARN_ON(!irqs_disabled());
 
-	debug_hrtimer_deactivate(timer);
+	debug_deactivate(timer);
 	__remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
 	timer_stats_account_hrtimer(timer);
 	fn = timer->function;
@@ -1160,7 +1182,9 @@ static void __run_hrtimer(struct hrtimer *timer)
 	 * the timer base.
 	 */
 	spin_unlock(&cpu_base->lock);
+	trace_hrtimer_expire(timer);
 	restart = fn(timer);
+	trace_hrtimer_callback_done(timer);
 	spin_lock(&cpu_base->lock);
 
 	/*
@@ -1569,7 +1593,7 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
 	while ((node = rb_first(&old_base->active))) {
 		timer = rb_entry(node, struct hrtimer, node);
 		BUG_ON(hrtimer_callback_running(timer));
-		debug_hrtimer_deactivate(timer);
+		debug_deactivate(timer);
 
 		/*
 		 * Mark it as STATE_MIGRATE not INACTIVE otherwise the
-- 
1.6.1.2

[PATCH v4 3/3] ftrace: add tracepoint for itimer

[Xiao Guangrong]

Those tracepoints are wanted and useful:
1: We can detect a itimer's delay
2: We can monitor the lifecycle and behaviors of a itimer

Thus they help in analysing and debuging.

Great thanks to Thomas for giving me so many valuable advices.

There have two case: 
case 1, if we use ITIMER_REAL itimer:
Example ftrace output:
  main-1849  [001]   889.355307: hrtimer_start: timer=cf59fc44 func=it_real_fn expires=891440459185ns softexpires=891440459185ns
  main-1849  [001]   889.355312: itimer_state: which=0 expires=0 it_value=0.500 it_interval=0.0
  main-1849  [001]   889.358327: hrtimer_cancel: timer=cf59fc44
  main-1849  [001]   889.358327: hrtimer_expire: timer=cf59fc44 now=891442992881ns
  main-1849  [001]   889.358400: itimer_expire: pid=1849 which=0 now=0
  main-1849  [001]   889.358473: hrtimer_callback_done: timer=cf59fc44
  main-1849  [001]   889.358792: itimer_state: which=0 expires=0 it_value=0.0 it_interval=0.0
ITIMER_REAL itime use hrtimer to calculate time, so we can cooperate with
hrtimer's tracepoint to get it's delay.

from this output information, the process set up a ITIMER_REAL
iteimr(which=0), use a hrtime which address is cf59fc44 , we can get the
delay is 891442992881-891440459185=2533696ns

case 2, if we use ITIMER_VIRTUAL/ITIMER_PROF itimer:
Example ftrace output:
  main-5409  [001] 12763.874835: itimer_state: which=1 expires=2 it_value=0.500 it_interval=0.500
  main-5409  [001] 12763.883495: itimer_expire: pid=5409 which=1 now=2
  main-5409  [001] 12763.883712: itimer_state: which=1 expires=0 it_value=0.0 it_interval=0.0
  
from this, we can know the itimer delay is 2-2=0 jiffies.

Changelog:
v1->v2:
Remove ktime_to_ns() in TP_fast_assign()
v2->v3:
Below changes are all base on Thomas's suggestion:
1: Remove ITIMER_REAL's timer address and 'state' from trace_itimer_state()
2: Don't save task's name in trace_itimer_state()
3: Save task's pid instead of task's name in trace_itimer_expire()

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
 include/trace/events/timer.h |   52 ++++++++++++++++++++++++++++++++++++++++++
 kernel/itimer.c              |    5 +++-
 kernel/posix-cpu-timers.c    |    3 ++
 3 files changed, 59 insertions(+), 1 deletions(-)

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index dd2f133..8649a67 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -261,6 +261,58 @@ TRACE_EVENT(hrtimer_cancel,
 	TP_printk("timer=%p", __entry->timer)
 );
 
