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Date: Thu, 06 Aug 2009 10:36:18 +0800
From: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
CC: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
Zhaolei <zhaolei@...fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Anton Blanchard <anton@...ba.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v5 2/3] ftrace: add tracepoint for hrtimer
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
v4->v5:
Rebase the patch against latest tip tree
Signed-off-by: Anton Blanchard <anton@...ba.org>
Signed-off-by: Xiao Guangrong <xiaoguangrong@...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
--
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