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Date: Mon, 10 Aug 2009 10:48:59 +0800
From: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To: Ingo Molnar <mingo@...e.hu>
CC: Thomas Gleixner <tglx@...utronix.de>,
Steven Rostedt <rostedt@...dmis.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
Anton Blanchard <anton@...ba.org>,
Peter Zijlstra <peterz@...radead.org>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Zhaolei <zhaolei@...fujitsu.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v6 1/3] ftrace: add tracepoint for timer
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@...ba.org>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Signed-off-by: Xiao Guangrong <xiaoguangrong@...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
--
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