+TRACE_EVENT(itimer_state,
+
+	TP_PROTO(int which, struct itimerval *value, cputime_t expires),
+
+	TP_ARGS(which, value, expires),
+
+	TP_STRUCT__entry(
+		__field(	int,		which		)
+		__field(	cputime_t,	expires		)
+		__field(	long,		value_sec	)
+		__field(	long,		value_usec	)
+		__field(	long,		interval_sec	)
+		__field(	long,		interval_usec	)
+	),
+
+	TP_fast_assign(
+		__entry->which		= which;
+		__entry->expires	= expires;
+		__entry->value_sec	= value->it_value.tv_sec;
+		__entry->value_usec	= value->it_value.tv_usec;
+		__entry->interval_sec	= value->it_interval.tv_sec;
+		__entry->interval_usec	= value->it_interval.tv_usec;
+	),
+
+	TP_printk("which=%d expires=%lu it_value=%lu.%lu it_interval=%lu.%lu",
+		  __entry->which, __entry->expires,
+		  __entry->value_sec, __entry->value_usec,
+		  __entry->interval_sec, __entry->interval_usec)
+);
+
+TRACE_EVENT(itimer_expire,
+
+	TP_PROTO(int which, struct pid *pid, cputime_t now),
+
+	TP_ARGS(which, pid, now),
+
+	TP_STRUCT__entry(
+		__field( int ,		which	)
+		__field( int,		pid	)
+		__field( cputime_t,	now	)
+	),
+
+	TP_fast_assign(
+		__entry->which	= which;
+		__entry->now	= now;
+		__entry->pid	= pid_vnr(pid);
+	),
+
+	TP_printk("pid=%d which=%d now=%lu", __entry->pid, __entry->which,
+		  __entry->now)
+);
+
 #endif /*  _TRACE_TIMER_H */
 
 /* This part must be outside protection */
diff --git a/kernel/itimer.c b/kernel/itimer.c
index 58762f7..7e9ee89 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -12,6 +12,7 @@
 #include <linux/time.h>
 #include <linux/posix-timers.h>
 #include <linux/hrtimer.h>
+#include <trace/events/timer.h>
 
 #include <asm/uaccess.h>
 
@@ -123,6 +124,7 @@ enum hrtimer_restart it_real_fn(struct hrtimer *timer)
 	struct signal_struct *sig =
 		container_of(timer, struct signal_struct, real_timer);
 
+	trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
 	kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
 
 	return HRTIMER_NORESTART;
@@ -139,7 +141,7 @@ int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
 	struct task_struct *tsk = current;
 	struct hrtimer *timer;
 	ktime_t expires;
-	cputime_t cval, cinterval, nval, ninterval;
+	cputime_t cval, cinterval, nval = 0, ninterval;
 
 	/*
 	 * Validate the timevals in value.
@@ -220,6 +222,7 @@ again:
 	default:
 		return -EINVAL;
 	}
+	trace_itimer_state(which, value, nval);
 	return 0;
 }
 
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index bece7c0..63e93bf 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -8,6 +8,7 @@
 #include <linux/math64.h>
 #include <asm/uaccess.h>
 #include <linux/kernel_stat.h>
+#include <trace/events/timer.h>
 
 /*
  * Called after updating RLIMIT_CPU to set timer expiration if necessary.
@@ -1160,6 +1161,7 @@ static void check_process_timers(struct task_struct *tsk,
 				sig->it_prof_expires = cputime_add(
 					sig->it_prof_expires, ptime);
 			}
+			trace_itimer_expire(ITIMER_PROF, sig->leader_pid, ptime);
 			__group_send_sig_info(SIGPROF, SEND_SIG_PRIV, tsk);
 		}
 		if (!cputime_eq(sig->it_prof_expires, cputime_zero) &&
@@ -1176,6 +1178,7 @@ static void check_process_timers(struct task_struct *tsk,
 				sig->it_virt_expires = cputime_add(
 					sig->it_virt_expires, utime);
 			}
+			trace_itimer_expire(ITIMER_VIRTUAL, sig->leader_pid, utime);
 			__group_send_sig_info(SIGVTALRM, SEND_SIG_PRIV, tsk);
 		}
 		if (!cputime_eq(sig->it_virt_expires, cputime_zero) &&
-- 
1.6.1.2