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* [PATCH v6 1/3] ftrace: add tracepoint for timer
@ 2009-08-10  2:48 Xiao Guangrong
  2009-08-10  2:51 ` [PATCH v6 2/3] ftrace: add tracepoint for hrtimer Xiao Guangrong
                   ` (2 more replies)
  0 siblings, 3 replies; 16+ messages in thread
From: Xiao Guangrong @ 2009-08-10  2:48 UTC (permalink / raw)
  To: Ingo Molnar
  Cc: Thomas Gleixner, Steven Rostedt, Frederic Weisbecker,
	Mathieu Desnoyers, Anton Blanchard, Peter Zijlstra,
	KOSAKI Motohiro, Zhaolei, LKML

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
v4->v5:
Rebase the patch against latest tip tree
v5->v6:
Rename timer_expire(), timer_callback_done() to timer_expire_entry(),
timer_expire_exit() as Ingo's suggestion

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..fcf65c7
--- /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_entry - called immediately before the timer callback
+ * @timer: pointer to struct timer_list
+ *
+ * When used in combination with the timer_expire_exit tracepoint we can
+ * determine the timer latency.
+ **/
+TRACE_EVENT(timer_expire_entry,
+
+	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_expire_exit - called immediately after the timer callback returns
+ * @timer: pointer to struct timer_list
+ *
+ * When used in combination with the timer_expire_entry tracepoint we can
+ * determine the timer latency.
+ **/
+TRACE_EVENT(timer_expire_exit,
+
+	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 33fc9d1..22e2ada 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);
@@ -521,6 +524,25 @@ 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)
@@ -549,7 +571,7 @@ 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);
@@ -568,7 +590,7 @@ 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)
@@ -632,7 +654,7 @@ __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);
 
@@ -787,7 +809,7 @@ 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);
 	if (time_before(timer->expires, base->next_timer) &&
 	    !tbase_get_deferrable(timer->base))
 		base->next_timer = timer->expires;
@@ -1000,7 +1022,9 @@ static inline void __run_timers(struct tvec_base *base)
 				 */
 				lock_map_acquire(&lockdep_map);
 
+				trace_timer_expire_entry(timer);
 				fn(data);
+				trace_timer_expire_exit(timer);
 
 				lock_map_release(&lockdep_map);
 
-- 
1.6.1.2


^ permalink raw reply related	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2009-10-13 18:58 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-08-10  2:48 [PATCH v6 1/3] ftrace: add tracepoint for timer Xiao Guangrong
2009-08-10  2:51 ` [PATCH v6 2/3] ftrace: add tracepoint for hrtimer Xiao Guangrong
2009-09-02 12:18   ` [tip:timers/tracing] hrtimer: Add tracepoint for hrtimers tip-bot for Xiao Guangrong
2009-10-13  3:25     ` Steven Rostedt
2009-10-13  7:08       ` Ingo Molnar
2009-10-13 13:17         ` Steven Rostedt
2009-10-13 13:18           ` Steven Rostedt
2009-10-13 13:26           ` Ingo Molnar
2009-10-13 14:02             ` Steven Rostedt
2009-10-13 15:35               ` [RFC] Trace types registry Mathieu Desnoyers
2009-10-13 18:41               ` [tip:timers/tracing] hrtimer: Add tracepoint for hrtimers Ingo Molnar
2009-10-13 18:56                 ` Steven Rostedt
2009-10-13  7:48       ` Peter Zijlstra
2009-08-10  2:52 ` [PATCH v6 3/3] ftrace: add tracepoint for itimer Xiao Guangrong
2009-09-02 12:18   ` [tip:timers/tracing] itimers: Add tracepoints " tip-bot for Xiao Guangrong
2009-09-02 12:18 ` [tip:timers/tracing] timers: Add tracepoints for timer_list timers tip-bot for Xiao Guangrong

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